Influence of weeding regime on the performance of aromatic Boro rice (Oryza sativa L.)

An experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, from December 2013 to May 2014 to investigate the influence of weeding regime on the performance of aromatic Boro rice (cv. BRRI dhan50). The experiment comprised nine treatments viz., un-weeded, one hand weeding at 20 DAT + pre-emergence herbicide after hand weeding, two hand weeding at 20 and 40 DAT, pre-emergence herbicide followed by one hand weeding at 20 DAT, pre-emergence herbicide followed by one hand weeding at 40 DAT, post-emergence herbicide + one hand weeding at 40 DAT, pre-emergence herbicide + post-emergence herbicide, pre-emergence herbicide + post-emergence herbicide + one hand weeding at 40 DAT and weed free throughout the growth period. Panida (pendimethalin) @ 2.5 L ha-1 as pre-emergence herbicide and granite (penoxsulam) @ 93.70 ml ha-1 as post-emergence were used for weed control. The experiment was laid out in a randomized complete block design with four replications. Thirteen weed species belonging to seven families were observed in the experimental field. The highest weed density and dry weight were observed in no weeding condition compared to other treatments. The tallest plant, the highest number of total tillers hill-1, number of effective tillers hill-1, total spikelets panicle-1, grains panicle-1, 1000-grain weight, grain yield, straw yield, biological yield and harvest index were obtained from weed free treatment. The highest grain yield (5.92 t ha-1) was obtained from weed free throughout the growth period. Grain yield was reduced by 56.42% due to weed infestation in unweeded condition. The highest benefit-cost ratio (2.28) was obtained from application of pre-emergence herbicide followed by post-emergence herbicide + one hand weeding at 40 DAT. Therefore, weeding treatment pre-emergence herbicide followed by post-emergence herbicide + one hand weeding at 40 DAT may consider for cultivation of aromatic Boro rice (cv. BRRI dhan50).