Sandy loam soil is the best for raising nursery on orthodox beds. Wherever possible, the nursery site should be on virgin soil. In absence of virgin soil, uprooted tea area or area with poor soil may be used after the site has been put under green crops like Crotolaria anagyroides, Mimosa invisa or grasses like Tripsecum laxum (Guatemala), Cymbopogon (Citronella), etc., for a period of about two years. The plants need lopping 2-3 times a year and the loppings should be left in situ for decomposition. Alternatively, the area may be heavily dressed with cattle manure @ 25 tons/ha. The area should be criss-crossed ploughed and harrowed about a month before the beds are ready for sowing. Beds should not be prepared during rains. If the green crop or Guatemala grass was raised, the land should preferable be deep hoed only. The seedbeds may be of any convenient length but should not be wider than 1.5m for convenience of cultural operations. In North East India, the beds are generally prepared flat 10-15 cm above the surrounding ground level. Each nursery bed is enclosed by a drain 20 cm deep and 20 cm wide, which is linked up with outlet drain. Single super phosphate (SSP) should be applied to the soil @ 50g/m2 before sowing the seeds. A nursery bed measuring 30m x 1.5 m or 37.5m x 1.2 m will accommodate about 1300 seeds when sown at 20cm x 20cm (triangular) spacing.
Tea seeds are planted on nursery beds in rows at a depth of 1.5 cm with the “eye” facing downwards or parallel to the ground surface. If the seedlings are to be lifted with the bheti (a cylinder of earth about 15 cm in diameter and 20-25 cm in depth around the roots) for transplanting in the field later, the seeds are sown with a spacing of 20 cm. This spacing can be reduced to 15 cm or so for preparing the seedling for stump or carrot planting where the lifting the plants with the bheti is not required. The nursery bedscan be of any convenient length and up to 120 cm wide.
Polythene sleeve Nursery
When land is insufficient, seedlings are raised in polythene sleeves (17 cm lay flat wide, 20-30 cm long and 150 gauge thick). Soil can be brought from any convenient site but must be tested for acidity and eelworm population. It should be mixed with superphosphate @500 g/m3 of soil and the sleeves filled with the soil 3-4 weeks before sowing. Seeds are sown at of 0.5-1cm depths with the “eye” facing downwards and covering the seeds with a thin layer of soil. The sleeves can be placed in a permanent nursery site where irrigation facilities exist. If irrigation facilities are not available, sleeves can be placed under usual overhead shade or green crop shade. Vigorous seedlings can be planted in the field in April-May when they are 5-6 months old. For planting 1-year old seedlings, seeds should be sown in 30 cm long sleeves. However, it will be necessary then to shift the sleeves once or twice after mid-July to prevent the taproot from penetrating the ground. For planting one hectare one would require 40-60 kg tea seeds depending upon the spacing.
Pre-germination of the seeds in moist sand kept in germinating pits with mulch cover is necessary in order to raise good nursery. They are ready to be transferred to the sleeves as soon as the seeds crack. Seeds that do not germinate even after 2 months should be discarded.
After sowing, the bed or the sleeves can be kept under mulch when the nursery is raised under green crop shade. Frequent examination is required to ensure scrapping of the mulch around the germinating seeds so that it does not cause any obstruction. Excess watering should be avoided. Only hand weeding should be done carefully and proper care against pests and diseases should be ensured to protect the plants.
The nursery is raised on a high land with adequate drainage and sunlight which is convenient for irrigation and frequent inspection. The soil should be neither too sandy nor too clayey with pH 4.5-5.0 and free from eelworm. If the soil is too acidic (below pH 4.5), it requires a treatment with slaked lime @ 2t/ha. Sub-acidic soils (pH above 5.1) can be amended with 2% aluminium sulphate solution 2-3 times. Soil should be tested before planting cuttings.
The nursery beds should be arranged east-west direction under overhead shade (bamboo lath and thatch) and keeping the north side open for better air circulation and light penetration. The northern height of overhead should not be more than 180 cm and should slope down towards south by 60 cm.
Beds under low shade should be north south oriented. Shade is provided with the help of bamboo lath frame about 22 cm over the propagation beds, supported by sidewalls. The bamboo lath frame should be raised gradually with increase in height of the plants. It is necessary to prepare the beds at least 6-8 weeks before planting cuttings. The period of heavy rain should be avoided for preparation of beds as clods are difficult to break when the soil is wet. The bed is generally 120 cm wide and of any convenient length. Each bed is enclosed by a 45 cm deep and 30 cm wide drain, which should run into one outlet drain. The surface of the beds should be slightly cambered for quick run-off of rain or irrigation water. Application of superphosphate @500g/m3 of soil used for filling sleeves or @50g/m2 of bed by incorporating in the soil to 15-20 cm depth helps in root development.
Polythene sleeve nursery
Clones can also be planted directly into sleeves (15 cm lay flat x 22cm long; 150 gauge thick). Smaller sleeves produce weaker plants. Before filling sleeves, the soil should be sieved through a No.4 wire mesh to eliminate undecomposed organic matter and pebbles. The sleeves should be filled with the sieved soil without much ramming and the filled sleeves should be kept covered preferably under shade for 6-8 weeks prior to planting cuttings.
Type of cuttings
Cuttings should be taken from the primaries with dormant apical buds (banji state) for higher success. In some clones, lateral shoots are produced from the lower portion of the primaries quite early. The unbranched portion of the primaries in such cases should be taken first followed by the laterals when they mature after a few weeks. A good cutting should have a fully mature healthy undamaged leaf, dormant or just swelling bud and a hard green stem of about 2.5 cm length below and about 0.5 cm above the leaf. A basal cut parallel to the slope of the leaf is more convenient for handling and for quick propagation of cuttings. In large leaf clones, reducing the leaf area by cutting away top-half of the leaf blade results in better rooting.
Planting of cuttings
With a dibber (small bamboo sticks slightly thinner than the stem) 2cm deep holes are made 5 cm apart on the bed. Cuttings are then planted firmly by holding the cutting at the node with the leaf pointing away from the hand in a semi erect position and inserting the stem on the holes upright. In north south oriented beds, the tip of the leaf should point towards north and in east west aligned beds, the tip should point towards west. Care should be taken to keep the petiole above the soil surface to prevent rotting of the mother leaf. The mother leaf should be more or less in an upright position after insertion into the holes. There should be no air pockets in the interspaces of cutting and soil. Dipping the cuttings in 0.1 per cent zinc sulphate solution before planting helps root initiation. The soil moisture should be maintained at field capacity. The cuttings should be transferred to sleeves just after initiation of roots. Over shading leading to excess moisture in soil and pH higher than 5.0 may cause excessive callus formation at the expense of root growth. Shade should be such that cuts about 50% of the mid-day sun light falling on the nursery bed. In the low lath frame shade, the bamboo frames should be raised on the east after the cuttings have produced 4-5 new leaves. Where thatch is used in overhead shade automatic thinning occurs in time. When bamboo lath is used, gradual removal of the roof (alternate one) ensures adequate hardening of plants. Young plants need protection from pests and diseases by high volume spray of suitable pesticide. Weeds are to be removed by hand. The plants should be kept outside without shade for a couple of weeks before taking them to the field.
Cutting nursery in Darjeeling
In Darjeeling, the nursery sites should preferably be located at low or mid elevation and on the northern aspect. The nursery site should be protected by contour drains and the beds (about 1.2 m wide and 15-20 cm high) must be aligned along the contour to guard against soil erosion. The sleeves should be arranged on raised beds (about 15 cm high) that have a slight camber as in orthodox propagation beds. Up to an elevation of about 1500m, bamboo lath frames or overhead shade of bamboo or thatch may be used. At higher
elevation overhead shade of bamboo or thatch is generally more useful. Below the shade, the beds may be completely covered by a polythene tent (45 cm above the cuttings) with semi-circular bamboo frames to conserve moisture and heat to help quick growth of the cuttings. The polythene tents should be gradually removed when the cuttings have rooted and most of them have produced 2-3 leaves. With further growth, the overhead shade should be gradually thinned.
Manuring of nursery plants
When the plants have produced 3-4 leaves, they are manured with a mixture of NPK (2:1:2) and sand at 1:9 ratio. One teaspoonful of this mixture should be applied per plant at 3-4 weeks interval during the growing season. If required, foliar application of nutrients can be started when the cuttings have produced 6-8 leaves during April-May and August-November.