Some Physiological Processes in Winter Wheat (Triticum Aestivum L.) and Cowpeas (Vigna Unguiculata L.) as Affected by Drought Stress
Author: Errol Garth Rhoden
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Published: 1984
Total Pages: 242
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Author: Errol Garth Rhoden
Publisher:
Published: 1984
Total Pages: 242
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DOWNLOAD EBOOKAuthor: Mohamed Salem Zaidi
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Published: 1982
Total Pages: 190
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Published: 1987-07
Total Pages: 452
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DOWNLOAD EBOOKAuthor: David Adrian Verbree
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Published: 2015
Total Pages:
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DOWNLOAD EBOOKIn the wake of rising temperatures, erratic rainfall, and declining ground water table, breeding for drought tolerance in food crops has become a top priority throughout the world. Phenotyping a large population of breeding lines for drought tolerance is time-consuming and often unreliable due to multiple possible mechanisms involved. In cowpea (Vigna unguiculata L. Walp), a box-screening method has been used to partition the confounding effects that shoot and root traits have on drought tolerance by restricting root growth and providing a homogeneous soil moisture environment across genotypes. Nonetheless, multiple mechanisms of shoot drought tolerance have been reported which further complicate phenotyping. In winter wheat (Triticum aestivum L.), canopy temperature depression (CTD) has been proposed as a good indicator of drought tolerance. The recent development of low-cost thermal imaging devices could enable high-throughput phenotyping of canopy temperature. While CTD can be an indicator of overall plant water status, it can be confounded by high stomatal resistance, which is another seemingly contradictory mechanism of drought tolerance. The objectives of this study were to explore the physiological basis and genetics of the two mechanisms of shoot drought tolerance previously reported in cowpea and to develop and evaluate a method of high-throughput phenotyping of drought tolerance in winter wheat using thermal imaging. In cowpea, a legume well known for its tight stomatal control, no differences in gas exchange between drought tolerant and susceptible genotypes were observed. A unifoliate stay-green trait was discovered that segregates as a single recessive gene. However, it did not correlate with trifoliate necrosis or overall drought tolerance. In winter wheat, CTD did not always correlate with yield under rainfed conditions. One drought-tolerant cultivar, in particular, had the hottest canopy temperature, possibly because it was able to conserve moisture by closing its stomata whereas another closely related drought-tolerant cultivar had the coolest canopy temperature. Therefore, it appears that no single method of phenotyping for drought tolerance can be broadly applied across all genotypes of a given species due to possible contrasting mechanisms of drought-tolerance and environmental differences. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/152439
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Published: 1989
Total Pages: 984
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Published: 1985-03
Total Pages: 610
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DOWNLOAD EBOOKAuthor: Mahmood Osmanzai
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Published: 1982
Total Pages: 136
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Published: 2001
Total Pages: 776
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Published: 1975
Total Pages: 1922
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DOWNLOAD EBOOKAuthor: Nereu Augusto Streck
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Published: 2002
Total Pages: 254
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