Water-Use Efficiency of Grasses Grown under Controlled and Field Conditions1
- A. B. Frank,
- R. E. Barker and
- J. D. Berdahl2
Forage production from grasses grown in the semiarid northern Great Plains is primarily a function of available water during the growing season. There is a need to develop procedures using controlled environments to shorten the time for identifying germplasm that differs in water-use efficiency (WUE). Field determination of WUE requires several years to evaluate genetic and environmental effects. This study compares WUE of field grown cultivars of crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Shult.], intermediate wheatgrass [Thinopyrum interdium (Host) Barkworth and Dewey], and western wheatgrass [Pascopyrum smithii Rybd. (Löve)] to identical plants grown in a controlled environment. Net CO2 assimilation (A), transpiration rate (E), A/E ratio, and conductances on a leaf basis for plants grown in a controlled environment were compared to WUE calculated from dry matter accumulation and total evapotranspiration for field grown plants. Generally, cultivars within a species that exhibited higher E and A and a lower A/E ratio in controlled environments also had higher field WUE. In contrast, comparisons among species indicated that crested wheatgrass had the lowest E, A, and A/E ratio, but had the highest field WUE. The intercellular C02 concentration (CJ differed among cultivars within species, with the stomates of the higher WUE cultivars functioning to maintain higher c1. Correlations of field WUE with controlled environment measurements suggest that the A/E ratio is not a good predictor of field WUE for the species examined in this study.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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