In:
Physiologia Plantarum, Wiley, Vol. 128, No. 4 ( 2006-12), p. 722-731
Abstract:
In this study, we have examined several physiological, biochemical and morphological features of Buddleja davidii plants growing at 1300 m above sea level (a.s.l.) and 3400 m a.s.l., respectively, to identify coordinated changes in leaf properties in response to reduced CO 2 partial pressure (P a ). Our results confirmed previous findings that foliar δ 13 C, photosynthetic capacity and foliar N concentration on a leaf area basis increased, whereas stomatal conductance (g s ) decreased with elevation. The net CO 2 assimilation rate (A max ), maximum rate of electron transport (J max ) and respiration increased significantly with elevation, although no differences were found in carboxylation efficiency of Rubisco (V cmax ). Consequently, also the J max to V cmax ratio was significantly increased by elevation, indicating that the functional balance between Ribulose‐1,5‐biphosphate (RuBP) consumption and RuBP regeneration changes as elevation increases. Our results also indicated a homeostatic response of CO 2 transfer conductance inside the leaf (mesophyll conductance, g m ) to increasing elevation. In fact, with elevation, g m also increased compensating for the strong decrease in g s and, thus, in the P i (intercellular partial pressure of CO 2 ) to P a ratio, leading to similar chloroplast partial pressure of CO 2 (P c ) to P a ratio at different elevations. Because there were no differences in V cmax , also A measured at similar PPFD and leaf temperature did not differ statistically with elevation. As a consequence, a clear relationship was found between A and g m , and between A and the sum of g s and g m . These data suggest that the higher dry mass δ 13 C of leaves at the higher elevation, indicative of lower long‐term P c /P a ratio, cannot be attributed to changes either in diffusional resistances or in carboxylation efficiency. We speculate that because temperature significantly decreases as the elevation increases, it dramatically affects CO 2 diffusion and hence P c /P a and, consequently, is the primary factor influencing 13 C discrimination at high elevation.
Type of Medium:
Online Resource
ISSN:
0031-9317
,
1399-3054
DOI:
10.1111/ppl.2006.128.issue-4
DOI:
10.1111/j.1399-3054.2006.00805.x
Language:
English
Publisher:
Wiley
Publication Date:
2006
detail.hit.zdb_id:
208872-1
detail.hit.zdb_id:
2020837-6
SSG:
12
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