Evaluation of promising rice genotypes for resistance to rice striped stem borer, Chilo suppressalis (Lepidoptera: Crambidae) in paddy field conditions

The objective of this study was to identify rice lines (genotypes) resistant to striped stem borer and to determine plant characteristics associated with resistance. In this research, a total of 63 rice lines were evaluated in the field under natural infestation conditions during 2016- 2017. The lines exhibited considerable variation for plant height (84.30-149 cm), stem diameter (3.7-6.3 mm), panicle length (21.1-32.9 cm), number of larvae (3.83-69.50), growth period (108-138 days), white heads infestation (1.11-11.72 %) and grain yield (3.7-8.2t.ha-1)in relation to the mentioned pest. The results showed that the white heads infestation percent had significantly correlated with plant height stem diameter and panicle length. And also, there was a significantly correlated the decrease of grain yield by increasing the stem diameter, more infestation and white heads. The cluster analysis based on the studied morphological characteristics showed that all genotypes were classified into three groups. So that, 8, 26 and 29 genotypes was located in A, B and C classes, respectively. Among all the genotypes, the lines of the third group (Class C) can be used as a source for breeding programs to achieve the new rice cultivars which is to be tolerant to rice striped stem borer pest.