WEED DYNAMICS AND YIELD OF TRANSPLANTED AMAN RICE AS INFLUENCED BY VARIETY AND INTEGRATED WEED MANAGEMENT PRACTICES

Abstract

Competitive rice cultivars can influence weed suppression. Managing weeds sustainably to achieve desirable crop yields is a major concern worldwide. When the same weed management strategies are used, such as using same herbicide year after year in a certain area, weeds become resistant to that herbicide. To study the impact of variety and integrated weed management practices on weed growth and yield of rice, an experiment was conducted at the Agronomy Field Laboratory of Bangladesh Agricultural University, Mymensingh during the period from June to October 2023. The experiment included three T. aman rice varieties viz., BRRI dhan71, BRRI dhan75 and BRRI dhan87 and five weed management practices viz., unweeded control, two hand weedings at 15 and 30 days after transplanting (DAT), application of pre-emergence herbicide followed by one hand weeding (HW) at 30 DAT, application of early post-emergence herbicide followed by one HW at 30 DAT, application of  pre-emergence herbicide followed by early post emergence herbicide. The experiment was laid out in randomized complete block design with three replications. Results showed that the experimental plots were infested with seven weed species belonging to five families. The most dominant weed species in the experimental fields were Panikachu (Monochoria vaginalis), Shama (Echinochloa crusgalli) and Sabuj Nakful (Cyperus difformis). The highest weed density and dry weight at 15 and 30 DAT were found in BRRI dhan75 with no weeding treatment and the lowest weed density and dry weight were observed in the variety BRRI dhan87 with application of pre-emergence herbicide followed by one HW at 30 DAT. In considering yield and yield attributes, BRRI dhan87 had highest number of effective tillers hill⁻¹, longest panicle, highest number of grains panicle⁻¹ and highest grain and straw yields. Application of pre-emergence herbicide followed by one HW at 30 DAT exerted the highest number of effective tillers hill⁻¹, highest number of grains panicle⁻¹ and highest grain and straw yields. The highest grain yield (5.22 t ha⁻¹) was recorded from the interaction of variety BRRI dhan87 with application of pre-emergence herbicide followed by one HW at 30 DAT due to highest number of grains panicle⁻¹ in this treatment combination. Numerically the lowest grain and straw yields were found in the variety BRRI dhan71 with no weeding treatment combination. From the results of the study, it may be concluded that BRRI dhan87 with application of pre-emergence herbicide followed by one HW at 30 DAT may be recommended for controlling weed efficiently and maximizing grain yield of T. aman rice.