Disentangling the contributions of osmotic and ionic effects of salinity on stomatal, mesophyll, biochemical and light limitations to photosynthesis

• Published in: Plant, cell and environment Vol. 38; no. 8; pp. 1528 - 1542
• Main Authors: CHEN, TSU‐WEI, KAHLEN, KATRIN, STÜTZEL, HARTMUT
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.08.2015
• Subjects: Cucumis sativus; FvCB model; ionic stress; Ions; Light; light condition; Mesophyll Cells - physiology; Mesophyll Cells - radiation effects; Osmosis - radiation effects; osmotic stress; Photosynthesis - radiation effects; Plant Stomata - physiology; Plant Stomata - radiation effects; quantitative limitation analysis; Salinity; Stress, Physiological - radiation effects; quantitative limitation analysis; FvCB model; osmotic stress; light condition; Cucumis sativus; ionic stress
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/pce.12504

There are conflicting opinions on the relative importance of photosynthetic limitations under salinity. Quantitative limitation analysis of photosynthesis provides insight into the contributions of different photosynthetic limitations, but it has only been applied under saturating light conditions. Using experimental data and modelling approaches, we examined the influence of light intensity on photosynthetic limitations and quantified the osmotic and ionic effects of salinity on stomatal (LS), mesophyll (LM), biochemical (LB) and light (LL) limitations in cucumber (Cucumis sativus L.) under different light intensities. Non‐linear dependencies of LS, LM and LL to light intensity were found. Osmotic effects on LS and LM increased with the salt concentration in the nutrient solution (Ss) and the magnitude of LM depended on light intensity. LS increased with the Na+ concentration in the leaf water (Sl) and its magnitude depended on Ss. Biochemical capacity declined linearly with Sl but, surprisingly, the relationship between LB and Sl was influenced by Ss. Our results suggest that (1) improvement of stomatal regulation under ionic stress would be the most effective way to alleviate salinity stress in cucumber and (2) osmotic stress may alleviate the ionic effects on LB but aggravate the ionic effects on LS. Interactions between osmotic and ionic effects on photosynthetic limitations were found. Osmotic stress of salinity has no effect on biochemical capacity but affects the magnitude of biochemical limitation. By applying quantitative limitation analysis at non‐saturating light conditions, non‐linear dependencies of stomatal, mesophyll and light limitations on light intensity were found. Our results strongly suggest that quantitative limitation analysis for saturating light conditions do not represent the photosynthetic limitation at canopy level.