Abstract

An experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during the period from August 2020-June, 2021 to assess the allelopathic effects of the Echinochloa crusgalli residues on both rice yields and weeds therein. The experiment consisted five treatments of doses of residues of E. crusgalli viz. i) no residues (control), ii) E. crusgalli residues @ 0.7 t ha^-1, iii) E. crusgalli residues @ 1.4 t ha^-1, iv) E. crusgalli residues @ 2.1 t ha^-1, v) farmers practice (two hand weeding @ 15 and 30 days after transplanting); and three treatments of the time of the application of the residues of E. crusgalli viz. i) one week before transplanting, ii) at the time of transplanting, iii) one week after transplanting. The experiment was laid out in a randomized complete block design (RCBD) with three replications. Five weeds belonging to the five families were identified in the field such as Echinochloa crusgalli, Marsilea quadriflia, Monochori vaginalis, Paspalum scrobiculatum and Fimbristylis miliacea. The doses of residues of E. crusgalli had significant effect on yield and yield contributing characters of rice except number of non-effective tillers hill^-1 and grains panicle^-1. The highest grain yield (5.13 t ha^-1), straw yield (6.19 t ha^-1) biological yield (11.32 t ha^-1) and harvest index (45.18%) were recorded when residues applied @ 2.1 t ha^-1. In case of time of application of the residues, the highest grain yield (3.84 t ha^-1) and straw yield (5.21 t ha^-1) were found when the residues applied one week before transplanting. In case interaction between doses and time of application of the residues of E. crusgalli the highest the grain yield (5.98 tha^-1), straw yield (6.67 t ha^-1) and biological yield (11.32 t ha^-1) were found when residues applied @ 2.1 tha^-1 at one week before transplanting. Results of the study shows that the residues of Echinochloa crusgalli possess weed suppressing ability. Therefore, Echinochloa crusgalli residues could be applied to the rice field before one week of transplanting of seedlings to control weed growth and to get higher rice production.