EVALUATION OF DUAL PURPOSE HERBICIDES IN WHEAT (Triticum aestivum L.) UNDER DIFFERENT TILLAGE REGIMES

Different doses of dual purpose herbicides (sulfosulfuron, metsulfuron-methyl 30 % + iodosulfuron–methyl–sodium 30 %, imazamethabenz- methyl and metribuzin) were studied to determine their effect on grain yield of wheat. The experiment was conducted at Islamic Azad University Experiment Station,Shooshtar Branch, Iran during 2006. Randomized complete block design was used having three replications, where two levels of tillage (conventional and minimum tillage) were assigned to themain plot while different levels of herbicides (sulfosulfuron 26.6 and 31 g a.i. ha-1, metsulfuron–methyl 30 % + iodosulfuron –methyl l- sodium 30 % 350 and 400 g a.i. ha-1, imazamethabenz - methyl 2 and 3 l ha-1 and metribuzin 200 and 300 g a.i. ha-1) were assigned to sub-plots. The results showed thatconventional tillage was better than minimum tillage in terms of weed control and significant difference was found between the tillage levels (P 0.01). Using 31 g ha-1 sulfosulfuron in conventional tillage and 31 g ha-1 sulfosulfuron and 400 g ha-1 metsulfuron – methyl 30 % + iodosulfuron – methyl – sodium 30 % in minimum tillage were the best treatments. No significant differences were found in the tillage levels regarding broadleaf weed control although their density was more in conventionaltillage. Using 31 and 26 g a.i. ha-1 sulfosulfuron, 350 g a.i. ha-1 and 400 g a.i. ha-1 metsulfuron – methyl 30 % + iodosulfuron –methyl – sodium 30 % in both tillage systems gave highest broadleaf weed control. Density of grassy weed was more in minimum tillage. The highest grassy weed control was observed using 31 and 26 g ha-1 sulfosulfuron, 350 g ha-1 and 400 g a.i.ha-1 metsulfuron–methyl 30 % + iodosulfuron –methyl–sodium 30 % in both tillage systems. There was no significant differencebetween two tillage systems regarding grain yield of wheat. Sulfosulfuron 26.6 and 31 g a.i. ha-1 and metsulfuron–methyl 30 %+ iodosulfuron–methyl–sodium 30 % 350 and 400 g a.i. ha-1 had the highest level of wheat grain yield, respectively.