Determination of Critical Period of Weed Control in Kala Zeera (Buniumpersicum Bios) in Gurez Valley of Kashmir

Critical Period of Weed Control (CPWC) is the period in crop growth cycle during which weeds must be controlled to prevent unacceptable yield losses.Two sets of treatments were imposed to represent both increasing duration of weed interference and the length of the weed-free period measured after germination. The first set of treatments consists of increasing duration of weed interference by delaying weed control from the time of crop emergence up to predetermined week (weedy up to 2,4,6,8,10 and 12 weeks after germination (WAG) of Kala Zeera) . The second set of treatments established six levels of increasing length of the weed-free period (weed free upto 2, 4, 6, 10 and 12 WAG). Besides two controls (Weed free and weedy check). These comprised of 14 treatments which were laid out in randomized complete block design with three replication. It was revealed that variation inKala zeeraseed yield due to weeds is upto 88% and yield gets reduced as low as 48 % in weedy check plots. Early weed competition does not have have profound influence in Kala zeeracrop.According to average data of two years investigation, it was concluded that Weeds emerging between 6-12 WAG appear to be most detrimental to Kala zeeragrowth and yield and hence qualifies critical stage for weed competition