Environmental Effects on Turgor Pressure Response in Range Grasses1

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Abstract
The effect of environment on turgor pressure responses was determined over a range of drought stress for the following grass species: Agropyron caninum (L.) Beauv.; A. desertorum [Fisch. ex Link] Schult.; A. intermedium (Host) Beauv.; A. trachycaulum (Link) Malte ex H. F. Lewis; Elymus cinereus Scribn. & Merr.; E. junceus Fisch. Plants of each species were started from seed and exposed to environments characterized by three nightday temperature combinations of 5/10, 10/15, and 15/25C. Water potential components of detached leaf samples were determined throughout a drying cycle with a psychrometric technique.Turgor pressure responses changed as environmental conditions changed. Generally, plants in the low‐temperature environment maintained turgor over a wider range of leaf water potentials than plants did in the two higher temperature environments. Temperature environments also influenced turgor responses to a larger degree in some species than in others. The effect of environments on the leaf water potential where turgor declined to zero ranged from about 4 bars in E. junceus and A. intermedium to more than 8 bars in E. cinereus. When values of leaf water potential where turgor equals zero were used to rank species for drought resistance, rankings changed in different environments. These resuls suggest that the environments in which plant materials are grown should be carefully considered if maintenance of turgor is used to estimate relative drought resistance.