Rice varieties are generally bred for higher yield but may possess genomic regions conferring tolerance to abiotic stresses. Climate change driven heat stress during reproductive stage of the crop affects spikelet fertility and yield. Though genetic regions associated with heat stress tolerance have been identified in rice, but response of rice varieties and allelic phenotypic effect favoring spikelet fertility during heat stress has not been comprehensively studied. Hence, the present study aimed at assessing the response of 198 rice varieties during the dry season (2016) followed by validation of selected 67 varieties in the second dry season (2017) through staggered sowing for high temperature. The analysis showed mean spikelet sterility of 21.82% and 33.81% for the first and second sowing, respectively. Further, average difference in spikelet sterility for unit increase in maximum temperature during the flowering period was observed to be 7.93%. Employment of nine heat stress associated markers for genetic analysis identified four sub-populations in the 67 varieties inferred through neighbor-joining phylogenetic tree and sub-structure analysis. Marker-trait association analysis showed two markers namely RM205, RM242 were significantly associated with spikelet sterility with phenotypic variance (R²) of 7.7% and 6.0%, respectively. Allelic phenotypic effect of favorable alleles for both the markers reduced spikelet sterility by 14.49% compared to mean spikelet sterility (33.81%). Furthermore, four rice varieties showed spikelet sterility < 15%. Thus, predominantly moderate tolerance to susceptible response was observed for rice varieties in this study. Besides, favorable allele of RM205, RM242 could be effectively used for improving tolerance in rice varieties to heat stress.

水稻品种通常以更高的产量进行育种，但可能拥有赋予非生物胁迫耐受性的基因组区域。气候变化驱动的农作物生殖期热应激会影响小穗的繁殖力和单产。尽管已经在水稻中鉴定了与耐热性相关的遗传区域，但是尚未全面研究水稻品种的响应和有利于小穗育性的等位基因表型效应。因此，本研究旨在评估198个水稻品种在旱季（2016年）的响应，然后通过交错播种高温对第二个旱季（2017年）选定的67个品种进行验证。分析显示，第一次和第二次播种的平均小穗不育性分别为21.82％和33.81％。更多，在开花期，最高温度每升高一单位，小穗不育性的平均差异为7.93％。通过使用九个与热应激相关的标记进行遗传分析，通过邻居结合的系统树和子结构分析推断出67个变种中的四个亚群。标记-性状关联分析表明，RM205，RM242这两个标记物与小穗不育与表型差异显着相关（R²）分别为7.7％和6.0％。与平均小穗不育（33.81％）相比，两种标记的有利等位基因的等位基因表型效应使小穗不育减少了14.49％。此外，四个水稻品种的小穗不育率<15％。因此，在这项研究中观察到水稻品种对敏感反应的耐受性主要为中等。此外，RM205，RM242等位基因有利于提高水稻品种对热胁迫的耐受性。