بررسی مقاومت لاین های امیدبخش گندم به بیماری لکه خرمایی و لکه برگی بایپولاریس در مزرعه

Tan Spot and Spot Blotch caused by Pyrenophora tritici-repentis and Bipolaris sorokiniana respectively are among the most important diseases of the wheat that can cause economically damages in the world. In this study, the resistance of 50 germplasms belong to the 7HLBSN Nursery of CIMMYT were evaluated against wheat Tan Spot and Spot Blotch in Mazandaran province where it is one of the main hot spot areas of these diseases in the north of Iran. A mixture of 10 isolates of each fungal pathogen was used to provide inoculum in field experiments. For this purpose, the inoculation of the plant was carried out with the aid of infected residues that were distributed uniformly throughout the experimental plots, as well as infected seeds that was artificially prepared in the laboratory. The experiment was carried out in a randomized complete block design with three replications in two regions of Mazandaran province including Gharakheil and Baikola research stations. Field disease evaluation was based on a double-digit system, which was D1 or the first component related to the height of the plant infected by the pathogen and D2 or the second component was related to the severity of the infection on the upper four leaves of the wheat. The system was capable of evaluating the disease at the range of 00-99. The range of evaluation in both components was from zero to nine. No. 5 was evaluated in the first part of the scale when the disease spread to the center of the plant, and No. 9 was the time when infection reached to the flag leaf. In the case of the second component, No. 1 was the severity of the disease when the four upper leaves showed a small amount of disease, while No. 9 indicated the total leaf infection. The final data were analyzed using SAS software. Finally, germplasms resistant to both diseases; Tans Spot and Spot Blotch, were identified. According to the results, the resistance of the lines to Spot Blotch was more than their resistance to Tan Spot. Of the 50 lines evaluated in this study, six lines, including No. 9, 20, 21, 23, 28 and 42, were resistant to both diseases in two stations of Mazandaran. These resistant lines could be used in breeding program of national agricultural research system.