Effects of potassium supply on limitations of photosynthesis by mesophyll diffusion conductance in Carya cathayensis

• Published in: Tree physiology Vol. 31; no. 10; pp. 1142 - 1151
• Main Authors: Jin, Song Heng, Huang, Jian Qin, Li, Xue Qin, Zheng, Bing Song, Wu, Jia Sen, Wang, Zheng Jia, Liu, Gen Hua, Chen, Miao
• Format: Journal Article
• Language: English
• Published: Canada Oxford University Press 01.10.2011
• Subjects: biochemical pathways; Carbon Dioxide - metabolism; carboxylation; Carya; Carya - metabolism; chlorophyll; electron transfer; fluorescence; gas exchange; leaves; mesophyll; Mesophyll Cells - physiology; nutrition; Photosynthesis; potassium; Potassium - metabolism; ribulose-bisphosphate carboxylase; seedlings; Seedlings - physiology; stomatal conductance; mesophyll conductance; concentration; Sarg; chloroplast CO; photosynthesis; potassium nutrition
• ISSN: 0829-318X; 1758-4469
• DOI: 10.1093/treephys/tpr095

Potassium (K) influences the photosynthesis process in a number of ways; however, the mechanisms underlying the photosynthetic response to differences in K supply are not well understood. Concurrent measurements of gas exchange and chlorophyll fluorescence were made to investigate the effect of K nutrition on photosynthetic efficiency and mesophyll conductance (gm) in hickory seedlings (Carya cathayensis Sarg.) in a greenhouse. The results show that leaf K concentrations <0.7–0.8% appeared to limit the leaf net CO2 assimilation rate (A), and that the relative limitation of photosynthesis due to gm and stomatal conductance (gs) decreased with increasing supplies of K. However, a sensitivity analysis indicated that A was most sensitive to the maximum carboxylation rate of Rubisco (Vc,max) and the maximum rate of electron transport (Jmax). These results indicate that the photosynthetic rate is primarily limited by the biochemical processes of photosynthesis (Vc,max and Jmax), rather than by gm and gs in K-deficient plants. Additionally, gm was closely correlated with gs and the leaf dry mass per unit area (MA) in hickory seedlings, which indicates that decreased gm and gs may be a consequence of leaf anatomical adaptation.