Phenotypic and SSR Marker-based Screening of Rice (Oryza sativa L.) Hybrids for Cold Tolerance

Abstract

The experiment was conducted during rabi, 2022–23 (December, 2022 to May, 2023) at the Regional Agricultural Research Station (RARS), Jagtial, Telangana, India to evaluate the cold tolerance of rice hybrids and parental lines under natural field conditions. During Kharif 2022 (July to November, 2022), four Cytoplasmic Male Sterile (CMS) lines and eight restorer lines were crossed to produce 32 rice hybrids. The experimental material comprised 32 hybrids, 12 parents, one susceptible check and one tolerant check. Seedlings were raised in a nursery during December 2022 and exposed to natural low-temperature conditions. Cold tolerance was assessed using the IRRI Standard Evaluation System (SES, 2013), along with SPAD chlorophyll measurements. The results indicated that the hybrids CMS 23A×IR 65514-5-2-19R-1, CMS 14A×IR 65483-14-1-1-4-13R, CMS 64A×IR 65514-5-2-19R-1, and CMS 64A×IR 63870-7-3-2-3-3R were tolerant to cold stress, whereas CMS 64A×JGL 29651 was moderately tolerant. Molecular confirmation of cold tolerance was carried out using 13 SSR markers, of which RM85, RM341, and RM561 exhibited clear polymorphism, while the remaining markers were monomorphic. These markers differentiated tolerant and susceptible genotypes based on specific banding patterns. The tolerant parental lines identified were CMS 64B, CMS 69B, and IR 65514-5-2-19R-1, whereas the tolerant hybrids included CMS 23A×IR 63870-7-3-2-3-3R, CMS 23A×IR 65514-5-2-19R-1, CMS 23A×JGL 27347, CMS 64A×IR 63870-7-3-2-3-3R, CMS 64A×IR 65483-14-1-1-4-13R, CMS 64A×IR 65514-5-2-19R-1, CMS 69A×JGL 21005, and CMS 69A×JGL 24444. These genotypes could serve as valuable sources of cold tolerance in future rice breeding programme.