WEED CONTROL AND YIELD OF WHEAT AS AFFECTED BY BRASSICA ALLELOPATHY

Abstract

The experiment was conducted at the Agronomy research field, Sher-e-Bangla Agricultural University, Dhaka from November, 2008 to March, 2009 to find out the allelopathic effect of Brassica biomass on weed control and yield of wheat. The treatment of the experiment consisted of 2 levels of field status viz. fallow land (C ) and field with Brassica (C 2 ); 2 levels of maturity viz. 25 days old Brassica (M ) and 35 days old Brassica (M ); and 3 levels of Brassica biomass amount viz. 0 kg biomass m -2 (B 1 2 ), 0.5 kg biomass m -2 (B 2 ) and 1.0 kg biomass m -2 (B ). Maximum weed population at 30 DAS (165 m -2 ) and at 60 DAS (291 m -2 ), dry wt. of weeds at 30 DAS was found in the plots having no biomass. The highest dry weight of weed at 60 DAS was found for the field status from fallow land (107.77 gm ), 25 days old Brassica (78.80 gm -2 ) & 0 kg biomass application (89.94 gm -2 ). The highest grain yield was found from Brassica fields (2.68 t ha -1 ), 35 days old Brassica biomass (2.59 t ha -1 ) & 1.0 kg biomass application (2.71 t ha -1 ). The interaction effect of field status and Brassica biomass concentration showed significant result on weed population (80.33 m -2 ), dry weight of weed (39.74 g m -2 ), plant height (33.98 cm), number of effective tillers linear m -1 (84.67), spike length (16.09 cm), number of filled grain spike -1 (50.93), number of leaves plant -1 (10.53), weight of 1000 grains (41.22 g), grain yield (2.83 t ha -1 ) and straw yield (4.08 t ha -1 ).The lowest weed population (124.0 m -2 ) and dry weight of weed (39.11 gm -2 ) at 60 DAS was found from the field with Brassica field and 25 days old biomass @ 1.0 kg m -2 . The highest thousand grain weight (41.84 g) was found from the field with 35 days old Brassica application @ 0.50 kgm -2 . The maximum grain yield (2.86 t ha -1 ) was found from the field with 35 days old Brassica biomass application @ 1.0 kgm -2 . Weed population and weed dry weight showed highest result in fallow land with no biomass application. Fallow land, less matured biomass and no biomass application and their interaction encouraged growth of weed and dry weight of weed that means Brassica biomass reduced weed growth in all cases of application. Weed control was quite positive with Brassica biomass. On the other hand, land with Brassica and application of 35 days old Brassica biomass @ 0.5 -1.0 kg m -2 increased yield contributing characters and yield of wheat.

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