Influence of abiotic factors on the weight and chemical properties of black currant berries

The paper presents results of the study into the correlation between the weather conditions and weight as well as biochemical properties of berries from 20 selected cultivars of black currant ( Ribes nigrum L.) bred in the Lupin Russian Research Institute. The content of vitamin C, total sugars, organic acids, and berry weight were measured in the laboratory of the Horticulture Department, the Lupin Russian Research Institute. Standard study methodologies involved measuring vitamin C content in the berries by iodometric method (titration with 0.001N potassium iodate in the presence of a 1 % potassium iodide solution); assessing total sugar by Bertrand method as per GOST 13192-73; estimating the total acidity by titration of the aqueous extract with 0.1N alkaline solution in accordance with GOST 25555.5-82. The diversity of weather conditions during the study period allowed for identifi cation of the most favorable year for berry weight gain and the accumulation of biochemical properties. The year 2021 proved to be the most advantageous for berry weight gain. Throughout the years of study, the average berry weight ranged from 1.7 to 2.8 grams. The genotypes 8-3-155, 8-3-176, and 8-3-137 appear to be the largest fruit-bearing forms with weights ranging from 2.6 to 2.8 grams, exhibiting a high level of homeostasis (V<10 %). Correlation analysis revealed a strong positive dependence of berry weight on total precipitation (r = 0.99) and a weak positive correlation with the sum of active temperatures (r = 0.21). The accumulation of vitamin C in the selected forms ranged from 96 to 208 mg/100 g. The most vitamin-rich forms, exhibiting low variability over the years (V<10 %), included 8-3-14 (195 mg/100 g), 7-2-157 (205 mg/100 g), and 7-19-100 (208 mg/100 g). A strong negative correlation (r=-0.98) was found between the sum of active temperatures and the accumulation of vitamin C in the berries. A higher accumulation of sugars was observed in 2022. Throughout the study period, this indicator varied from 5.7 % to 8.5 %. Selection numbers 6-15-65 (8.2 %), 8-3-171 (8.2 %), 8-3-129 (8.3 %), and 8-3-113 (8.5 %) were marked with high and stable sugar accumulation (V<10 %). A strong positive correlation was found between sugar accumulation and the sum of active air temperatures from May to July (r=0.99). The average acid content across the samples ranged from 1.4 % to 2.5 %. The genotypes 8-3-176, 8-3-110, 8-3-129, 8-3-113, 8-3-125, and 7-18-31 demonstrated consistent low acidity (from 1.4 % to 1.9 %). Correlation analysis revealed a strong positive relationship between total acidity and precipitation (r=0.99).