In Kerala and Tamil Nadu regions the seedlings are transplanted to secondary nursery beds when they are about 6 months old, where as in Karnataka, the practice is sowing seeds in the primary nursery and thinning out excess seedlings and then allowing the remaining ones to grow right in the same place. Transplanting seedling to secondary nursery reduces nursery diseases. Korikanthimath (1982) has shown that following both primary and secondary nursery practices would be needed to get vigorous seedlings having 4-5 tillers with in a span of 10 months and with lesser incidence of pests and diseases.
On an average, 10 secondary beds are required for transplanting seedlings from one seedbed. Beds for transplanting are prepared in the same way as for primary nursery seedbeds. A mixture of powdered cow dung and wood ash is spread over the secondary beds before transplanting. In Karnataka, where seeds are sown during August-September, transplanting or thinning out takes place in November-January. In Kerala and Tamil Nadu states, seedlings from primary beds are transplanted to secondary nursery beds at a spacing of 20 X 20 cm during June-July. Rate of mortality was found to be higher when transplanting was done in second leaf stage (25.4 per cent) as against fifth leaf stage (1.1 per cent). Korikanthimath (1982) reported that the number of tillers produced per seedling was significantly more at the wider spacing of 30 X 30 cm (11.9) compared to the lesser spacing at 22.5 X 22.5 cm (9.2) or 15 X 15 cm (7.3). However, taking into consideration the larger area required and greater expenditure involved in raising nursery by transplanting seedlings at 5-6-leaf stage, a spacing of 15 X 15 cm is commonly recommended.
Well-decomposed compost, cattle manure and fertile top forest soil are used for application to each bed at the rate of 8—10 kg (2.5 X 1.0 m) both in primary and secondary nursery. On average, 120 g nitrogen, 20 g phosphorous and 300 g potash, 50 g magnesium and 75 g calcium are removed from a bed planted with 100 seedlings. To promote uniform growth, 250 g mixture made of nine parts of NPK 17:17:17 and eight parts of zinc sulphate dissolved in 10 l of water may be sprayed once in 15—20 days, starting one month after transplanting (Anonymous, 1990). Regional Research Station, Mudigere, recommends NPK mixture at the rate of 160 g per bed one month after planting. This is to be increased by 160 g every month until a maximum of 960 g per bed is reached. The proportion of NPK is one part urea, two parts superphosphate and one part muriate of potash (Anonymous, 1979).
Korikanthimath (1982) observed that application of 45 g N, 30 g P2O5 and 60 g K2O per bed of 2.5 X 1m size in three equal splits at an interval of 45 days would result in better growth and higher number of tillers. First dose of fertilizer may be applied 30 days after transplanting in the secondary nursery. Application of diammo-nium phosphate (DAP) along with muriate of potash is found to be beneficial for tiller and root production (Anonymous, 1989).
To protect the seedlings from sun, overhead shade has to be provided. Erecting a framework with wooden poles and sticks and then spreading over it nylon nursery (green house) mat or coconut leaves is usually used for this purpose. Nursery mat that can give 50 per cent shade is ideal, as growth and tiller production is found to be much better under such conditions. The shade nets have to be removed with the onset of monsoon.
The nursery beds should be irrigated twice a day immediately after planting up to 8—10 days, thereafter once a day up to 30 days. Once the seedlings establish and put forth new growth, watering may be resorted on alternate days till the monsoon starts. Flood and splash irrigations should be avoided as it may increase the problem of damping off and leaf spot diseases. Adequate drainage should be ensured to avoid stagnation of water, particularly in the low-lying areas during monsoon by providing central and lateral drains.
Hand weeding has to be done once in 20—25 days to keep nursery beds free from weeds. The weed growth will be smothered once the seedlings attain sufficient growth.
The topsoil between the rows of cardamom seedlings would normally get washed away and deposited in pathways provided between nursery beds. Scraping of soil deposited from pathways and application in a thin layer up to collar region may be taken up 2 months after transplanting seedlings in secondary nursery. Application of the fertile soil collected from jungle along with cattle manure would be beneficial. Earthing up may be taken up immediately after split application of fertilizers.
It would be ideal to shift nursery sites once in 2-3 years to avoid build up of insects/pests in the area. Where such shifting is not possible due to non-availability of alternate site, it would be better to follow rotation of land with green manure crops (like Crotalaria, Sesbania etc.) and raising of cardamom seedlings. Green manure crops should be ploughed back and incorporated in soil once in 2 years and then cardamom seedlings may be raised. The practice of leaving part of the area fallow after deep digging/ploughing for a year would help in exposing of insects/pests to sun and bringing down the inoculum build up in the nursery site during the previous years.
By following cultural practices regularly, seedlings would be ready for transplanting in main field (plantation), 10 months after sowing seeds. Raising of seedlings in primary nursery and later transplanting them to secondary nursery is found to be more advantageous, as it facilitates better establishment and initiation of adequate number of suckers per plant.
A survey conducted in Coorg, Hassan and Chickmagalur districts of Karnataka has shown that most small and marginal farmers raise cardamom nursery in paddy fields (wet lands) as water is easily available. Sufficient drainage has to be provided both in and around the nursery to avoid water stagnation during monsoon. Beds are separated by deep channels where in natural water is always available. As soils are frequently heavy, there is some risk of excessive moisture in the soil (Mayne, 1951). Such areas which normally possess sandy loam soils facilitate better root development and adequate growth of seedlings.
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