Weed suppression ability of wheat cultivars vary under different weed scenarios

A two-year study was conducted at the Regional Research Station, Abohar, India, of Punjab Agricultural University to evaluate the effects of wheat cultivars and row spacing on weed dynamics, weed growth and wheat yield under different weed scenarios. Grass weed species tended to populate wheat cv. PBW 725, while broadleaf weeds were more in wheat cv. HD 3086 at one or the other observed stages. However, total weed biomass was similar in both the cultivars, which resulted in similar grain yield. Wide row spacing (20 cm) resulted in higher weed densities of most of the weed species, thereby had higher weed biomass and lesser wheat yield than narrow row spacing (15 cm). Broadleaf weeds accumulated higher weed biomass (67-92%) than grass weeds, however, grain yield reduction was more due to grass weeds (14-18%) as compared to broadleaf weeds (9-11%). Crop kept weed free for 45 days nullified the simple effect of cultivar and spacing on weed density and biomass. The study revealed that response of cultivar for weed suppression may be different for different weed species. Also, yield reduction in a crop may have more dependence on composition of weed flora in population, besides the weed biomass accumulated in the crop.