Physiological and biochemical approaches in studying adaptation mechanisms of subtropical, fruit and ornamental crops grown in Russian subtropics

A problem of assessing the sustainability in crops, for which the humid subtropical zone of Russia is quite favorable, has a great value since there are a lot of stress factors (for example droughts, high or low temperatures, fogs etc.) due to climatic features of the region. For the first time we have carried out a 20-year comprehensive study of physiological and biochemical responses of plants, their organs, tissues and systems to the effect of abiotic stressors with the aim to identify some specific adaptation mechanisms of subtropical, southern fruit and ornamental crops as well as tea to the environment. This paper reports the peculiarities in water regime and photosynthetic apparatus (basic physiological functions), activity of catalase enzyme and carotenoid content (protective components in plants' oxidant-antioxidant system). As a result, there were selected some physiological and biochemical parameters (quantity of water scarcity, concentration of cell sap, catalase activity, carotenoids content, etc.), which allowed to estimate the crop state and resistance to abiotic stressors in Corylus pontica C. Koch, Prunus persica (L.) Batsch, Actinidia deliciosa Chevalier, Camellia sinensis (L.) Kuntze, beautifully-blossoming shrubs Hydrangea macrophylla Ser., Weigela ½ wagneri L.H. Bailey, etc. The regularities in changing physiological parameters as a response to the impact of adverse conditions are identified; the criteria, scales and methodology are proposed for assessing adaptive capacity of the studied cultures. Specific features of the dynamics of photosynthetic pigments accumulation for all the cultures are studied; the dependence of this process on the main regional factors was revealed; the parameters of water regime and drought resistance coefficients are determined; the influence of hydrothermal factors on enzyme activity is identified, as well as correlation between enzyme activity and abiotic environmental factors; the effect of microelements on increase of plants adaptive properties (for example, tea) was determined. As a result, there were developed some recommendations on micronutrients foliar feeding for young tea plantations and mature tea plants, as well as on the diagnostics of plants micronutrient requirements, on the application of sustainability indicators of tea plants to stress factors, and on evaluation of H. macrophylla Ser. drought resistance. The most adaptive cultivars of subtropical, southern fruit, ornamental crops and tea are identified and recommended for growing. They are characterized by increased resistance to stress factors in humid subtropics of Russia (for kiwi - Monty cultivar, for filbert - President cultivar originated by All-Russian Research Institute of Floriculture and Subtropical Crops; for peach - Donetskii zheltii, Medin Red, Earley Red, Earley Blow, Larisa, Slavutich and Redhaven; for H. macrophylla - Mariesii Perfecta, Draps Wonder и Madame Maurice Hamard. The data obtained relate to the fundamental physiological bases of adaptation to stress conditions, and in particular to plant adaptive features in specific conditions of Russian subtropics.