STUDIES ON GENETIC DIVERGENCE, COMBINING ABILITY AND STABILITY FOR GRAIN YIELD AND ITS COMPONENTS IN MAIZE (Zea mays L.)
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Title |
STUDIES ON GENETIC DIVERGENCE, COMBINING ABILITY AND STABILITY FOR GRAIN YIELD AND ITS COMPONENTS IN MAIZE (Zea mays L.)
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Creator |
RAM REDDY, VADALA
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Contributor |
FARZANA JABEEN
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Subject |
yields, planting, grain, heterosis, hybrids, genotypes, maize, crossing over, biological phenomena, developmental stages
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Description |
The present investigation “Studies on genetic divergence, combining ability and stability for grain yield and its components in maize (Zea mays L.)” was undertaken to identify the diverse parents in maize and study the combining ability, heterosis, nature of gene action, genetic parameters, character association, G X E interaction and stability of experimental hybrids for yield and yield components. The data was collected on days to 50 per cent tasseling, days to 50 per cent silking, days to maturity, plant height (cm), ear height (cm), ear girth (cm), ear length (cm), number of kernel rows per ear, number of kernels per row, 100-seed weight (g) and grain yield per plant (g). During rabi, 2010-11 fifty genotypes were evaluated for genetic diversity at College Farm, College of Agriculture, Rajendranagar, Hyderabad. The analysis of variance revealed significant differences among the genotypes for all the 11 characters studied. Based on Mahalanobis D2 analysis the 50 genotypes were grouped into eight clusters. The pattern of distribution of genotypes into various clusters revealed that there was no relationship between geographical distribution and genetic diversity. Greater genetic divergence was found in clusters II and VI, suggested exploitation of these two clusters by intermating the genotypes in a definite breeding design to explore the fullest range of heterosis and to realize good recombinant lines. Based on genetic divergence studies, the genotypes CM-211, BML-2782 and BML-5233-5 from cluster I, BML-2486, BML-6 and BML-15 from cluster II, BML-7 from cluster IV, BML-2910 from cluster V, BML-2 from cluster VI and BML-3044 from cluster VII were selected for hybridization programme as they were expected to produce high heterotic crosses. Ten divergent parents were crossed in diallel fashion excluding reciprocals during kharif, 2011 at College Farm, College of Agriculture, Rajendranagar, Hyderabad. The resulting 45 crosses along with parents and two standard checks viz., DHM-117 and 900 M Gold were evaluated in Randomized Block Design replicated thrice during rabi, 2011-12 at three locations viz., Rajendranagar, Karimnagar and Kampasagar. The pooled analysis of variance for combining ability revealed significant differences due to environments, parents, hybrids and various interactions indicating the existence of wider variability in the material studied. The ratios of GCA/SCA variances revealed that non additive gene action was predominant in the inheritance of all the characters viz., days to 50 per cent tasseling, days to 50 per cent silking, days to maturity, plant height (cm), ear height (cm), ear girth (cm), ear length (cm), number of kernel rows per ear, number of kernels per row, 100-seed weight (g) and grain yield per plant (g). Combining ability analysis revealed that among the parents, BML-5233-5, CM-211and BML-2 were found to be good general combiners for earliness viz., days to 50 per cent tasseling, days to 50 per cent silking and days to maturity. The parents, BML-6, BML-7 and BML-5233-5 recorded significant positive gca effects for grain yield, these inbreds may be utilized in population improvement or in the development of synthetics and composites. The hybrids, BML-2486 X BML-2, BML-7 X BML-3044 and BML-6 X BML- 3044 were found to be good specific combiners for earliness. While the hybrids, BML-15 X BML-2910, BML-6 X BML-3044, BML-2782 X BML-7, BML-7 X BML-3044 and BML- 2486 X BML-3044 which recorded positively significant sca effects for grain yield. Hence, considered as good specific combiners, therefore, these hybrids could be recommended for heterosis breeding. Estimates of relative heterosis, heterobeltiosis and standard heterosis were variable among crosses in desirable direction and some of them turned out to be the best specific crosses. Heterosis for grain yield per plant is mainly because of simultaneous manifestation of heterosis for yield component traits. The highest standard heterosis for grain yield per plant was recorded for hybrids, BML-15 X BML-2910, BML-6 X BML-3044, BML-2782 X BML-7, BML-7 X BML-3044 and CM-211 X BML-7 along with per se, relative heterosis, heterobeltiosis and with high sca effects. These hybrids may be further exploited in multilocation evaluation before releasing them for commercial cultivation. In pooled analysis high narrow sense heritability estimates were recorded in days to 50 per cent silking, days to 50 per cent tasseling, ear height, days to maturity, number of kernels per row and ear girth. Thus, these traits are predominantly under the control of additive gene action and hence these characters can be improved by selection. On the whole based on the overall performance among the parents, BML-6, BML-7, BML-5233-5, CM-211 and BML-2 and among hybrids BML-15 X BML-2910, BML-6 X BML-3044, BML-2782 X BML-7, BML-7 X BML-3044, CM-211 X BML-7 and BML-2486 X BML-2 were found to be the best for yield and yield attributes in the present investigation. Results of stability analysis revealed that ten hybrids viz., BML-15 X BML-2910, BML-7 X BML-3044, CM-211 X BML-7, BML-6 X BML-2, BML-2782 X BML-6, BML-6 X BML-7, BML-5233-5 X BML-2910, BML-5233-5 X BML-2, BML-6 X BML-15 and BML-2 X BML-3044, were identified as stable and best performing hybrids for grain yield per plant and other traits hence, suitable for wider environments. Five hybrids, BML-6 X BML-3044, BML-2782 X BML-7, BML-5233-5 X BML-3044, CM-211 X BML-6 and BML-2782 X BML-2, performed well in favorable conditions, where as the hybrid BML-7 X BML-2910 excelled in grain yield under poor environmental condition. Studies on correlation and path coefficient analysis, emphasized the need for selection, based on plant type with grater days to 50 per cent tasseling, 100- seed weight, ear length, days to maturity, number of kernels per row, ear height, number of kernel rows per ear and plant height. Since, these traits were found to be the important direct contributors for grain yield. Keeping in view of the above facts, by considering all factors like per se performance, sca effect, standard heterosis, relative heterosis, heterobeltiosis and stability, the most promising hybrids identified were BML-15 X BML-2910, BML-7 X BML-3044 and CM-211 X BML-7. These hybrids may be further tested over locations, seasons, years before recommending for commercial release. |
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Date |
2016-06-14T11:46:44Z
2016-06-14T11:46:44Z 2012 |
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Type |
Thesis
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Identifier |
http://krishikosh.egranth.ac.in/handle/1/67335
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Language |
en
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Relation |
D9322;
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Format |
application/pdf
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Publisher |
ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY
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