Effects of water-deficit stress on photosynthesis, its components and component limitations, and on water use efficiency in wheat (Triticum aestivum L.)

• Published in: Plant physiology (Bethesda) Vol. 100; no. 2; pp. 733 - 739
• Main Authors: Martin B, Ruiz Torres N.A
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.10.1992
• Subjects: balance hidrico del suelo; bilan hydrique du sol; Biological and medical sciences; calvin cycle; Carbon dioxide; chemical reactions; ciclo de calvin; cycle de calvin; deficiency; Dehydration; dioxido de carbono; dioxyde de carbone; Drought; drought stress; echange gazeux; effects on; efficacite; efficiency; eficacia; Environmental and Stress Physiology; estoma; estres de sequia; feuille; fotosintesis; Fundamental and applied biological sciences. Psychology; gas exchange; Geometric lines; hojas; intercambio de gases; Leaves; Linear regression; Mesophyll; Metabolism; photosynthese; Photosynthesis; Photosynthesis, respiration. Anabolism, catabolism; Plant physiology and development; plant water relations; Plants; reacciones quimicas; reaction chimique; relaciones planta agua; relation plante eau; soil water balance; stomata; stomate; stress du a la secheresse; transpiracion; transpiration; Triticum aestivum; uso del agua; utilisation de l' eau; vapeur d' eau; vapor de agua; water; water use; water vapour; Wheat; Monocotyledones; Oxygen; Water deficit; Carbon dioxide; Environmental factor; Plant leaf; Water use efficiency; Water potential; Cereal crop; Stress; Gramineae; Angiospermae; Spermatophyta; Gas exchange; Photosynthesis; Triticum aestivum
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.100.2.733

It is of theoretical as well as practical interest to identify the components of the photosynthetic machinery that govern variability in photosynthesis rate (A) and water-use efficiency (WUE), and to define the extent by which the component processes limit A and WUE during developing water-deficit stress. For that purpose, leaf exchange of CO2 and H2O was determined in two growth-chamber-grown wheat cultivars (Triticum aestivum L. cv TAM W-101 and cv Sturdy), and the capacity of A was determined and broken down into carboxylation efficiency (c.e.), light- and CO2-saturated A, and stomatal conductance (gs) components. The limitations on A measured at ambient CO2 concentration (A350) were estimated. No cultivar difference was observed when A350 was plotted versus leaf water potential. Light- and CO2-saturated A, c.e., and gs decreased with decreasing leaf water potential but of the corresponding photosynthesis limitations only those caused by insufficient c.e. and gs increased. Thus, reduced stomatal aperture and Calvin cycle activity, but not electron transport/photophosphorylation, appeared to be major reasons for drought stress-induced inhibition of A350-WUE measured as A350/gs first increased with stomatal closure down to a gs of about 0.25 mol H2O m-2 s-1 (water potential = -1.6 MPa). However, it was predicted that A350/gs would decrease with more severe stress due to inhibition of c.e.