Department of Agronomy, Himachal Pradesh Krishi Vishvavidyalya, Palampur-176062 (H. P)
To study the effect of weed control methods in economising the phosphorus and their combined effect on crop-weed competition in Gobhi Sarson, a field experiment was conducted in acidic soils (pH 5.6) of Himachal Pradesh Krishi Vishvavidyalya Palampur during rabi 1987–88 and 1988 89. Significantly higest seed yield, straw yield and P uptake were obtained with hand weeding twice and 60 kg Pa Os/ha. The next best weed control method was pendimethalin 1.5 kg/ha (Pre.). Increasing phosphorus levels increased the phosphorus uptake by the crop significantly. Significantly higher phosphorus use efficiency (45.8%) was obtained with combination of pendimethalin and 40 or 60 kg Pa03 and was statistically at par with combination of hand weeding twice at 40 or 60 kg P205 per hectare. Weed control methods did not influence oil and protein contents significantly while phosphorus levels increased the oil content significantly
