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Carbon Isitope Discrimination, Water Relations, and Photosynthesis in Tall Fescue
Author(s) -
Johnson Richard C.
Publication year - 1993
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1993.0011183x003300010030x
Subject(s) - water use efficiency , transpiration , agronomy , biology , festuca arundinacea , stomatal conductance , photosynthesis , irrigation , brassica , germplasm , drought tolerance , poaceae , botany
Carbon isotope discrimination (Δ) shows promise for estimating water‐use efficiency (WUE) in crop species. Research was undertaken to examine Δ and water relations of tall rescue ( Festuca arundinacea Schreb.) accessions and to determine if low Δ is associated with high gas exchange WUE as predicted by theory. The accession PI 438522 had lower Δ than the accession PI 231522 in both a dryland and an irrigated field environment and at two sampling dates. Correlations among Δ, water potential, solute potential, and turgor pressure were not significant under irrigation. Under dryland conditions, correla. tions among these factors were generally significant and positive for PI 438522, but not significant for PI 231561. In a greenhouse experiment, plants selected for low Δ from the irrigated field environment had lower A and internal leaf [COz] (Ci), and a higher ratio of CO2 assimilation rate (A) to transpiration than high‐A selections. This was true for both well‐watered plants and plants stressed with a ‐0.38 MPa polyethylene glycol solution. Stomatal conductance and A were positively correlated with Δ, suggesting that lower stomatal conductance was a factor leading to lower C 1 and Δ. The results suggest that associations between water relations and Δ vary depending on accession and environment, but selecting tall rescue plants for low Δ does identify genotypes with low C 1 and high WUE. Using Δ for germplasm enhancement of WUE in tall rescue appears promising.