EFFECT OF BISPYRIBAC-SODIUM AND SPACING ON THE WEED CONTROL AND PERFORMANCE OF AROMATIC RICE VARIETIES

Abstract

A field experiment was carried out at the Agronomy research field of Sher-e-Bangla Agricultural University, Dhaka, Bangladesh from July to December-2019, to investigate the effect of bispyribac-sodium and spacing on the weed control, growth, and yield of aromatic rice varieties in Bangladesh. The experiment consisted of three factors i.e., weed control treatment (2) viz.weedy check (no weeding) and Bispyribac sodium WP @ 150 gha -1 ; aromatic rice varieties (2) viz. Kalizira and BRRI dhan37, and spacings (4) viz. 20 cm × 15 cm, 25 cm × 15 cm, 20 cm × 20 cm, 25 cm × 25 cm. The experiment was laid out in a split-split plot design with three replications. Thirteen different weed species infested the experimental plots belonging to nine families where the most dominating was broad leaf and sedge weed species and among different weeds, Monochoria vaginalis was the most dominant weed (24.67 and 19.67 density m -2 and 15.93 and 16.98 % relative density) at 30 and 60 DAT. Application of different weed control treatments, varieties, spacings and their combination significantly influenced weed regime and crop performance. Application of bispyribac-sodium WP @ 150 g ha -1 reduced weed growth and biomass and increased grain yield. BRRI dhan37 rice variety recorded the maximum grain yield (2.99 t ha -1 ). Among different spacing 20 cm × 20 cm reduced weed density and recorded the maximum grain yield allowing a relevant reduction of herbicide input. Although optimal weed control and good yield were achieved without significant differences between all treatments, the highest yield (3.20 t ha ii -1 ) and benefit-cost ratio (1.48) was achieved by the combination of Bispyribac-sodium WP @ 150 g ha along with BRRI dhan37 and 20 cm × 20 cm. Therefore, the application of bispyribacsodium WP @ 150 g ha -1 with 20 cm × 20 cm spacing seemed to be the best way of controlling complex weed flora and enhancing productivity and profitability from transplanted aromatic rice.