QUANTITATIVE GENETIC ANALYSIS IN RELATION TO POPULATION IMPROVEMENT IN SORGHUM (SORGHUM BICOLOR (L) MOENCH)M.P. Deshmukh, R.B. Deshmukh and P.B. Ghorpade
Quantitative genetics studies of the random mating sorghum ICSP 2BR/MFR population was undertaken to investigate the inheritance of grain yield and other quantitative traits and to utilize the information to make decision as to which breeding system are the most likely to be successful in achieving population improvement. Six agronomic traits were evaluated in 200 half-sibs, 200 full-sibs and 200 S1 in rabi and kharif seasons. Genetic components of variance, heritability, genetic correlations and correlated response to selection, expected genetic gain from selection and predicated gains from index selection were estimated for each trait in each type of family. The S1 families had lower mean values than full-sib and half-sib families for all the characters studied in rabi and kharif seasons, respectively. The half-sib families displayed a narrow range of values for all the traits studied than the full-sib and S1 families. The additive genetic variance ( sA ) was predominant for all the agronomic traits in both seasons. Estimates of dominance variance were negative due to sampling error and assortative mating .The estimated additive genetic variances ( A) were higher than the variances due to the average effect of gene substitution in S1 families ( A* ) for all characters under study in rabi and kharif seasons, respectively. The ratio of A* to A were less than one for all characters in both seasons. The heritability estimates, in narrow senses, on family mean basis were very high in both seasons for S1 , full-sib and half-sib families for most of the traits except for earhead girth in half-sib families for kharif season. Highly heritable traits, days to flower and plant height could easily be improved by mass selection. In S1 family testing, the expected genetic advance for seed yield per plant was 27.66 % in rabi and 21.29 % in kharif season at 10 % selection intensity. For grain yield per plant, S1 family testing and selection offers the greatest promise for population improvement than fullsib and half-sib selection. The association between days to flower and grain yield was positive, therefore the selection for grain yield alone, indicate that the population would become taller and late in maturing. In general, favorable correlated responses were predicted for most of the agronomic traits in both the seasons. The results from this study indicated the limited usefulness of index selection in this material. The performance of ICSP 2BR/MFR population is good in both rabi (77.96 g/plant ) and kharif (96.01g/plant) seasons, therefore this population may be effectively utilized in development of cultivars for rabi as well as kharif seasons.
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