اثر تناوب زراعی بر ترکیب جمعیت و تراکم علف‌های‌هرز گندم در استان گلستان

Weeds are considered as one of the most important factors for crops yield reduction and rotation can break their life cycle in a specific cropping system due to change of growing media. In order to study of crop rotation on weed population density, Randomized Complete Block Design was conducted with 3 replications from autumn of 2004 in Gorgan agricultural research station for 5 years period. Canola, bean, barley, white pea, soybean, cotton, maize, sorghum, millet and wheat have considered as rotational crops. Each plot has signed to prevent cropping inaccuracy. Weeds flora and their density was recorded one month before crops harvesting. Results showed that rotation decreased 36% summer weeds density in the state of maximum sharing of crops in the rotation. In addition to, rotation can significantly reduce total weed population density if maize has planted in the previous summer season. Results also showed that wheat/maize rotation could reduce weeds density up to 33% more than rotational systems where maize is cultivated once every five years. The most summer broadleaf and grasses weeds were control in rotations consist of maize and soybean.