<p>Cashew is one among the important commercial crop of India. Though India stands first in area and second in production contributing 21 and 18 per cent of total world’s area under cultivation and production respectively, per hectare yield is very low (664 kg/ha) (as per 2010-11 data). One of the main constraints for lower yield is the lack of maintaining optimum plant population according to, National Research Centre for Cashew (NRCC).</p> <p>The normal planting spacing adopted in cashew cultivation is 8m X 8m with planting density of 156 plants per hectare or 7.5m X 7.5m with density of 175 plants per hectare.</p> <p>High density planting (HDP) is a recent technique recommended for enhancing the productivity per unit area of cashew plantations. The method involves the planting more number of grafts per unit area and thinning them at later stages. Instead of the normal planting density, grafts are planted initially at a closer spacing of 4m X 4m, 5m X 5m or 8m X 4 m so that there will be 625, 400 or 312 plants respectively per hectare.</p> <p>Considering the soil fertility status, climate and the level of management in terms of fertilization, irrigation etc., the initial plant population is to be decided carefully, for every agro-climatic environment. During later years, as the canopy develops, plant population is to be regulated by selective felling in order to minimize competition so that there will be 625 or 312 plants initially. This population can be retained for a period of 10 to 12 years depending upon the canopy expansion rate.</p> <p>HDP technique would be more useful in poor soils where the rate of canopy expansion is slow. When the plants attain full growth, the spacing between the plants can be regulated at 8 m x 8 m by removing one row alternatively.</p> <p>The high yielding varieties viz., 44/3, Anakkayam-1, H-1608, Ullal-4, Vengurle-4, NDR-2-1, Goa 11/6 and H-32/4 are suitable for HDP.</p> <p><strong>Advantages of HDP: </strong></p> <p>· During early years, per hectare yield will be more from high density plantations (due to higher plant population) compared to the normal density plantations. During later years, when the plant population is equalized to that of normal density plantation, the productivity of both the plantations would be more or less the same</p> <p>· The higher yield obtained during the early years would be substantial in HDP</p> <p>· In addition to obtaining higher yields, good quantities of firewood can be obtained by thinning, which will fetch additional revenue to the farmer.</p> <p>· The weed growth in the inter spaces will be less.</p> <p>· HDP is the effective method for soil conservation especially in forest lands.</p> <p><strong>The major concerns in adoption of HDP are</strong>,</p> <p>· HDP being an intensive system requires high capital to establish than the normal density planting</p> <p>· HDP however needs suitable dwarf and / or compact cashew varieties so that overlapping of canopy is minimized but In India, suitable dwarf and compact types with high yield are not yet available</p> <p>· HDP often exacerbates disease problems.</p> <p><strong>Some of the Research details on HDP in cashew</strong></p> <p>In order to explore the possibility of increasing yield and profit per unit area, National Research Centre for Cashew (NRCC), Puttur and Centres of All India Co-ordinate Research Project on Cashew located in West and East Coast regions, are conducting trials on spacing / plant density by adopting various tree densities/unit area. Out of the different tree densities tried and pruning and thinning practices at various stages, it was found that maintaining plant densities of 384, 400 and 500 plants/ha against 156 plants/ha are most beneficial getting maximum yield and profit during the first 10 to 12 years period. It was worked out that the net profit/ha was Rs. 77,054, Rs. 73,735, Rs. 70,050 and Rs. 58,790 per ha in high density planting plots with 625, 384, 500 and 400 trees/ha respectively, for the initial 12 years, when compared to Rs. 31,278/ha of normal density plot (156 trees/ha).</p> <p>The various other encouraging results out of the projects are as follows:</p> <p>· The biomass of dried branches in high tree density plots was 10 times more than widely spaced trees.</p> <p>· Weed biomass collected from high tree density plots was significantly lesser than that of low tree density plots.</p> <p>· Total biomass per hectare basis was higher in high tree density plot compared to that of low tree density plot.</p> <p>· Organic matter content available in soil up to 1 m depth and soil moisture level at the top 0-30 cm were higher in high tree density plots.</p> <p>· Heavy deposit of cashew leaves under high density planting system when incorporated in soil will be a good source of nutrients for better plant growth and yield.</p> <p>Higher production resulting from high density planting has also been reported from West Bengal state from the research centre at Jhargram.</p> <p>In Tamil Nadu by adopting HDP can obtain high yield of about 3250 kg nuts per hectare with higher B:C ratio of 3.35:1 as against conventional method of 1.50:1 and net returns of 68,876/- every year from 6th year onwards according to scientist Dr. M. S. Aneesa Rani and co-workers.</p> <p> </p>