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Physiological responses of sorghum and six forage grasses to water deficits
Abstract
Experiments were conducted in the field and greenhouse, to investigate osmotic and other physiological responses or sorghum (Sorghum bicolor (L.) Moench cv. "RS610", 121-18-2", "4104", "DK46", "N94B", and "Redlan"), indiangrass (Sorghastrum nutans (L.) Nash cv. "Nebraska 54"), switchgrass (Panicum virgatum L. cv. "Pathfinder"), big bluestem (Andropogon gerardii Vitman cv. "Pawnee"), reed canarygrass (Phalaris arundinacea L. cv. "Ioreed"), smooth brome (Bromus inermis Leyss. cv. "Lincoln"), and tall fescue (Festuca arundinacea L. cv. "Kentucky 31") to water deficit stress. Osmotic adjustment (OA) occurred for all five forage grasses measured in study one, and was greater for C4 than for C3 grasses. Despite less OA, C3 grasses appear stress resistant since they had more elastic cell walls (low modulus of cell wall elasticity). In study two tall fescue had lower leaf water potential, lower full turgor osmotic potential, and greater OA, than sorghum. Fructose, glucose and sucrose were significant contributors to leaf osmotic potential, at levels approximately equal in sorghum and tall fescue (26%). In sorghum, 30.9% (and in some cases more) of observed OA could be attributed to accumulation of sugars. In tall fescue, only 9% of OA could be attributed to accumulation of sucrose, with fructose and glucose unresponsive to water stress. Osmotic adjustment was observed for all six sorghum lines in study three, but was greatest for Redlan and DK46. In the greenhouse, increases in fructose, glucose, and sucrose, accounted for an average 30.5% to measured OA. There was variation in the pattern of sugar accumulation with 4104 and DK46 appearing to be fructose and glucose accumulators, Redlan, 121-18-2, and RS610 appearing to be sucrose accumulators, and N94B appearing to accumulate all three sugars. The contribution of sugars was least for DK46, and other solutes almost certainly account for its high OA. Large increases in leaf proline with water stress occurred in the greenhouse but rarely in the field, for all three studies. Physiological effects of proline accumulation appear uncertain, since even dramatic increases in proline content were insufficient to influence osmotic potential.
Subject Area
Agronomy|Botany|Range management
Recommended Citation
Barker, David John, "Physiological responses of sorghum and six forage grasses to water deficits" (1990). ETD collection for University of Nebraska-Lincoln. AAI9121909.
https://digitalcommons.unl.edu/dissertations/AAI9121909