EFFECT OF DIFFERENT WEED CONTROL METHODS ON THE YIELD OF TRANSPLANTED AMAN RICE VARIETIES

Abstract

A field experiment was conducted at Sher-e-Bangla Agricultural University, Dhaka, Bangladesh during August to December, 2013 in T. aman season with a view to find out the performance of two transplanted aman rice varieties BRRI dhan56 and BRRI dhan57 under different weed control methods viz. chemical herbicide Rifit 50EC (Pretilachor 500 g L-1) @ 1 L/ha (W1), polythene paper (W2), stale seedbed (W3), one hand weeding at 20 DAT (W4), two hand weeding at 20 and 40 DAT (W5) and no weeding (control) (W6) using split plot design. Eighteen different weed species infested the field among which Cyperus michelianus (36.73%), Cyperus esculentus (17.31%) at 30 DAT; Cyperus esculentus (25.13%) Alternanthera sessilis (21.53%) and Cyperus difformis (15.79%) at 60 DAT, Fimbristylis miliaceae (19.50%) at 90 DAT were dominant. Two hand weeding at 20 and 40 DAT (W5) showed highest weed control efficiency 89.90% at 30 DAT, 59.74% at 60 DAT and 78.85% 90 DAT. The results showed that BRRI dhan56 produced the highest (3.70 t ha-1) grain yield when two times weeding were performed at 20 and 40 DAT. BRRI dhan56 produced longest panicle length (23.39 cm), 1000-grain weight (23.12 g), grain yield (3.14 t ha1), straw yield (5.16 t ha-1), biological yield (8.90 t ha-1), harvest index (35.08%) better than the BRRI dhan57. Economic analysis of the weed control parameters shows that, the highest (1.92) BCR was recorded from the chemical herbicide Rifit 500EC weed control. While the two hand weeding, stale seed bed and one hand weeding produces 1.79, 1.69 and 1.48 BCR respectively.