The study of leaf vascular systems is important in order to understand the fluid dynamics of water movement in leaves. Recent studies have shown how these systems can be involved in the performance of photosynthesis, which is linked to the density of the vascular network per unit of leaf area. The aim of the present study was to highlight the correlation between a leaf vein density (VD) and net photosynthetic rate (PN), which was undertaken using a digital camera, a stereoscopic microscope, and a light source. The proposed hypothesis was tested, for the first time, on the leaves of two cultivars of Vitis vinifera (L.). A significant difference was found between the VD of mature leaves of the two cultivars. VD was also significantly correlated with the maximum leaf PN. These findings support the hypothesis that the vascular system of grape leaves can be correlated with leaf photosynthesis performance., M. Pagano, P. Corona, P. Storchi., and Obsahuje bibliografii
Growth of the tocopherol-deficient vte1 mutant and Col-0 wild type of Arabidopsis thaliana in a sunlit glasshouse revealed both similarities and differences between genotypes. Photosynthetic capacity and leaf mesophyll features did not differ between mutant and wild type. Likewise, the total volume of water conduits (tracheary elements, TEs), sugar conduits (sieve elements, SEs), and sugar-loading cells (companion and phloem parenchyma cells) on a leaf area basis were unaffected by tocopherol deficiency. However, tocopherol deficiency yielded smaller and more numerous minor veins with fewer phloem cells and smaller TEs, resulting in greater ratios of TEs to SEs. The smaller TEs in the vte1 mutant may present a decreased risk for cavitation under high evaporative demand or in response to freezing. In turn, compensation for fewer phloem cells and smaller TEs by more numerous veins may bolster resistance to cavitation at no cost to photosynthetic capacity., J. J. Stewart, W. W. Adams, C. M. Cohu, B. Demmig-Adams., and Obsahuje bibliografické odkazy