Journal Article

Water deficit affects mesophyll limitation of leaves more strongly in sun than in shade in two contrasting <i>Picea asperata</i> populations

Baoli Duan, Yan Li, Xiaolu Zhang, Helena Korpelainen and Chunyang Li

in Tree Physiology

Volume 29, issue 12, pages 1551-1561
Published in print December 2009 | ISSN: 0829-318X
Published online December 2009 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/tpp085
Water deficit affects mesophyll limitation of leaves more strongly in sun than in shade in two contrasting Picea asperata populations

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The aim of this study was to examine the response of internal conductance to CO2 (g i) to soil water deficit and contrasting light conditions, and their consequences on photosynthetic physiology in two Picea asperata Mast. populations originating from wet and dry climate regions of China. Four-year-old trees were subjected to two light treatments (30% and 100% of full sunlight) and two watering regimes (well watered, drought) for 2 years. In both tested populations, drought significantly decreased g i and the net photosynthesis rate (A) and increased carbon isotope composition (δ13C) values in both light treatments, in particular in the sun. Moreover, drought resulted in a significantly higher relative limitation due to stomatal conductance (L s) in both light treatments and higher relative limitation due to internal conductance (L i) and abscisic acid (ABA) in the sun plants. The results also showed that L i (0.26–0.47) was always greater than L s (0.12–0.28). On the other hand, drought significantly decreased the ratio of chloroplastic to internal CO2 concentration (C c/C i), photosynthetic nitrogen utilization efficiency (PNUE) and total biomass in the sun plants of the wet climate population, whereas there were no significant changes in these parameters in the dry climate population. Our results also showed that the dry climate population possessed higher δ13C values with higher ratio of internal conductance to stomatal conductance (g i/g s), suggesting that increasing the g i/g s ratio enhances water-use efficiency (WUE) in plants evolved in arid environments. Thus, we propose that the use of the g i/g s parameter to screen P. asperata plants with higher water deficit tolerance is certainly worthy of consideration. Furthermore, g i is an important variable, which reflects the population differences in PNUE, and it should thus be included in plant physiological investigations related to leaf economics.

Keywords: carbon isotope discrimination; internal conductance; limitation analysis; photosynthesis; stomatal conductance

Journal Article.  7948 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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