Evaluation of resistance of Iranian rice (Oryza sativa) lines to the striped stem borer, Chilo suppressalis.

Rice is one of the most important staple food crops for more than half of the world population. The striped stem borer Chilo suppresalis is one of the most devastating pests of rice, reducing yield world wide. The use of resistant cultivars remains one of the most reliable methods to manage the pests. In this study, mechanism of resistance in 10 lines of rice for 3 kinds of resistance (antixenoses, antibioses and tolerance) were studied. The egg set of striped stem borer on the leaf of lines, mean weight of larva and survival percentage of larva were measured for antixenosis and antibiosis resistance, respectively. Also, in this study the tolerance of 10 lines of rice was evaluated in the field against the striped stem borer. Percentage of white head was used for determination of tolerance to striped stem borer. The results showed that the maximum egg set, percentage of survival, dead heart and white head belong to line 3 (Sang-e-Tarom × Tarom-e- Daylamani) and the highest weight of larva was obtained on the line 5 (Iri-2 × Nok-siah). In this study the most susceptible and resistant genotypes were line 3 (Sang-e-Tarom×Tarom-e-Daylamani) and line 4 (fajr×Nok-siah), respectively. Also, results of greenhouse exaperiments proved the results of field exaperiments. The results of correlation study showed that the height of plant and amount of chlorophyll were effective on antixenosis. Also, stem diameter and number of tillers were effective on antibios mechanism. Finally, mechanism of tolerance was affected by stem diameter.