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Wheat (Triticum aestivum L.em Thell) has remained a major source of food for humans for
several millennia because of its many desirable qualities, such as the ease of harvesting,
transporting, storing seed from one season to the next, minimal preparation required
for producing and consuming a wide variety of food products (it is the only plant or cereal
which forms gluten upon mixing of its flour with water allowing the production of leavened
bread), easy digestibility, high nutritive value (>10% protein, 2.4% lipids and 79%
carbohydrates). Still, world population is growing at an annual rate of 1.5% or higher,
adding about 1 billion people every 14 years. At this rate, it is expected to be close to
10 billion by 2050 (Shewry, 2009). To meet the requirements of this population, the
breeders have to develop a new set of bread wheat varieties with higher productivity
(Vasil, 2007; and Kumar et al., 2009). In genetic system, most characters are associated
with each other and such association may be the product of some pleiotropic effects of
gene, existence of two genes on the same chromosome, chromosomal segmental affiliation
or due to environmental influences. Therefore, information of character association
between traits and yield component is important in selecting high yield genotypes So, the knowledge of the association of yield and its contributing traits are also essential
for selection of parents to subsequently guide the breeders for practicing selection in
segregating populations/generations. Grain yield is the production influenced both directly
and indirectly and the breeder is naturally interested in investigating the extent and type
of association of such traits.
The grain yield is the result of many physiological processes and association with
component traits which are dependent upon the genetic makeup of the wheat genotypes
which may be interacting with the environment. The breeders obviously are interested in
investigating the suitable parents and to identify the specific cross-combinations which
are likely to throw desirable recombinants in segregating generations and further to
exercise selection for isolation of the appropriate recombinants, keeping in view the
interrelationship of various components with grain yield. Correlation analysis provides
information about the association of plant characters and therefore, leads to a directional
model for yield prediction. Earlier, Zecevic et al. (2004) reported the strongest positive
genetic correlation between grain weight per spike and 1,000 grain weight and between
spike lengths with number of spikelets per spike. Phenotypic correlation analysis was
reported by them to be positive and significant for these traits conducted on 50 genotypes
of winter wheat grown during two years.
However, Chowdhary et al. (2000) studied that the yield components like tillers per
plant, grains per spike and 100 grain weights were the main contributors to the grain
yield in wheat. There was positive but nonsignificant correlation between spikelets per
spike and 1,000 grain weight both at genotypic and phenotypic levels. According to Khan
et al. (2003), a positive and significant correlation was observed between the number of
tillers per plant and peduncle length both at genotypic and phenotypic levels. Highly significant
correlations between spike length and grain yield per plants were also reported by them.
The knowledge regarding relative contribution of individual traits to yield may be
accomplished by correlation studies (Akbar et al., 2009; Haq et al., 2010; and Jaiswal et al.,
2010). The present investigation was conducted on a set of 18 genotypes with their 72 F1
hybrids to generate information on genetic variability and character association for wheat
improvement to draw the inference which would be helpful to specify certain parameters
that could be used as selection indices for the identification of potentially high-yielding
wheat genotypes.
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