Fruit growing
and viticulture of South Russia
Physiology and biochemistry of plants
In the conditions of the climate change in southern Russia, unpredictable fluctuations in meteorological factors negatively affect the adaptive capacity of the apple tree to the summer stresses. The parameters of the water regime, the pigmental complex, and the area of the leaf blade serve as reliable criteria for the drought resistance of plants. The aim of this work is to study the features of water metabolism, photosynthetic activity of apple trees in the summer period; to identify the most drought-resistant varieties for cultivation in the Krasnodar region. The objects of research were apple varieties of various ecological and geographical origin: Interprase, Florina, Orfey, Idared, Ligol, Prikubanskoe. Physiological and biochemical adaptation of apple varieties to deficit water supply and high temperatures is achieved by increasing the fraction of bound water in the total water content, increasing the proportion of carotenoids in the pigmental composition of the leaf. It was found that by the end of summer, all studied varieties had a decrease in water content in leaf tissues, and to a greater extent in varieties Idared, Ligol, Prikubanskoe by 12.2-14.2%. The varieties Orfey and Prikubanskoe were distinguished as the most drought-resistant with the ratio of bound and free forms of water 3.0 and 2.8, respectively. The lowest indicators of the ratio of the chlorophylls sum and carotenoids (2.01-2.03) due to an increase in the proportion of carotenoids performing a protective function were found in the varieties Florina, Orfey, Prikubanskoe. The decrease in the area of the leaf blade in response to stress is the least shown in the varieties Orfey, Idared, Prikubanskoe. Apple varieties Orfey and Prikubanskoe proved to be more adaptive in comparison with other studied varieties in the summer of 2020 and are recommended for cultivation in the Krasnodar region.
The adverse effect of temperature fluctuations during the summer affects the productivity and yield of the apple tree, which actualizes the need for breeding for adaptability and increasing resistance to abiotic stress factors. Physiological and biochemical studies disclose the mechanisms of a protective response to the action of stressors. The purpose of this work is to study the peculiarities of the physiological and biochemical response of the various types of apple trees on the stressful conditions of the summer period, allocate the most stable varieties for use in breeding purposes. Objects of research 6 varieties of apple trees of various ecological and geographical origin: Idared, Interprais (USA), Ligol (Poland), Orfey, Prikubanskoe (Russia, NCFSCHVW), Florina (France). It is shown that a decrease in the content of water-soluble sugars is associated with the oppression of assimilative processes in the leafy tissues against the background of the action of elevated temperatures and the lack of precipitation. It has been established that in varieties Interprais and Orfey content of the proline increased during the summer in 1.7-2.9 times, indicating active participation in osmotic regulation. The content of abscise acid increased during the period of elevated temperatures and droughts in Florina, Orfey and Idared varieties in 1.21-2.08 times depending on the variety indicating the participation of this phytohormone in osmotic adjustment. The largest contribution of organic acids in osmotic regulation is marked at the Orfey and Prikubanskoe varieties. The smallest heat resistance defined by the leakage of electrolytes is marked at Florina, Idared and Ligol varieties. Based on the generalized data, apple tree varieties Interprais, Orfey and Prikbanskanskoe showed themselves more adaptive in comparison with other studied varieties in the summer of 2020. The obtained results are of interest for using them in breeding purposes as a diagnostic indicators of the degree of resistance to the stress of the summer period.
In the southern regions of Russia, during the active growing season of pears, almost every year there is an impact of drought, heat, dry winds, which affects their water status, growth, productivity and adaptation. When selecting varieties for optimal placement, it is necessary to take into account their adaptability to dry growing conditions. From the collections of the Maykop experimental station VIR, more than 120 samples of pears were included in experiments to study the drought resistance of plants: 59 varieties, including 43 varieties of European origin and 16 East Asian, 26 species, 38 ecological forms of the Caucasian pear. Field assessment of the plant condition was carried out visually after prolonged exposure to stress. In parallel, a laboratory method of leaf wilting was used, which allows judging the degree of endurance of various samples to the dehydration factor and the relative drought resistance of plants by the parameters of the water regime. On the basis of adaptability and indicators of the water regime, pear samples with increased resistance of leaves to dehydration are identified, which can be recommended for cultivation in the foothill zone of the Republic of Adygea in areas with limited water supply. These are such European varieties as Bessemyanka, Borup, Williams, Krasnodarskaya letnyaya and Lastochka, whose leaves lost only 30-40 % of water in 6 hours of dehydration. Under the same conditions, the lowest water losses 42-46%) were observed in the varieties Minueli, Olga and Pinli from East Asian pears. From the MES VIR species collection, P. caucasica Fed., P. elaeagnifolia Pall., P. nivalis Jacq., P. salicifolia Pall., P. ussuriensis Maxim. may be of interest for breeding for drought resistance.
In the Krasnodar region over the past 20 years, during the summer vegetation period of fruit plants, the main abiotic stresses are increased air temperature exceeding the long-term climatic norm by up to 7 degrees, and prolonged droughts, the combination of which negatively affects the growth, development and yield capacity of fruit plants, especially in conditions of insufficient irrigation regime. The greatest manifestation of high-temperature stress is observed in two periods in the first decade of July and the third decade of August. Considering that it is at this time that two most important stages of apple tree development take place simultaneously the differentiation of fruit buds (July) and the ripening of the fruits of the current year's harvest (August), the resistance of fruit plants to high-temperature stresses is a necessary condition for the normal course of their production process. The effect of mycorrhization of apple young plants with a biopreparation based on symbiotic fungi of arbuscular mycorrhiza Glomus sp. on the drought-resistance of Prikubanskoe apple variety on the dwarf rootstock of SK 7 was studied. Mycorrhization of plants with a biopreparation based on symbiotic fungi Glomus sp. in most variants positively affected the resistance to high temperatures and drought of experimental apple trees. The best water-retaining ability of the leaves (for 2 and 4 hours of exposure) was shown by plants in the variant with root treatment at a dose of 1.0 g of a biological preparation. Mycorrhization of apple young plants can be recommended as a nature-like technology that increases the adaptive potential of apple plants by mobilizing the mechanisms of symbiotic interaction of arbuscular mycorrhiza fungi and the root system of plants.
In condition of humid subtropical zone of Russia during 2002-2020, the degree of drought resistance of pear varieties and hybrids was assessed by anatomical, morphological and physiological parameters to study their adaptation mechanisms. Researchs objects different genotypes of genus Pyrus L. (varieties: Bere Zhiffar, Vega, Williams, Red Williams, Chernomorskaya Yantarnaya, Yuzhanka, Nektarnaya, Slavyanka, Verbena, Luchistaya, Bere Bosk, Rassvet, hybrid 8520, Kilchu). A set of physiological, anatomical and morphological indicators was used to assess the adaptability of the studied pear varieties to stress factor of the summer period (high temperature and low water-holding). It is established that change in the physiological processes affect the anatomical and morphological structure of the leaf. The assessment of drought resistance of the studied varieties and hybrids by the nature of changes in the parameters of the water regime is given. It was determined that water-holding capacity of the leaf blade in all genotypes has a high inverse dependence (r= -0,77) on the number of stomates on lower epidermis of the leaf. According to quantitative ratio of chlorophylls a and b, the varieties Bere Zhiffar, Bere Bosk and Chernomorskaya Yantarnaya were identified, confirming stability of the pigment system to water deficit at the most arid period. Continuous modification of the photosynthetic function of leaves associated with productivity and viability was noted. It was found that the influence of stressful weather conditions leads to the appearance of such xeromorphic traits in the genotype as increased development of the palisade parenchyma layer and a decrease in the number of stomates per unit surface. Varieties Red Williams, Chernomorskaya Yantarnaya, Vega and Rassvet are identified by the complex of the above characteristics as the most adaptive to the abiotic stress factors of the summer period of humid subtropics. Revealed adaptive features of these varieties allow to use them in breeding as sources of resistance to drought.