Studies on Crop-Weed Competition and Weed Dynamics in Maize under Mid-Hill Conditions of N-W Himalayas

Impact of weed types on crop-weed competition and weed dynamics in maize was assessed. Grassy weeds of fered maximum competition to crop reducing grain yield by 77.4% followed by non-grassy weeds (44.2%) and sedges (38.4%). Competition with non-grassy and sedges as mix flora had less weed index than mix weed flora consisting of grasses, nongrasses and sedges. Competition with grassy and sedges as mix flora had impact similar to that of where all types of weeds competed with the crop. Grasses and non-grasses or sedges grown together resulted in more infestation of grassy weeds than non-grasses and sedges when compared with mix flora of all the three weed types. Infestation of E. colona, B. ramosa and P. repens under sole grasses, B. ramosa and P. repens under grasses+non-grasses or sedges was more than that of where grasses+non-grasses+sedges were grown. The maximum increase was recorded in B. ramosa. Density of E. colonum under mix flora of grassy and non-grassy was reduced than mix flora consisting of grasses, non-grasses and sedges. Non-grassy and sedges grown together resulted in more infestation of non-grassy weeds as compared to sedges. The maximum increase was recorded in G. parviflora.