The effects of different time of weed control on yield and yield components of corn (Zea mays L.) Hybrids in different densities

In order to investigate the effects of plant density، time and number of weed control on yield and yield components on corn hybrids، a factorial experiment in completely randomized blocks design with 3 replications was conducted in 2011 growth season at Research farm of College of Agriculture، University of Shahid Bahonar، Kerman. Weed control treatments were including: weed control during corn growth season (W1)، weed control in 2، 4 and 8 weeks after planting (W2)، weed control in 4 and 8 weeks after planting (W3)، no weed control during corn growth season (W4). Corn varieties were Single cross 704 (C1) and Maxima from FAO580 (C2) that were planted in two densities of 70. 000 (D1) and 90. 000 plants per hectare (D2). The results showed that corn weed competition caused a significant decrease in W4 treatment. Grain yield increased with increasing density، but the number of grains per ear، 100-grain weight، ear length and shoot dry weight were reduced. Maxima variety showed increase in grain yield، 100 seed weight، number of ears per plant and ear length compared to single cross 704. Results of this survey indicated that weed control in two stages after planting stage was suitable to achieve favorable results in Kerman environmental condition.