Genetics of Panicle Exsertion in Cold-Tolerant Rice (Oryza sativa)

Four cold-tolerant rice varieties, viz. ‘Khonorullo’, ‘Namyi’, ‘Abor B’ and ‘Meghalaya-1’ were crossed with two cold-susceptible ones, viz. ‘Pusa 33’ and ‘Subhadra’ (DR92), in all possible combinations to study the inheritance of gene(s) governing panicle exsertion and their allelic relationship among cold-tolerant varieties. F₁ hybrids of all the crosses showed complete panicle exsertion indicating dominance of this trait. Segregation pattern of panicle exsertion in F₂ and backcrosses show that all the four cold-tolerant varieties possessed a single dominant gene designated as Ctr-1. Absence of segregation for panicle exsertion in an F₂ generation obtained from intercrosses of cold-tolerant varieties suggests that the dominant genes in all the four cultivars are allelic.