Biochemical Composition of Sweet Cherry Leaves Depending on the Method of Soil Maintenance in an Organic Garden

Abstract

Conducting sustainable agriculture involves not only increasing the productivity of crops and increasing the volume of crop production, but also preserving ecosystems. Mulching the soil in orchards is one of the ways to preserve the natural balance of agricultural landscapes. But the effect of competition with grasses on the biochemical composition of fruit tree tissues has not yet been definitively elucidated. The purpose of this study was to determine the influence of soil retention under mulching (compared to pure steam) on the biochemical composition of cherry leaf tissues. The research was conducted in an organic cherry orchard (Prunus avium L. / Prunus mahaleb) during 2017-2019 in the conditions of the Southern Steppe of Ukraine. A significant decrease in the content of ascorbate, glutathione, sugars, total reducing activity and activity of antioxidant enzymes was established under conditions of prolonged drought and an increase in the content of titrated acids. The total reducing activity under mulching conditions tended to increase. A gradual increase in the content of titrated acids, ascorbate, sugars, phenolic substances, and glutathione was recorded in the leaves of cherry trees from the flowering phase to November. In the autumn phase, a significant increase in sugars and phenolic substances was established in cherry leaves under the conditions of mulching in 2017, and in 2018 – phenolic substances; in 2019 – phenolic substances and ascorbate. An increase in the content of malondialdehyde (MDA) and the activity of antioxidant enzymes was found during the growing season of cherries in both variants of the experiment. In the November phase only in 2019, the MDA content was significantly higher by 14% under the condition of mulching. Under mulching conditions, a significant increase in ascorbate peroxidase (by 28-30%) and polyphenol oxidase (by 45-46%) was determined. In 2018 and 2019, a 2.4-fold increase in peroxidase activity in cherry leaves was determined. Research results help to understand the mechanisms of adaptation of fruit plants to stress factors (drought, competition with natural grasses) and can be used as an argument in favour of mulching in organic cherry orchards.