Publication Date:
2011-11-24
Description:
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 ( g m ) 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 CO 2 assimilation rate ( A ), and that the relative limitation of photosynthesis due to g m and stomatal conductance ( g s ) decreased with increasing supplies of K. However, a sensitivity analysis indicated that A was most sensitive to the maximum carboxylation rate of Rubisco ( V c,max ) and the maximum rate of electron transport ( J max ). These results indicate that the photosynthetic rate is primarily limited by the biochemical processes of photosynthesis ( V c,max and J max ), rather than by g m and g s in K-deficient plants. Additionally, g m was closely correlated with g s and the leaf dry mass per unit area ( M A ) in hickory seedlings, which indicates that decreased g m and g s may be a consequence of leaf anatomical adaptation.
Print ISSN:
0829-318X
Electronic ISSN:
1758-4469
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
