Abstract In rice, higher temperature (> 33 °C) during anthesis and fertilization impacts spikelet fertility and thereby affecting grain-filling and yield. The genus Oryza exhibit variability, at species level, for flower opening time (FOT) trait. Understanding this trait in rice wild relatives will help identify potential wild species that could be used in wide-hybridization program for introgression of this valuable trait for multiple utilities. The FOT trait was studied morphologically in 15 Oryza taxa that were in anthesis at the wild rice garden jointly maintained by ICAR-CRRI and ICAR-NBPGR-Base Center, Cuttack; and the extreme phenotype species’ FOT variability was validated at ICAR-NBPGR-Regional Station, Thrissur. Among the Oryza species studied, the earliest diurnal FOT was observed in O. granulata (05:30 AM). The wild relatives whose FOT were found to be earlier than the cultivated rice were: O. meyeriana , O. minuta , O. alta, and O. latifolia . These were prospective species as sources for FOT trait introgression to induce early morning flowering (EMF). Species like O. longistaminata and O. australiensis that flowers late afternoon (1–4 PM) can be a promising source for restoring fertility in TGMS-based 2-line hybrids (RFiTH) which otherwise might fail to set seeds due to higher diurnal temperature at anthesis and fertilization. Our studies identified these seven species as promising resource for introgression of genes or quantitative trait loci (QTL) associated for the FOT trait variability, EMF and RFiTH, in cultivated rice to overcome the effect of high temperature on spikelet fertility and thereby imparting climate resilience in cultivated rice.
Rai et al. (Mon,) studied this question.