Varietals Performances of Aman Rice Against Weed Infestation During Early Growth Stages At Mymensingh Area of Bangladesh

An experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during the period from June to December 2017 to study the tolerance of local, inbred and hybrid rice varieties to weed stress in early stage of growth during aman season. The experiment consisted of six cultivars viz. Parsoom, Razamohon, BRRI dhan49, Binadhan-7, Agrodhan-13 and Dhani Gold and six different weeding regimes such as weedy (no weed control measure), weed free (weeds are not allowed throughout the growing season), weedy up to 21 DAT followed by (fb) weed free, weedy up to 28 DAT fb weed free, weedy up to 35 DAT fb weed free and weedy up to 42 DAT fb weed free. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replicates. Varieties were found to have significant effect on different crop characters and rice yield. The highest grain yield (6.437 t ha^-1) as well as the straw yield (7.736 t ha^-1) were found in BRRI dhan49 while the lowest grain yield (1.599 t ha^-1) was obtained from Parsoom and the lowest straw yield (4.102 t ha^-1) was found in Razamohon. The different growth, yield and yield contributing characters varied significantly in response to variety and different weeding regimes. The highest plant height (122.3 cm), highest number of total tillers hill^-1 (7.476) and the highest number of effective tillers hill^-1 (6.356) was produced in weeding treatment, weedy up to 28 DAT fb weed free. On the other hand, the shortest plant height (117.1 cm), the lowest number of total tillers hill^-1 (6.919), the lowest number of effective tillers hill^-1 (5.844) and the smallest panicle length (22.29 cm) were observed in weeding treatment, weedy up to 42 DAT fb weed free. So, in order to get efficient weeding regimes in response to higher grain yield in transplanted aman rice, BRRI dhan49 with weedy up to 21 DAT fb weed free treatment can be recommended.

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