Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 9/1/1997
Publication Date: N/A
Technical Abstract: Carbon isotope discrimination (CID) can be used to estimate water use efficiency (WUE) in C3 plants, but its response to selection is less clear. Tall fescue (Festuca arundinacea) populations were divergently selected for high and low CID for two cycles and studied along with the original selection population and check cultivars. In both 1995 and 1996, and in dryland and irrigated environments, selection response for CID was strong and symmetrical in high and low directions, indicating that WUE is heritable and can be manipulated in a breeding program. In 1995, leaf turgor pressure was greater in high than in low WUE (high CID) selections. In 1996, however, no differences in water relations were observed. Dry matter production was reduced in low WUE selections in 1995, but results for dry matter production in 1996 were variable. The results show that selection for high or low WUE is possible in tall fescue, ,but the effects of WUE on plant productivity and water relations are more difficult to predict.