POST PURCHASE HANDLING OF SEEDLINGS

By Farai Mutoti

For your winter horticultural crops

With the advent of commercial nurseries, farmers can now focus more on crop production than worrying about producing their own seedlings. This article will provide best practice guidelines in post-purchase handling and transportation of seedlings.

The first step to successful vegetable production is raising healthy vigorous seedlings. Young plants propagated from seed or vegetatively require a lot of care particularly during the early stages of growth. They have to be protected from adverse temperatures, heavy rains, drought, wind and a variety of pests and diseases. Short, sturdy, slightly hardened, with a well-developed root system, seedlings perform better after transplanting than soft, lanky, etiolated plants. The traditional transplant size is when the plant is at its 5 to 6 true leaf stage. Younger plants of the desired size perform better than older ones. Under warm growing conditions, most of these crops will reach the transplanting stage within 4 to 6 weeks, but this period may be doubled under colder conditions we are going towards.

Transportation of seedlings from nursery to planting site or farm

  1. If the seedlings are to be transported in stacks, they must be removed from seedling trays and placed in crates lined with moist hessian bags for transportation. Lift the plants carefully, with as little root damage as possible and cover them with moist-hessian sacks placed in a plastic lined crate. This should be done carefully for minimal damage. Cover the crate on top with a damp hessian cloth to minimize dehydration and increase humidity. Crates are there to provide safe transit when piled up in a truck without damaging the seedling roots, leaves and stem. Any plants showing signs of being weak, diseased or abnormal should be discarded.
  2. If the seedlings are to be transported in stacks, they must be removed from seedling trays and placed in crates lined with moist hessian bags for transportation. Lift the plants carefully, with as little root damage as possible and cover them with moist-hessian sacks placed in a plastic lined crate. This should be done carefully for minimal damage. Cover the crate on top with a damp hessian cloth to minimize dehydration and increase humidity. Crates are there to provide safe transit when piled up in a truck without damaging the seedling roots, leaves and stem. Any plants showing signs of being weak, diseased or abnormal should be discarded.

The time difference between the seedlings being collected from the nursery and their transportation to the respective farming area should be as short as possible. They must be constantly protected from strong light, heat and drying out.

a) A crate that can be lined with hessian bag

(b) A hessian bag cloth

Transplanting

Seedlings need to reach a certain size before they are transplanted. However, some of the seedlings may have to be transplanted at a later stage due to their slow growth, but studies show that such seedlings are less likely to grow.

Hardening-off

The practice of hardening-off must be done prior to transportation and transplanting. This can be explained as a process where plant tissues are toughened to withstand harsh natural conditions. Most seedlings are often grown indoors subjecting them to high humidity and low light. Such conditions will not only result in the seedlings being susceptible to poor stomatal functioning, but they will have a thin cuticle with their chloroplasts not adapted to high light intensity and consequently soft seedlings will be the result. When these types of seedlings are subjected to a harsh environment (cold, heat, wind and water stress) they suffer a severe transplant shock. To avoid this, hardening-off should take place 7 to 14 days prior to transplanting. Ways of hardening-off is by slowly removing all forms of protection; gradual reduction of water through less frequent irrigation making sure the growth medium does not dry out and gradually exposing them to more light (intensity and duration).

A well hardened plant can be recognised by a darker green colour and the development of a slight purple tinge in the leaf veins on the lower side of the leaf. When the whole leaf on the underside is purple it indicates that the plant has not only hardened-off but is also stunted.

Essence of time when transplanting

Timing is important when it comes to transplanting: transplanting too early in the day during the winter period may result in your plants succumbing to frost and transplanting too late in the day in summer may result in your plants getting baked by the sun. Ideally, transplanting should be done early in the morning or late in the afternoon. This is when humidity is at its highest, reducing desiccation, as well as it being the coolest time of the day.

How to minimise diseases in horticultural vegetable transplants

Media and water: All growing media and irrigation water should be pathogen free. In some instances, water pipes should have filters fitted to exclude propagules of known pathogens.

Planting materials: Make sure strict sanitation measures are followed when handling seedlings during the transplanting process after transportation. Thoroughly washed and sanitized hands should handle the seedlings for both the greenhouse and open field. No smoking and chewing of tobacco whilst the transplanting process is being carried out.

Cultural practices: Attention must be given to practices such as fertilisation, irrigation and temperature. Free moisture from sprinklers or condensation on plants for prolonged periods should be avoided.

Soil tillage: It is often possible to destroy one or more flushes of weeds while tilling the land before planting, particularly when soil preparation starts some while before planting. In such circumstances the final cultivation should be as follows (less than 20mm) as possible, to avoid bringing fresh weeds closer to the soil surface where they can germinate.

e-mail: rfmutoti@gmail.com

cell: 0774686470

Featured image- https://www.growveg.com/guides/hot-weather-vegetable-transplanting-tips/


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