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Results and
discussion
The analysis of variance revealed highly significant differences
for all the characters studied, it
thereby indicating
existence of genetic diversity among the lines under sodic stress
conditions. The grain yield, plant height, number of ear-bearing
tillers and number of spikelets per spike contributed, as a whole,
more than 80 per cent of the genetic diversity (Table1).
Mahalanobis D2
analysis was
conducted and all the 99 lines were grouped in 10 clusters
(Table2).
Clusters formed on the basis of D2 values were such that
lines belonging to the same cluster had, on average, smaller
D2
values than those
belonging to the other clusters. The so formed clusters were not
entirely based on the geographical diversity of the material, because
genetic drift and intense natural and human selection for diverse
adaptive gene complexes could also cause considerable genetic
diversity (Murty and Arunachalam 1966). Similar trends were observed
in Pennisetum typhoides (Singh 1979a) and in Brassica
juncea L. (Singh 1979b) when they were grown under salt affected
soils.
Cluster VI consisted of lines that were tall in stature and
considered to be salt tolerant. Kharchia 65 is a well known salt
tolerant variety used in hybridization programme for development of
high yielding salt tolerant genotypes. Accompanying with Kharchia 65
were KRL 3-4, KRL 4-1,KRL 4-4, KRL 4-10 and KRL 9 which
were the improved Kharachia derivative lines. This cluster had a high
grain yield (Table3)
and had the highest plant height. Cluster VIII consisted of high
yielding salt tolerant lines including KRL1-4 which is the only one
specifically released variety for salt-affected areas. WH 157 is also
a high yielding and salt tolerant variety. The other entries of this
cluster were also good yielders under sodic stress as was indicated
by the highes cluster mean grain yield. Contrary to the cluster VI,
this cluster was comprised of dwarf types. Cluster IV is also worth
consideration as the cluster mean grain yield was quite high (137.68
g) and it had high tillering ability. The clusters having salt
sensitive lines were I and IX, as was indicated by their extremely
low grain yields. Though cluster I had a high tillering ability, it
had less number of grains per ear and also showed low grain weight
per ear. This could be possibly due to sterility occurring under salt
stress, as already reported by Singh and Rana (1983) in Triticale
where poor correlation was observed between grain weight and number
of ear-bearing tillers per plant in sodic soils.
Table4
gives the intra- and inter-cluster distances between cluster
centroids. The first and second largest distances were between
cluster I and VIII (6.64) and cluster I and VI (6.03), as the former
cluster consisted of poor yielders and the later of high yielders
under sodic stress.
References
Murty BR and Arunachalam V (1966) The nature of genetic divergence in
relation to breeding system in crop plants. Indian J Genet 26A:
188-189.
Rao CR (1952) Advanced statistical methods in biometrical research.
(Ed.) John Wiley and sons, Inc, New York: 357-363.
Singh KN (1979a) Genetic diversity and performance of some bajra
genotypes tested under saline sodic conditions. Indian J Heredity II
(1): 71-76.
Singh KN (1979b) Genetic divergence in Indian mustard in sodic soil
conditions. Indian J Genet 39 (3): 439-443.
Singh KN and Rana RS (1983) Genetic variability and path analysis in
triticale grown in alkali soil. Indian J Agric Sci 53 (1): 21-24.
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