Effect of Water Regime and Weed Control Treatments on Weeds, Growth and Yields in Hybrid Rice

Abstract

Two field experiments were conducted at Rice Research and TrainingCenter, Sakha, Kafr El-Sheikh, Egypt during 2015 and 2016 seasons to detect the effect of water regime and weed control treatments on weeds, growth and yields of hybrid rice (Sk2034H). Water regime (4-days on and 6-days off, saturation and continuous flooding) were allocated in main plots while weed control treatments were Thiobencarb 50% EC at three rates; 1.8 , 2.4 and 3.6 kg ai ha-1 in addition to weedy check were distributed in sub-plots. Weed species and hybrid rice yields were greatly influenced by water regime and weed control treatments. Echinochloa crus-galli and total weeds dry weights were significantly reduced under flooded or saturated plots than under shortage of water (4-days on + 6-days off). In different response, Cyperus difformis considerably reduced under the water shortage than saturated or flooded plots. The highest values of panicles per hill and grain yield of hybrid rice were recorded under flooding conditions followed by saturated soil. The application of Thiobencarb 50% EC at the high rate (3.6 kg ai h-1) resulted in the best weed control and highest grain yield followed by the application of 2.4 kg ai ha-1 from the same compound, while weedy check plots recorded the highest in weed presence and the lowest in rice yields. For the interaction, the lowest dry weights of Echinochloa crus-galli, Cyperus difformis and total weeds, also the largest weed control efficiency (%), number of panicles per hill and the highest rice grain yields were obtained under flooded plots treated with Thiobencarb at both rates of 2.4 and 3.6 kg ai ha-1. This trend was true under all treatments even the weedy check plots except for Cyperus difformis which increased significantly by soil saturation or flooding in un-treated plots.