THE EFFECT OF PRECIPITATION AND TEMPERATURE CONDITIONS ON SUGAR CONTENT OF POMEGRANATE FRUITS IN DRY SUBTROPICS

The aim of the research was to study the effect of agroecological factors on individual indicators of fruit quality in pomegranate plantations in the dry subtropics of Southern Dagestan. The role of the cultivar in the quality of mature fruits for highly productive raw pomegranate plantations was established. This paper determined the effect of meteorological factors on the sugar content in 6 pomegranate cultivars providing high-quality and safe fruits for universal use. The potential of using mathematical statistics methods to quantify the relationship between the average annual precipitation and the quality of pomegranate cultivars, as well as with the absolute maximum, absolute minimum, average annual air temperature and maximum daily precipitation amounts is demonstrated. Some correlations and regression dependences of the pomegranate sugar content on the meteorological conditions of the year were revealed. It is shown that the sugar content of ripe pomegranate fruits is in a greater degree dependent on more dynamically changing environmental factors, which, in particular, are climate-related. The effect of precipitation on the sugar content of pomegranate fruits, compared with temperature, is more noticeable and more clearly expressed, both for the warm period and the cold period. Precipitation in any phase of pomegranate development has a beneficial effect on yield, but, as a rule, reduces sugar content. The sugar content in ripe pomegranate fruits of the cultivars ‘Apsheronsky’, ‘Kazake Anor’, ‘Gulosha Rozovaya’, ‘Krmyzy Kabukh’, ‘Agdashsky’ and ‘Krmyzy Shirin’ was evaluated. Using the standard method of constructing confidence intervals based on the average value and standard error, a confidence interval with a confidence level of 95 % was obtained. The confidence interval for estimating sugar content lies in the range from about 15.6 to 16.7 %. The constructed polynomial model of the second row describes 94.53 % variation in the sugar content of pomegranate fruits, which indicates the high quality of the model. At the same time, the average approximation error was 72.75 %, which, with acceptable values of 10–15 %, indicates rather low predictive qualities of the model. The calculated Pearson correlation coefficient (-0.76) indicates an inverse and noticeable relationship between the average annual precipitation and the sugar content in mature fruits. Applied statistical modeling with a comprehensive consideration of the dependence of the sugar content in ripe pomegranate fruits on meteorological growing conditions allows us to quantify the dependence of sugar content on meteorological conditions of the year, as well as to assess in advance the climatically determined component of the territory’s total potential designated for growing pomegranate as a whole or a certain cultivar group.