Effect of rice residue and nitrogen management on weeds and productivity of oilseed rape (Brassica napus L.)
AbstractA field experiment was conducted during the winter (Rabi) seasons of 2023-24 and 2024-25 at Punjab Agricultural University, Ludhiana, to evaluate the effects of rice residue and nitrogen management on weeds in oilseed rape (Brassica napus L.) of rice (Oryza sativa L.)- should be in the middle oilseed rape rotation. The experiment was laid out in a split-plot design with three replications. Main plot treatments included three rice residue management practices involving oilseed rape seeding with Happy seeder (Happy seeder), surface seeding-cum-mulching, and conventional method while the subplot treatments comprised of three nitrogen levels, viz. 75%, 100% and 125% of the recommended dose of nitrogen (RDN). Among the rice residue management practices, both the surface seeding-cum-mulching and Happy seeder method recorded significantly lower weed density and biomass compared to the conventional method at 30 days after sowing (DAS). Application of 75% RDN resulted in significantly lower weed density and biomass at 30 DAS compared with 100% and 125% RDN. Further, application of 125% RDN increased seed yield by 19.6% over 75% RDN, whereas 100% RDN produced a 15.3% higher yield than 75% RDN. The highest weed density and biomass were observed with the conventional method, indicating that residue retention practices using Happy seeder and surface seeding-cum-mulching methods, combined with 75% nitrogen dose were more effective in suppressing weed emergence and growth in oilseed rape based on the two-year pooled analysis. Happy seeder-sown oilseed rape produced 10.4% and 23.3% higher seed yield than conventional method and surface seeding-cum-mulching, respectively.