G E N E T I C D I V E R G E N C E A N D P A T H A N A L Y S IS I N S O Y B E A N (Glycine m*x ( L . ) M e r r i l l)
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Date
1993
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Mahatma Phule Krishi Vidaypeeth, Rahuri
Abstract
This investigation's objectives were to know the extent of variability for
11 c h a r a c t e r s in the soybean genotypes under study, to estimate broad sense
heritability and genetic advance, to study the association among different
c h a r a c t e r s and find out direct and indirect effects of various c h a r a c t e r s on seed
yield, to measure the genetic divergence between different genotypes and group
them into suitable clusters. The studies involved 65 genotypes of soybean from
18 diverse origins, laid in a randomized complete block design with three
replications during kharif 1992, at Agril. Botany Farm, College of Agriculture,
Pune. Observations were recorded for days to 50 per cent flowering, days to
maturity, plant height (cm), mean internodal length (cm), number of branches
per plant, number of pods per plant, pod length (cm), number of seeds per pod,
100 seed weight (g), oil content and seed yield per plant (g).Appreciable amount of variability among the genotypes for all the
characters was observed. Genotypic as well as phenotypic coefficient of
variation was highest for plant height (37.42 and 39.09, respectively), followed
by number of pods and seed yield per plant. Genotypic coefficients of variation
for other characters ranged from 6.55 (number of seeds per pod) to 18.92
(number of branches per plant). Heritability in broad sense was high for all the
traits and ranged between 39.1 (seed yield per plant) and 98.4 per cent (days
to 50% flowering). Genetic advance was highest for plant height (36.75), followed
by number of pods per plant (29.4).
Correlation study revealed that seed yield was significantly and positively
associated with number of pods per plant (0.767), days to 50 per cent flowering
(0.735), mean internodal length (0.681), plant height (0.658), days to maturity
(0.477) and number of branches per plant (0.397). Only pod length had
significantly negative correlation with seed yield (-0.320). Path analysis
revealed that pods per plant was the most important component in determining
the seed yield, which had highest direct as well as final contribution towards
yield, thus can be considered as most reliable yield indicator in soybean.
Divergence analysis following Mahalanobis's (1936) D2 analysis has revealed
presence of substantial amount of genetic diversity among the genotypes. D2
values ranged from 1.58 to 1642.07. Clustering of genotypes based on the D2
values, following Tocher's method as described by Rao (1952), led into grouping
of the genotypes into 13 clusters, out of which 6 were monogenotypic. On the
other hand as many as 22 genotypes were grouped into cluster III. Inter cluster
distances (D2) ranged between 49.96 (cluster IV and VIII) and 1521.88 (cluster
VII and IX). Grouping pattern of the genotypes suggested no parallelism
between genetic divergence and geographical distribution of the genotypes.
Variance of cluster means revealed that pods per plant and plant height had
maximum contribution towards divergence in the present material. A tentative
crossing programme between clusters, separated by moderate genetic distance
was also suggested.
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