Effect of Herbicidal Weed Control Method on the Yield of T. Aman Rice Varieties

Abstract

Weed competition is a major factor limiting the productivity of transplanted aman rice, particularly where labor shortages limit timely manual weeding. An experiment was carried out at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, from July to November 2022 to study the effect of variety and herbicidal weed control method on the yield performance of T. aman rice varieties. Two rice varieties, BR11 and BRRI dhan49, were included in the experimental treatments, along with six weeding treatments: T1 (no weeding), T2 (hand weeding at 25 DAT), T3 (pre-emergence herbicide Superhit 500 EC), T4 (pre-emergence herbicide with one hand weeding at 35 DAT), T5 (post-emergence herbicide Livina 18 WP), and T6 (post-emergence herbicide with one hand weeding at 35 DAT). The experiment was designed using Randomized Complete Block Design (RCBD) with three replications. Weed pressure was highest under no weeding (T1), resulting in the lowest grain yield (4.88 t ha-1). In contrast, the integrated treatment of pre-emergence herbicide followed by one hand weeding at 35 days after transplanting (T4) proved most effective, reducing weed density (5.51 m-2) and increasing grain yield (5.88 t ha-1). Among the varieties, BR11 consistently produced higher yield (5.65 t ha-1) than BRRI dhan49 due to better yield components. The interaction effect revealed that BR11 combined with integrated weed management (pre-emergence herbicide + hand weeding) produced the highest grain yield (6.19 t ha-1), highlighting the importance of genotype × management synergy. The finding indicates that combining pre-emergence herbicide with one hand weeding is an effective, sustainable strategy for improving aman rice yield.