FULL DIALLEL ANALYSIS IN PEARL MILLET (Pennisetum glaucum (L.) R. Br.)
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Date
2011-08
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jau,junagadh
Abstract
The present investigation was undertaken on pearl millet in order to estimate heterosis, combining ability and nature of gene action involved in the inheritance of grain yield and its component characters, viz., days to 50% flowering, days to maturity, number of effective tillers per plant, earhead length (cm), earhead girth (cm), earhead weight (g), plant height (cm), number of grains per square cm, grain yield per plant (g), 1000-grains weight (g), dry fodder yield per plant (g) and harvest index (%). The crosses were attempted by adopting diallel analysis (including reciprocals) involving eight elite inbreds during summer-2009. The resultant 56 hybrids along with their parents and one standard check hybrid (GHB-744) were evaluated in randomized block design with three replications during kharif-2009 at Main Pearl Millet Research Station, Junagadh Agricultural University, Jamnagar (Gujarat), India.
The analysis of variance for experimental design revealed that mean square differences among genotypes, parents and hybrids and reciprocals were significant for all the traits indicating sufficient amount of genetic variability for the twelve traits under study. The mean square due to parents Vs hybrids and F1 Vs reciprocals were significant for all the traits. On the basis of per se performance revealed among the crosses, J-2454 x J-2467 (69.07g) and among the parents, J-2467 (65.21g) gave the highest grain yield per plant.
Considerable degree of heterosis over better parent and standard check was observed in different hybrids for most of the traits. The magnitude of heterotic effects was high for grain yield per plant, number of effective tillers per plant, ear head weight and harvest index; and it was moderate to low for rest of the traits. The highest significant positive standard heterosis for grain yield per plant and some of its component traits were recorded in the crosses viz, J2454 x J2467, J2454 x J2511, H77/833-2 x J2405 and J2340 x J2511. The crosses exhibited high heterosis for grain yield also expressed high heterosis for at least one or more component traits.
The general and specific combining ability variances were highly significant for all the characters indicating both additive and non-additive gene effects played a vital role in the inheritance of all the traits. However, the gca:sca variance ratio less than unity confirmed the preponderance of non-additive gene action for the traits under studies and emphasized the utility of hybrid breeding approach to exploit existing heterosis in pearl millet. The estimate of GCA effects indicated that it was difficult to pick good general combiner parents for all the traits. However, the parents J2405, J2467 and J2511 were found good general combiners for grain yield per plant and some of its component traits. Hence, these parents were considered to be good source of imparting favorable genes for grain yield per plant and its components. Considerable harmony was observed between per se performance of parents and their GCA effects for grain yield and most of component traits.
The best crosses on the basis of SCA effects for grain yield per plant were J2467 x J2454, J2511 x J2454 and J2511 x J2340. The estimate of SCA effects revealed that crosses showing high SCA effects for grain yield also depicted high SCA effects for one or more yield components. The cross J2467 x J2454 had also high SCA effects for ear head weight, ear head length, number of grains per square cm and harvest index. The cross displaying high SCA effects did not always involve parents with high GCA effects, suggesting that interallelic interactions were also important for the characters. The per se performance of crosses for various traits was not related with their SCA effects.
Average degree of dominance revealed over dominance for all the traits except, number of effective tillers per plant, ear head girth and number of grains per square cm. Asymmetrical distribution of positive and negative genes in the parents was observed for most of the traits and nearly symmetrical distribution for days to 50% flowering, days to maturity and ear head girth. Inheritance of most of the characters including grain yield per plant was generally governed by a few genes or group of genes. The estimate of narrow sense heritability was found high for ear head weight, number of grains per square cm, grain yield per plant, dry fodder yield per plant and harvest index. Ear head length manifested moderate heritability whereas, rest of the traits displayed low heritability.
Considering the overall performance, three best promising crosses viz., J2454 x J2467 (poor x good), J2454 x J2511 (poor x good) and J2340 x J2511 (average x good) exhibited the highest per se performance as well as high positive significant standard heterosis, heterobeltiosis and SCA effects for grain yield per plant. These crosses also registered significant heterosis and SCA effects in desired direction for yield and its component traits. Therefore, these crosses to be segregate the favorable good sergeants in later generations for selection of superior inbred lines in pearl millet. These crosses also recorded 14.29, 13.09 and 12.37 per cent higher grain yield over standard check hybrid (GHB-744) respectively. Therefore, these crosses could also be exploited for heterosis breeding programme to boost the grain yield in pearl millet.
Overall results of present investigation suggested that reciprocal recurrent selection procedure make up the additive gene effects and would also allow dissiparation of non-additive gene effects. Bi-parental mating may also be used in the segregating generations to break the undesirable linkages and to exploit both additive and non-additive gene effects, simultaneously for isolating superior transgressive segregants in later segregating generations. Due to the preponderance of non-additive gene effects of grain yield and most of its component traits, heterosis breeding would also be practically feasible in crop like pearl millet.
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