Indian Institute of Natural Resins and Gums, India
Soumen Ghosal is a Principal Scientist in Lac Production Division ,Indian Institute of Natural Resins & Gums India.
Lac cultivation is a profitable venture for the farmers of Jharkhand, Chhattisgarh, Odisha, Madhya Pradesh, West Bengal etc. Rangeeni strain of lac insect is cultivated mainly on Palas (Butea mononperma) which is found abundantly in the lac growing regions. Lac yield from palas tree is relatively less in comparison to other hosts. An experiment comprising different levels of growth factors like liming (liming as per recommendation and no liming) and potassium (0, 500 and 1000 g/ tree) to make 6 treatment combinations replicated five times was conducted in the research farm of Indian Institute of Natural Resins and Gums, Ranchi during 2010-11 to 2012-13 to study the effect of soil fertility on rangeeni lac yield in the summer season (Oct/ Nov to June/July) on medium sized trees. Shoot age was 2.5 years for the first year and 7 months for next two years. Findings of the experiment visualized that Lac yield ratio obtained in liming was 71 percent higher compared to no liming in case of 7 months age of shoots. However, no significant difference in lac yield ratio was observed in case of 2.5 years old shoots. Its effect was also reflected on yield attribute like sticklac weight per 100 g broodlac. Increased soil fertility due to liming might have supplied better nutrition to the host and the host in turn could supply better nutrition to the insect. Lac yield increased significantly (4 to 7 times) if rest period is increased to 2.5 years for medium sized trees. Interaction effect of liming and potassium was found to be significant in case of 7 months old shoots. Effect of potassium application was observed in the absence of liming and the highest dose could increase lac yield 2.8 times than that of control on 7 months old shoots. Similarly, liming in the absence of potassium application proved to be the best treatment and response of liming decreased steadily with increase in level of potassium. Applied potassium might have facilitated host to support nutrition of lac insect in a better way which ultimately increased lac yield.
Keywords: Income, Lac yield, soil fertility, shoot age.