اثر تناوب گياهان زراعي بر پويايي جوامع علف هاي هرز در سورگوم علوفه اي

Effect of Crop Rotation on Weed Community Dynamic in Fodder Sorghum

In order to evaluate the effect of crop rotation on weed community, a 3 - year field study was conducted with four crops including wheat, canola, fodder corn and sorghum in Mashhad. The statistical design was randomized complete block, with rotation factor in four levels, and three replications . Weed study was undertaken 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 indicated that both rotation and previous crop have significant effect on weed dry matter and density. Weed dominant species and weed flora also affected by rotation . All variables were higher in the first period than the second . In most cases boardleaf weed dry matter and density were higher than narrowleaf weed . In both periods , only forth rotation had highest weed dry matter and density. Previous crop especially canola was a volunteer plant on the next crop and only in the first period.