Vivekananda Institute of Hill Agriculture (ICAR), Almora, Uttarakhand-263 601, India.
1Present Address: CRIDA, Hyderabad, Andhra Pradesh-500 059, India.
A field experiment was conducted during the winter (rabi) seasons of 2001–02 to 2003–04 at Almora (Uttarakhand) to study the effect of different herbicides on wheat and associated weeds under zero and conventional tillage systems. Weeds totalled an average of 215/m2 in the untreated weedy check. There was severe competition between wheat and the predominant weed species Polygonum plebijum, Phalaris minor and Ranunculus sp. and an average decrease in grain yield by 37.9% was observed due to season long weed-crop competition. Conventional tillage recorded significantly lower weed dry weight compared to zero tillage. The grain yield; however, did not differ significantly among the tillage systems. All herbicides provided significant control of weeds compared to weedy check under both the tillage systems. Metribuzin at 250 g/ha and sulfosulfuron at 33 g/ha being at par with each other recorded significantly lower weed dry weight compared to tank mix spray of isoproturon (750 g/ha) + 2,4-D (500 g/ha) and weedy check. Slight crop injury in terms of yellowing of leaves and stunted growth were observed in the plots treated with metribuzin. The injury; however, disappeared with the advancement of crop growth. Sulfosulfuron at 33 g/ha and metribuzin at 250 g/ha produced similar but significantly higher grain yield compared to tank mix spray of isoproturon (750 g/ha) + 2,4-D (500 g/ha) and weedy check. Conventional tillage gave higher gross and net returns compared to zero tillage. Among the herbicides, metribuzin at 250 g/ha recorded maximum net return (Rs. 14021/ha) and benefit: cost ratio (1.83). Sulfosulfuron at 33 g/ha was the next best remunerative treatment.
