Shade trees are propagated by seed. It is always advisable to obtain genuine shade tree seeds from own sources. For this purpose, the mother trees that possess all the desirable characters of an ideal shade tree are selected in the tea estate from which seeds are collected. In leguminous trees, the seeds are enclosed inside pods. As soon as the pods turn brown, they should be collected from the selected mother plants during January-February.
After the pods are dried thoroughly under the sun, the seeds are extracted by hand pounding. The seeds should be stored in wooden bins or gunny bags in well- ventilated, cool, dry room.
The shade tree nursery should be on deep well-drained high sandy loam soils rich in organic matter. The site should be near a perennial source of water. The best time for land preparation for shade nursery is between November-December when the soil is neither too wet nor too dry. It is very important to prepare the soil into a good tilth by deep cross ploughing, harrowing and leveling. Dry well decomposed cattle manure or organic manure @ 25 tons per ha and dolomite @ 2 tons per ha used during land preparation will improve the soil condition.
The size of the nursery bed should be 1.50 m wide and of convenient length. It is advisable to complete the preparation of nursery beds in January. While preparing the beds, for a good growth of the tap root, the soil in the beds should be loosened to a depth of 60 cm. SSP should be applied @ 125 g/m2 of bed area. Each bed should be separated by 60 cm deep and 30 cm wide drain which should be connected to 120 cm deep and 45 cm wide perimeter drain.
The best time of sowing of seeds is between February-April. Before sowing, the seeds are soaked overnight in water. The dormancy of seeds with hard seed coats can be broken by immersing the seeds in water which is heated up to 80°C (without boiling) and allowing cooling in that water overnight. The seeds are sown in the following morning on moist beds at 0.5-1 cm depth and 20 cm apart in rows spaced at 30 cm distance. The seeds are covered with a thin layer of soil. The beds may be watered initially using a hand operated sprayer frequently so that beds do not go dry.
Nursery in Polythene Sleeves
Shade tree seedlings can also be raised in polythene sleeves of 60 cm length, 30 cm wide (lay flat) and 150 gauze thickness. For filling the sleeves, sandy loam virgin soil rich in organic matter is preferable. In absence of this, the available soil should be improved by mixing friable soil (4 parts) and dry well decomposed cattle manure (1 part) with 1 kg of SSP and 500 g of dolomite per cubic meter of soil. The above ingredients are thoroughly mixed, moistened lightly and are allowed to incubate for 7-10 days under shade before filling up the polythene sleeves.
The size of nursery beds, drainage etc is as mentioned under bed nursery. The sleeves are watered 24 hours before sowing. Two to three seeds are drilled to a depth of 0.5-1.0 cm per sleeve and covered with a layer of soil.
It is observed that during the initial period under low overhead shade, shade nursery raised in polythene sleeves does well. Low overhead shades made of any vegetative matter/Netlon can be used. The sleeves are watered lightly using Bakpak fitted with a Fan/Cone jet nozzle. As the seedlings grow, the quantum of water will have to be increased depending upon the weather.
Pests, Diseases and Weeds in the Nursery
Sucking pests like Psyllids and leaf defoliators do considerable damage to the germinating seedlings in their early stage. Red rust is the most serious disease of shade nurseries and is the principal cause of failure in many instances. Therefore, from the beginning care must be taken to keep the nurseries free of pests by taking timely action. In addition, proper weed control and drainage should be given attention.
In the 7th or 8th month, it will be necessary to remove the congestion in the nursery. All the laggards, weak and stunted seedlings should be thinned out to provide more room for growth and development of the promising ones.