CROP PRODUCTION III ( NURSERY PRACTICES)

Introduction

• Planting materials are either planted directly in a seedbed or indirectly through a nursery bed.
• A seedbed is a piece of land which could be small or large and prepared to receive planting materials.
• A nursery bed on the other hand is a small plot of land specially prepared for raising seedlings or planting materials before transplanting.
• It is usually 1m wide and any convenient length depending on the quantity of seedlings to be raised.
• A seedling bed is a special type of nursery bed used for raising seedlings pricked out from the nursery bed due to overcrowding before they are ready for transplanting.
• Pricking out refers to the removal of seedlings from a nursery bed to a seedling bed.
• Nursery practices refer to all the activities carried out throughout a nursery life to raise seedlings. .

Importance of Nursery Bed in Crop Production

• To facilitate the production of many seedlings in a small area.
• It is easy to carry out management practices in a nursery than in the seedbed.
• It facilitates the planting of small seeds which develop into strong seedlings that are easily transplanted.
• It ensures transplanting of only healthy and vigorous growing seedlings.
• It reduces the period taken by the crop in the field.
• Excess seedlings from the nursery may be sold to earn income. 

Selection of a Nursery Site

Factors to consider;

• Nearness to the water source.
• Type of soil.-should be well drained, deep and fertile, preferably loam soil.
• Topography.-it should be situated on a gentle slope to prevent flooding and erosion through surface run-off.
• Previous cropping.-to avoid build up of pests and diseases associated with particular plant families, consider the preceding crops.
• Security.-select a site that is protected from theft and destruction by animals.
• Protection against strong winds and heat of the sun.-select a sheltered place. i.e. to avoid excessive evapotranspiration and uprooting seedlings. 

Types of Nurseries

Categories of nurseries:

Vegetable Nursery:

• They are used for raising the seedlings of vegetable crops.

Tomatoes, cabbages, kale, onions, brinjals and peppers.

Vegetable Propagation Nurseries:

• They are used for inducing root production in cuttings before they are transplanted,
• The cuttings can be planted directly in the soil and hence called bare root nurseries.
• Or planted into containers such as pots, polythene bags and others, hence called containerized nurseries.

Tree Nurseries:

• These are used for raising tree seedlings.
• The seedlings can be raised in bare root nurseries or in containerized nurseries.

Nursery Management Practices:

• These are the practices carried out in the nursery while the planting materials are growing.

They include:

• Mulching. –light mulch should be applied on thenursery bed.It be  should be removed on the 4^th day
• Weed control.
• Shading.
• Pricking out.
• Pests and disease control.
• Hardening off
• Watering. 

Preparation of vegetative materials for planting:

• Cuttings -These are plant parts such as stems, leaves and roots induced to produce roots and used as planting materials.
• Grafting –
• It is the practice of uniting two separate woody stems.
• The part bearing the roots is referred to as root stock while the part which is grafted onto the rootstock is known as
• The scion has buds which develop into the future plant.
• The ability of the rootstock and the scion to form a successful union is termed as

Methods of Grafting

Whip or tongue grafting:

• In this case the diameter of the rootstock and the scion are the same.
• It is carried out when the diameter of the scion and the rootstock is ‘pencil’ thick.

Side grafting: In this case the diameter of the rootstock is bigger than that of  the scion.

Other types of grafting include ;

• Approach grafting,
• Notch grafting
• Bark grafting.

Budding:

• It is the practice of uniting a vegetative bud to a seedling of another plant.
• The scion has only one bud and some bark with or without wood.
• The bud is inserted in a slit made on the bark of the stock.
• It is held tightly on the stock by tying with a budding tape until it produces a shoot.

Methods of Budding:

• T-budding
• Top budding
• Patch budding.

Importance of Budding and Grafting:

• Plants with desirable root characteristics but with undesirable products may be used to produce desirable products for example lemon­-orange graft.
• They facilitate the changing of the top of the tree from being undesirable to desirable

• They make it possible to grow more than one type of fruit or flower on the same plant.
• They help to propagate clones that cannot be propagated in any other way.
• They help to shorten the maturity period.

Layering

• It is the process by which a part of a plant is induced to produce roots while still attached to the mother plant.
• Once the roots have been produced, the stem is then cut off and planted.

Types of layering;

• Marcotting or aerial layering.
• Tip layering.
• Trench layering.
• Compound or serpentine.

Tissue Culture for Crop Propagation

• Tissue culture is a biotechnology used in cloning vegetatively propagated plants.
• It is based on the ability of plant tissue (or cells) to regenerate other parts of the plant.
• The tissues are derived from shoot tips where cells are undergoing rapid cell division and are not differentiated.
• The cells are then provided with the right conditions which enable them to multiply and develop roots. 

    The Right Conditions  for tissue culture:

• Culture medium.
• Correct temperature.
• Correct light intensity and
• Correct relative humidity.

Importance of Tissue Culture in Crop Propagation

• It is used to recover and establish pathogen-free plants especially in the control of viral diseases.
• It is used in mass production of plantlets or propagules.
• It is fast and requires less space than the cultural methods of using cutting which requires a bigger space.

Transplanting Seedlings

• Transplanting of vegetable and tree seedlings are generally the same.
• Generally, vegetable seedlings are ready for transplanting when they are one month old or have 4 -6 leaves or are about 10-15cm in height.
• Before transplanting, the nursery bed is adequately watered 3 – 4 hours before lifting the seedlings.
• This ensures the seedlings are lifted easily with a ball of earth around the roots to minimize root damage.
• Tree seedlings take a little longer to reach transplanting age compared to vegetable crop seedlings.
• The roots are trimmed before lifting the seedlings.
• Transplanting should be done at the onset of the long rains to give the young trees a good start.
• After transplanting the young trees should be protected from damage by animals for a period of about one year.