Anatomical and morphological structure of the leaf of the genus Malus spp.

The article describes changes in the structure, leaves, (including mesophyll structure, structure of the midrib, distribution of stomata, and the number of vascular bundles) in Malus during the growing season (from June to August) under the influence of prolonged drought. The leaves anatomy and morphology were investigated by methods of light and scanning electron microscopy. The study was carried out on four representatives of the genus Malus: M. niedzwetzkyana Borkh., M. baccata ‘Pendula’, M. domestica ‘Eliza Rathke’, M. domestica ‘Renet Simirenko’. The influence of drought on the size of the mesophyll of the leaf plate and the number of stomata along the stretch from June to August was studied. The cell circumference of the sclerenchyma ranged from μm in 27.33 (M. niedzwetzkyana) to 81.92 μm (in M. domestica ‘Elise Rathke’). The number of stomata varied from 214.0 units in (M. domestica ‘Renet Simirenko’) to 304.0 units in (M. baccata ‘Pendula’), length from 11.6 μm (M. baccata ‘Pendula’) to 28.63 μm (M. domestica ‘Elise Rathke’), width from 9.4 μm (M. domestica ‘Elise Rathke’) up to 21.8 μm (M. domestica ‘Elise Rathke’) μm. The length of the trichomes varied from 409.92 μm (M. domestica ‘Renet Simirenko’) to 745.09 μm (M. niedzwetzkyana). Also, the anocytic stomatal type, the number, different stomata and trichomes, the presence of wax on the cuticle, and the found druses of calcium oxalate in M. baccata ‘Pendula’, can be important for systematic phylogeny. Thanks to these studies, it is possible to suggest physiological adaptability of apple trees to prolonged drought, as well as to identify more resistant phenotypes for the breeding process to develop resistant cultivars.