Physiological response of Miscanthus genotypes to salinity stress under elevated CO2

• Published in: Global change biology. Bioenergy Vol. 14; no. 7; pp. 858 - 874
• Main Authors: Liang, Kehao, Peng, Xiaoying, Liu, Fulai
• Format: Journal Article
• Language: English
• Published: Oxford John Wiley & Sons, Inc 01-07-2022; Wiley
• Subjects: Abiotic stress; Abscisic acid; Agricultural production; Biomass; Carbon dioxide; Carbon dioxide concentration; Crops; Drought; element accumulation; elevated CO2; Energy crops; gas exchange; Genotypes; Homeostasis; Miscanthus; Photosynthesis; Photosystem II; Physiological responses; Physiology; Renewable energy; Salinity; Salinity effects; salinity stress; Salinity tolerance; Salt; Salt tolerance; Sodium chloride; Stomata; Stomatal conductance; Stress; Stress concentration; Water potential; water relation; Water use; Water use efficiency; Xylem
• ISSN: 1757-1693; 1757-1707
• DOI: 10.1111/gcbb.12948

Miscanthus is a class of C4 perennial grasses, which can be cultivated on marginal land even with high salinity. However, the future environment may be altered by elevated atmospheric CO2 concentration ([CO2]) and knowledge is limited about the interactive impacts of CO2 enrichment and salinity on this C4 bioenergy crop. In this study, three Miscanthus genotypes (M. sacchariflorus, M. × giganteus, and M. lutarioriparius) were grown under either ambient (400 ppm) [CO2] (a[CO2]) or elevated (800 ppm) [CO2] (e[CO2]) at five salinity levels (0, 50, 100, 150, and 200 mm NaCl denoted as S0, S1, S2, S3, and S4, respectively), and the impacts of e[CO2] on plant physiological responses to salt stress were investigated. Our results suggested that e[CO2] had no obvious effect on net photosynthetic rate (An), but significantly reduced the stomatal conductance (gs), thus improving water use efficiency regardless of salinity levels. In addition, e[CO2] could improve water potential of plants under both control and saline conditions, but the magnitude of increase was highly genotypic dependent. The maximum quantum yield of photosystem II (Fv/Fm) was not altered by e[CO2], which, however, could alleviate the negative effect of salt on Fv/Fm. Furthermore, salt stress increased the concentration of abscisic acid (ABA) in xylem sap and leaves, while the effect of e[CO2] on ABA level was closely associated with genotypes. e[CO2] reduced Na+ concentration and had positive influences on maintaining Na+/K+ ratio, thus favoring ionic homeostasis, although such effect was genotype dependent. Collectively, our data suggested that e[CO2] could partially mitigate the detrimental effects of salinity, conferring higher salt tolerance of Miscanthus.
For C4 plants Miscanthus, elevated CO2 (e[CO2]) had no obvious effect on net photosynthetic rate (An), but significantly reduced the stomatal conductance (gs), thus improving water use efficiency regardless of salinity levels. e[CO2] could improve water potential of plants under both control and saline conditions, but the magnitude of increase was highly genotypic dependent. Salt stress increased the concentration of ABA in xylem sap and leaves, while the effect of e[CO2] on ABA level was closely associated with genotypes. e[CO2] reduced Na+ concentration and had positive influences on maintaining Na+/K+ ratio, thus favoring ionic homeostasis.