Effect of crop density on spring wheat cultivars (Triticum aestivum and T. durum) competition with mallow (Malva rotundifolia) under Bushehr conditions

The effects of crop seed densities on mallow weed (Malva rotundifolia) suppression and grain yield of wheat cultivars was investigated at two separate (weedy and weed free conditions) factorial experiments with randomized complete block design with four replications. Four spring wheat cultivars (Atila 5, Yavaros, Zagros and Koohdasht) were sown at four densities. Mallow weed was sown at constant density of 10 m-2. Increasing wheat density significantly increased the grain yield, kernel per spike, spike number per m-2 and plant height. Under weed free conditions, the highest and the lowest grain yield belonged to Atila5 (3721.7 kg ha-1) and Zagros (3040.3 kg ha-1) cultivars, respectively. Yavaros cultivar had the highest ability to withstand competition (AWC) and competition index (CI). Increasing wheat density up to 500 plant m-2 reduced 8.5% of grain yield in competition with mallow compared to 18% in 350 plant m-2. Individual weed biomass was differed among wheat cultivars and crop densities. Mallow had higher and lower biomass when compete with Yavaros and Zagros cultivars, respectively. In general, the results showed that the wheat cultivars were different in yield stability and competition with the mallow and increasing the crop density up to 500 plants m-2, increased the competitiveness of wheat cultivars with mallow.