Weed Smothering in Mustard (Brassica spp) by its High-Density Uniform Broadcast Sowing

Manual weed control in mustard is very expensive because of its high labour requirement i.e., 150-250 labourers/ha. Chemical weed control again imposes environmental hazards. Mechanical weed control in mustard is not still that popular till date. Due to severe weed competition, the yield reduction in Indian mustard may go as high as 70 per cent. Thus weed control in zero till mustard using its high-density sowing (HDS) was studied in different farmers’ field, at ICAR-CRIJAF, in North 24 PGS and Purulia, from 2018-2022. Fast growing and high- density uniform mustard canopy (100-200 m2) developed at early stages hinders sunlight penetration (up to 99.98 per cent) below its canopy (at 35- 40 days), leading to scanty and under developed growth of different composite weed species at harvest, those germinate or grow below mustard canopy. Weed population below mustard canopy was reduced by 92 to 97 per cent at mustard harvest. It was only 10-80/m2 at harvest over 350-1000/m2 in weedy situation at initial germination. The reduction of dicot weed biomass below matured mustard at harvest was 81-99 percent (5-150g/ m2) percent over weedy plots (500-800/ m2). Reduction of effective flowers/pods of different weeds under matured mustard canopy were up to 99.5 percent. Proper agronomic management practices of HDS mustard e.g., seed rate, date of sowing, uniformity of sowing, irrigation and fertiliser application will eliminate the herbicide application or manual weeding in mustard. Nearly 80 percent mustard plants remain active at harvest. It saves 150-250 labours /ha depending on weed species and its density of germination. Mustard grain yield ranged from 15-30 q/ha depending on management and varieties used. This weed smothering merit of mustard can be used for eco friendly weed control in other wide spaced field/horticultural crops using its dwarf variety (Toria).