Bio-efficacy of sequential application of herbicides on weed control, growthand yield of wet-seeded rice

摘要

Due to shortage of labour and increased wages, transplanting is becoming difficult and farmers are resorting to wet-seeded rice in Krishna, Godavari zones of Andhra Pradesh, as it saves labour, time and energy, early crop maturity, ensures efficient water use and increased benefit cost ratio (Ravi Shankar et al. 2008). However, in wet-seeded rice, weeds are the major limiting factor in obtaining higher yields and uncontrolled weed growth may cause yield reduction to the extent of 64% (Rao et al. 2007). Use of pre-emergence herbicides such as butachlor, pretilachlor has been found effective in early stages but the second flush of weeds at later stages has become problematic. In such situations, sequential application of herbicides is the only alternative, in order to achieve broad spectrum and season long control during the critical period of the crop. The present experiment was under taken to evaluate the performance of various new herbicides alone and in sequential applications.