Division of Agronomy, Indian Agricultural Research Institute, New Delhi-110 012, India.
Online published on 31 October, 2011.
The dry biomass of resistant Phalaris minor was significantly reduced in T2 (metribuzin 150g + 500 + 5WAS) and T4 (metribuzin 150g + 500 + 6WAS) than in T1 (metribuzin 150g + 250 + 5WAS) in the first year. Otherwise all other metribuzin treatments remained at par with T2 and T4. T6 (metribuzin 200g + 500 + 5 WAS) also caused a drastic reduction in resistant P. minor's biomass. However, T caused maximum reduction in dry matter production of the broad-leaved as well as of total (composite) weeds and registered a significant increase in the number of ear-bearing tillers and grain yield of wheat. The number of ear-bearing tillers was significantly reduced at the higher dose at 120kg N ha−1 than at the lower dose (60 kg N ha−1) and accordingly the wheat grain yield. In the second year, the population and fresh biomass accumulation of resistant P. minor, wild oat and total weeds were significantly reduced in all the metribuzin treatments compared to T10 (unweeded control). The resistant P. minor fresh biomass was however the lowest in T6 (metribuzin 200g+500 litres+4 WAS). The fresh biomass of wild oat and total weeds were significantly reduced in T9 (one hand weeding at 30 DAS) than in others except T6 and T2 T6 on the contrary caused more reduction in fresh weight as well as height of wheat plants and thus proved more phytotoxic to wheat plants. The higher dose and higher spray volume of metribuzin were more effective in reducing the population and fresh biomass accumulation of resistant P minor wild oats as well as total weeds than their respective lower levels The higher dose and higher spray volume on the contrary brought more phytotoxicitv
Metribuzin, nitrogen, wheat, wild oat
