Greenhouse evaluation of rice cultivars for resistance to gall midge, Orseolia oryzae (Wood-Mason) and studies on mechanism of resistance

Abstract

A total of 2256 germplasm accessions, 3000 advanced generation breeding lines and 150 released varieties of rice were screened under artificial infestation in the greenhouse. Among these, 15 new germplasm accessions, 50 breeding lines derived from 16 crosses and 15 released varieties were resistant. Antibiosis was the predominant resistance mechanism; antixenosis affecting oviposition was noted in 33 resistant varieties. Biochemical composition of a set of resistant varieties along with susceptible checks, revealed that nitrogen content of seven test varieties was significantly higher than that of the susceptible checks, while in other six varieties it was lower than the checks. Similarly, eight of the resistant varieties had considerably higher percentage of polyphenolic compounds in basal stem portion, but seven other cultivars showed significantly lower concentration as compared to susceptible checks. Thus, it was apparent that there was no clear trend among the resistant cultivars as a group in relation to quantitative differences of chemical components analysed.