Phenolic content in pear leaves of different cultivars

The purpose of the study is to determine the content of phenolic compounds in the leaves of different pear varieties during the summer period on the territory of fruit plantations of the Krasnodar Territory. The studies were carried out in the Prikubansky horticultural zone of the Krasnodar Territory in 2021-2022. on the basis of the genetic collection of the center for collective use "North Caucasian Federal Scientific Center for Horticulture, Viticulture, Winemaking" (SKFNTSSVV). The objects of the study were four varieties of pear grafted on rootstock BA-29: two introduced varieties Williams and Conference and two varieties of domestic selection Flamenco and Lyuberskaya (selection SKFNTSSVV). The content of total phenols, flavonoids and malonic dialdehyde was determined by conventional methods. The latter indicator was used as a marker of stress. In the first year of the study, all varieties had the same dynamics of the content of total phenols, flavonoids and malondialdehyde. With the rapid increase in malondialdehyde, the concentrations of phenolic compounds increased. In the second year of the study, with slight variations in the stress indicator, changes in the accumulation of phenolic compounds were different in different pear varieties. The first group includes domestic varieties that are able to gradually accumulate phenolic substances in the leaves with increased stress in the summer period. In cultivars Lyuberskaya and Flamenco, an increase in total phenols from ~14 to 29 mg/g fresh weight was observed. The European varieties Conference and Williams form the second group, which is characterized by a decrease in the content of phenolic compounds in the absence of an increase in the concentration of malondialdehyde by the middle of the summer period. The concentrations of total phenols in them decreased from 14 to 7-12 mg/g wet weight, flavonoids - from 2-2.4 to 1.4-1.5 mg/g wet weight. Domestic varieties are distinguished by a high content of phenolic compounds and the ability to accumulate them during the summer period.