Spikelet Fertility Strongly Influences the Genetic Structure of F2 Population of CB174R/Iguapecateto Cross in Rice (Oryza sativa L.)

Author: J. Piyari, R. Saraswathi, R. Sangeetha, B. Meena Kumari, D. Kumaresan, C. Gopalakrishnan and V. Balasubramani

Download PDF

Abstract

The next generation of hybrid rice is based on exploitation of inter subspecific heterosis for which, development of restorers in indica/tropical japonica background suitable for tropical countries like India assumes importance. The progenies of sub-specific crosses exhibit spikelet sterility of varying degrees that have an impact on genetic structure of the population and further selection. Hence, the present study was aimed to understand the F2 population structure of an inter sub-specific cross CB174R/Iguapecateto in terms of mean, frequency of individuals, variability, heritability, correlation, direct and indirect influence of seven quantitative traits in whole and a subset of population for further selection. The population consisting of 781 plants was evaluated during June 2019 at Paddy Breeding Station, Department of Rice, CPBG, TNAU Coimbatore. Plants with 75% spikelet fertility were considered as highly fertile. Fifty five plants with above 75% spikelet fertility was formulated as a subset population. Majority of plants (70.87%) possessed 50.0-70.0% spikelet fertility in the whole population. A wide range noticed in the original population has been retained from 50-75% in subset population in different characters except spikelet fertility. The subset population had higher mean performance for most of the traits except 100-seed weight. Selection for spikelet fertility has influenced other traits like plant height, productive tillers, panicle length and single plant yield in frequency classes. Though PCV was higher than GCV for all the traits in both populations, differences were noticed for the traits spikelet fertility, hundred seed weight and single plant yield. Regarding heritability and genetic advance, spikelet fertility exhibited differences compared to whole population. High heritability coupled with high genetic advance as percent mean revealing additive action was noticed for the traits plant height, total tillers, productive tillers and single plant yield in both the populations and selection is effective in this generation. None of the traits expressed significant correlation with single plant yield in the original population, but values were in positive direction. In subset, spikelet fertility, number of total tillers, productive tillers and panicle length had a positive and significant influence on single plant yield of which, the influence of spikelet fertility was highly significant with high positive direct effect (0.5992). Total tillers showed moderate positive direct effect on the dependent variable. Selective advancement of highly fertile plants to F3 and observation for further segregation will give us some conclusive evidences for fertility inheritance and stability of spikelet fertility in later generations.

Keywords

Rice, inter sub-specific cross, Spikelet fertility (%), Frequency distribution, Variability, Heritability, Correlations and Path

Conclusion

The indica/tropical japonica cross synthesized using diverse parents was aimed to develop inter sub specific derivatives for restorer development. Though the F1 had 72.70%spikelet fertility, the F2 generation showed a wide range from 16 to 92% fertility signifying its impact on the structure of the population, which consisted of only 7.04% fertile plants. The cause behind this drastic reduction of fertility needs to be further explored. In the present breeding material, selection, and advancement of highly fertile plants to F3 and observation of these families for further segregation of spikelet fertility will give us some conclusive evidence for fertility inheritance and stability of spikelet fertility in later generations up to F6 for restorer development.

References

-

How to cite this article

J. Piyari, R. Saraswathi, R. Sangeetha, B. Meena Kumari, D. Kumaresan, C. Gopalakrishnan and V. Balasubramani (2023). Spikelet Fertility Strongly Influences the Genetic Structure of F2 Population of CB174R/Iguapecateto Cross in Rice (Oryza sativa L.). Biological Forum – An International Journal, 15(5): 651-661.