Effect of Herbicide Combinations on Nutrients Depletion by Weeds in Wheat under Mid Hill Conditions of Himachal Pradesh

Abstract

Sixteen weed control treatments viz. pinoxaden (40 g ha^-1), isoproturon (1250 g ha^-1) alone, isoproturon + pinoxaden (1000 + 40 g ha^-1), isoproturon + pinoxaden (750 + 30 g ha^-1), isoproturon + 2,4-D (1000 + 500 g ha^-1), isoproturon + metsulfuron-methyl (1000 + 4 g ha^-1), pinoxaden + 2,4-D (40 + 1000 g ha^-1), pinoxaden + metsulfuron-methyl (40 + 4 g ha^-1), isoproturon fb pinoxaden (1000 fb 40 g ha^-1), isoproturon fb pinoxaden (750 fb 30 g ha^-1), pinoxaden fb isoproturon (40 fb 1000 g ha^-1), pinoxaden fb isoproturon (30 fb 750 g ha^-1), pinoxaden fb 2,4-D (40 fb 1000 g ha^-1), pinoxaden fb metsulfuron-methyl (40 fb 4 g ha^-1), handweeding (30&60 DAS) and weedy check were evaluated at Palampur to study their effect on nutrient depletion by wheat associated weeds. Avena ludoviciana and Phalaris minor were the major weeds constituting 31 and 19.6%, respectively of total weed dry weight. Lolium temulentum, Vicia sativa, Anagallis arvensis and Coronopus didymus constituted 12.2, 17.1, 10.9 and 9.2%, respectively of the total weed dry weight. Weed control treatments significantly decreased total weed dry weight and thereby NPK depletion by weeds as compared to weedy check. Application of pinoxaden fb MSM (40 fb 4 g ha^-1) being statistically at par wih pinoxaden + MSM (40 + 4 g ha^-1), pinoxaden fb 2,4-D (40 fb 1000 g ha^-1) and hand weeding was significantly superior in reducing the total weed dry matter and nutrition depletion and increasing yield and NPK uptake as compared to the other herbicidal treatments. Weeds in weedy check removed 60.5 kg N, 14.8 kg P and 58.9 kg K ha-1 depriving thereby the wheat crop for that much amount of nutrients. Pinoxaden fb MSM (40 fb 4 g ha^-1) increased NPK uptake by wheat to 88.5, 19.2 and 49.6 kg/ha from 47.5, 9.1 and 29.2 kg/ha, respectively, that under weedy check.