Morphological, anatomical and physiological features of assimilation apparatus changes in Prunus armeniaca L. infected by Plum pox virus
The southern coast of the Crimea refers to an arid climate zone with unstable moisture. Under these conditions drought and disease resistance, heat tolerance should be considered as the main criteria for apricot plants normal growth and development. The objective of the present study was to identify the effects of apricot plant assimilation apparatus changes on the structural and physiological characteristics associated with the appearance of Plum pox virus (PPV) symptoms. Four apricot cultivars and one form were investigated in late July 2017 (the average daily air temperatures were 24-28°C, the maximum was 35.6°C, relative air humidity was 24-57%, the supply of productive moisture in soil was 38-49 mm (25-37% MR moisture retention). The main symptoms of PPV were revealed in 10-40% of leaves and up to 30% fruits. Leaf blade structure in the damaged cultivars was characterized by decrease of a leaf size and thickness (Iskorka Tavrydy from 220±17 to 174±11 μm) as well as palisade tissue (Iskorka Tavrydy and Salyeri 99-266 were 24-30%), and increase of intercellular spaces in spongy parenchyma in Ananasniy Ukrainskiy. In Khersonskiy-23 and Salyeri 99-266 increase of stomata number 1.5-2 times was noted in the damaged plants. Evaluation of a photosynthetic apparatus activity demonstrated photoinhibition in leaves with the visible symptoms in Khersonskiy-23, Iskorka Tavrydy and Salyeri 99-266 (Fm (maximum fluorescence)-Fst (stationary fluorescence))/Fm = 0.52-0.58 approximate units. The total water content in leaf tissues was 62-68%. Water deficiency was 14-23% (maximum in damaged cultivars Khersonskiy-26 and Iskorka Tavrydy). Thus, the indicated morphological, anatomical and physiological changes have decreased the resistance to hydrothermal stress and deteriorated of functional state of the damaged apricot plants.
Brailko, V.A., Mitrofanova, O.V., Chirkov, S.N., Gorina, V.M. and Mitrofanova, I.V. (2020). Morphological, anatomical and physiological features of assimilation apparatus changes in Prunus armeniaca L. infected by Plum pox virus. Acta Hortic. 1280, 203-208
apricot, PPV, symptoms, tolerance, structural characteristics, water regime, photosynthetic apparatus