Variability of mesophyll conductance in grapevine cultivars under water stress conditions in relation to leaf anatomy and water use efficiency

摘要

Background and Aims: Stomatal (g_s) and mesophyll conductance (g_m) limit photosynthesis significantly and consequently, apart from g_s, g_m is also a physiological process that could affect leaf water use efficiency (WUE). The aims of the present study were to analyse the genetic variability of g_m in the grapevine, to relate the variability of leaf WUE with relative changes in g_s and g_m and to analyse the importance of leaf structural parameters in the variability of g_m. Methods and Results: The g_m in seven potted grapevine cultivars (Vitis vinifera L.) were compared in three experiments under irrigation and moderate water stress treatments. Significant variability of g_m was observed among cultivars associated with change in intrinsic WUE. No clear relationship with anatomical traits was found. Conclusions: Variability of g_m was associated with leaf WUE, although it could not be explained by anatomical variability. It is likely that biochemical mechanisms play an additional important role in the diffusion of CO_2 in grapevines. Significance of the Study: This study shows that the variability of g_m in different grapevine cultivars offers a potential target for improving leaf WUE by increasing net photosynthesis (A_N) without increasing plant water losses.