The agronomic characteristics and combining ability of glutinous Thermo-sensitive Genic Male Sterile rice (Oryza sativa) lines

Glutinous rice (Oryza sativa), despite its unique culinary qualities, typically yields less than other rice varieties, posing agricultural and economic challenges. The construction of a glutinous thermo-sensitive genic male sterile (TGMS) rice variety could indeed be a way to improve the yield and cultivation efficiency of glutinous rice. Among them, the two-line system operates by crossing a TGMS line, which is sterile at high temperatures but fertile at lower temperatures, with a normal fertile line. In this study, we conducted to access morphological characteristics and combining ability of some glutinous TGMS lines. The parental lines were characterized on 13 agronomic traits including growth duration, plant height, flag leaf width, flag leaf length, panicle length, rachis length, number of primary branches, number of secondary branches, number of panicles per plant, percentage of filled grains, P1000 seeds, grain yield, and amylose content. The obtained results revealed significant variations in growth traits, yield, and amylose content of studied rice lines. Hierarchical clustering based on principal component analysis of rice lines on all measured traits showed three major clusters with high genetic diversity. Furthermore, fifteen glutinous TGMS rice lines and three testers were used in a Line x Tester mating system to produce 45 hybrids. The 45 hybrids were evaluated on 6 traits related to grain yield and morphology in a randomized complete block design experiment with three replications. A line x tester analysis was conducted to estimate the combining ability, genetic variance, and the contribution of parental lines to genetic variation in hybrids. These findings were valuable for rice breeders to orient the strategy for breeding of hybrid glutinous rice varieties with high efficiency.