Leaf and Plant Water Use Efficiency in Cocksfoot and Tall Fescue Accessions under Differing Soil Water Availability

Abstract

ABSTRACTWater availability is one of the most important limiting factors in plant production worldwide. Such limitation is expected to increase in regions with a Mediterranean climate type during the next few decades. The objectives of this study were to evaluate plant water use efficiency (WUE) in contrasting accessions of two perennial grasses, Dactylis glomerata L. (cocksfoot) and Festuca arundinacea Schreb. [syn. Lolium arundinaceum (Schreb.) Darbysh.] (tall fescue), under two different water availability regimes and to study the relationship with instantaneous and intrinsic leaf WUE. Six accessions of D. glomerata and five accessions of F. arundinacea were grown under well irrigated and progressive drought conditions. Plant biomass, water consumption, and gas exchange parameters were measured to estimate the plant and leaf WUE. Few differences in biomass accumulation and gas exchange parameters were observed among the accessions within both species. Plant WUE and total plant biomass accumulation were positively correlated in both species and water treatment. The leaf WUE parameters did not show a consistent relationship with the plant WUE in either species. In contrast, the stomatal conductance decreased as the plant WUE increased in water‐limited D. glomerata, suggesting that stomatal conductance may be a good estimator of plant WUE under water deficit conditions.