Effective qualitative traits in resistance mechanisms of rice varieties to stem borer (Chilo suppressalis (Walker)

The use of resistant cultivars remains one of the most reliable methods to manage the pests. In this study the mechanism of resistance in 10 lines of rice for 3 kinds of resistance (Antixenoses، Antibioses and tolerance) was studied. The egg set of striped stem borer on the leaf of considered lines for Antixenoses and larva weight mean and survival percentage of larva were evaluated for Antibioses resistance. Percentage of white head was used for determining the tolerance mechanism to striped stem borer. The results showed that the maximum egg set، percentage of larva survival، dead heart and white head belong to L3 [(Sang-e-Tarom × Tarom-e- Daylamani)] and the highest weight of larva obtain on the L5 [(IRRi-2 × Nok-siah)]. In this study the most susceptible and resistant genotypes were L3 [(Sang-e-Tarom×Tarom-e-Daylamani)] and L4 [(fajr×Nok-siah)]، respectively. Study of correlation coefficient showed that the height of plant and amount of chlorophyll were effective on Antixenoses. Stem diameter and number of tiller were effective on Antibioses mechanism. Finally، mechanism of tolerance was also affected by stem diameter.