Combining Ability and Heterosis Analysis for Some Physio-morphological Traits in Rice (Oryza sativa L.)
Résumé
The success of a plant breeding programme greatly depends on correct choice of parents for hybridization and the information on gene action involving different economic and drought tolerant traits. Combining ability analysis provides such information so as to frame the breeding programme effectively. Combing ability analysis is extremely useful in studying the nature and magnitude of genotypic variability and to facilitate correct choice of parent in any breeding programme. The present study aimed to assesses the heterosis and combining ability of rice under aerobic condition, an experiment was conducted at SCS college of Agriculture, Assam Agricultural University, Dhubri, Assam, India, with ten traditional upland genotypes and five HYVs of rice. Both additive and dominance gene effects were found to be important in the inheritance of seventeen traits in Line x Tester analysis. Based on General Combining Ability (GCA) estimate three genotypes each from line and tester were identified as good general combiner, while six crosses were identified with high specific combining ability (SCA) effect for increasing number of characters. Data recorded for plant traits were analyzed according to Analysis of variance (ANOVA). Heterosis was estimated from mean values as per standard protocol. Combining ability analysis was done using line x tester method. Days to anthesis, days to maturity, plant height and height growth rate were found to have significant SCA and heterobeltiosis in favourable direction in higher number of crosses. Four crosses viz. Aus Jaria/ IR 36, Kasalath/IR 36, Dimrow/KMJ-13A-6-1-2 and Tamdao/IR36 recorded heterobeltiosis for maximum number of characters (4 each). Contribution of interaction of line and tester was found to be higher than both individual line and tester for five number of characters (days to anthesis, days to maturity, harvest index and relative water content) indicating higher estimates of SCA variance effects. The proportional contribution of line and tester interaction was highest in relative water content (54.64) followed by grain yield (45.49) and days to maturity (44.95) indicating preponderance of non-additive gene action. Plant height, proline content, and the number of productive tillers were shown to be highly responsive to improvement based on genetic characteristics calculated from the Line x Tester experiment. In contrast, proline content, root shoot ratio, number of productive tillers, and grain yield were found to have significant genetic variability. The investigation succeeded in assessing the genetic variability in the material tested and also identified few promising genotypes and crosses. Genotypes like Banglami, Nagina 22, and Tamdao were identified with their outstanding combining ability to be included as parents in future breeding programme.