Growth and survival during drought: the link between hydraulic architecture and drought tolerance in grasses

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Show simple item record Ocheltree, Troy W. 2012-05-07T15:07:03Z 2012-05-07T15:07:03Z 2012-05-07
dc.description.abstract The pathway for the movement of water through plants, from the soil matrix to the atmosphere, constitutes the hydraulic architecture of a plant. The linkage between the hydraulic architecture of woody plants and drought tolerance has received considerable attention, but much less work has been done on grasses. I investigated the linkage between the hydraulic architecture of grasses to physiological patterns of water use across a range of species and conditions. The rate of stomatal conductance (g[subscript]s) and photosynthesis (A) increased acropetally along the leaves of 5 grass species, which is a unique feature of this growth form. The internal structure of leaves also changed acropetally in order to minimize the pressure gradient across the mesophyll that would otherwise occur as a result of increasing g[subscript]s. The resistance to water movement through the mesophyll represented 80-90% of leaf resistance in six genotypes of Sorghum bicolor L. (Moench). This resistance was most important in controlling g[subscript]s and A when water was readily available, but as soil-moisture decreased it was the efficient transport of water through the xylem that was most important in maintaining plant function. I also investigated the relationship between hydraulic architecture and stomatal responses of grasses to increasing Vapor Pressure Deficit (D). Grasses with a larger proportion of their hydraulic resistance within the xylem were less sensitive to increasing D and plants with high root conductance maintained higher rates of gas exchange D increased. Finally, I investigated the tolerance of grasses to extreme drought events to test if there was a trade-off between drought tolerance and growth in grasses. Plants with drought tolerant leaf traits typically sacrificed the ability to move water efficiently through their leaves. Having drought tolerant leaves did not limit the plants ability to have high rates of gas exchange, and, in fact, the most drought tolerant plants had the high rates of g[subscript]s when expressed on a mass basis. Leaf-level drought tolerance did contribute to species’ occurrence, as the drought intolerant species I studied are not commonly found in low precipitation systems. The results presented here highlight the importance of studying the hydraulic architecture of plants to provide a better understanding of what controls plant function across a range of environmental conditions. en_US
dc.description.sponsorship K-State Center for Sorghum Improvement, Konza Prairie Long-Term Ecological Research Site, Schrader-Massier Fellowship en_US
dc.language.iso en_US en_US
dc.publisher Kansas State University en
dc.subject Plant Hydraulic Architecture en_US
dc.subject Drought Tolerance en_US
dc.subject Grass Anatomy en_US
dc.subject Grass Physiology en_US
dc.subject Stomatal Conductance en_US
dc.title Growth and survival during drought: the link between hydraulic architecture and drought tolerance in grasses en_US
dc.type Dissertation en_US Doctor of Philosophy en_US
dc.description.level Doctoral en_US
dc.description.department Department of Agronomy en_US
dc.description.advisor P.V. Vara Prasad en_US
dc.subject.umi Agronomy (0285) en_US
dc.subject.umi Ecology (0329) en_US
dc.subject.umi Plant Biology (0309) en_US 2012 en_US August en_US

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