GENETIC DIVERGENCE, COMBINING ABILITY AND STABILITY FOR COB YIELD AND OTHER TRAITS IN BABY CORN (Zea mays L.)
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Date
2015
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PROFESSOR JAYSHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD
Abstract
The present investigation “genetic divergence, combining ability and stability for cob
yield and other traits in baby corn (Zea mays L.)” was undertaken to identify the diverse parents
in maize and study the combining ability, nature of gene action, heterosis, genetic parameters,
character association, G X E interaction and stability of experimental hybrids for yield and other
traits.
During rabi 2011-12 eighty 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 characters studied except moisture
content. Based on Mahalanobis D2 analysis the 80 genotypes were grouped into eight clusters.
Cluster I was the largest having 38 genotypes followed by cluster III with 26 genotypes, cluster
V with 7 genotypes, cluster VI with 5 genotypes and the clusters II, IV, VII and VIII had one
genotype each. From this clusters 25 parents were selected and used in hybridization
programme.
Twenty five divergent parents were crossed in Line x Tester mating design by involving
three testers during kharif 2012 at Maize research center, ARI, Rajendranagar, Hyderabad.
The resulting 75 crosses along with parents and two standard checks viz., DMR-1142 and
DMR-1144 were evaluated in Randomized Block Design replicated thrice during rabi 2012-13
at three locations viz., in Central Telangana Zone (Rajendranagar, Ranga Reddy), Northern
Telangana Zone (Jagityal, Karimnagar) and Central Telangana Zone (Kampasagar, Nalgonda).
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. Combining ability analysis revealed that among the parents, BML-5222, QPM-69-2,
BML-5121, BML-5212 and BML-5207 were good general combiners for earliness viz., days to
50 per cent tasseling and days to 50 percent silking. Parents, BML-5212, BML-5121,
BML-5118-3, QPM-57-1, BML-5161 and CM-131(Tester) recorded significant positive gca
effects for cob yield per plant and these inbreds may be utilized in the development of hybrids,
synthetics or composites. The hybrids, QPM-62 X BML-6, CM-201 X BML-6 and
BML-5342 X CM-131 were found to be good specific combiners for earliness, While the
hybrids BML-5118-3 X BML-6, BML-5121 X BML-6, BML-5212 X BML-13, BML-5161 X
BML-6 and QPM-62 X BML-13 which recorded positively significant sca effects for cob yield
per plant are considered as good specific combiners. Therefore these hybrids may be
recommended for heterosis breeding.
In pooled analysis high narrow sense heritability estimates were recorded in plant
height, green fodder yield, cob yield, baby corn length, ear height and cob weight. Thus these
traits are predominantly under the control of additive gene action and hence, these characters
can be improved by selection in the development of new inbred lines.
Estimates of heterobeltiosis and standard heterosis were variable among crosses in
desirable direction and some of them turned out to be best specific crosses. Heterosis for cob
yield per plant is mainly because of simultaneous manifestation of heterosis for yield
component traits. The highest standard heterosis for cob yield per plant was recorded for
hybrids BML-5121 X CM-131, BML-5212 X BML-13, BML-5121 X BML-6,
BML-5212 X CM-131 and BML-5121 X BML-13 along with per se performance,
heterobeltiosis. These hybrids may be further tested in multilocation evaluation before releasing
them for commercial cultivation.
Results of stability analysis revealed that ten hybrids viz., BML-5121 X BML-6,
BML-5161 X BML-6, QPM-69-2 X CM-131, BML-5016 X CM-131, BML-5219 X CM-131,
BML-5204-5-2-1 X CM-131, CM-119 X BML-13, BML-5347-2 X CM-131 and QPM-57-1
X CM-131 are identified as stable and best performing hybrids for cob yield per plant and other
traits hence, suitable for wider environments.
Based on overall performance the best hybrid identified was BML-5121 X BML-6 with
highest cob yield per plant of 27.93 g, with high sca effect (1.95), significant standard heterosis
(77.32 %) and significant heterobeltiosis (78.33 %) over the check DMR-1142. This hybrid was
stable over locations for cob yield per plant, days to 50 per cent tasseling, days to 50 per cent
silking, plant height, ear height, baby corn length, baby corn girth, cob weight and cob yield per
hectare. The next best hybrid was BML-5161 X BML-6 with a cob yield per plant of 20.39 g
with significant sca effect (1.42), significant standard heterosis over DMR-1142 (29.43%) and
significant heterobeltiosis (39.53%). This hybrid was stable over locations for cob yield per
plant, days to 50 per cent tasseling, days to 50 per cent silking, plant height, baby corn length,
baby corn girth, cob yield per hectare, green fodder yield and TSS.
The correlation and path coefficient analysis, emphasized the need for selection based
on plant type with greater number of cobs per plant, cob weight, corn length, days to 50 per cent
silking, plant height, corn girth. Since these were found to be the important direct contributors
for cob yield per plant.
Keeping in view of the above facts, by considering all factors like per se performance,
sca effect, standard heterosis, heterobeltiosis and stability, the most promising hybrids identified
were BML-5121 X BML-6, and BML-5161 X BML-6.These hybrids may be further tested over
locations, seasons, years before recommending for commercial release.
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Keywords
yields, planting, hybrids, plant oils, heterosis, genotypes, silk, biological phenomena, crossing over, maize