Determination of Critical Weed Free Period for Peanut Cultivation in Hambantota Area in Sri Lanka

Abstract

Field studies were conducted at research field of grain legumes and oil crops research and development centre at Angunakolapelessa in 2011/12 Maha, 2012 Yala and 2012/13 Maha seasons to evaluate the effects of mixed weed species on peanut yield. The naturally occurring weeds co-exists in the crop plant field were allowed to interfere for various intervals to determine the critical weed-free period. Weeds were broadly categorized into 3 categories grasses, broadleaves and sedges. Two sets of treatments were maintained in the experiments, first set of treatment consisted of weed free periods [WFP] of 2 (Tl), 4 (T2), 6[T3), 8 (T4), 10 (T5) weeks from planting, total weed free [T6) and full season weedy (T7). The plots were maintained weed-free until the beginning of the period as treatments, and then weeds were allowed to germinate and compete until the end of the cropping period. The second set of treatments consisted of weedy periods (WP) of 2(T8), 4 (T9), 6 (T10), 8 (T il), and 10(T12) weeks from planting were compared with total weedy and total weed free treatments. The effects of weed existence in various intervals and weed free periods on peanut yield were investigated. Weed free condition was maintained by hand-weeding. The crop was maintained according to the recommendations of Department of Agriculture. The predicted critical period of weed control, in the presence of a mixed population of weeds, was found to be from 3 to 8 weeks after planting (WAP). Peanut yield decreased as weed interference intervals increased, demonstrating the need for weed control throughout the growing season in the presence of mixed weed populations.