Kusmi lac yield in winter season as affected by weather and directional effect on ber (Zizyphus mauritiana) trees

Abstract

An experiment consisting of 96 trees was laid out in the Institute Research Farm during June 2007–February 2010 to assess the influence of factors like directional effect of lac on ber trees (northern and southern halves) and rainfall pattern on lac yield and yield ratio (output: input of broodlac). Average lac yield ratio in southern half was 26% higher than northern half in 2007–08 and the same was 21% higher in 2008–09. More sunlight might have kept the tree canopy warmer, which might have boosted up growth and development of the lac insect on the southern half in first two years. Due to meager rainfall in third year, sunlight was not a limiting factor influencing yield which resulted in a non- significant difference. At the same time, mean lac yield ratio was 4.9 in first year as against 7.15 in the third year; difference was significant and it could be attributed to weather differences. The typical patterns of rainfall in three different years have been described in details which revealed that lac yield decreased significantly with intensity of rainfall, number of consecutive weeks with 50 mm rain, amount of rainfall received after sexual maturity etc. As a result, 31% reduction in lac yield ratio was observed in first year compared to third year. The study also indicated that lac yield from trees of smaller canopy spread are least affected due to adverse weather condition.