واكنش رقابتي گندم زمستانه TRITICUM AESTIVUM به تغيير تراكم يولاف وحشي AVENA IUDORICIANA و مصرف كود نيتروژن

Competitive response of winter wheat (Triticum aestivum) to various plant densities of wild oat (Avena ludoviciana) and nitrogen fertilizer

Competitive response of a winter wheat cultivar (C73-5) to various plant densities of wild oat and levels of nitrogen fertilizer was investigated at the field Research Station of Ferdowsi University of Mashhad, College of Agriculture, in 1999-2000. A split plot experiment based on a randomized complete block design with 4 replications was used. Four levels of nitrogen fertilizer (25, 50, 75 and 100 kg/ha) were assigned to the main plots and wild oat plant densities (0, 30, 50 and 80 plant/m^2 ) to the subplots. The results showed that, wheat shoot dry weight and grain yield. the number of tillers and spikes per unit area and wheat 1000 grain weight were declined as wild oat plant density increased. Both crop and weed shoot dry weight and number of tillers per unit area increased, but the proportion of crop from total shoot dry weight and number of tillers per unit area decreased, as nitrogen fertilizer increased. Loss of wheat grain yield with increasing weed density was greater in high than in low nitrogen levels. Regression models were used to describe the effect of wild oat plant density on wheat grain yield. Wheat yield was described well by a linear regression model, using both absolute plant density and relative biomass of wild oat or a nonlinear regression model, using the relative density of wild oat in the weed-crop stand.