The conditional chalky grain mutant ’flo11-2ʹ of rice (Oryza sativa L.) is sensitive to high temperature and useful for studies on chalkiness

Abstract

Chalky grains of rice are increased due to high temperature (HT) during a ripening period. However, the underlying mechanisms of the chalkiness are not well known, seemingly due to the obtuse response of wild type and lack of effective mutants. In this study, we isolated and characterized the flo11-2 mutant, which showed higher number of chalky grains than wild type under HT but quite small number of chalkiness under cool temperature as well as similar growth, development, and yield to that of the wild type. Using this high sensitivity of the flo11-2 mutant, we identified the most critical meteorological factor and developmental stage affecting chalkiness with 5 days HT treatments over 4 consecutive years. The results demonstrated that daily maximum temperature was more causative than daily mean or minimum temperatures which have been regarded as important factors before this. Besides, the developmental stage around 20 days after flowering (DAF) was most sensitive to HT rather than the early stage up to 15 DAF. In addition, we found that the flo11-2 mutant with a high chalky ratio was vulnerable to preharvest sprouting, which has never been reported before for chalky grains, but could cause significant yield and quality loss after extremely hot and dry summers followed by rainy cool autumns. The flo11-2 mutant is, therefore, a useful material for chalky grain research.

COMPARATIVE ASSESSMENT OF SELECTED EXOTIC HYBRID RICE (Oryza sativa L.) BASED ON QUANTITATIVE TRAITS ANALYSIS

“…Variety itself plays an influential role for the improvement of a specific crop even in a distinct character. And effective utilization of the available genetic diversity exists in rice varieties can helps for its improvement strategies (Sarkar et al, 2021;Tabassum et al, 2020a;Tabassum et al, 2020b). In the meantime, the government of Bangladesh as well as private research organizations has imported some hybrid rice varieties from China, India and Philippines for enhancing the total yield.…”