Recent Advances in Hi-Tech Vegetable Nursery Production

Vegetable nursery production has become a highly commercialized business, wherein most farmers buy their plugs from professional growers. A vegetable nursery is a place or an establishment for raising or handling young vegetable seedlings until they are ready for more permanent planting. The seeds of some vegetables are first sown in the nursery beds and the seedlings from these beds are later transplanted in the main field.

Such vegetables are generally small-seeded crops that belong to solanaceous, cruciferous, and cucurbitaceous families besides onion, lettuce, asparagus, etc. In the future, many more crops may be grown as seedling transplants, especially those of high economic value and potentially high seed cost.

Advantages of nursery raising: Nursery raising is an essential practice owing to the following reasons (Nandpuri and Singh, 1986):

It is convenient to look after the ‘baby seedlings’ with better care in nursery bed.
The size of seeds being small, it is almost impossible to do direct sowing properly.
The hybrid seeds being expensive can receive better care and thus ensuring uniform crop stand.
The land can be economically used as it can be put under some other crop when the nursery is being raised.
Less expense is involved in controlling insect-pests and diseases in nursery beds.
Undesirable seedlings can be discarded at the time of transplanting.
Availability of sufficient time for field preparation, manure and fertilizer application after harvesting the previous crop.

Yearly demand of vegetable seedlings and seeds in India:

Crop	Seedling (millons)	Seed (kg)
Tomato	13028	600
Brinjal	200000	635
Chilli	14157	195
Onion	695000	2779
Cabbage	22963	101
Cauliflower	12669	87

(Source: Resource Book on Horticulture Nursery Management, NAIP, ICAR, 2012)

Components and processes involved in modern nursery raising system: Seedling tray, media, mechanization, irrigation, nutrients, a protected structure, light and seed pelleting and priming, biological enhancement, and hardening.

Selection of site: The following points should be taken into consideration while selecting an area for nursery production:

The land should be well-drained, fertile, and rich in organic matter.
The area should be free from waterlogging.
It should always be away from shade to get desired sunlight.
The nursery area should be near a water source.
The area should be fenced from the pet and wild animals.

A. Conventional method: For raising healthy nursery through conventional method following protocol is mainly adopted:

Raised nursery beds of well-pulverized soil with 3m × 1m × 0.15m size are prepared.
The beds are fertilized with 20 to 25 kg well rotten FYM, 200 g SSP, and 15-20 g Dithane M-45.
To prevent damping off disease, nursery beds are treated with formaldehyde (25 ml/liter of water) and are covered with air-tight polythene for one week and after removing the polythene the soil is turned up and down for three weeks to remove the remains of the formalin fumes.
Pre-treatment of seed with Captan and Bavistin (2 -3 g/kg of seed) is also practiced to check the attack of damping off.
The treated seeds are sown in the lines 5 cm apart at 0.5-1.0 cm depth and are covered with a thin layer of well rotten FYM and soil mixture.
In order to conserve soil moisture, beds are mulched with dry grass and are irrigated in morning and evening hours regularly till the seedlings emerge out.
Mulched grass is removed as soon as the seedling emergence is observed and nursery beds are drenched with a mixture of Dithane M-45 (0.25%) and Bavistin (0.1%) to avoid damping-off disease.
In case seedlings are weak/deficient in nitrogen, urea is sprayed @ 0.3% when seedlings are 8-10 cm tall.
The seedlings become ready for transplanting in 4-6 weeks or when they attain a height of 10-15 cm.
Irrigation is withheld 3-4 days prior to transplanting so that plants become hardened. But, on the day of transplanting, sufficient water is applied in the nursery bed, and then seedlings are taken out for transplanting.
The transplanting is mainly carried out during evening hours for better crop establishment.

B Hi-tech nursery raising techniques

Covering with polythene sheets

In order to ensure early germination, thatching can be swapped with transparent/white polythene sheet (150-micron thickness). After seed sowing, irrigation water is applied in the nursery beds up to field capacity. Then the beds are covered with transparent/white polythene sheets and are made airtight by covering the sheet edges with soil. The polythene sheath is removed after the competition of the germination process. The rest of the cultural practices are similar to the conventional method of nursery raising.

2 Polytunnels for normal weather

The nursery beds are covered with pre-fabricated tunnels of size 3m long, 1.5m wide, and a central height of 1.0m. The semi-circular structure is clad with a UV-polythene sheath (200 microns) with 75 percent transmittance. Once the seed sowing, covering, and irrigation to field capacity are over, the bed can be covered with the tunnels. Both the openings can be closed if the nursery is grown in winter.

3 Sunken nursery for weather extremes

Prepare a trench of any length, 1.2m wide and 50cm deep.
Prepare a raised bed of 5-10 cm height at the bottom of the trench. The soil should not be imported from outside the trench. Albeit, FYM (25kg) and inorganic fertilizer mixture (100g) may be added as recommended earlier. Precautions must be observed in applying FYM. It may be treated with fungicide/Trichoderma (1kg/100kg dung) at least 15 days prior to bed preparation.
Seed treated with Captan/bavistin may be sown in lines at 5cm width and cover the seed with the same soil.
Drench the beds with water to the field capacity of the soil.
Cover the trench with white, transparent polythene sheath, providing taper to both sides.
Make the sheath air tight from all sides.
Start observing the emergence of the seed through the poly sheath from tenth day onwards.
Once the emergence is over, irrigation may be regulated, as required till the 4 leaf stage is achieved.
Polythene cover may be removed in sunny days or converted into a roof in rainy days.
4 Naturally ventilated polyhouse

For commercial nursery production, naturally ventilated polyhouses can be used. In a polyhouse of 100 m² area, 40,000 seedlings can be raised in one batch and we can have a total of five such batches per year.

(i) Polybags for cucurbits

Most of the cucurbits are seed propagated and in situ sowing is practiced. In some cases where the early crop is desired, seeds can be sown in alkathene bags and germinated under protected cover from low temperature. The seedlings are transplanted from the bags at the 2-true-leaf stage. This practice is prevalent in Punjab, especially in the case of muskmelon and it can be done in the hills to get the early crop in July. Normally, the cucurbits do not stand transplantation beyond this stage due to injury to taproot. There is a considerable saving in seed quantity, nearly 50 to 60 percent as compared to in situ sowing (Bose and Som, 1986).

(ii) Plug tray technique

Plastic trays or pro-trays having different sizes of cells are commonly used for raising vegetable seedlings. Mainly two kinds of plastic pro-trays are used for raising the seedlings in several European countries and Israel. In case cucumber, muskmelon, tomato, and brinjal require plastic trays of 187 cells of 3.75 cm (1.5”) size, whereas lettuce, cabbage, cauliflower, and capsicum require trays having 345 cells of 2.5 cm (1.0”) size. These trays help in proper germination, provide an independent area for each seed to germinate, reduce the mortality rate, maintain uniform and healthy growth of seedlings easy to handle and store, reliable and economical in transportation.

The seedling tray (pro-tray) is filled with the growing medium (coco peat, perlite, and vermiculite).
A small depression (0.5 cm) is made with a fingertip in the center of the cell of the pro tray/ plug tray for sowing.
One seed per cell is sown and covered with medium.
Coco peat with 300 to 400 percent moisture is used and hence no immediate irrigation is required until germination.
After sowing 10 trays are kept one over the other for 3 to 6 days, depending on the crops.
The entire stack will be covered using a polyethylene sheet to ensure the conservation of moisture until germination. The stacked trays are spread once the germination commences avoiding etiolation.
The trays are shifted to the net house on germination of seedlings and spread over the beds.
The trays are irrigated lightly every day depending upon the prevailing weather conditions by using a fine sprinkling rose can or with a hose pipe fitted with a rose.
Drenching the trays with fungicides as a precautionary measure against seedling mortality is also being done.
Spraying of 0.3 percent (3g/liter) water-soluble fertilizer using poly feed (19 all with trace elements) twice (12 and 20 days after sowing) is practiced to enhance the growth of the seedlings.
The trays are provided with protective cover from rain by covering with polyethylene sheets in the form of a low tunnel whenever it rains.
- The seedlings at the right stage of planting are hardened by withholding irrigation and reducing the shade before transplanting or selling to the growers.
- Systemic insecticides are sprayed 7-10 days after germination and before transplanting for managing the insect vectors.
- The seedlings would be ready in about 21-42 days for transplanting to the main field depending upon the crop.
Seedling management

Damping-off control:

Young seedlings may develop a sunken, brown, necrotic lesion near the soil line due to fungal infection. If the lesion girdles the stem, the seedling collapses and soon dies. To prevent this problem, apply 1 g Bavistin + 2 g Dithane M-45 or 1 g Bavistin + 2 g Kavach per liter of water after thinning. If damping-off symptoms develop further, apply 2 g Kavach + 1 g Roko per liter of water during the seedling stage.

Symptoms of damping-off: the necrotic, brown lesion girdles the stem, and the seedling collapses (red circle) and soon dies.

Conclusion

The advent of different nursery growing techniques has opened new vistas for growing vegetable crops in any month of the year irrespective of any vegetable crop. Such innovative techniques are facilitating the growers in producing off-season vegetables for fetching remunerative prices.

References

Bose, T.K. and Som, M.G. (1986). Vegetable crops in India. Naya Prokash, Bidhan Sarani, Calcutta. P. 128.

Nandpuri, K.S. and Singh, S. (1986). Vegetable growing in Punjab. PAU, Communication centre, Ludhiana. P. 141.