THE REGULATION OF PHOTOSYNTHESIS IN THE LEAVES OF THE SIBERIAN CRABAPPLE UNDER THE EFFECT OF AIR DROUGHT

Original title

ВЛИЯНИЕ ВОЗДУШНОЙ ЗАСУХИ НА ЭФФЕКТИВНОСТЬ РАБОТЫ ФОТОСИНТЕТИЧЕСКОГО АППАРАТА ЯБЛОНИ СИБИРСКОЙ MALUSBACCATA (L.) BORKH.В УСЛОВИЯХ ЗОНЫ КОНТАКТА ЛЕСА И СТЕПИ СЕЛЕНГИНСКОЙ ДАУРИИ

Authors

A. V. Rudikovskii, E. G. Rudikovskaya, L. V. Dudareva

Contact information

Siberian Institute of Plant Physiology and Biochemistry, Irkutsk, Russia

Pages

111-113

DOI

10.31255/978-5-94797-318-1-111-113

Abstract

We studied the influence of spring-summer air drought in the zone of forest and steppe contact onto photosynthesis processes in the leaves of Siberian Crabapple trees with a sufficient provision of soil moisture. We revealed the adaptation of apple tree photosynthetic mechanism to these conditions resulting in the decrease of the content of chlorophylls summary at a constant ratio of chlorophyll: carotenoids. The functioning of photosystem 2 (PS-II) in apple trees growing under the conditions of forest and dry steppe contact is characterized by the decrease of fraction of light energy used for photochemical function and by the increase of fraction of non-photosynthetic thermal quenching. These changes on the background of high values of Fv/Fm suggest a decreasing regulation of photosynthesis functioning as a universal photoprotective mechanism. At noon, the combination of high temperature and of low air humidity resulted in the decrease of values of potentially maximal photochemical quantum yield of the photosystem II (Fv/Fm) and photosynthesis efficiency (PI) PS-II. The air drought resulted in the decrease of the carbon dioxide assimilation level by apple trees leaves by >27%. The coefficient of water use during photosynthesis increased; from our viewpoint, this reflects processes of Siberian Crabapple tree adaptation to unfavourable conditions.