Determination of Critical Period of W eed Control in Kala Zeera ( Buniumpersicum bios ) in Gurez V alley of Kashmir

Abstract

Critical P eriod of W eed Control (CPWC) is the period in crop growth cycle during which w eeds must be controlled to prev ent unacceptable yield losses.T w o sets of treatments w ere imposed to represent both increasing duration of w eed interference and the length of the w eed-free period measured after germination. The first set of treatments consists of increasing duration of w eed interference by delaying w eed control from the time of crop emergence up to predetermined w eek (w eedy up to 2,4,6,8,10 and 12 w eeks after germination (W AG) of Kala Zeera ) . The second set of treatments established six lev els of increasing length of the w eed-free period (w eed free upto 2, 4, 6, 10 and 12 W AG). Besides tw o controls (W eed free and w eedy check). These comprised of 14 treatments which w ere laid out in randomized complete block design with three replication. It w as rev ealed that v ariation in Kala zeera seed yield due to w eeds is upto 88% and yield gets reduced as low as 48 % in w eedy check plots. Early w eed competition does not hav e hav e profound influence in Kala zeera crop.According to av erage data of tw o y ears inv estigation, it w as concluded that W eeds emerging betw een 6-12 W AG appear to be most detrimental to Kala zeera growth and yield and hence qualifies critical stage for w eed competition.