Efficacy of different herbicides over manual weeding in controlling weeds in transplanted rice

An experiment was conducted on transplanted Aman (monsoon) rice at the Sher-e-Bangla Agricultural University farm Dhaka (90033′ E longitude and 23077′ N latitude), Bangladesh during June-November, 2005. There were seven different weed control treatments viz. T1= Amchlor 5G @ 15 kg ha-1 + IR5878 50 WP @ 120 g ha-1, T2= Ronstar 25EC @ 1.25 L ha-1 + IR5878 50 WP @ 120 g ha-1, T3= IR5878 50 WP @ 150 g ha-1, T4= IR5878 50 WP @ 120 g ha-1, T5= Set-off 20WG @ 50 g ha-1 + IR5878 50 WP @ 120 g ha-1, T6= Two hand weeding and T7= Weedy check. There were 14 different weed species infested the field among which Panicum repens was the most important. Among the herbicides T2 was the most efficient with the lowest weed population and weed dry weight. The yield and the yield contributing characters (plant height, number of effective tillers per hill, panicle length and no. of filled grains) were influenced according to the effectiveness of the treatments, with T2 being the highest yielding herbicide treatment, reaching the yield level of the hand weeding treatments (T6). Maximum benefit-cost ratio with T2 suggested that this herbicidal treatment can be used as an alternative when labour is a limiting factor in producing transplant Aman rice