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Subject: Genetics and Plant Breeding × Author: Ahlawat, Shweta × Start date: 1999 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Genetic variability in wheat for staygreen character and its association with grain growth under normal and late sown conditions
    (CCSHAU, 2005) Ahlawat, Shweta; Chhabra, Ashok
    High temperature has a marked effect on cellular processes, growth development and economic yield of wheat plants. Large proportion of wheat area 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. 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 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. Genetic analysis of grain yield and its components were conducted on thirty six 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. 23rd November 2004 and 10th January 2005. 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 heat tolerance were examined. Our data showed significant variations among wheat genotypes under stagger sowing for there character expression, particularly days to flowering, grain growth, biomass, grain yield staygreen. Delayed leaf senescence showed significant positive correlation with yield under then condition (late sown). Among the other traits, higher biomass at harvest, more 1000 grain weight, faster grain growth rate, chlorophyll content were also found to be associated with yield under heat stress conditions. Two genotypes MLU-2 and WH147 M expressed the strongest staygreen trait. These plants were staygreen even in the month of May when the high temperature led to moisture stress conditions. AGPase enzyme was being assayed to determine relationship between staygreen, starch metabolism and grain development in early, 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 avioided and sustained growth could be achieved by combining staygreen post anthesis translocation of carbohydrates to grain sinks.