School Science Lessons
(Foodgardens2)
2024-10-28
Crop care
Please send comments to: j.elfick@uq.edu.au
Contents
Preface
9.1.0 Crop care
9.2.0 Planting
9.3.0 Seeds
9.4.0 Vegetative reproduction
9.1.0 Crop care
9.1.1 Fertilizing
9.1.2 Harvesting sweet potato
9.1.3 Hoeing
9.1.4 Mulching
9.1.5 Plant protection
9.1.10 Protect indoor plants over summer
9.1.6 Staking
9.1.7 Thinning and pruning
9.1.8 Watering and drainage
9.1.9 Weeding
9.2.0 Planting
9.2.1 Soil preparation
9.2.2 Companion planting
9.2.3 Interplanting
9.2.4 Pot plants
9.2.5 Potting mix
The four methods of planting:
9.2.6 Planting seeds
9.2.7 Direct planting of seeds and cuttings
9.2.8 Planting in a seedbed
9.2.9 Planting in a seed box
9.2.10 Planting in a plant nursery
9.2.11 Transplanting
9.4.2 Planting material
9.3.0 Seeds
See: Seeds (Commercial)
9.3.1 Seed packet labels
9.3.2 Depth of sowing
9.3.3 Growing your own seed
9.3.4 Packet seeds, Advantages and Disadvantages
9.3.5 Seed germination
9.3.6 Seed sterilization
9.4.0 Vegetative reproduction
9.4.1Vegetative reproduction
9.4.2 Planting material
9.4.3 Bulbs
9.4.4 Corms
9.4.5 Cuttings
9.4.6 Division, vegetative propagation
9.6.0 Grafting
9.4.8 Rhizomes
9.4.9 Stooling
9.4.10 Layering
9.4.11 Marcotting, air layering
9.4.12 Offsets
9.4.13 Plantlets
9.4.14 Runners, stolons
9.4.15 Suckers, root sprouts
9.4.16 Tissue culture
9.4.17 Tubers
Biology
9.1.1.0 Bulb, onion, Narcissus, Oxalis
9.1.2.0 Corm, gladiolus, crocus, taro
9.1.3.0 Lignotuber, Banksia, Eucalyptus
9.1.4.0 Rhizome, ginger, iris, banana
5.5 Banana rhizome
9.1.5.0 Runners, strawberry
9.1.6.0 Potato stem tuber
9.1.8.0 Tuberous roots, root tuber, sweet potato
9.4.5 Cuttings
9.5.1 Cuttings
9.5.2 Rooting powders for stem cuttings
9.5.3 Leaf cuttings
9.5.4 Root cuttings
9.5.5 Stem cuttings, top cuttings
9.6.0 Grafting
9.6.1 Grafting
9.6.2 Bud grafting
9.6.3 Whip and tongue grafting
9.1.1 Fertilizing
Plant fertilizers
1. Fertilizers
Standard fertilisers contain about 10% Nitrogen, 4% Phosphorous and 6 to7% Potassium.
Most Australian soils are deficient in the micronutrients, trace elements, iodine, selenium and boron.
Foliar fertilizers are a solution containing water-soluble fertilizer that is sprayed on the foliage of a plant.
Organic fertilizers come from a source that is or has once been alive, so they are never artificial synthetic fertilizers.
Top dressing is an application of manure or fertilizer to the surface layer of soil.
Slow-release fertilizers release their nutrients gradually and evenly over a period of time.
Side dressing is an application of manure or fertilizer to a growing crop, e.g. nitrogen fertilizer for tomato and hibiscus cabbage.
Dig a shallow ditch with the hand or hoc around each plant, put the fertilizer in, and cover it with soil.
2. Soil pH
Acid soils have pH readings less than about pH 6.5.
Alkaline soils have pH readings above pH 7.4, and are preferred by cabbages and onions.
Australian soils are generally slightly to moderately acidic.
Nutrients are available for plant use at around pH 6.5 to 6.7.
To "sweeten" the soil, (or smelly compost heap), means adding lime to make it more alkaline.
6. Blossom end rot
It occurs where calcium is deficient in soil when the fruit darkens and rots at the blossom end of tomato, eggplant and capsicum fruit.
The condition worsens in conditions of extreme heat, inconsistent watering and root damage.
9.1.2 Harvesting sweet potato
Harvesting must be done regularly and just before the crop is needed in the kitchen.
Sweet potato can be stored for a few weeks if it is:
* not damaged when dug up,
* kept in a moist atmosphere for a few days to toughen the skin,
* stored in a cool place.
After harvest work, clear out all the crop plants and weeds left behind and put them on the compost heap.
Then dig in rotten compost or manure for the next crop.
You may plant a legume cover crop if the garden will not be planted for some time, e.g. sunn hemp, butterfly pea, kudzu, cowpea.
This will protect the soil from erosion, control weeds, and put some nitrogen plant nutrient in the soil.
9.1.3 Hoeing
Hoeing is used to control young weeds and let air into the soil.
Hoeing up or hilling-up means to use the hoe to pull up soil around the plant stems and cover the roots well.
It is used for plants, e.g. maize, which have shallow roots and for sweet potato to cover exposed tubers and protect from weevils.
The hoe should never be used so deeply as to damage the plant roots.
9.1.4 Mulching
See diagram 55.17: Mulch
See diagram 51.9: Mulch for planting bananas
See diagram 52.11: Mulch for planting coconuts
Organic mulches come from plant material, e.g. wood chips, leaf material.
Mineral mulches come from rocks, e.g. sand, granite rocks, gravel
Mulches suppress weed growth with the added advantage that organic mulches break down to add organic matter to the soil.
They prevent moisture loss and regulate the temperature of the soil.
However, mulches can make it hard for water to penetrate, especially if spread too thickly.
Mulch is surface layer spread over the ground to conserve moisture and suppress weeds.
Mulch may consist of lucerne, sugarcane residue, straw, rice hulls, peanut shells, bark.
1.0 The word "mulch" comes from "mulsh" meaning "soft".
Garden mulch is a cover of dead plants, a 10-15 cm thick layer of leaves, chopped grass, husks, weeds and other plants that act as a blanket layer over
garden soil.
The best mulch has particles larger than 5 mm to allow any rain to filter through.
Finer particles capture and hold rain water and may prevent the water reaching the soil and plant roots.
During dry periods fine textured mulch absorbs water that may later be lost by evaporation and not passed on to the plants, so use broad-textured mulch that
allows water to percolate down to the plants.
The finer the mulch, the shallower the mulch layer.
All garden soil should be completely covered with mulch, leaving no bare patches on the soil.
Note any weeds on the bare soil and under the mulch.
Measure the temperature of the bare soil and the soil under the mulch.
Mulch should not touch the stems of plants, because it may contain pests and diseases, e.g. collar rot.
Black plastic is sometimes used as mulch when vegetation is not available.
In the spring, add mulch and use an organic soil conditioner to improve the water holding capacity of the soil.
Apply a wetting agent after mulching to prevent waste of water.
Mulch is not mixed into the soil, but it enters the soil as it rots down slowly into the soil to improve the soil structure.
As the mulch slowly rots into the soil, new plant material should be added on top of the mulch.
2.0 Advantages of mulching garden beds:
* controls of weeds by shading them from sunlight,
* stops rainfall from washing away the soil,
* conserves water that the plant can use in the dry season,
* lessens evaporation from the soil,
* improves the soil structure, as mulch rots slowly into the soil,
* acts as a slow release fertilizer as it adds nutrients to the soil,
* provides a home for plant friendly insects.
* insulates soil from sunlight and the radiant heat from the sun,
* protects the soil from compacting and the splash erosion from heavy rain drops,
* stops rainfall from washing away the soil,
* stabilizes soil pH,
* increases beneficial soil organisms.
3. Disadvantages of mulching garden beds
* Insect pests and disease may live in infected plants used for mulch, so always ask a field officer from the Department of Agriculture whether it is safe to use
mulch with food crops.
* More work is needed to collect, cut and put plant material on the soil.
* The work is often not done properly, leaving bare patches.
* Dry grass mulch or dry compost that is not rotten may take nitrogen plant nutrients out of the soil, called "nitrogen draw down".
3.0 Mulching experiment
3.1 Use a sloping garden bed.
Cover half with mulch and leave the other half not covered.
After about one month note the following differences:
3.2 Feel the bare soil and the soil under the mulch.
What differences do you see and feel?
3.3 All your garden beds should be mulched, completely covered to a depth of five cm.
This mulch will gradually rot down into the soil so each month new mulch should be added.
The best mulch is chopped grass, however some people should banana leaves and even black plastic.
Because of the danger from pests and diseases living in the mulch do not let the mulch touch the stems of the plants.
9.1.5 Plant protection
1. Plant protection is control of plant pests and plant diseases and should follow practices of the national policy of Integrated Pest Management (IPM).
Use regular pruning to remove diseased, damaged or dead plant material.
2. Remove any diseased plant material from garden beds to minimise spread of the disease.
3. A low level of pests are part of a healthy garden so do not try to eliminate all pests in the garden.
4. Bio-control sprays and insecticides used outdoors may include petroleum oil based sprays on scale insects, Bacillus thuringensis spray on caterpillars,
Confidor ® (imidacloprid) on thrips and azalea lace bug.
5. In plant nurseries, Cryptolaemus ladybirds may be used to control aphids, scale and other sucking insects or use petroleum oil based sprays or pyrethrum, if infections become severe.
Plant disease control relies on good crop hygiene and sanitation using detergent and bleach to control fungal diseases, e.g. Powdery Mildew.
6. Plant protection refers to controlling pests and disease by:
* picking out by hand diseased plants or insect pests,
* spraying with pesticides or fungicides,
* burning diseased plants or parts of plants,
* pulling out all plants left over from the previous crop and other weeds.
This work is called garden hygiene.
9.1.6 Staking
See diagram 63.9: Yam staking
Staking means giving support, using sticks or wires, to vegetables, e.g. tomato, winged bean, eggplant and choko.
Climbing plants save space in the kitchen garden.
Espalier is a method of training a tree to grow many horizontal side branches against a wall, used for pear and apple trees.
9.1.7 Thinning and pruning
1. Thinning is the removal of some plants in the crop or parts of plants to give more room for growth.
Plants with tiny seeds, which cannot be transplanted, can be sown along a shallow drill.
Later, weaker seedlings can be pulled out, leaving the stronger seedlings at the recommended spacing.
Another method of thinning is to plant a group of seeds in shallow holes at the correct distance, and when the plants are three cm high, destroy all plants except the biggest ones.
Thinning of trees is the removal of small diameter branches growing close to nearby branches at the edge of the canopy to improve light penetration.
2. Pruning is to remove diseased, damaged or dead material on plants for the maintenance of hygiene and to prevent fungal disease.
Also pruning is used to reshape or remove any plants that pose a potential safety risk.
Material created by pruning can be chipped to create mulch.
9.1.8 Watering and drainage
1. Plants need water for life and growth.
If there is not enough water in the soil, plants will wilt then die.
If there is too much water in the soil, there is not enough air for the plant roots to breathe and then the plant will die.
In good soil, a loam, the water will drain down leaving enough water and air in the soil for the plant.
The soil around plant roots should always be damp, but not wet.
Test this with your finger.
2. Sandy soils drain too quickly.
In dry weather sandy soil in raised beds must be watered every day.
Sandy soils should be watered more often than clay soils.
Clay soils drain too slowly and need watering only once each week.
3. Plants should be watered in the late afternoon with a fine spray so as not to wash away the soil.
Water during the afternoon or evenings and keep the leaves dry.
However, some gardeners in tropical regions do their watering only in the early mornings to keep plant foliage dry and be less easily infected by viruses andbacteria.
4. If you water every day, the plant will only grow shallow roots.
Soak the soil thoroughly every few days to make the plant grow deep roots.
Deep-rooted plants like tomato, pumpkins and sweet potatoes should be watered every 2 weeks.
5. Do not wet the plants, because this helps plant disease, so only water the ground.
If you cover soil with mulch made of chopped grass and leaves, the soil will not lose much water.
6. Before starting a garden you should test the drainage.
After rain or a heavy watering, dig holes 50 cm deep.
If water remains in the holes for a day make their garden somewhere else or dig drains.
7. The best drains are trenches 50 cm deep filled with large rough stones to a depth of 20 cm, then covered with small stones, then topsoil.
Raised beds, ridges and hills or mounds provide drainage.
8. After heavy watering, dig holes 50 cm deep to see if the soil is well-drained.
9. Watering on a hot day at noon does not damage the plants by scorching the leaves, because the water evaporates.
However, some water is wasted by the evaporation.
10. The best time for watering is late in the afternoon to allow time for the water to soak deep into the soil where it can be taken up by the roots.
9.1.9 Weeding
Weeds are plants that lower the yield of garden plants.
A weed is a plant in the wrong place.
1. Weed control methods
* Use mulch to smother the weeds.
* Use manual removal of weeds – by hand, gardening fork, hoe.
* Add a non-toxic red dye to weedicide to give a visual aid to show what has been sprayed.
2. Safety precautions when spraying
* Wear protective clothing and masks.
* Do not spray when windy, or near other people, not on near the ponds.
* Aim spray directly at the weeds, not at anything else.
* Remember that it is impossible to remove all the weeds.
For weed control in an enclosed nursery use manual weeding, boiling water and white vinegar.
3. Weeds harm crops by:
* taking in water from the soil, then the garden plants do not have enough water,
* taking plant nutrients from the soil, then the garden plants do not have enough nutrients,
* shading the young crop plants then the garden plants do not have enough sunlight for photosynthesis,
* having pests and diseases on them, which can later infect the garden plants, mixing with the crop, and
* making it hard to harvest, e.g. sensitive plant growing among sweet potato.
4. The three types of weeds:
* Very strong plants that are no use to us, e.g. lantana, common guava,
* Plants that are weeds only when they grow in crops, but they may also be used by themselves.
For example, purslane is a common garden weed, but it can be eaten as a green vegetable.
* Plants from old crops are weeds, because they may have pests and diseases on them.
For exmple, old maize (corn) plants left over from a previous crop may carry disease.
5. Weeds can be controlled by:
* pulling out by hand, ring weeding around trees in tree crops,
* hoeing,
* cutting down with a bush knife,
* shading by leaves of plants close enough so that their leaves will shade the ground, e.g. sweet potato (kumara) or cover crops
* spraying with chemicals called herbicides or weedicides.
6. Herbicides are dangerous, expensive and hard to use properly.
See 4.4 Herbicides, weedicides.
9.1.10 Protect indoor plants over summer
Protect indoor plants by keeping them out of direct sunlight by keeping them in the shade.
Move plants away from harsh afternoon sun during summer, even if the plants do best in a north-facing window most of the year, or move them to a south-facing window.
Keep plants alive when you are away from home by using an empty bathtub.
For temperatures above 38 degrees Celsius, move the plants to a cool, dark area, e.g. the bathroom, and spray the plants in the bath each morning.
Misting your plants leaves can help keep them cool.
Airflow and air conditioners can affect overheated plants.
Air conditioners reduce the humidity in the air and many indoor plants were rainforest plants, so they need humidity in the warmer months.
Do not allow cold air from the air conditioner to blow directly on the plants.
On hot days, improve airflow with a ceiling fan.
Fertilise plants before summer, not when the hot weather sets in, because fertilisers can stress plants.
Pesticide oils can burn the plants, so apply them only at night to give the plant time to absorb it, then keep the plant in a shady area until no oil residue is left on the plant.
Growing plants against key windows and walls can help block heat and act as a kind of living air conditioner.
9.2.1 Soil preparation
Digging the ground before planting allows seeds to germinate easily and quickly, allows roots to penetrate the soil easily, improves the plant nutrients in the soil, and helps to control weeds and insect pests.
Good preparation of ground does need hard work, but later the crops will grow better and less work will be needed to look after them.
If beds and ridges run North-South, then all the plants in one row get the same amount of light.
Their shadows fall on the inter-row area and not on each other.
Tamping is firming the soil around a plant after planting, so that the soil supports the plant and the roots have close contact with the soil.
1.0 The need for good preparation of ground:
* to loosen the soil so roots can grow easily,
* to make a fine even seedbed so seeds will germinate easily and quickly,
* to control weeds and insect pests by digging them up,
* to improve the soil by mixing in dead plants and compost.
* to form the soil into raised beds or ridges so it is ready for planting.
2.0 The steps in preparing the ground are:
2.1 turn the ground over to a depth of 15-20 cm.
Work backwards using spades for turning and hoes for breaking up clods of earth.
Dig out a trench and put the soil near.
2.2 Turn the soil one into the trench, then turn 2, 3, 4, five and put the trench soil into 6.
2.3 Dig in compost or other fertilizers.
2.4 Use rakes and hoes to make the soil fine and flat.
3.0 Give each student a small part of the ground to dig up and keep clear of weeds until sowing.
9.2.2 Companion planting
1. Companion planting plants are planted together, because this may improve pest control, nutrient uptake and pollination.
Another advantage of interplanting is that some plants have "plant friends", which can protect the plants from pests and help them to grow better.
Marigolds in a border around a garden bed can protect plants of the tomato family from nematode worms and can keep beetles away from beans.
Velvet bean can protect tomato from nematode worms.
2. Examples of plants and their friends:
* Bean, Friends: maize, cabbage, cucumber, lettuce
* Eggplant (aubergine), Friend: bean
* Pumpkin, Friends, maize, sweet potato
* Taro, Friend: spring onion
9.2.3 Interplanting
1. Interplanting, intercropping, is when plants are grown together to increase the productivity of land or to extend cropping season, e.g. grow rows of beans between rows of maize.
Interplanting is used when you grow different kinds of plants in different rows in the same garden.
Interplanting allows more food grown without increasing the size of the garden.
Grow small plants with short growing periods, e.g. radish, okra, lettuce, dwarf bean and spinach, between rows of large plants with longer growing periods, e.g. tomato, cabbage, capsicum and eggplant.
Many food crops, e.g. peanut, maize, pineapples, banana and ginger, can be grown between coconuts and papaya or banana can be interplanted with pineapple.
Grow plants as close together as possible without the plants becoming stunted.
Always to have a mixture of plants in the garden.
If you plant maize on ridges in the fields, also plant bean between the ridges.
Try some trials comparing single crops with interplanted crops, e.g. Bed 1. sweet potato, Bed 2. maize, Bed 3. sweet potato interplanted with maize.
2. Examples of interplanting:
Row 1: maize, mung bean, lettuce, cucumber
Row 2: Chinese cabbage, tomato, tomato, maize
Row 3: radish, spring onion, lettuce, cucumber
Row 4: lettuce, tomato, tomato, maize
Row 5: radish, mung bean, lettuce, cucumber.
Advantages of interplanting:
* can grow more food in the garden,
* plants called "companion plants" can help others by protecting them against pests and disease,
* pests and disease cannot move between the same kinds of plants,
* weeds are controlled by shading.
9.2.4 Pot plants
Planting in a container should be the ideal way to create optimum conditions for plant growth.
However, some plants have very specific requirements and some plants should never be grown in pots.
For example citrus grows well in pots, but a tuberous begonia does not.
Before using pots, check which plants that grow well in pots in your area.
Overwatering is a common cause of pot plant death, especially kitchen herbs, so group pot plants together according to their watering needs.
To check whether wate is needed in the pot, push the pointing finger down in the pot soil to the second joint.
Add water only if the tip of the inserted finger feels dry.
A drip irrigation system makes watering easier.
Pots made of terracotta or stone make take water away from plants, so use a coat of sealant to make them less porous.
Maintain constant applications of fertilizer, because the pot plant has little surrounding soil compared to the plant growing in the ground.
Some pot plants have very specific fertilizer needs.
"Seasol" and fish oils are useful soil conditioners for pot plants.
Root-bound plants have been left too long in the pot so that the roots begin to encircle the pot and do not grow normally.
The girdling roots must be cut off before transplanting.
Pot on, or pot up means to move a growing plant into a larger pot for more root space and allow room for further growth.
Repotting is advisable at least every two years.
Ceramic or terracotta pots are preferable, because plastic pots in the sun can tend to overheat the root system.
1. Dig a hole 4 × width and 2 × depth of the pot.
Loosen the soil at the sides of the planting hole.
Fill the hole with water and allow it to drain away.
Add wetting agent to half of the soil taken out and to be used as back fill.
Remove the plant from the pot by inverting the pot and tapping it until the plant with root ball emerges.
Place the plant in the hole with the top of the root ball level with the surrounding soil surface.
Fill the remaining hole with back fill.
Press the back fill down to leave a saucer-shaped depression around the plant.
Water the plant after planting and then water it once a week for two months with the volume of water equal to twice the volume of the original pot.
Then water only when the soil feels dry.
Add some coarse mulch in a 50 cm radius, but not touching the stem of the plant.
The applied mulch should contain composted animal manure and leaf litter.
Do not put fertilizers or new animal manure in the bottom of the planting hole, because they may burn the plant roots.
Prune off broken branches from the new transplants.
2. Clay pots and plastic pots are tapered, i.e. they are wider at the top than at the bottom.
The taper makes it easy to get the plant and soil out without damaging the roots when you hit the upside down pot sharply.
However, clay pots are expensive, heavy and break easily if dropped or trodden on.
3. Use iron fish tins, drink tins, jam tins and aluminium beverage cans for containers.
However, they are not tapered, so cut the sides with tin snips to get the plant and soil out.
Punch holes in the bottom and sides of these tins and drink-cans from the inside out.
These containers are so cheap and plentiful, so it is a good idea to experiment with them.
Collect aluminium or tin plate beverage cans, half fill with soil mixture and use one for each seed.
4. Make basket pots by winding banana leaves around a log then taking the log away.
Also, you can cut bamboo to make pots, but you may have to split them to get the plant and soil out.
5. Buy special pots made of compressed peat, e.g. "Jiffy Pots".
They are excellent for transplanting single plants, but they do not stand up for long before collapsing and they are expensive.
Stand them in a shallow tray to take up water then you can transplant without damaging the plants.
6. Do not add a layer of gravel to the bottom of the pot to improve drainage.
The layer of gravel forces the temporary wet soil layer higher, bringing it closer to the plant roots and increasing the risk of root rot.
If the hole in the bottom of the pot are blocked by plant roots, push a screwdriver up into the holes or transfer the plant to a bigger pot.
9.2.5 Potting mix
1. Potting mix: Commercial potting mix with trace elements.
A free draining mix of composted pine bark and coarse river sand (90:10 or 95:5) has a high air filled porosity for good aeration and drainage.
Pasteurise potting mix before use.
For nursery plant beds, use decomposed granite / coarse river sand, composted pine bark fines (50:50).
For nursery orchids in pots, use coco chips, pine bark nuggets, charcoal.
For nursery epiphytes (includes orchids), use redwood bark, charcoal (60:40).
For permanent pots, use commercial potting mix of composted pine bark, coarse river sand and coir.
Be careful using potting mix.
Wear a mask so you do not hale any dust and do not shake the bag.
Wash the hands and clothes after using the potting mix then store it in a cool place.
Soil is not suitable for potted plants, because it can get compacted too quickly.
A good potting mix will keep a balance between holding water and letting water out - enough water for roots without becoming waterlogged.
To stop too much soil being lost through the hole in the bottom of the pot, do not use a stone, but use a piece of cotton cloth.
Some people include 20% coarse 60/40 coir (coconut fibre) in potting mix to "open" its structure.
2. Experiments
Prepare two control mixes:
* Minimal nutrient mixture of coconut fibre (50%), pearlite (25%), and vermiculite (25%).
* Good nutrition, but poor texture mixture of volcanic rock dust (50%), and cow manure (50%).
Test plants from a legume crop, a leafy crop, a fruit crop, and a root crop.
For hothouse tests, use seedlings of basil, lettuce and tomato planted in 8 cm diameter peat pots.
For a full sunlight test use seeds of bean, radish, rocket, spinach and tomato sown in 5 x 10 cm plastic pots.
Test home-made and commercial mixes by comparing growth of plants in them with growth in the controls.
A successful commercial mix may contain animal manure, hoof and horn meal, trace elements, potassium phosphate and other constituents.
9.2.6 Planting seeds
Seeds can be sown into propagating containers in good quality seed raising mix and lightly covered.
Seeds may require no pretreatment before sowing
Some seeds require soaking in water for 24 hours before sowing.
Some seeds require hot water treatment, by placing them in a cup of boiling water, allowed to cool, and leaved to soak for up to 3 days before sowing.
Some seeds must be placed in a refrigerator for up to 3 weeks before sowing.
Some seeds must be placed in vinegar for 24 hours before sowing.
The seeds should be kept in a warm, well-lit area out of direct sunlight.
Seedlings can be pricked out at the second "true leaf" stage into small pots for growing on to a size suitable for planting out.
Young plants should be hardened off before planting by gradually introducing them to drier and more exposed conditions.
Seeds can be sown year round if greenhouse conditions are available.
The best sewing times are from spring to early autumn.
The four methods of planting
9.2.7 Direct planting of seeds and cuttings into the field
See diagram 61.6: Sweet potato planting, planting material
1. If they are direct planting, always dig the soil one month before planting seeds.
The soil should be prepared and fertilized 2 weeks before planting by digging in rotted compost, wood ashes or fertilizer.
Planting must be done at the correct depth and correct spacing.
The seeds must look fat and healthy.
Plant them in furrows or holes, singly or plant 2 seeds per hole and destroy the smaller seedling.
You may plant cuttings singly, but there are many different methods.
Backfilling is replacing soil taken out of planting hole after planting.
2. Advantages of direct planting
* It is a cheap and simple method, and saves time.
* There is no damage due to transplanting.
* Plants are easy to look after.
* Surviving plants may be stronger.
* Some seeds must be sown this way, e.g. bean
3. Disadvantages of direct planting
* Less seed germinates so there are fewer seedlings.
* You have less control over what is grown in the field.
4. The two dangers for a seed
* The seed may dry out, then it may not germinate, because it has no water.
You can stop this danger by covering the soil very lightly with some powdered animal manure or leaf mould.
It also helps if you mix some sand with the topsoil, because this sand will keep the soil open and let rain in.
* The other danger is that seed may get too wet and be attacked by a fungus called the "damping off" fungus.
You can stop this fungus by putting sand in the topsoil which will let a lot of rain drain away quickly.
The general rule about sowing seed is to plant it shallow.
Planting too shallow is better than too deeply.
9.2.8 Planting in a seedbed
See diagram 6.0.4: Seed beds, seed boxes
1. A seedbed, seedling bed, is a garden bed for raising seeds, made by digging, levelling and removing weeds and rocks for a fine even soil.
Plant seedlings in a seedbed of fine even soil sheltered by a roof and later chose the best plants for transplanting.
The crumbly finely broken down surface layers of topsoil needed for a seedbed is called a "tilth".
The seedbed soil is a mixture of 2 buckets of sieved good soil and 1 bucket of washed river sand and 1 bucket of rotten compost.
Sterilize the mixture to kill weed seeds, pests and diseases, by heating in a drum oven.
Seedlings may need thinning out and may be hardened by not watering and by gradually removing the roof a few weeks before transplanting.
Select the strongest plants for transplanting on a dull afternoon and water the transplants well.
2. Seeds and other planting material can be planted in:
See diagram 61.7: Sweet Potato Gardens, ridges, mounds
* Long deep grooves in the raised bed or field called furrows, made with a hoe.
* Short shallow grooves in the seedbed called drills, made with a rake handle.
* Hills or mounds to allow drainage for sweet potato, maize and pumpkins.
3. Advantages of planting in a seedbed:
* More seeds germinate and more seedlings live.
* Seedbeds save time, because other plants can be growing in the field while seedlings are in the seedbeds.
* Seedbeds give more control over what is grown in the gardens
4. Disadvantages of planting in a seedbed:
* Seedbeds are an expensive and complicated method.
* Seedbeds waste time.
* Transplanting from seedbeds may damage roots.
* The plants in the seedbed must be watered every day.
* Skill is needed to look after seedlings properly in a seedbed!
Broadcasting is a method of lightly raking seed, e.g. salad vegetables, into the soil surface, water it in, and cover the soil with sieved soil or mulch.
9.2.9 Planting in seed boxes
1. Seed boxes, seedling trays, about 24 x 24 x 15 cm are kept on shelves in greenhouses, with a roof of sticks or artificial shade, e.g. "Salon".
Before using the seed boxes, sterilize the seed boxes and soil in them to kill pests and diseases.
Plant the seeds in regularly spaced holes in the seed box soil
The seeds are planted in regularly spaced holes in the seed box soil.
Very tiny seeds may be mixed with a dry sand before sowing so that the sand spaces the seeds.
Take the seed boxes to the field when transplanting.
Make seed boxes with wood or tin plate, e.g. kerosene tins.
However, you must make sure that air can get into the soil and that the soil is well drained, otherwise the roots will not grow well.
Pricking out is the transferring of germinated seedlings into larger seed boxes or a garden bed.
Sprinkle small seeds along a shallow drill, and when the cotyledons have just opened, transplant the seedlings into a second box with spaced holes.
2. To propagate plants from seeds, buy special seed raising mixtures or use the same potting mix for seeds as you do in the pots.
Fill the trays with potting mix, smooth off the top, and water with a fine nozzle.
Put a small indentation with your finger in each cell.
Sprinkle in seeds.
For fine seeds, put up to six in each cell.
For big seeds, put two in each cell.
Cover with perlite to give a light weight cover for the seeds to push through, and providing moisture retention.
The smaller the seed the thinner the cover, larger seeds should be covered by the same depth as they are in diameter.
Cover the seedling trays with plastic to provide high humidity and to avoid moisture loss.
Keep the seeding trays moist.
When the true leaves have emerged, you will need to fertilize.
When the seedlings are ready to pot up, or plant in the ground, place the trays in the sun for three to five days, to "harden" the top growth and increase the
strength of the root system.
9.2.10 Planting in a plant nursery
1. Use a plant nursery for the three following reasons:
* Give seeds and young plants the best conditions for germination and rapid growth.
* Use the land for other purposes while the plants are in the nursery.
* Prepare the land for planting right up to the time of transplanting.
2. Site of a plant nursery
Choose the site of the nursery carefully.
It should have a constant water supply and not be flooded.
The land should be flat and sheltered from strong winds.
The soil should be well drained, with a pH between 6 and 7, cleared of tree roots and weeds and be cultivated to produce a plot to be shaded.
3. Protection from wind for a plant nursery
Plants in the nursery must be protected from strong winds, the hot sun in the middle of the day, and raindrop damage.
The best protection from strong winds is a brush fence 3 metres high, but for long term plant windbreaks using trees, e.g. Leucaena.
In most places build walls and a door that you can lock to keep out animals.
4. Shade for a plant nursery
A shade roof 2 metres above the ground supported by posts 3 metres apart can protect plants from the hot sun and heavy rain.
The roofing material that is the easiest to collect and put on the roof are coconut palm leaves.
However, this material has the disadvantages that the shade is uneven and blocks out too much sun in patches.
Also light rain may run off the roof and not get to the plants at all.
The best roofing material is sticks about 5 cm in diameter, arranged to provide an even shade and let some light and rain pass through.
Shade should have lots of small spaces.
Shade made of plastic called "Sarlon" works well, but it is expensive and may not last many years in the hot tropical sun.
5. Two weeks before transplanting, harden the plants by gradually removing the shade, leaving plants that can grow well in the hot sun.
Hardening off is gradually acclimatising plants to outdoor conditions after protected cultivation, so they can survive without harm from heat or frost.
Hardening off and transplanting is the same for both types of seedbeds.
6. Seedbeds in a plant nursery
Plants can be grown in the seedbed or in seed boxes or other containers.
The advantage of using the seedbed is that it does not take much preparation or looking after.
The disadvantage is that you may damage the plant roots when transplanting.
The advantage of using seed boxes or containers is that you have more control over the plants and you can select the best plants for transplanting.
The disadvantages are the costs of containers and benches, the plants must be looked after more.
Water them every day and sometimes the plant roots do not grow properly in the containers.
Using seed boxes and containers in a plant nursery is always worthwhile provided you prepare the students to look after them.
6. Soil mixtures for a plant nursery
There are many ways to make up a soil mix.
A mix could be: 2 buckets sieved black topsoil, 1 bucket river sand, 1 bucket old sawdust or crushed dry leaves, 1 drink can of NPK fertilizer,
4% N, 6% P, 4% K + trace elements, and it should contain sulfur.
If the pH is less than 6, add lime.
The soil mixture used in the seedbeds must be light and crumbly.
It should allow air to get in, hold water and let the extra water out easily.
If the soil mixture packs down in the seed box or container, the plant roots will not grow well, provide the right amounts of plant nutrients, be free from pests and diseases.
7. Sterilizing the soil for a plant nursery
Cook the soil mixture to kill disease and weeds.
You must cook the soil mixture over a fire for a couple of hours to kill off all the disease and weed seeds.
Cut the top out of an oil drum.
Make many small holes in it.
Make holes through the drum 30 cm above the bottom, and put iron bars through the drum.
Put the lid inside the drum so it rests on the iron bars.
8. How to sterilize the soil for a plant nursery
See diagram 6.0.1: Sterilizing soil
Put water in the bottom of the drum.
Put soil in the top part of the drum.
Make the soil slightly wet.
Put a sweet potato in the soil near the top, put a cover on the drum.
Light a fire underneath the drum to boil the water and "cook" the soil.
After about 2 hours of cooking, check to see if the sweet potato is cooked.
If it is cooked, then the soil is ready.
You can use the seed box mixture again, but you must sterilize it each time before you use it.
If any of the plants in the seed box get a disease, then you must also sterilize the box before you use it again.
Put in boiling water for 15 minutes.
9.2.11 Transplanting
See diagram: 58.6: Young plant before transplanting
1. The three causes of "transplanting shock":
* Root damage
The root hairs are very delicate and are in contact with the soil particles.
Even if the soil is slightly shaken the root hairs can be broken and then it takes some time for the plant to grow new root hairs.
* Stem damage
If the plant cannot be picked up by digging the soil and lifting, the plant can be safely lifted up by a cotyledon or leaf.
If you damage this the plant it can soon grow a new leaf.
However, if you try to pick it up by the stem and you damage the stem then the plant cannot repair it and will die.
* Loss of water
If the plant is transplanted from shade to sunlight it will dry up easily, because the leaves are used to being in the shade.
A week before transplanting, start removing the shade so that the plant is used to full sun before transplanting to prevent excess loss of water.
2. Polybags
See diagram: 53.12.2: Polybags
1. Avoid transplanting shock by growing seedlings in black plastic bags (polybags), usually available from the Department of Agriculture.
Use for plants that must be left in a nursery for a long time, e.g. coconuts.
Poly bags may get very hot if left in the sun and this can damage the roots.
They may come in the form of sleeves to provide extra drainage.
Large coconuts may not fit easily into these polybags if you lay them on their sides, but you can trim off part of the husk to make them fit.
3. Teaching transplanting
Use 3-4 seedlings for each student, a place for transplanting the seedlings, and spoons or trowels.
Individual practice on why seedlings must be transplanted gently. let each student dig a transplanting hole and water it.
Then water the seedlings.
Show the students how to dig up a seedling.
Then plant the seedlings in the transplanting hold deeper than it was in the seedbed and water again.
Let each student transplant one seedling.
Watch for any accidents.
Tell them to water their seedlings then put some shade over them.
Visit the seedlings each day for 2-3 days.
If they are they all growing well, remove the shade.
Notice if any plants have setbacks.
9.2.12 Planting material
See diagram 9.81: Bulb
See diagram 9.82: Corm
See diagram 9.83: Rhizome
See diagram 9.93.1: Stem cuttings
See diagram 9.93.2: Cuttings
1. Collect examples of the different kinds of planting material to show the students in the classroom.
Planting material means seeds or parts of plants that can grow to become a new plant.
The parts of plants may be pieces of stems or special kinds of stems.
Seeds are produced in the ovary of a flower after pollen from the stamen (father) fertilizes the ovary (mother).
So seeds are like the children of the stamen and the ovary.
The pollen that fertilizes the ovary may come from the same flower as the ovary (self-pollination) or come from a different flower on a different plant
(cross-pollination).
The seeds (children) will have a mixture of the different characters of the parent plants.
So the seeds will be like brothers and sisters.
When they grow, they will all look like the
parents and like each other, but none will look the same.
Plants that grow from parts of plants will grow to look the same as the parent plant.
2. Parts of plants used for planting material:
Stem cutting: When the nodes of some plant stems touch damp soil, they will produce roots.
If these stems are cut between the nodes then each node can form roots and shoot and grow into a new plant, e.g. sweet potato or cassava.
Stems or stem tips are cut and planted so that some nodes are under the ground and some are above the ground.
The nodes under the ground produce roots and the nodes above the ground produce leaves.
Corms area swollen stem bases, e.g. taro and banana.
The corm will have small buds growing from the nodes.
The corm can be cut into "bits", which are pieces of corm with buds.
Each "bit" can be planted to grow into a new plant.
Stem tubers are swollen stems or branches that grows in the ground, e.g. yams.
Each "eye" in the tuber is really a very small leaf and axillary bud.
The tubers can be cut into pieces, each containing an eye, and planted.
Each piece will grow into a new plant.
Root tubers cannot be used for planting material, because there are no nodes or axillary buds in roots.
However, at the neck of the tuber where the root becomes stem axillary buds can sprout, be separated, and then used as planting material, e.g. sweet potato
or cassava.
Bulbs are shoots with fleshy leaves that store food, e.g. spring onion.
Some plants can produce little daughter bulbs that can be separated and planted to grow into big plants.
Shoots are from underground stems that produce shoots from their axillary buds.
They can be separated by cutting, then planted out, e.g. sword suckers of banana corms, tops and slips of pineapples.
Rhizomes are shoots that grows horizontally underground.
It can be easily broken into pieces, with each piece containing axillary buds.
The axillary buds can form new roots and shoots, e.g. ginger or turmeric, and many grasses.
Aerial suckers are branches which grow in the air than touch the ground.
Where a node touches the ground, a new plant can grow, e.g. pineapple aerial suckers, taro suckers, yam bulbils.
9.3.1 Seed packet labels
Plant nurseries, fruit trees, seeds (Commercial websites)
Description of type of plant
Common name and scientific name
Annual life cycle: 4 to 12 months, Biennial life cycle: up to 20 months
Hardy, survives frost / cool soil
Sow in soil at +10oC to + 20oC
Position: Full sun, part sun part shade, full shade
Months to flower, Months to harvest
Watering: Thirsty plant, seasonal watering, drought tolerant
Height and width of mature plant / flowers
Fungicide protection: Chemically treated / untreated
Sow: Direct / transplant
Best use by date
Germination %
Seed count in packet
Price
Packing reference number or lot number
Address of supplier
1. Choose seed from a group of plants that all have the characters you are looking for, e.g. large fruit or resistance to pests and disease.
There is then a good chance that the plants produced from this seed will have the same characters as the parent plants.
2. Other planting material, e.g. stem cuttings should be chosen from the best plants in the crop and must be free of pests and disease.
The best time to harvest seed is when the fruits are fully ripe, but you may have to protect the fruit from birds and insects with paper or plastic bags.
3. Seed should be dried in the shade and any juicy material picked off.
The seed must be clean of leaves, stalks and dust.
Put the dry seed in a jar, shake with copper oxychloride fungicide and then keep in a cool place.
Do not let students breathe in the fungicide dust or eat the seeds, because all fungicides are poisonous.
Plant most tropical seeds soon after harvest.
4. When seeds remain alive and can germinate to form seedlings, we say the seeds are viable.
Test the viability of seed before planting, otherwise, you waste time and effort on useless seed.
To test the viability of small seeds, soak 20 seeds for an hour then put the seeds on wet newspaper in a closed container.
After a few days, count the number of seeds that produce healthy roots.
Percentage germination = (No. germinated seeds / No. seeds planted) × 100.
5. With large seeds it is best to plant 20 seeds in a container in the nursery.
If fungus attacks the germinating seeds, shake the seed with copper oxychloride fungicides and do the test again.
Some seeds with very hard seed coats, e.g. Acacia, should be dropped in boiling water before sowing.
Most larger seeds germinate more quickly if soaked for 1-2 hours first.
6. If you are direct planting, always dig the soil one month before planting seeds.
About 2 weeks before planting dig in rotted compost, wood ashes and fertilizer, which should have a high content of phosphate, e.g. NPK 4%, 6%, 4%.
Phosphate makes roots grow well.
Also, you can plant a group of seeds in shallow holes at the correct distance and when the plants are 3 cm high destroy all plants, except the biggest.
9.3.2 Depth of sowing.
See diagram 9.113.2d: Seeds planted at different levels
The depth of sowing is usually printed on the packets of imported seed.
For your own seed the best rule is to sow the seed at a depth of at least 2 cm, or at a depth of 3 times the width of the seed (but not > 8 cm).
Set up some interesting trials comparing the germination of seeds soaked and unsoaked, and at different depths in the soil.
If you sow seeds at too shallow a depth they may be uncovered by the wind, eaten by birds or rats, or the roots will not grow properly.
If you sow seeds too deeply, the plant may become exhausted and be unable to push the cotyledons above the soil.
Sometimes students will dig up sown seed of plants, e.g. peanut and eat them.
This is a problem of student discipline, but it can be quite dangerous if the seeds have been treated with fungicide.
9.3.3 Growing your own seed
1. Advantages of growing your own seed
* The cost of producing your own seed is less than imported seed.
* Seeds from the best plants in your garden should be suitable for the conditions in your garden.
2. Disadvantages of growing your own seed
* The plants produced may vary a lot due to genetic variation.
* The seed may carry disease or insect pests if not treated with pesticide.
* The seed may die if it not stored in cool dry conditions.
* There may not be enough seed for your needs in the garden.
9.3.4 Packet seeds, Advantages and Disadvantages
1. Advantages of packet seeds
* They are free from diseases and insect pests.
* All the plants grown from the seed in a packet will be genetically the same.
* The seed has been chosen to give a high yield.
Calculate exactly how much seed is needed and buy that number of packets.
2. Disadvantages of packet seeds
* Imported seed is expensive.
* There are many different varieties and it is hard to know which to choose.
* You cannot use hybrid seed to produce seed for another crop so you need new hybrid seed for each crop.
* Imported seed may not be suitable for the local conditions.
9.3.5 Seed germination
See diagram 9.111: Epigeal germination, French bean
See diagram 9.110.2: Hypogeal germination, Broad bean
See diagram 9.113.4: Monocotyledon germination, Maize
The radicle is the first part of the plant embryo to grow once water and oxygen enter the seed, then the plumule emerges.
The shoot has three main parts:
1. Cotyledons (seed leaves),
2. The part of the shoot below the cotyledons (hypocotyl)
3. The part of shoot above the cotyledons (epicotyl).
Dicotyledons
In hypogeal germination, the epicotyl elongates and grows straight up and the cotyledons remain underground, e.g. peas, gram, mango.
In epigeal germination, the hypocotyl elongates and forms a hook, pulling the cotyledons and apical meristem through the soil until it straightens above the
soil surface and pulls up the cotyledons and shoot tip, e.g. means, tamarind, papaya.
Monocotyledons
The coleorhiza covering embryo's radicle and the coleoptile covering the cotyledon grow out of the seed, and pushed up through the ground to the surface,
where the first leaves emerge.
Germination
1. Germination is the growth of a seedling from a seed.
5.27 Germination test (Primary)
If a seed is given the right conditions and the embryo is alive it will start to grow.
2. Conditions for good germination:
* Most vegetable seeds germinate best in the dark, but dill and onion germinate best in some light.
* Tilth - The plant embryo must push its parts through the soil as it emerges from the testa and grows towards the soil surface.
Soil must be friable to permit air and water to enter and to allow plant roots to forage through it.
* Water is necessary for chemical reactions and poor germination is often caused by over-watering or under-watering.
Water newly-sown seeds with a mixture of one fifth of a teaspoon of Epsom salts in a litre of water to aid the germination process.
The magnesium in the salts will help stimulate the enzymes that make the food in the endosperm more readily available to the young seedling.
Water softens and splits the testa to allow water and oxygen to enter the seed.
Water enters the seed through a small hole in the testa, the micropyle.
* Oxygen is from the air is necessary for respiration.
The food stored in the seed produces energy by respiration for the growing embryo.
* Heat is needed to speed up the chemical reactions that take place in the seed during germination.
Each species of plant will have a particular temperature range that its seeds will germinate in.
24 to 27 o C: cucumber, pumpkin, squash, watermelon
21 to 24 o C: eggplant, onion, parsley, pepper, tomato
18 to 21 o C: basil, broccoli, cabbage, cauliflower, dill, kale
* Healthy seed
* Correct depth of planting
If seeds are sown too shallow they may be uncovered by the wind, eaten by birds or rats, or the roots will not grow properly.
If seeds are sown too deeply, the plant may become exhausted and be unable to push above the soil.
If the seed is planted too deeply, the tiny developing plant exhausts the food supply in the endosperm, long before the shoot and leaves have broken through
the soft surface and it dies.
The general rule is to plant a seed at a depth of at least two cm, or at a depth of three times the width of the seed, but not more than 8 cm.
Small seeds should be only lightly covered with soil, but larger seeds will be planted at a greater depth.
The surface of the soil dries out more quickly than it does a few millimetres deeper.
So small seeds that are surface-sown should be kept moist while the larger seeds should be given a good soaking at planting time and then watered
again only after they break through the ground.
If you water the larger seeds too much, they will rot in the moist soil.
The depth of sowing of seeds is usually printed on the packets of imported seeds.
Set up some interesting trials comparing the germination of seeds soaked and unsoaked, and at different depths in the soil.
Sometimes students will dig up sown seed of plants, e.g. peanuts and eat them.
This is a problem of student discipline, but it can be quite dangerous if the seeds have been treated with fungicide.
* Correct variety kind of seed for local conditions.
To select tomato seed for planting, squeeze the pulp and the seeds on absorbent paper, e.g. a paper towel, and spread it evenly over the paper.
Remove as much pulp as possible and lay the remainder in the sun for two weeks to dry the germination inhibiting enzymes.
Lay the paper towel with seeds uppermost on seed raising mix and lightly cover with fine seed mix.
Water lightly until the seedlings emerge.
The seed of many vegetables and flowering annuals are F1 hybrids, where the plant breeders have combined two different strains each with desirable
characteristics.
However, F1 hybrids usually do not set seed or the seeds are not viable.
9.3.6 Seed sterilization
1. Sterilization procedures may be enhanced by:
1.1 Placing the material in a 70% ethyl alcohol solution prior to treatment with another disinfectant solution.
The use of a two-step (two-source) sterilization procedure has proven beneficial with certain species.
1.2 Using a wetting agent, e.g. "Tween 20", added to the disinfectants to reduce surface tension and allow better surface contact.
1.3 Conducting the sterilization process under vacuum.
This results in the removal of air bubbles and provides a more efficient sterilization process.
2. Orchid seeds are very small and contain little food reserves.
A single seed capsule contain 1, 500 - 3, 000, 000 seeds.
Sowing the seed in vitro makes it possible to germinate immature seed (green pods).
It is much easier to sterilize green capsules about two-thirds ripe than individual seeds after the capsule has split open.
For example, the time to maturity of Cymbidium is 10 months.
For green capsule sterilization, soak the capsule in a 100% bleach solution for 30 minutes.
Dip the capsule into 95% alcohol, and flame.
Under aseptic conditions, open the capsule and scrape out the seed.
Carefully layer the seed over the surface of the culture medium.
3. Dry seed sterilization
Collect seed and place in either a small flask or bottle, or place in a shortened pipette which has one end sealed with cotton.
Seal the other end of the pipette with cotton, once the seed has been placed in the pipette.
Prepare a solution containing 5-10% commercial bleach containing a few drops of "Tween 20".
Add the bleach solution to the flask, or draw up the solution into the pipette.
Swirl the flask containing the seed and bleach or repeatedly draw and aspirate the bleach solution in and out of the pipette.
Sterilize the seed for 5-10 minutes.
Remove the bleach solution and rinse the seed with sterile tissue culture grade water.
Transfer the seed to sterile culture medium.
Parts of plants used for planting material:
9.54.0 Stems
1. Stem cuttings
See diagram 9.93.1: Stem cuttings
When the nodes of some plant stems touch damp soil, they will produce roots.
If these stems are cut between the nodes then each node can from roots and shoot and grow into a new plant, e.g. sweet potato or cassava.
Stems or stem tips are cut and planted so that some nodes are under the ground and some are above the ground.
The nodes under the ground produce roots and the nodes above the ground produce leaves.
2. Stem tubers
9.1.6.0 Stem tuber, potato tuber
Stem tubers are swollen stems or branches that grow in the ground, e.g. yams.
Each "eye" in the tuber is really a very small leaf and axillary bud.
The tubers can be cut into pieces, each containing an eye, and planted.
Each piece will grow into a new plant.
3. Shoots are from underground stems that produce shoots from their axillary buds.
They can be separated by cutting, then planted out, e.g. sword suckers of banana corms, tops and slips of pineapples.
4. Root tubers cannot be used for planting material, because there are no nodes or axillary buds in roots.
However, at the neck of the tuber where the root becomes stem axillary buds can sprout, be separated, and then used as planting material, e.g. sweet potato
or cassava.
Dry seed sterilization
1. Collect seed and place in either a small flask or bottle, or place in a shortened pipette which has one end sealed with cotton.
Seal the other end of the pipette with cotton, once the seed has been placed in the pipette.
Prepare a solution containing 5-10% commercial bleach containing a few drops of Tween 20.
Add the bleach solution to the flask, or draw up the solution into the pipette.
Swirl the flask containing the seed and bleach or repeatedly draw and aspirate the bleach solution in and out of the pipette.
Sterilize the seed for 5-10 minutes.
Remove the bleach solution and rinse the seed with sterile tissue culture grade water.
Transfer the seed to sterile culture medium.
2. Orchid seeds are very small and contain little food reserves.
A single seed capsule contain 1, 500 - 3, 000, 000 seeds.
Sowing the seed in vitro makes it possible to germinate immature seed (green pods).
It is much easier to sterilize green capsules about two-thirds ripe than individual seeds after the capsule has split open.
For example, the time to maturity of Cymbidium is 10 months.
For green capsule sterilization, soak the capsule in a 100% bleach solution for 30 minutes.
Dip the capsule into 95% alcohol, and flame.
Under aseptic conditions, open the capsule and scrape out the seed.
Carefully layer the seed over the surface of the culture medium.
9.4.1 Vegetative reproduction
See diagram 9.93.2: Vegetative reproduction
Propagation by cuttings, division, grafting and tissue culture is used to produce genetically identical plants, i.e. clones.
Producing more plants by taking pieces of a plant to grow new whole plants is called vegetative reproduction.
The advantages of using vegetative reproduction is that the piece of the plant usually grows easily, and the new adult plants produced will all have exactly
the same characters as the parent plant.
1. Use plant stems suitable for cuttings, e.g. Hibiscus.
The plant stems for cuttings should be about one cm thick.
Count the nodes.
The leaves will grow out of the nodes.
Cut the branch to make a cutting with four nodes.
Cut at an angle.
Push the cutting into the ground with two nodes underground.
2. A cutting may be a piece of root, stem, leaf or bud.
A root cutting must be able to produce a shoot and a stem cutting must be able to produce roots, usually from a node.
Cuttings must get enough water and air so that they can produce roots and shoots.
New roots and shoots can come from buds at the nodes.
If a cutting is half buried in sand, roots will grow from the lower part and shoots from the part above ground.
Do not mix compost or leaf mould with soil used for cuttings, but use clean sand.
After the cuttings have rooted, they can be moved to a richer soil with leaf mould in it.
3. To propagate plants from cuttings, fill trays with potting mix, smooth off the top, and water.
The best cuttings medium is 1 : 4 peat : perlite.
Collect cutting material from healthy plants.
Use sharp clean secateurs and cut below a node.
For small-leaved plants remove lower leaves from the cutting.
Larger-leaved plants may also require some remaining leaf area to be reduced.
Make a hole in the potting mix by using a stick with diameter not much bigger than the cutting and place a prepared cutting in the hole.
Gently press around the planted cutting and water in well to ensure that the cutting is in contact with the potting mix.
Keep the potting mix moist.
Once cuttings have roots you will need to fertilize them.
4. Compounds to improve the success rate with rooting cuttings include auxin hormones which induce root formation.
Fungicides used along with the rooting powder may have a stimulatory effect or a depressing effect on root production.
In Australia, rooting hormone compounds are available as a dry powder, gel or liquid, e.g. "Ezi Root Gel", a blend of (indole-3-butyric acid) (IBA) and
(naphthylacetic acid) (NAA), hormones, with a wetter and fungicide.
5. An experimental problem is how to score "rooting" in numerical values to allowing calculation of a mean of all cuttings for one treatment?
6. Roots from plant parts
Obtain a box of sand and put it out of direct sunlight.
Wet the sand thoroughly and keep it moist.
Plant the following in sand: | various bulbs | cuttings of begonia and geranium stems | a section of sugar cane stem with a joint buried in the sand | bamboo
stem with a joint in the sand | carrot, radish and beet tops, each with a small piece of root attached | an onion | an iris stem | piece of potato with "eyes" |
a branch of willow |.
9.4.2 Planting material
See diagram 9.93.2: Vegetative reproduction
Planting material includes seeds, fruits, parts of aggregate fruits used for planting, parts of plants used for vegetative reproduction, e.g. bulbs, potato tubers.
Planting material means seeds or parts of plants that can grow to become a new plant.
The parts of plants may be pieces of stems or special kinds of stems.
Plants that grow from parts of plants will grow to look the same as the parent plant.
Some horticulture schools do not use the term "planting material" and in some dictionaries the word does not exist.
9.4.3 Bulbs
|See diagram 9.81: Bulb
9.1.1.0 Bulb
Bulbs expanded parts of the stem around central shoots of new plants, surrounded by juicy layered leaves.
Examples of bulbs are fennel, garlic, leek, lily, onion, shallot, spring onion, tulip.
Bulbs are perennial underground food storage organs, like a big bud enclosed in overlapping scales.
Bulbs are shoots with fleshy leaves that store food, e.g. spring onion.
Some bulbs can produce little daughter bulbs that can be separated and planted to grow into big plants.
9.4.4 Corms
See diagram 9.82: Gladiolus corm
See diagram 62.7: Taro corm
9.1.2.0 Corm
Corms are enlarged underground food storage organs with of a thick stem section of fleshy tissue surrounded by a skin of papery leaves.
Examples of corms are banana, Crocus, Gladiolus, taro.
The parent corm can produce daughter corms.
Corms are swollen stem bases, e.g. taro and banana.
The corm will have small buds growing from the nodes.
The corm can be cut into "bits", which are pieces of corm with buds.
Each "bit" can be planted to grow into a new plant.
9.4.6 Division, vegetative propagation
Division is a simple means of vegetative propagation for plants that produce suckers, stolons, bulbs, tubers or rhizomes.
To propagate by division, dig up the plant and divide it carefully using a spade or secateurs.
The newly divided portions of plant are potted into appropriate potting media, containing controlled release fertiliser.
Plants that are easily divided often have fleshy bulbs or tubers that can easily rot, like, e.g. Goodeniaceae family.
Division includes are separation of side shoots from spring onion bulb, separate suckers from banana corm, break ginger rhizome into pieces.
Division is a propagation technique used for landscape plants that do not have a single stem or crown.
Many plants have just one stem emerging from the ground and cannot be propagated using division.
However, there are quite a few different plants that have multiple stems emerging from the ground and can be propagated through division.
Division is multiplying mature perennial plants by cutting plants with woody crowns or fleshy roots, or by pulling apart large clump into smaller
portions using forks so that each separated section has shoots and roots.
Division is a natural process when a plant forms new plants as offshoots.
Offshoots are parts of the plant grow to form new plants and later separate from the mother, e.g. spring onion, Chinese taro.
Experiments
1. Pull apart the diffuse plants with many shoots or offsets.
Adult cells of plant organs may revert to meristematic activity and reveal their original embryonic characters.
Division is a natural process when a plant forms new plants as offshoots, e.g. bulbs, corms, rhizomes.
Parts of the plant grow to form new plants and later separate from the mother, e.g. Michaelmas daisy, delphinium, suckers of raspberry canes.
2. To propagate plants by division, turn pot upside down squeeze and shake plant out.
Remove as much potting mix as possible.
Pull plant apart into sections, depending on whether you want to produce a few well established plants or many smaller plants.
Use a knife or secateurs to divide plants with large roots or rhizomes.
Matted pot-bound roots can be cut.
Trim long roots to a depth of half a pot.
Half fill pots with potting mix.
Hold newly divided plant in the pot and fill with potting mix.
Water in well, then water in with a liquid seaweed-based fertilizer, to prevent transplant shock.
9.4.8 Rhizomes
See diagram 9.83: Rhizome
9.1.4.0 Rhizome
A rhizome is an underground stem with nodes, roots and which can form shoots, a rosette of basal leaves which radiate from a central axis.
Rhizomes are shoots that grow horizontally underground.
It can be easily broken into pieces, with each piece containing axillary buds.
The axillary buds can form new roots and shoots, e.g. ginger, turmeric, and many grasses.
8. Aerial suckers are branches which grow in the air then touch the ground.
Where a node touches the ground, a new plant can grow, e.g. pineapple aerial suckers, taro suckers, yam bulbils.
9.4.9 Stooling
See diagram 51.13.0: Banana stool
The plant is cut down to ground level where it forms lots of new shoots.
Each shoot then produces its own roots.
These rooted shoots can be cut off and planted separately.
Stooling can be used on guava and bananas.
9.4.10 Layering
See diagram 9.10.11: Layering
See diagram 9.93.2: Layering
1. Layering is bending branches to the ground to be covered with soil and develop adventitious roots.
Example of plants used for layering are carnation, rubber plant, lilac, rhododendron, rose, clematis, blackberry, mango
The plant is bent the down until a branch touches the ground, then the branches are secured it with pegs or wire ground hoops.
New shoots and roots then form from each node touching the ground, then, by cutting between each node, new plants are formed.
2. Bend a branch down over the soil and fix pegs so that some nodes are below the surface.
Adventitious roots grow from the buried nodes.
The axillary bud near the peg grows upwards into an aerial shoot.
Cut the layered stem from the parent plant and let it grow independently.
2. For air layering of the rubber plant, make a longitudinal cut below a node almost to the centre of the stem.
Treat the cut with plant cutting powder then bind on moist cotton wool covered with polythene film.
Roots form in the layering.
3. Find a plant whose branches you can bend down for layering.
Bend the branches down and use a peg or piece of wire to keep the branch bent under the ground.
After about a week, examine the branch by gently washing away the soil.
New shoots and new roots come from the nodes.
When the new shoot is growing strongly above the ground you can cut the old branch away from the new plant.
9.4.11 Marcotting, air layering
See diagram 9.93.3: Marcotting
See diagram 9.93.2: Marcotting
Air layering, is scraping and replanting of tree branches to develop into trees.
1. In marcotting a cut is made below a joint or node and covered with a moss into which new roots grow.
Remove a strip of bark 1-2 cm wide, then scrape it to remove any remaining bark or cambium tissue.
Cover girdle with moist sphagnum moss.
Wrap with polyethylene film.
Wrap and tie ends with polyethylene tape or electrician's tape.
2. Propagation by air layering or marcotting, by Paul Moore, Indoor Citrus and Rare Fruit Society
Air layering is a method of propagating several kinds of evergreen, broad-leaved, tropical and subtropical fruit trees.
The Chinese have used this technique, which they call "gootee", extensively for more than 1,000 years to propagate the lychee, a species difficult to
propagate by other asexual methods.
Air layering, "marcotting", is the preferred method of propagating guava, lychee, longan and the ornamental Ficus elastica.
Other fruits and nuts that can be propagated as marcots are acerola (Barbados cherry), carob, carambola, cashew, citron (Citrus medica),
fig, lime, lemon, pomelo, loquat, macadamia and mango.
Grafting and cuttings are preferred over marcotting, because they are easier, less time-consuming and more economical of propagating material.
Also, grafting and cuttings can be more successful in non-humid regions.
Air layering is more reliable in outdoor climates that remain humid and rainy during the rooting period, and in greenhouse environments.
The most limiting factor in marcotting is keeping the rooting medium continuously moist.
Periodic rewetting will be required if it dries.
The air layer is started by selecting mature branch tips that developed in the previous growing season.
The selected terminals are girdled by removing a ring of bark 1 to 2 cm wide and about 12 to 15 cm below the tip.
Scrape the remaining inner bark tissue, removing it down to the wood to prevent the girdle from healing and to induce rooting above the cut.
Treating the exposed cut and the bark above the girdle with rooting hormone preparation, e.g. indolebutyric acid (IBA), 8000 ppm or 16000 ppm.
Place a double handful of moist, sphagnum moss about the girdled surfaces and the intact bark above the cut, wrap with polyethylene film.
Tie the upper and lower ends tightly around the stem.
Rewetting the sphagnum may be necessary if it dries during the rooting process.
Leave the marcot on the mother tree until the roots are visible through the plastic film.
This may take from two to six months.
After adequate rooting occurs, sever the marcot, unwrap and transplant it into a container.
Survival is improved if the air layer is kept in a humid greenhouse or a cool, shaded site until well established.
Since there is an imbalance between root and top, is also recommended to prune back the top when it is potted.
Marcots are not planted into the open ground until the spring following potting, or until they are well rooted and established in their containers.
3. Marcotting means wrapping bags of damp soil or other material around a stem so that roots will grow out of it.
Later the stem can be cut into lengths with roots growing out of the lower end.
It is a way of multiplying some plants that are hard to strike (start to grow) as cuttings.
Cut out a complete ring of bark from a stem, and then use a cloth to bind damp earth, sawdust, or plant material around the cut stem.
Sometimes it helps to paint the cut with a substance that causes growth, e.g. indole acetic acid (IAA), but this is not essential.
Roots will grow from the cuts and so new plants can be formed by cutting between the cut rings.
This can be used on woody plants, e.g. mango, avocado and cashew.
Choose some plant, e.g. hibiscus, cordyline or fig.
Ring bark it at several places up the stem.
Use a sharp knife and cut a shallow "V" right around it.
Get some husk fibre from a coconut and soak it in water.
Cut it into pieces.
Wrap a handful of wet fibre around each cut made in the stem and hold it in place with a piece of rag and string.
If possible wrap a piece of silver paper around the bundle to reflect the sun and stops it getting too hot.
Marcotting can be used on woody plants, e.g. mango, avocado and cashew.
4. Marcotting or air layering means to cut out a complete ring of bark from a stem, and then use a cloth to bind damp earth, sawdust or plant material around
the cut stem.
Sometimes it helps to paint the cut with a substance which causes growth, e.g. indole acetic acid (IAA), but this is not essential.
Roots will grow from the cuts and so new plants can be formed by cutting between the cut rings.
This can be used on woody plants, e.g. mango, avocado, and cashew.
9.4.12 Offsets
An offset is a growth arising from the base of a plant and producing roots while still attached to the plant.
Offset part of a rhizome, bamboo
Elephant Yam, Amorphophallus paeoniifolius, Araceae can be propagated from offsets of the corm
9.4.13 Plantlets
See diagram: Plantlets
Plantlets are miniature plants structures that arise from meristem in leaf margins that roots and detach from the parent leaf
Bryophyllum reproduces by seed and also produces plantlets along the edges of its leaves.
Its fleshy succulent leaves can form roots and develop into new plants after breaking off the main plant.
Pandanus gemmifer can produce plantlets (pups) along the trunk which fall to the ground and take root, forming thickets.
9.4.14 Runners, stolons
See diagram: Runners, stolons
Runners, stolons, are modified stems grow from existing stems below the soil surface.
Examples of runners are strawberry, currant and Sturt's Desert Pea, Swainsona formosa Fabaceae, which produce long runners covered with flowers.
9.4.15 Suckers
See diagram 51.13.2: Banana, Different types of suckers
See diagram 62.2.2: Planting suckers taro tops
See diagram 60.2: Pineapple parts, sucker
Suckers are shoots arising from the roots or the trunk below ground level.
Suckers, root sprouts, may grow and form a dense compact mat that is attached to the parent plant.
Plants that form suckers are often invasive.
Mature suckers may be transplanted to a new area where they develop into new plants.
Suckers, root sprouts, are plant stems from buds on the base of stems or roots of apple, elm, banana
Coppice shoots are suckers, i.e. small more or less vertical shoots which are attached to the base of the stem
Examples of plants that reproduce with suckers: blackberry, raspberry, many Rubus species, apple tree, cherry tree, plum tree, pear tree, pineapple,
banana, locust tree, elm tree chaste tree (Vitex agnus-castus), tallow tree, lilac, forsythia, anemone, rose, trumpet creeper.
9.4.16Tissue culture
In tissue culture, plant cells are cultured in a sterilized medium to produce callus tissue to be cultured by hormones in the culture medium to develops into
plantlets.
9.4.17 Tubers
A tuber is a thickened underground part of a stem or rhizome bearing buds to form new plants.
Unlike corms or bulbs, tubers do not have a basal plant from which new shoots or roots grow.
Tubers are a means of asexual reproduction which allow the plants to survive winter or dry seasons as a store of nutrients and then regrow during the next
growing season.
Tubers produce nodes, buds or “eyes” on their surface, which can grow up to form shoots and stems, or grow down as roots.
Stem tubers
See diagram 9.85: Sprouting potato tuber
See diagram 63.5: Yam tubers
A stem tuber is a swollen stem that stores water and nutrients to be used during drought, winter months, dry seasons.
Example of stem tubers are begonia, potato, yam.
Stem tubers form near the surface of the soil at the sides of the parent plant.
A stem grows out of the upper side of the stem tuber and roots grow out of the bottom of the stem tuber.
The underground stems of the stem tubers are thickened rhizome and around the underground parent stem tuber, smaller stem tubers form.
They have several nodes called eyes that may develop into new plants.
Root tubers
Root tubers propagate from roots that are modified to store nutrients.
A root- tuber, tuberous root is a modified lateral root storage organ.
Examples of plants with tuberous roots are sweet potato, cassava, dahlia, beet, carrot, parsnip.
Root tubers are swollen roots for the storage of water and nutrients.
Root tubers have no nodes nor reduced leaves and have one end that was attached to the old plant producing foliage buds and the other end producing roots.
So the plant can die at the end of the growing season leaving root tubers in the ground which will produce the next generation for the next growing season
9.5.1 Cuttings
See diagram 9.93.1: Cuttings
See diagram 9.93.2: Cuttings
Cuttings are part of stem or a leaf, is cut off and planted to form adventitious roots and leaves, rose, hibiscus
Cuttings may be treated with hormones before planting.
A small cutting or a part to be used for grafting is called a "slip".
1. Cuttings are sections of a root, stem, leaf or bud, used to propagate a new plant complete with its own roots.
Cuttings must get enough water and air so that you can produce roots and shoots.
Stem cuttings of sweet potato, cassava, yam, banana, ginger, turmeric, pineapple, and taro.
Select planting material suitable for cuttings that are the correct size and free from disease.
Plant out the cuttings at the recommended correct distances.
2. Select healthy end growth 10 mm or less in diameter after the growth period of the plant.
Cut at an angle or select a "heel", where a branch joins.
Cuttings leave two terminal leaves.
Moisten the cut end of the cutting, dip it into the cutting powder and plant into free draining soil.
Water the cuttings daily.
If you plant next to the side of a glass jar, you can observe roots forming near the cut surface.
3. A cutting should be 50 mm to 150 mm long with an end growth diameter of 100 mm or less.
Take three cuttings from the parent plant after the growth period, i.e. late summer or early autumn.
For shrubs that flower in winter, e.g. camellias or daphnes take cuttings in midwinter.
For shrubs that flower in the spring, e.g. azaleas, take cuttings in autumn.
For roses, take cuttings from new growth in late autumn, early winter.
Make an angled cut to take a healthy cutting from a parent branch.
Remove the bottom leaves, but leave three small leaves at the top of the cutting.
Take cuttings in early morning or late afternoon.
Immediately put in water after cutting and as soon as possible apply plant striking hormone by pushing the cutting into the bag of powdered hormone.
The potting mix used for the initial root stage should be free flowing and light weight.
However, free draining sandy loam can also be used.
9.5.2 Rooting powders for stem cuttings
Use commercial plant cutting powder (rooting powder, plant striking hormones), e.g. "Root Strike", to stimulate and produce healthy roots on cuttings.
Active constituents of the powder are indole acetic acid (IAA), the main auxin of most plants, or indolebutyric acid (IBA), or naphthalene acetic acid (NAA).
Store the plant striking hormone in a dark cool place and do not let it contaminate streams, ponds or soil.
9.5.3 Leaf cuttings
Make leaf cuttings from African violet, begonia, episcia, haya blanca, peperomia
1. For begonia, African violet, cape primrose, make cuts in the raised veins in the underside of the leaf at 5 cm intervals.
Press the leaf cut side down into moist potting mix and cover the edges of the leaf with potting mix to keep it flat.
Some people push the cut veins down into the potting mix with staples or pieces of semi-circular wire.
2. For African violets, remove the leaf with petiole and insert the petiole into moist potting mix in indirect sunlight.
New plants will form on the petiole in about 8 weeks.
3. For plants with succulent leaf blades, e.g. cathedral bells, mother-in-law's tongue, stonecrop, cut long leaves into 7 cm sections, dip into hormone rooting
gel, then insert the sections into moist potting mix.
For smaller leaves, just push them upright into the potting mix.
Keep the potting mix moist in bright shade.
9.5.4 Root cuttings
A root cutting must be able to produce a shoot.
Make root cuttings from phlox, hollyhocks, wild cherry
Cut horizontally at the top of the root and cut at an angle at the base of the root for easy insertion into the ground.
Also, cut off the top of the plant just above the ground to form new shoots.
9.5.5 Stem cuttings, top cuttings
A stem cutting must be able to produce roots, usually from a node.
Make stem cuttings from geranium, poppy, fuchsia, chrysanthemum, blackcurrant
See diagram 9.93.1: Stem cuttings
See diagram 9.93.2: Cuttings
1. Put one end of a cut stem in damp sand.
Note the wound tissue, callus, that develops from which roots form.
At the other end, dormant lateral buds form new shoots.
2. Cut two pieces of stem with leaves, from a geranium plant.
The most suitable are short, compact shoots on which the leaves are close together.
Make a cut just underneath a stalk bud.
Fill two flowerpots with sandy soil to just below the rim.
Plant a cutting half a finger length deep in each pot.
Press the soil firmly down around the stem and add water so that it packs closely around the cutting.
Put an inverted beaker over each cutting.
Label each flowerpot and put in the light, but not direct sunlight.
Water the cuttings regularly.
The cuttings develop into new independent geranium plants.
Cuttings can form adventitious roots.
You can propagate poppies, geraniums, fuchsias, chrysanthemums and black and red currants by cuttings.
Fill two flowerpots with sandy potting compost.
Take two cuttings with leaves on attached from a geranium.
Make the cut close to and just under a bud.
Sturdy shoots with leaves close together are the most suitable.
Remove the bottom leaves from each cutting.
Plant each cutting 3 cm deep in a flowerpot and water well so that the soil is packed tight around the cuttings.
Put a beaker over each cutting, but making sure you allow air to get in and out.
Keep the soil moist and do not expose the cuttings to direct sunlight.
After some time the shoots begin to grow.
At the point where the cut was made adventitious buds have formed and have put out roots so that the cutting develops into an independent plant.
3. Hibiscus cutting should be 8 cm long.
Remove everything, but the top set of leaves.
Trim the bottom of the hibiscus cutting to be cut just below the bottom leaf node.
Dip the bottom of the hibiscus cutting in rooting hormone.
4. Stem rooting of Chinese Hibiscus.
Use a plastic litre soda drink bottle with its bottom cut out and slit along one side, so it could be slipped around the Hibiscus stem.
Tie the plant in place upside down and filled with potting soil.
Some plant stems sprout roots if their stems make contact with moist soil.
The stem will fill the potting soil with roots.
Cut the stem below the mouth of the bottle's mouth, remove the bottle.
When the root-filled soil is planted, there will stand a new Chinese Hibiscus already one metre tall.
9.6.1 Grafting
See diagram 9.93.2: Budding and grafting
Grafting is used to propagate plants where the tissues of one plant are physically fused with the tissues of another plant.
It is used widely in commercial horticulture for propagating gymnosperm and dicotyledon trees and shrubs.
Monocotyledons do not have enough vascular cambium, the thin layer between bark and wood, necessary for grafting.
One plant, the stock or rootstock, is chosen for the qualities of its roots.
The other plant, the scion, is chosen for the qualities of its stems, leaves, flowers or fruits.
For successful grafting, the vascular cambium of the stock and scion must be aligned so they can grow together.
The scion and stock will become fused to form a single plant.
A shoot from such a graft shows the character of the scion, not of the stock that nourishes the scion.
Successful grafts are usually between closely related plants.
Grafting attaches a scion, the desired cutting, to the stem of another plant, the growing stock to give the fruiting characteristics of scion, e.g. mango, guava.
Grafting involves two different woody plants combined by joining cuttings, joining a fruiting top stock to an adaptable root stock.
1. Grafting is difficult to do and usually can be done only by people who have studied horticulture in an agriculture college.
Grafting means to make part of one plant grow on another whole plant.
This is done when other forms of vegetative reproduction do not work and when you want to combine the characters of two plants with different characters.
The piece of plant or branch which is grafted is called the scion and the tree on which it is grafted is called the stock or rootstock.
2. This means to make part of one plant, the scion, grow on another whole plant, the stock or rootstock.
This is done when other forms of vegetative reproduction do not work, to combine the characters of two plants with different characters.
For example, if one kind of plant produces good fruit, but its roots are easily attacked by pests and disease, and if a second plant produces small fruit, but
its roots arc not attacked by pests and disease, then if you could graft branches of the first kind of plant onto the stem of the second kind of plant, you would
have a tree that produces good fruit and that has roots not attacked by pests and disease.
For grafting you need a sharp knife, a saw for large trees and tying material, e.g. string, tape.
3. Always buy grafted fruit trees, because:
* the fruit quality of the mother tree may not be retained in the fruits of the seedling tree,
* the seedling tree takes longer to reach the fruit-bearing stage,
* the seedling tree grows taller and so is more difficult to manage and to harvest fruit from it.
4. Top wedge cutting grafts, Australian National Botanic Gardens
Select a piece of stock material (scion) approximately 100 mm long and remove the lower leaves.
At the top of the rootstock, make a cut approximately 5 – 10 mm long.
The cutting to be grafted (scion) should be 60 – 80 mm long with the same number of leaves as a standard cutting.
The lower portion of the scion is cut into a wedge shape 5 – 10 mm long and inserted into the cut in the stock stem.
The join is wrapped in a stretchable tape such as florists tape.
The stem of the rootstock is cut and dipped in rooting hormone.
9.6.2 Bud grafting
See diagram 9.93: Bud graft, shield graft, saddle graft
See diagram 9.93.2: Budding and grafting
Bud grafting is used on orange, rose, fruit trees, apple, pear, plum, orange, rose, fruit trees, apple, pear, plum
1. Remove a bud from a plant with a small strip of bark and cambium, then insert it into a T-shape slit in the stock.
Tightly bind and wax the parts.
If the two areas of cambium are in contact, they produce a callus that unites scion and stock.
To obtain good quality fruit select only the best buds for the graft.
2. Bud grafting allows the following:
* rapid multiplication of desirable plants from a single individual,
* preservation of a type that does not come true from seed, navel orange and hybrids,
* modification of the scion, apples and pears are grafted to dwarfing stocks to grow a smaller tree for convenience of size,
* improved yield, grape varieties may yield better when not grown on their own roots,
* extended climatic ranges using extreme climate tolerant root stocks,
* disease resistance by grafting susceptible scions to resistant stocks.
9.6.3 Whip and tongue grafting
See diagram 9.96: Whip and tongue grafting
The genetic "parent" species are Citrus medica, Citron | Citrus reticulata, Mandarin orange | Citrus maxima, Pomelo | Citrus sinensis Sweet orange
1. Whip and tongue grafting is used for citrus fruit and ornamental trees.
The scion and stock will become fused to form a single plant.
A shoot from such a graft shows the character of the scion, not of the stock that nourishes the scion.
Successful grafts are usually between closely related plants.
Citrus trees can be grafted on rootstocks of hardy orange, Poncirus trifoliata.
Insert a cut twig, the scion, into an incision on the stem or root of another plant, the stock.
Bind the two tightly together to give firm contact between the cut surfaces.
Cover the join with an antiseptic wax to prevent infection.
The cambium tissue of the cut surfaces of the scion and stock form a mass of callus, soft, thin walled parenchyma, that joins the two.
2. Grafting
2.1 Cut the stock within 10 cm of the ground level.
Make a long slanting upward cut on the stock about 4 cm long.
2.2 Make a small downward cut on the stock to form a tongue near the top of the slanting cut.
Make a similar slanting downward cut on the scion, leaving a bud midway on the opposite side of the cut.
Make a tongue on the scion to correspond with the tongue on the stock.
2.3 Fit the tongue of the scion neatly into the tongue of the stock to hold the graft firmly in position.
The cut surfaces must be flush.
2.4 Bind the graft with moistened string and apply some warm grafting wax or tree dressing, e.g. "Arberex", to make the joint airtight and watertight.
In all grafting the vital area is the "cambium layer", the thin green layer that lies between bark and wood.
See it in any young stem that is cut through diagonally.
The cambium cells retain the power of growing and knitting with similar cells.
When grafting, the cambium of the scion must be in direct contact with the cambium of the stock so the nearer the two cut surfaces can coincide in length and width the better.
Other methods of grafting include the following: clematis (root grafting) rhododendron (saddle grafting) birch (inarching, one tree to another).
Preface
Before teaching this project, discuss the content of the lessons with a field officer of the Ministry of Agriculture and get advice on planting material, planting
distances, sites for planting, approved mulch, composting, and control of pests and diseases.
Use only the procedures, agricultural chemicals and insecticides recommended by the local field officer of the Ministry of Agriculture.