CHARACTERIZATION OF MAIZE (Zea mays L.) GENOTYPES USING MORPHOPHYSIOLOGICAL TRAITS AND MOLECULAR MARKER
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Date
2023
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Birsa Agricultural University, Ranchi
Abstract
Maize (Zea mays L.) belongs to family, Poaceae, having worldwide growing
versatility ranges from 58° N to 40° S; from below sea level to altitudes higher than 3000
m and in areas with 250 mm to more than 5000 mm of rainfall per year. Germplasm
distribution across the world’s geographical area represents the wide spectrum of
exploitable genetic variability for specific purpose like higher productivity or quality or
combination thereof under drought stress. Drought stress being the integral part of any
agro-ecosystem affecting the growth and development of crop plants. Drought is one of
the major constraints in deciding maize productivity all over the world. In India, out of
total maize area about 4.0 million hectares are prone to drought. Drought effects the
growth and development of plants in variety of ways. For development of drought
tolerant maize cultivars, the knowledge of critical sensitive stages and consequences of
moisture stress, variability of germplasm, screening techniques and breeding strategies to
be adopted are having very crucial importance for getting the effective result. Classical
and/or molecular breeding approaches can be adopted for incorporation of available
drought stress tolerant genes in appropriate genetic background. The present experiment
was conducted to identify the inbreds and hybrids suitable for irrigated (30kpa) and
moisture stress (50kpa) for that significant traits to be used for selection under theses
environments. To determine best selection method, mean performance values, correlation
coefficient, components of variance and heritability, diversity, Stress tolerance indices
were analysed. Keeping above facts in mind 4 testers (drought tolerant) and 8 lines were
used for development of thirty two single cross hybrids to study the genetics of yield and
yield attributes under normal moisture (30kpa) and under, moisture stress condition
(50kpa). Twelve parents (8 lines and 4 testers) were mated in LX T mating design, thirty
two hybrids were developed and compared with checks (CM600 (inbreds), Suwan
Composite, BAUMH-5 (hybrids), 1532 X Suwan (hybrids)). All the forty eight
genotypes were evaluated at Research Farm, Birsa Agricultural University, Kanke,
Ranchi, Jharkhand, during kharif 2020 seasons. Extensive phenotyping for morphophysiological
characters along with stress indices were done for all the trials. The
experimental materials were found to be significantly different from each other for all the
characters under normal moisture (30kpa) and under, moisture stress condition (50kpa)
and this is evident from the analysis of variance for RBD. This showed the inherent
genetic difference among the genotypes under study. Correlation studies delineated that
crop yield under moisture stress indicated highly significant positive genotypic and
phenotypic correlation with plant height, ear height, number of plants with grain yield
and number of kernels per row. This suggested that these characters can be considered
for selection of plants tolerant to moisture stress. This reflected preponderance of nonadditive
gene action in controlling these traits which further suggested reliable crop
improvement through selection of such traits. Different genotypes responded
differentially under different environments for the expression of different quantitative
traits. The genotype which performs well in one environment may not perform same on
the other environments. Grain yields were higher under the optimum environment
compared to stress environments. Four tester parents BAUIM-1, BAUIM-2, BAUIM-5,
IC622968 were found to be significantly superior stress condition for maximum number
of traits including grain yield (GY/P) and yield attributing traits. These tester parents
may be used for development of improved lines and hybrids for the respective
environments where they were found to be significant. All the thity two Hybrids viz.,
IC624174 XBAUIM-2, IC624159 X BAUIM-2, IC624148 X BAUIM-2, IC624160 X
BAUIM-2, IC624180 X BAUIM-2,IC624161X BAUIM-2, IC624157 XBAUIM-2,
IC624151 X BAUIM-2, IC624174 XIC622968, IC624159 XIC622968, IC624148
XIC622968, IC624160XIC622968, IC624180X IC622968, IC624161 XIC622968,
IC624157 X IC622968, IC624151 XIC622968, IC624174 XBAUIM-5, IC624159
XBAUIM-5, IC624148 XBAUIM-5, IC624160X BAUIM-5, IC624180 X BAUIM-5,
IC624161X BAUIM-5, IC624157X BAUIM-5, IC624151 XBAUIM-5, IC624174
XBAUIM-1, IC624159 X BAUIM-1, IC624148 X BAUIM-1, IC624160 X BAUIM-1,
IC624180 XBAUIM-1, IC624161 XBAUIM-1, IC624157 X BAUIM-1, IC624151 X
BAUIM-1 under stress condition were found to be significantly superior for maximum
number of traits than the best check including grain yield (GY/P ) observed through the
standard heterosis. These superior hybrids may be used for cultivation or development of
superior segregants depending upon their gene action and effect. The analysis of
variances for L x T analysis under normal moisture condition (30kpa) and moisture stress
(50kpa) revealed significant difference in environments for all the forty six
morphophysiological traits confirming diverse nature of environments selected, which
influenced the expression of the traits studied among each other in relation to the
performance of the genotypes. All The traits showed non-additive genetic variance with
over dominance effect of genes under all the environmental situations indicating the over
expression of heterozygous loci for these characters. The predominance of non-additive
gene action on implies that breeding gains can be made via inbreeding followed by
crossbreeding. The type of genetic effects for grain yield is highly variable, depending on
the type of parents and environments under consideration. Molecular analysis indicated
that the genotypes IC622968 and IC624176 were the most diverse ones. These diverse
parents can be used for development of superior hybrids and segregants tolerant to stress
condition. These superior hybrids may be used for cultivation or development of superior
segregants depending upon their gene action and effect. The hybrids were good
performer (heterotic) across the different moisture regimes under variable moisture
regimes. These hybrids may be recommended for cultivation under wide range of
environment. For leaf characters angle between blade and stem under irrigated condition
and non-irrigated condition maximum frequency of (55.55%) and (72.22%) as found for
“small” state of expression while minimum frequency (4.44) found for “medium” state
of expression under moisture stress condition. AMOVA (Analysis of molecular variance)
revealed mean sum of squares due to genotypes showed highly significant differences for
all the traits under study at 5% and 1% level of significance. In molecular Dendrogram
picture using Jaccard’s similarity coefficient ranged from 0.52 to 0.95. Further this 2
main clusters were classified into 6 subcluster. Further, Cluster A showed four subcluster
and Cluster B showed two subcluster.