Effects of Irrigation Regimes and Duration of Weed Interference on Grain Yield of Wheat (Triticum aestivum L.) in Middle Egypt

TWO EXPERIMENTS were performed at Farm of Faculty of Agriculture, El-Minia University Egypt, during two consecutive winter seasons 2017-2018 and 2018-2019 to evaluate the impact of weed removal period and different irrigation regimes on weeds, critical period of weed competition and yield and its components on wheat crop. A strip-plot design with three replications was used. Four irrigation regimes were in the horizontal plots and eight treatments of weed competition (4 weed-free periods and 4 weed competition periods) were in vertical plots. Results showed that omitting two irrigation (IR4) significantly decreased total density and dry weight of weeds, wheat traits, i.e. plant height, spike length, number of grains spike-1, 1000-grain weight, number of spikes m-2, grain yield and grain ability. Weed infestation for whole season significantly decreased all studied traits compared with weed removal even once after wheat sowing (DAS). Maximum yield losses of wheat due to weed infestation in whole season were 28.52 and 28.17% compared with weed-free treatment in the 1st and 2nd seasons, respectively. Cubic model was the best model for weed-free and weed competition over all treatments of the two seasons. The critical periods for weed control were 28 to 52 and 28 to 67 DAS in the two seasons, respectively.