ALLELOPATHIC EFFECT OF RICE STRAW AND WATER HYACINTH ON WEED CONTROL AND YIELD OF BORO RICE

Abstract

The experiment was conducted at the Agronomy research field. Sher-e-Bangla Agricultural University, Dhaka from November. 2009 to May, 2010 to find out the allelopathic effect of rice straw and water hyacinth biomass on weed control and yield of boro rice. The treatments of the experiment consisted of 2 rice varieties viz. BRRI dhan29 (V1 ) and BRRI hybrid dhan2 (V 2 ); 2 allelopathic materials viz, rice straw (Mi) and water hyacinth (M 2); and 3 levels of biomass concentration viz. 0 kg biomass m 2 (Co ). 0.5 kg biomass m 2 (C1 ) and 1.0 kg biomass m 2 (C2 ). The experiment was laid out in a spilt split-plot design with 3 replications having varieties in the main plots, allelopathic materials in the sub plots and concentrations in the sub sub-plots. The lowest weed population (11.33 rn' 2 and 16.00 rn'2 at 30 and 50 DAT respectively) and minimum dry weight (4.89 g rn'2 ) at 30 DAT was found from rice straw application irrespective of variety. The highest grain yield (7.50 t ha") was obtained from BRRI hybrid dhan2 with water hyacinth @ 1.0 kg m 2. The highest number of effective tillers hilr' (19.67) was observed from BRRI dhan29 with water hyacinth @1 1.0 kg m 2 and the lowest number of noneffective tillers hill (1.67) was recorded from the same variety with rice straw and at the same concentration. The highest panicle length (26.65 cm) was found in BRRI dhan29 with rice straw @ 1.0 kg biomass m'2. BRRI hybrid dhan2, water hyacinth and 1.0 kg biomass m 2 and their interactions encouraged growth and dry weight of weeds as well as yield of rice. Rice straw reduced weed growth whereas water hyacinth enhanced weed growth as well as grain yield of rice.