Effect of nitrogen level and duration of weed competition on weed biomass, yield and yield attributes of wheat

Abstract

An experiment was conducted during Rabi season of 1993-94 at IPSA farm to investigate the effects of nitrogen levels (100, 120 and 160 kg ha*1) and duration of weed competition (weed-free, weed competition up to 20, 30, 40 days after emergence (DAE) and no weeding) of wheat. The highest weed biomass (104 g m"2) was obtained in the unweeded plots treated with 160 kg N ha"1 sampled at 50 DAE. There was no significant difference in grain, straw yield and yield attributes of wheat due to N levels. Grain yields were found identical with weed-free and weed competition up to 20 and 30 DAE. Straw yield was at par to all treatments except no weeding. Grain yield was reduced significantly when the weeds were allowed to grow beyond 30 DAE. Plant N concentration and uptake were higher with higher N level both in wheat and weeds. Duration of weed competition did not affect N concentration in wheat but affected N concentration and uptake in weeds.