Abstract

Field experiment was conducted at Agricultural College and Research Institute, (Tamil Nadu Agricultural University) Killikulam during January to April 2008 to study the effect of post emergence herbicide imazethapyr on weed characters, growth and yield of black gram variety (ADT 3) under rice fallow situation. The experiment was laid out under split plot design with three replications. The treatments consisted of three times (14, 21 and 28 days after sowing) of application in main plot and post emergence herbicide imazethpyr at 60, 75 and 90 g ai ha-1 and an absolute control formed the subplot treatments. The results revealed that the effect of imazethapyr on weed density, weed dry weight and weed control efficiency was on par when applied on either 21 or 28 DAS. Application of imazethapyr at the rate of 90 g ai ha-1 recorded lowest weed density and weed dry weight and on par with that of 75 g ai ha-1. Higher growth and yield attributes of black gram were associated with imazethpyr application on 21 DAS at 90 g ai ha-1. The highest grain yield of 759 kg ha-1 was recorded under 21 DAS than other times of application of herbicide. Among the doses, application of imazethapyr at 90 g ai ha-1 registered significantly the highest grain yield (751 kg ha-1) than other doses and control. The favourable economic benefits interms of higher gross income, net income and benefit – cost ratio were also observed by the application of imazethpayr at 90 g ai ha-1 on 21 DAS.

Keywords: Black gram, Imazethapyr, Weed control, Grain yield, Economics