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Planting is the placement of the planting material in the soil for the purpose of regeneration in order to produce more of the plant species.
Types of planting materials
Seeds
Seeds are produced by flowering after pollination and fertilization. They contain the part of the plant that germinates and subsequently grows in to new plants.
Advantages of using seeds as planting materials.
- Seeds are easily treated against soil borne pests and diseases.
- They are not bulky therefore storage is easy.
- They are easy to handle during planting making operation easy.
- When planting seeds, it is easy to use machines like seed planters and drillers.
- It is easy to apply manures and fertilizers together with seeds during planting.
- Fertilizers and manures application can be easily mechanized.
- It is possible to develop new crop varieties due to cross pollination.
Disantivantages of using seeds as planting materials.
- Some seeds have long dormancy and they may need special treatment in order to germinate.
- Plants raised from seeds have variations from the mother plant due to cross pollination, This may introduce undesirable characteristics.
- Soil borne pests may damage seeds if left for sometime in the soil before rain falls.
- Some seeds may lose viability if stored for a long time. This leads to gaps in the farm.
Vegetative materials.
- These are plant parts which have the ability to produce roots, they grow and develop in to new plants.
- Plant parts such as leaves, roots or stems can be used for planting as long as they are capable of rooting.
Advantages of using vegetative materials for planting.
- Crops originating from vegetative materials matures faster than those from seeds.
- The crops shows uniformity in such qualities as disease resistance, seed size, colour, keeping or storing quality and chemical composition.
- It is possible to produce many varieties of compatible crops on the same root stock.
- Use of the vegetative materials is easier and faster, especially where seeds show prolonged dormancy.
- The resulting plant has desired shape and size for ease of harvesting and spraying.
- It facilitates the propagation of crops which are seedless or those that produce seeds which are not viable or have a long dormancy period.
- Such crops include sugar-cane, bananas, Napier grass and others.
Disadvantages.
- Vegetative propagation does not result in new crop varieties.
- Keeping the materials free of diseases is difficult.
- Materials cannot be stored for long.
- The materials are bulky and there fore difficult to store and transport.
- Plant parts used for vegetative propagation.
Bulbils.
- These are tiny sisal plants produced in the inflorescence almost at the end of the plant growth cycle.
- They resemble the mother plant except that they are smaller in size.
- They are produced by the branches of the sisal pole.
- When manure they mature they develop rudimentary roots and fall off to the ground just below the pole.
- They are the collected and raised in the nurseries before they are transplanted t\o the main field.
- One sisal pole may produce as many as 3,000 bulbils. They are usually 10cm long. They make good planting materials and are better than sucke
Splits
- These are plantlets divided from the existing mother plant with complete with complete leaves and rooting system.
- They are used to propagate most pasture grasses and pyrethrum.
- Pyrethrum splits are raised first in nursery and then transplanted to the field.
Crowns and slips
- These are materials used to propagate pineapples
- Crowns are born on top of the fruits and are broken off and prepared for planting.
- They are more preferred to suckers because they give uniform growth and take two years to reach maturity.
- Slips are borne to the base of the pineapple fruits.
- They are cut and prepared for plantings.
- Their growth rate is faster than for crowns giving average uniformity.
- They take 22 months from planting to maturity.
- Crowns and slips are planted in the nurseries first before transplanting to the main seed bed.
Suckers
- These are small plants that grow from the base of the main stem.
- They have adventitious roots which grow quickly when planted to form a new plant.
- They are used to propagate bananas, sisal, and pineapples.
- When planted, suckers give uneven growth leading to maturity at different times. They should be planted when they are young.
Tubers
- These are underground food storage organs which are short and thick.
- They are used as vegetative propagation materials because they sprout and produce roots for growth.
- There are mainly two types of tubers, the stem and root tubers.
- Root tubers develop from the thickening of the adventitious roots.
- Root tubers are not commonly used for propagation since they produce weak stems.
- A good example of a root tuber is the sweet potato.
- On the other hand stem tubers have some auxiliary buds which are sometimes referred to as eyes.
- These eyes sprout to produce stems which grow into plants. Stem tubers are therefore swollen stems with scales leaves.
- A good example of a stem tuber is Irish potato.
Vines.
- These are soft wood cuttings which produce roots easily upon planting to give rise to new plants.
- They are cut from the mother plants and planted directly into the field.
- Soft wood cuttings (vines) are taken from rapidly growing shoots.
- The soft upper parts of the shoots are preferred.
- When preparing the cuttings, some leaves and nodes are included.
- Roots are produced from the nodes.
Cuttings and setts
- Cuttings are portion of plants parts which are cut and then planted.
- They may be from stems, roots or leaves.
- A stem cutting must have a bud which develops into shoot.
- The root cutting must have an eye. Cutting must have an eye.
- Cuttings must produce leaves as soon as possible so that they can start making their own food.
- Sometimes cuttings are induced to produce roots by use of rooting hormones.
- Once the cuttings have developed roots, they give rise to new plants.
- In some crops, the cuttings are big enough to be planted directly to the main seedbed whereas there are some plants whose cuttings are first raised in special nurseries before they are transplanted to the seedbed.
- The cuttings of Napier grass and sugar-cane are planted directly on the seedbed but those of tea; have to be raised in special nursery before they are transferred to the seed bed.
- Examples of crops which are propagated by use of stem cuttings include: tea, cassava, and sugar-cane and Napier grass.
- The stem cuttings used to propagate sugar-cane are known as setts. Setts are stem cuttings which have 3-5 nodes are usually 30-45 cm long.
Factors affecting rooting of cuttings.
- Temperature: for the cuttings to produce roots warm temperatures are required around the root zone while cool temperatures are important for the aerial part of the cuttings. For most species optimum day and light temperatures for rooting are 22 -27°c and 15-21° c respectively.
- Relative humidity: Proper rooting of cuttings requires high humidity which lower the transpiration rate. It also increases and maintains leaf turgidity all the time. As such, cuttings should be rooted in green houses or under shady conditions, where relative humidity can be regulated. Sometimes the propagation area can be sprayed with water to keep it moist.
- Light intensity: soft wood cuttings need high intensity light to produce roots. This is because light promotes the production of roots since it affects the rate of photosynthesis. Hard wood cuttings do well in dark conditions since they have high amount of stored carbohydrates and therefore rooting is excellent in darkness.
- Oxygen supply: plentiful supply of oxygen is required for root formation. The rooting medium used must therefore be capable of allowing proper aeration.
- Chemical treatment: these rooting hormones which promote the production of roots in cuttings. The common ones include IAA (Indoleacetic acid).
- Leaf area: Soft woods cuttings require a lot of leaves for photosynthesis while hardwood cuttings will produce roots better without leaves.
Selection of planting materials
When selecting materials for planting the following factors must be considered:
- Suitability to the ecological conditions the selected planting materials should be well adapted to the soil conditions, temperatures and amount of rainfall in the area. There are many varieties of maize, for example, which are suitable to different ecological conditions. Hybrid 622f or example is mainly for the high altitudes areas of Kenya 513 for the medium altitudes and the Katumani composites for the low rainfall areas while the coast composites are suitable for the coastal conditions each variety will grow well and produce high yields if grown under the correct conditions
- Purity of the materials - planting materials should be pure and not mixed with other off types the percentage purity of planting materials will affect the seed while higher seeds rates are used for impure seeds.
- Germination percentage - This is a measure of the germination potential of seeds it is expressed as a percentage for example a germination percentage of 80 means that for every 10 seeds planted 80 of them are expected to germinate. Germination percentage helps to determine the seed rates of crops lower seed rates are used for crops with higher germination percentage while higher seed rates are used for those with lower germination percentage.
- Certified seeds - These are seeds which have been tested and proven to have 100 germination potential and free from diseases and pests they give high yields after the first planting but the subsequent yields decline if replaced therefore in this case it is always advisable to buy new seeds which are certified every time planting is done
In Kenya certified seeds are produced by the Kenya seed company (KSC) and distributed by Kenya Farmers Association (KFA) and other agents.
PREPARATION OF PLANTING MATERIALS.
After the planting materials are selected they are prepared in different ways before they are planted. Some of the methods used to prepare planting materials include the following:
(a)Breaking the seed dormancy.
- Some seeds undergo a dormancy period between maturity and the time they sprout. The dormancy period is the stage whereby a seed cannot germinate, the stage of inhibited growth of seed. It should be broken before the seed is planted.
Methods of breaking seed dormancy.
The following methods are used to break seed dormancy:
(I) Mechanical method: This is a method which aims at scratching the seed coat to make it permeable to water. Scarification is done by rubbing small sized seeds against hard surface such as sand paper, while filling or nicking the seed coat with a knife is done to large sized seeds such as croton seeds.
(ii) Heat treatment: this involves the use of hot water or burning the seeds lightly. It softens the seed coat making it permeable to water and thus is able to germinate. The seeds are soaked in hot water about 80c for 3-4 minutes after which the water is allowed to drain off. Example of seeds treated in this way include: leucean 7a^2+3^2=2^2 calliadra and acacia.
Light burning also serves the same purpose as hot water treatment. In this case trash is spread over the seeds which are already covered with a thin layer of soil. The trash is burned, after which the seeds are retrieved and planted. Examples include acacia and wattle tree seeds. Overheating should be avoided as this will cook the seeds.
(iii)Chemical treatment: seeds are dipped in specific chemicals such as concentrated sulphuric acid, for two minutes and then removed. The chemical wears off the seed coat making it permeable to water. Care should be taken not to leave the seeds in the chemicals for too long as this will kill the embryo. Cotton seeds are normally treated with chemicals to remove the lint or fibres.
iv) Soaking in water: seeds are soaked in water for a period of between 24 48 hours until they swell. They are then removed and planted immediately. The seeds treated thus germinate very fast. Pre-germinated seeds are used when raising rice in the nurseries.
b) Seed dressing
- This is the coating of seeds with fungicides or an insecticide or a combination of the two chemicals. This is particularly common with cereals, sugar-cane and legumes.
-The chemicals protect the seedlings from soil-borne diseases and pests. Certified seeds which are sold by seed merchants in Kenya have been dressed with these chemicals. Farmers can also buy the chemicals and dress their own seeds.
C) Seed inoculation
In areas where soils are deficient in nitrogen, legumes such as beans, clovers and peas should be coated with an inoculant. An innoculant is a preparation which contains the right strain of Rhizobium depending on the type of legume and encourages nodulation, hence nitrogen fixation. Below is a table showing different legume crops and their right strain of Rhizobium.
