Genetic variability for chlorophyll stability and its association with grain growth under normal and late sown conditions in wheat
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Date
2009
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Publisher
CCSHAU
Abstract
Large proportion of wheat in India is planted after the first week of
December (late sown) that warms up towards the grain filling stage of the
crop there by leading to significant yield losses due to heat and water stress
created by increased temperatures. High temperature has a significant effect
on cellular processes, growth development and economic yield of wheat
plants. In such situations, wheat genotypes which could sustain grain growth
over longer post anthesis span or further deposition of carbohydrates in grain
sink would prove promising. So, to sustain wheat productivity, research
emphasis has been given to develop genotypes which could remain staygreen
along with larger leaf area and high relative water content so that they can
carry out photosynthesis for a longer period as compared to the normal
senescent cultivars and thereby enhancing yield through higher grain growth
rate even after 3-4 weeks after anthesis.
Genetic analysis of grain yield and its components were conducted on
twenty four elite genotypes of wheat. The material was grown in randomized
block design with three replications at CCS Haryana Agricultural University,
Hisar, Research Farm under two natural photothermal environments created
through alteration of dates of sowing i.e. 13th November 2007 and 3rd
January 2008. Beside field experiments, lab experiment on chlorophyll
estimation, AGPase enzyme activity and RAPD markers were also conducted.
Under field experiment, relationships of some morphophysiological
traits and Grain Growth Rate were examined. Our data showed significant
variations among wheat genotypes under different dates of sowing for their
character expression, particularly days to flowering, grain growth, biomass,
grain yield staygreen. Delayed leaf senescence, leaf area, showed significant
positive correlation with yield under normal sown conditions and GGR3, and
days to flowering in late sown condition. Among the other traits, grains per
spike, harvest index and biological yield were also found to be associated with
yield under heat stress conditions. Two genotypes WH1057 and DBW16
expressed staygreen trait. Their chlorophyll content and grain growth rate
(GGR3) was higher in late sown conditions as compared to other genotypes.
AGPase enzyme was being assayed to determine relationship between
staygreen and grain development in normal and late planting. These
genotypes could be used as candidate ‘plants’ for isolating genes governing
delayed monocarpic senescence. However, the staygreen character can be
transferred to genotypes having fast growth so that their early senescence in
rainfed and late sown conditions may be avoided and sustained growth could
be achieved by combining staygreen post anthesis translocation of
carbohydrates to grain sinks.
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Keywords
Wheat, Staygreen, Grain growth, Photosynthesis, Chlorophyll, Senescence