Influence of pre-and post-emergence herbicides in castor (RicinuscommunisL.)

Abstract

This experiment evaluated the efficiency of weed management programmes using pre-emergence (pendimethalin and trifluralin) and post-emergence herbicides (quizalofop-p-ethyl and fenoxy propethyl) applied at 25 days after emergence in castor cv. GCH 6 under irrigated conditions at Main Oilseeds Research Station Farm of Junagadh Agricultural University, Junagadh for three consecutive years 2010, 2011 and 2012. The experiment was conducted in randomised block design (RBD) with three replications on medium clay soils with pH 7.9. The experimental field was infested with narrow leaved and broadleaved weeds viz., Echinochloa colonum, Eluropus villosus, Dactyloctenium aegyptium, Brachiaria sp., Cyperus rotundus, Commelina benghalensis, Digera arvensis, Indigofera glandulosa and Amaranthus viridis. Weed free condition recorded highest castor seed yield during individual and pooled results (4429, 2546, 2581 and 3183 kg/ha, respectively). Among the herbicidal treatments, trifluralin @ 1.0 kg a. i./ha+post-emergence application of quizalofop-p-ethyl @ 0.05 kg a. i./ha at 25 DAS recorded maximum seed yield of 3005 kg/ha with lower dry weight of weeds (374 kg/ha), higher weed control efficiency (85.9%) at 75 DAS and lower weed index (5.5%) besides higher gross returns (Rs. 120208/ha), net returns (Rs. 90398/ha) and B: C ratio of 3.0. However, pendimethalin @ 1.0 kg a. i./ha+post-emergence application of quizalofop-p-ethyl @ 0.05 kg a. i./ha at 25 DAS remained at par with each other.