اثرالگوهاي تناوب گياهان زراعي برپويايي جوامع علفهاي هرز در ذرت علوفه اي

Effect of Crop Rotation on Weed Community Dynamic in Fodder Corn

In order to evaluate the effect of crop rotation on weed community, a three-year field study was conducted with 4 crops including wheat, canola, fodder corn and sorghum in a research farm of agricultural faculty of Mashhad. The statistical design was arandomized complete block with rotation factor in four levels and three replications. Weeds study were laid out on two periods, first before crop canopy closure and second before crop harvesting. The effect of rotation was investigated on the last crop. The results indicate that both rotation and previous crop have significant effect on weed dry matter and density. Weed dominant species and weed flora were also affected by rotation. All parameters in the first period were higher than the second period. In most cases boardleaf weed dry matter and density were higher than narrowleaf weed. Second and third rotations had the highest dry matter and weed density respectively. Previous crop, especially canola, was as volunteer crop on the next plant but only in the first period. This research emphasizes the effect of crop rotation on unstability of weeds communities. Crop and sequential cropping system have an influence on both periods, but the effect of corn was higher in the second period.