Scientific nursery raising of vegetable crops

AK Bijaya Devi / Sinam Sharmila Devi / Mrinalini Longjam *

Increasing susceptibility of vegetables to various biotic, abiotic stresses and very high cost of hybrid seeds has warranted the attention of the vegetables growers to improve the nursery technology of vegetables. Raising a nursery from seeds provides an easy and convenient way to nourish tender the young seedling in a well-managed, small and compact area for better germination of small and costly seed.

In general, vegetable crops are divided into three groups according to their relative ease of transplanting. Beet root, broccoli, Brussels sprouts, cabbage, cauliflower, tomato and lettuce are efficient in water absorption and rapidly form new roots after transplanting.

Vegetable crops that are moderately easy for transplanting are brinjal, onion, sweet pepper, chilli, celery which do not absorb water as efficiently as crops that are easy to transplant but they form new roots relatively quickly. The vegetable crops which are difficult to transplant are cucurbits and sweet corn which require special care during nursery raising and transplanting.

Seedlings not only reduce the crop span but also increase the uniformity of crop and thus harvesting as compared to direct sown crops. Transplanting of seedlings also eliminates the need for thinning and provides a good opportunity for virus free vigorous and off-season nursery if grown under protected conditions.

NURSERY:

A vegetable nursery is a place or an establishment for raising or handling young vegetable seedlings until they are ready for more permanent planting.

ADVANTAGES OF NURSERY MANAGEMENT:

1. It is possible to provide favourable conditions i.e. germination of seeds and growth and development of seedlings.
2. Insect-pests and disease can be controlled easily and efficiently.
3. It facilitates better utilization of land.
4. Seedlings are uniformly healthier and stronger.
5. Growing conditions can be easily manipulated for germination emergence etc.

SELECTION OF LOCATION AND SITE:

1. The area selected should be well drained and free from water logging.
2. There should be proper sunlight.
3. The nursery bed should be near the water supply and so that irrigation can be easy.
4. The area should be well protected from pets and wild animals.
5. Soil should be loam to sandy loam, loose and friable rich in organic matter and well drained.

A. SOIL TREATMENT:

1. SOIL STERILIZATION: This treatment was done 10-15 days before sowing of seeds. Drench the nursery bed with 2% solution of formalin by spraying 4-5 litres of solution per square meter. Cover beds with plastic sheet/tarpaulin for 24 hours. After that the polythene sheet should be removed and the soil should be turned over so that the smell of formaldehyde disappears. The soil should be kept as such for some time by turning again and again until the smell goes off. When there is no smell of the chemical, soil is used for sowing of seeds.

2. SOIL DRENCHING: Soil drenching was done with Captan @ 2g/1 litre of water and applied to soil till it was completely saturated with water up to a depth of 15 cm. Soil drenching can also be done by Thiram, Cerasan etc. By doing so, soil borne fungi like Pythium, Phytopthora, Fusarium, Rhizoctonia can be controlled effectively.

3. BURNING OF NURSERY BEDS: Spread dry leaves or paddy straw in a thin layer in the nursery bed and burnt it. This helps in destroying diseases and pests. But nowadays it is not practiced as it is not environmentally friendly due to the production of smoke in the atmosphere.

B. DIFFERENT WAYS TO RAISE HEALTHY NURSERY:

1. RAISING NURSERY ON BEDS: Dig the soil thoroughly to make it in a fine tilth and remove clods and raise nursery beds. It needs a deep cultivation of nursery land either by soil turning, plough or by spade and subsequent two-three hoeing with cultivation. Mix top soil, dried and well decomposed farmyard manure and sand in a ratio of 2:1:1 or 500g vermicompost/sq.m and mix properly in the soil.

After that all the clods, stones, weed stubbles are removed from the bed and then land should be levelled. Raised bed of 10-15cm height, 60-90 cm width and convenient length is prepared. Sprinkler water as and when necessary. Keep in mind not to over water as excessive moisture encourages damping off seedlings. In between two beds leave space 25-30cm.

In the prepared beds the seeds are sown by opening miniature furrows about 2-4cm. deep and 8-10 cm apart. The depth of the furrow will depend upon the size of the seeds. Bolder the seed, deeper the furrow. After sowing the seeds in the furrow, the seeds should be covered.

2. RAISING NURSERY IN POLYTHENE BAGS: This method is commonly used in cucurbits. Early crops raised in polythene bags mature 15-20 days earlier than directly seeded crops. The polythene bags of 15 cm. x 10 cm. size and of soil and well rotted farmyard manure and equal proportion or with a mixture of soil and well-rotted farmyard manure and silt in equal proportion when soil is sandy.

Five to six kg. of bags are required to raise seedlings for an acre. The seed should be sown in bags in the last week of January or in the first week of February. The bags should be placed near the wall facing the sun.

The seeds should be sown deeper than 1.5 cm. After, water should be applied daily in the afternoon, preferably with a sprinkling can. Transplanting should be done by the end of February or first week of March when the seedlings are 25-30 days old and have two true leaves.

3. RAISING NURSERY IN PLUG-TRAYS/WOODEN BOX: Seedlings are raised in polypropylene trays such as portrays, flat trays and plug trays provided with holes at bottom. Portrays of 96 cells are commonly used for raising seedlings and size of container varies with crop. Trays and medium should be thoroughly disinfected with formaldehyde.

Trays are filled with well decomposed and sieved soil and sand mixture in the ratio of 2:1 before filling in the trays. These trays help in proper germination, reduce mortality rate, maintain uniformity and healthy growth of seedling, are easy to handle and store, reliable and economical in transportation. Seeds are sown @ one/cell and irrigated with a water can.

After this, place the 8-10 trays one over the other to create a hot and humid condition suitable for germination of seeds. Trays are placed in poly houses or net houses after germination. Place a plastic sheet under the trays to avoid penetration of roots to soil. When three true leaves appear, spray 0.25% soluble fertilizer (NPK) in 1:1:1 ratio. After this for hardening, place trays in direct sunlight before transplanting in the field.

C. SEED SOWING:

Treat the seed with Captan or Thiram @ 3g per kg of seed before sowing. Seeds are sown either by broadcasting or sowing in rows/lines. Later one is more advantageous due to easiness in weeding, application of plant protection chemicals and uprooting for seedlings. After preparation of nursery bed, shallow furrows are made with finger or sticks at a distance of 5-10 cm. on levelled beds.

Seeds are sown uniformly in furrows. Furrows can be made with special furrow making frames. Small sized seeds are sown by mixing with fine sand. Sowing should be thin so as to have 2-4 a seed per cm. Depth of furrow is kept at four times the diameter of seed. Seeds of cabbage, cauliflower, chilli, brinjal, tomato, etc. are sown 1.0-1.5 cm. deep.

Cover the furrow with a thin layer of paddy straw to avoid crust formation and irrigate the nursery bed with water so as to keep the nursery bed moist. During the peak summer season raise the nursery under shade net to protect seedlings from hot weather conditions.

Nursery can be made in ploy house made up of transparent UV stabilized polythene film which provide a controlled and favourable environment for proper germination of seeds and also checks incidental entry of insect pest.

D. DISEASES AND INSECT PESTS OF NURSERY PLANTS:

DAMPING OFF SEEDLINGS: This disease commonly occurred in poorly managed nursery beds. The symptoms of disease occur in two phases i.e. pre-emergence and post-emergence death of seedlings. In the former, there is failure of seedling emergence from soil either due to seed rots or killing of young seedlings before their emergence from soil, hence resulting in patchy appearance of seedling stands in nursery. In post emergence damping off, the disease outbreak is characterized by toppling over the infected seedlings at any time after their emergence from soil.

CONTROL MEASURES:

1. Treat the seeds with Captan or Thiram @ 3 g per kg of seed before sowing.
2. Drench the nursery beds with 0.4% Captan or Thiram (400g in 100 litres of water) 5-7 days after germination. Repeat the drenching after 7 to 10 days if necessary.
3. If there is an attack of insect spray recommended insecticide to control the insect.

E. ESSENTIAL OPERATIONS IN NURSERY RAISING:

1. MULCHING: Immediately after sed sowing about 5 cm. thick layer of mulch (farm residues, saw dust, ash, polythene etc.) should be applied over the bed to conserve moisture in the soil. When the seed germinates, the layer of mulch should be removed.

2. PRICKING: The transferring of young seedlings into another bed, pan or tray is termed as pricking. This operation is practiced when the seedlings at two leaves stage and the seedlings become large enough to handle. It is done with the objective of fast and vigorous development of seedling and minimizing transplantable time.

3. HARDENING OFF: This is a practice of exposing the plants to full sunlight and withholding the irrigation for seven to ten days before transplanting so as to make the plant able to tolerate external growing conditions.

F. UPROOTING OF SEEDLING:

One or two weeks before transplanting restrict or withhold irrigation for 7-10 days for hardening of seedlings. Hardened seedlings withstand transplanting shock better than in the main field. Irrigate nursery beds heavily on the previous day of uprooting to facilitate easy uprooting of seedlings without damage to roots of seedlings. Seedlings should always be transplanted at their suitable age.

Generally, it has been seen that over-aged seedlings have a high percentage of mortality and a slow established rate. Bolting in onion and premature seeding in cabbage are the best examples of negative effects of planting over-aged seedlings in the field. Suitable ages for transplanting seedlings of some crops are given below.

Sl. No. Vegetable crops Age in weeks
1. Brinjal (3-4)
2. Tomato (3-4)
3. Brussels sprouts (6-8)
4. Cabbage (4-6)
5. Cauliflower (3-4)
6. Sprouting broccoli (3-4)
7. Celery (6-8)
8. Leek/lettuce/Parsley (4-5)
9. Onion (6-8)


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