Investigating on the respons of Irrigated Wheat Cultivars to herbicide Total® WG 80% (Metsulfuron-methyl + Sulfosulfuron) in Different Regions of Iran

Wheat cultivars have been found to vary in responding to commonly used herbicides and their tank mixes, resulting in grain yield loss and reduced farm profits (Ramsey et al. 2010, Lemerle and Cousens, 1993). There are more than 45 commercial wheat cultivars and 20 herbicides formulations registered for weed control in wheat, in Iran that sensitivity test has not been done yet (Nourbakhsh, 2016). In our experiments, we determined the response of 11 common wheat cultivars to herbicide metsulfuron sulfosulfuron (Total®) as the most important herbicide to control wild barley at different regions.
A field study was conducted in four regions of Iran, including Mashhad, Jolgeh-Rokh (in Torbat-Heidarieh), Darab (in Fars) and Karaj during 2011 and 2012 growing seasons. The layouts was completely randomized block design in factorial arrangement of the treatments with four replicates. Treatments were wheat cultivars (Five cultivars chosen from 11 recommended cultivars for each region) and three herbicide application times (whether at 13, 16 or 31 growth stages of wheat according to Zadoks). Root and shoot dry weight of plants sampled in early growth stages, grain yield and visual injury assessment were subjected to statistical analysis and mean separated by DMRT (α=5%).
Results showed significant differences in grain yield of wheat cultivars irrespective of herbicide spraying in different growth stages. The maximum grain yield obtained from Pishgam cultivar in Mashhad and Jolgeh-Rokh, Pishgam, Mihan and Pishtaz cultivars in Karaj and Behrang, Chamran and Yavaroose cultivars in Darab. Herbicide application at Zadoks 13 on Mihan (32%), Zare (40%) and Gascogene (29%) cultivars in Mashhad caused significant reduction in root dry weight but no significant reduction in shoot dry weight and grain yield (percent of corresponding untreated control). Herbicide application on Orum and Zare cultivars at Zadok 31 caused significant reduction of root (41.5% and 30% respectively), shoot dry weight (16% and 29%) and grain yield (39 and 35%) at first year of the experiment in Karaj. Grain yield, however, was not significantly decreased in the second year. Pishgam cultivar didn’t showed unfavorable response to herbicide application in different growth stages. In Jolgeh-Rokh and Darab, neither visible injury of herbicide on wheat cultivars nor reduction in root and shoot dry weight and/or grain yield were observed. Cold temperatures appeared soon after herbicide application in Karaj and Mashhad may be responsible for the sensitivity of cultivars although they recovered in the most cases. Cultivars responses to temporarily stress are complicated, and may be dependent to settled condition and must be studied more accurately.
Among 11 tested cultivars, most of them shown no sign of sensitivity to Total® application. Zare was recognized as the most sensitive and then after, Oroum and Gascogene showed relative sensitivity.
Acknowledgements: We wish to thanks Professor Eskandar Zand, Dr. Masoud Ezatahmadi, Mr. Seyed Hoseein Torabi and Mr. Mohammad Pasban for very useful convenience on this project.