Abstract

A field experiment was conducted at Instructional Farm, N. M. College of Agriculture, Navsari Agricultural University, Navsari during rabi season in two consecutive years during 2010–11 and 2011–12 to study the effect of critical period of crop-weed competition on nutrient content and uptake by weed and rabi castor (Ricinus communis L.). The 12 treatments viz., weed free up to 30 DAS, weed free up to 60 DAS, weed free up to 90 DAS, weed free up to 120 DAS, weed free up to harvest, weedy up to 30 DAS, weedy up to 60 DAS, weedy up to 90 DAS, weedy up to 120 DAS, weedy up to harvest, two hand weedings and interculturing at 30 and 60 DAS and pendimethalin @ 1 kg/ha (as pre-emergence)+ one hand weeding and interculturing at 60 DAS were evaluated with three replications in a randomized block design (RBD). The results revealed that treatment weed free up to harvest recorded significantly lowest weed density, dry weight of weeds, nutrient uptake by weed and maximum in castor seed yield and nutrient uptake by plant followed by the treatment weed free up to 120 DAS and weed free up to 90 DAS. However, highest net monetary returns (Rs. 46.6 x 103/ha) and B: C ratio (3.02) were obtained with the treatment weed free up to 90 DAS which was found more critical period for crop weed competition.