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Wheat Information
Service
Number 76: 35-38
(1993)
Genetic
divergence in bread wheat (Triticum aestivum L. em Thell)
under sodic soil conditions
K. N. Singh and Ravish Chatrath
Central Soil Salinity Research Institute, Karnal, 132 001,
India
Genetic divergence as measured by Mahalanobis D2
statistics was
studied under sodic soil conditions for yield and its component
traits in ninety-nine bread wheat lines obtained from different parts
of India. The lines were grouped into 10 different clusters. The
clustering pattern of lines did not follow their geographical
origins, although some clusters consisted of lines having a common
geographical origin. Grain yield, ear-bearing tillers and plant
height were the potent variables which could be used as parameters in
selecting genetically divergent parents in crossing programme for
breeding high yielding wheat varieties for salt-affected soils.
Genetic divergence is dependent on geographical diversity as well as
phenotypic components of varieties, and its quantitative assessment
could provide a rational basis for the selection of parents for any
breeding programme. The main objective of the present study was to
identify and classify the available wheat materials into genetically
different, distinctive groups so as to enable the breeders to
efficiently plan the hybridization programme. The present
investigation was, thus, aimed at assessing the genetic divergence
among ninety-nine bread wheat lines under sodic soil conditions. The
lines were of diverse geographical origin, and included indigenous
one, Kharchia, grown locally in remote parts of Rajasthan State of
India, lines developed through single plant selections of advanced
generations of diverse crosses and commercially grown high yielding
varieties for normal soils.
Materials and methods
Ninety-nine lines of wheat were selected from10 States and Union
Territory of India, viz., Bihar, Delhi, Gujarat, Haryana, Madhya
Pradesh, Maharashtra, Punjab, Rajasthan, Uttar Pradesh, and West
Bengal.
The experiment was laid out in a randomized block design with two
replications with single row-plots of 6 m length and 30 cm inter-row
spacing under sodic stress (average pH 9.3) in the winter season of
1990-91 at the experimental farm of Central Soil Salinity Research
Institute, Karnal. Data were recorded for grain yield based on whole
plot (5 m row) and for number of earbearing tillers per plant on the
basis of 5 m length (finally averaged to one m length), while random
10 plants were chosen from each row-plot for recording of characters
like grain weight per ear, grain number per ear, 1000 grain weight,
plant height, ear length and number of spikelets per spike.
The analysis of divergence using Mahalanobis D2
Statistics and
subsequent grouping of genotypes following Tocher's method were
carried out as described by Rao (1952).
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