مهار علف هاي هرز پهن برگ در زراعت سويا با ميزان كاهش يافته و خردشده بنتازون

Broadleaf weed control with split and reduced bentazon rate in soybean(Glycine max L) crop

In order to obtain a sustainable agriculture and environment protection, there have been many efforts in recent years to reduce herbicide uses. This research was conducted in 1379 (year 2000) at Sari agricultural college experimental station as a randomized complete block design with 11 treatments and four replications to investigate the effects of reduced Bentazon rate application on weed control and the corresponding soybean growth and yield. The treatments were: reduced bentazon rates of 0.84 (recommended rate), 0.75, 0.58, 0.24 and 0.25 kg ai/ha for one-stage spraying, (0.25+0.58), (0.25+6.42) and (0.42+0.42) kg ai/ha for split-application of two-stage spraying, and (0.25+0.25+0.25) for split - application of three-stage spraying and two control treatments of weed-free check and weedy check. Based on soybean yield (number of pod and production rate), it was concluded that bentazon use could be reduced up to 30 percent to control velvetleaf (Abutilon teophrasti), which is important in reducing production costs and environmental pollution. Use of reduced bentazon rate and split-application could control velvetleaf as much as 90 percent which is equal to the effect of the recommended rate. Comparison of reduced bentazon rate using a split application at three stage spraying (0.25+0.-15+0.25) with normal to recommended rate did not significantly differ in velvetleaf control percentage and soybean yield.