GROWTH AND YIELD OF HYBRID AND INBRED BORO RICE AFFECTED BY DIFFERENT WEED CONTROL METHODS

Abstract

A field experiment was carried out at Sher-e-Bangla Agricultural University, Dhaka, Bangladesh during the period from December, 2008 to May, 2009 to evaluate the Growth and yield of hybrid and inbred boro rice affected by different weed control methods. The experiment comprised of seven weeding treatments viz. no weeding, one weeding at 30 DAT (Days after transplanting), two weeding at 30 DAT and 50 DAT, application of herbicides: Sunrise 150WP recommended dose at 100g ha-1, Sunrise 150 WP 25% higher than the recommended dose, Commit 500EC recommended dose at 1000ml ha-1, Commit 500EC 25% lower than the recommended dose; boro rice varieties viz. Hira-6(hybrid), Sonarbangla-6(hybrid) and BRRI dhan29(inbred). The experiment was carried out in RCBD with three replications. Eight weed species belonging to four families were identified in the experimental field of which Echinochloa colonum, Leersia hexandra, Cynodon dactylon, Cyperus rotundus, Scirpus mucronatus, Spilanthes acmella, Enhydra fluctuans and Desmodium trifolium. Population density of weeds was recorded from 7 DAT to 50 DAT at 7 days interval. It was evident that among the weed control treatments, application of Sunrise 150 WP 25% higher than the recommended dose showed best performance in respect of the highest plant height (103.35cm), maximum tillers hill-1 (22.00), the maximum plant dry matter (192.8g hill-1), effective tillers hill-1(20.34), lowest number of ineffective tiller hill-1(1.33) and consequently produced highest grain yield (9.50 t ha-1), straw yield (10.25 t ha-1) and harvest index (41.16) in comparison all other treatments. Among the weed control treatments, Sunrise 150WP at 25% higher than the recommended dose control 81% weed population, where as Commit 500EC 55% and hand weeding only 52% which was costlier than others. The highest grain yield, straw yield as well as benefit cost ratio was obtained from the variety Sonarbangla-6(hybrid). Application of Sunrise 150 WP 25% higher than the recommended dose increased 22.63% higher grain yield than Commit 500EC 25% lower than the recommended dose and 34.9% higher grain yield than two hand weeding due to higher number of panicles hill-1 and higher number grains panicle-1.