Golam Mostafa, Uttam Kumer Sarker, Md. Towkir Ahmed, Md. Abdus Salam and Md. Romij Uddin
Abstract
Weed management is vital for achieving optimal crop performance and yield in rice cultivation. Post-emergence herbicides are widely used to control weed populations, but their effectiveness can vary with different dosages and combinations. In this phenomenon, an experiment conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, from December 2019 to May 2020, studied the dose response of post-emergence herbicides on herbicide-resistant weeds and boro rice (cv. BRRI dhan58). The herbicides tested included H1-Ethoxysulfuron, H2-Penoxsulam + Escape 35 WP, H3-Sentry 25 EC + Escape 35 WP, H4-Agroxone, and H5-Cut out 10 WP, at four dosages: D1-no herbicide, D2-half the recommended dose, D3-recommended dose, and D4-double the recommended dose. Using a split-plot design with three replications, herbicide doses were the main plot and herbicide types the subplot. Results showed significant effects on weed dry weight, population, and inhibition. Twelve weed species from five families, including Echinochloa crus-galli, Monochoria hastata, Leersia hexandra, Cyperus difformis, and Scirpus mucronatus, infested the plots. H2 (Penoxsulam + Escape 35 WP) and H3 (Sentry 25 EC + Escape 35 WP) demonstrated superior weed control and rice growth. The recommended (D3) and double doses yielded the best results. The H5D4 combination achieved the highest weed control efficiency (90.58%), and H1D4 interaction observed in the maximum grain yield (6.05 t ha-1), straw yield (7.20 t ha-1), biological yield (13.25 t ha-1), and harvest index (45.67%). Weed density results indicated that Echinochloa crus-galli, Scirpus articulates, Leersia hexandra, and Digitaria sanguinalis survived even at double doses. So, post emergence herbicides can be effectively used for identification of herbicide resistant weeds and yield of boro rice.
Keywords: Resistant weeds; Herbicides; Boro rice; Grain yield.
