Journal Article

Effects of potassium supply on limitations of photosynthesis by mesophyll diffusion conductance in <i>Carya cathayensis</i>

Song Heng Jin, Jian Qin Huang, Xue Qin Li, Bing Song Zheng, Jia Sen Wu, Zheng Jia Wang, Gen Hua Liu and Miao Chen

Edited by Ülo Niinemets

in Tree Physiology

Volume 31, issue 10, pages 1142-1151
Published in print October 2011 | ISSN: 0829-318X
Published online October 2011 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/tpr095
Effects of potassium supply on limitations of photosynthesis by mesophyll diffusion conductance in Carya cathayensis

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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.

Keywords: Carya cathayensis Sarg.; chloroplast CO2 concentration; mesophyll conductance; potassium nutrition; photosynthesis

Journal Article.  7156 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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