Evaluation of resistance of some wheat cultivars to the take-all disease

Take-all disease, caused by Gaeumannomyces graminis var. tritici (Ggt), is the most devastating root disease of cereals throughout the world. The disease has been reported from different regions of Iran, including Kermanshah province. To evaluate current wheat cultivars for resistance or tolerance to take-all disease, 17 wheat cultivars were inoculated by a mixture of four selected isolates of Ggt and their resistance was evaluated under field conditions. In the spring of 2012, these cultivars were sown in microplots with 100×50 cm dimensions. The inoculum, prepared on autoclaved oat seeds, were added to every row of sowing and then covered with soil. Different traits including grain yield, biological yield, thousand grain weight, root fresh weight, shoot fresh weight, total fresh weight, root dry weight, shoot dry weight, percent of diseased rootlets, number of tillers, number of grains in the spike, weight of grains in 1 m rows, average weight of grains in the spike, total dry weight, harvest index, and grain yield in 1 m2 were recorded and analyzed. In this study, different stress indices including stress susceptibility index (SSI), stress tolerance index (STI), yield index (YI), and Harmonic mean (HAM) were calculated. Based on the RS parameter, which includes all the indices, Marvdasht, Parsi, and Aflak were introduced as tolerant cultivars. Moreover, Sardari, Sivand, Shiraz, and Alvand were identified as susceptible cultivars.