Effect of mineral fertilizers on the taste qualities of apple varieties

Abstract

This article presents the results of a 3-year research study into the effect of soil and foliar application of nitrogen and potassium fertilizers on the taste qualities of the Veniaminovskoe (Rvi6) and Sinap Orlovskii (3×) apple varieties bred at the Russian Research Institute of Fruit Crop Breeding (VNIISPK). The assumption that varietal features are the most important factor that determines taste was confirmed. In addition, the influence of weather conditions of the growing season on the chemical composition of fruits was observed. Thus, the year of 2019 was characterized by the most favorable weather conditions of the growing season. In August, during fruit ripening, the optimum temperature and humidity regime had a positive effect on the accumulation of soluble solids, sugars, and titratable acids in both varieties under study. However, the varieties responded differently to the same doses of mineral fertilizers. The application of fertilizers had no significant impact on the content of the studied components and the sugar-acid ratio in Veniaminovskoe fruits. Conversely, Sinap Orlovsky was found to be responsive to this agricultural practice. In 2019, the joint application of triple foliar and soil fertilizing using N30K40, N60K80, and N90K120 in various doses had a positive effect on the reduction of titratable acidity in fruits of this variety. As a result, the sugar-acid ratio increased by 1.3–1.9 times. Over the entire study period (2017–2019), a significant decrease in the content of sugars in Sinap Orlovsky fruits was observed in the variant with additional foliar fertilizing compared to the control. During the study period, the high doses of N90K120 nitrogen and potassium fertilizers along with foliar application contributed to a significant increase in the sugar-acid ratio in Sinap Orlovsky fruits, which significantly exceeded the control.