WEED MANAGEMENT THROUGH ALLELOPATHIC INTERACTION OF MUSTARD VARIETIES

Abstract

A series of experiments were carried out in the laboratory and agronomic field of the Sher-e-Bangla Agricultural University, Dhaka, Bangladesh, from October-2019 to February 2020 in Rabi season to investigate the effect of weed management through allelopathic interaction of mustard varieties. The experimental design in laboratory bioassay was a completely randomized design (CRD) with three replications. The field experiment consisted of two factors. Factor-A: Mustard varieties (5) viz, RAI-5, BARI Sarisha-7, BARI Sarisha-8, BARI Sarisha-15, BARI Sarisha-18 (canola), and factor-B: Weed management (3) viz, no weeding, 1 hand weeding at 15 DAS, and 2 Hand weeding at 15 and 30 DAS. The field experiment was laid out in a split-plot design having 3 replications. Data on different parameters in laboratory and field conditions were collected for assessing the results. In the laboratory, RAI-5, BARI Sarisha-7, BARI Sarisha-8, and BARI Sarisha-18 significantly reduced the germination, root and shoot growth of model plants (Lactuca sativa and Raphanus sativus) and weed (Echinochloa colona). There was a dominance of Cynodon dactylon, Cyperus rotundus and E. colona weed species in the mustard field. However, weed densities were minimal in the Rai-5 and BARI Sarisha-18(Canola) raised plots. The allelopathic potentiality of these varieties may be important reason for suppressing weeds in the field which support the lab experiments. BARI Sarisha18

(canola) variety recorded the maximum seed yield (1.81 t ha ii

-1 ), comparable to others mustard varieties. Weed management had shown a non-significant effect on the seed yield of mustard. Although the combination of BARI Sarisha-18(canola) with two weeding gave the highest seed yield (1.85 t ha -1 ), the most economically viable combination was BARI Sarisha-18(Canola) with no weeding which gave the highest gross return (115140 Tk.), net return (74852 Tk.), and benefit-cost ratio (2.86). This suggests that the allelopathic trait of mustard is independent of local adaptation and yield potential under weed-free conditions and would be most useful to help farmers maximize yield and control weeds.