Screening of twenty rice genotypes for tolerance or resistance to striped stem borer (Chilo suppressalis) in paddy field

Rice striped stem borer, Chilo suppressalis Walker (Lep.: Pyralidae) is considered as the most important pest in paddy fields in north of Iran and causes severe damages to rice cultivation. Currently, the use of chemical insecticides is the most common practice in controlling this pest. However, considering environmental problems, it is advisable to look for alternative methods, including the use of resistant or tolerant cultivars to rice striped stem borer. Thus in the current study 20 lines and cultivars of rice were considered. The results indicated that all 20 cultivars and lines tested in the first generation of rice striped stem borer showed dead hearts ranging from 15.29 to 21. 85% based on the standard evaluation system of rice (IRRI) and relatively stood in resistant group (Scale 5). In the second generation of the pest the infection symptom of white heads clusters depicted that the line number 4 was in the resistant group, and lines 2, 4, 5, 7, 13, 11, 14, 15 and 18 in relatively resistant group. The results of this study showed that cultivars and lines of 1, 3, 6, 8, 9, 12, 16 and 19 are grouped in a relatively sensitive group to rice striped stem borer. Our study also showed that the Gohar cultivar with 31.28% white heads in reproductive stage was placed in the sensitive group. Therefore, in the present study, line 5 (row 11(, line 14 (row 10) and line 37 (row 17) are recommended for breeding and integrated management programs for rice striped stem borer.