Relevance. Although there is notable success in breeding vegetable crops to obtain heterotic F1 hybrids, traditional selection methods have been gaining in popularity as a means of improving the economically important traits of local traditional varieties in Russia today. These varieties suffered the reduction in their valuable starting parameters (yield, the uniformity of marketable produce and biochemical composition) over the many years of reproduction. The Department of Potato Breeding and Horticulture (FSBSI “FSC of Agricultural Biotechnology of the Far East named after A. K. Chaiki”) have been working on the creation of new squash variety-populations with large fruits using the variety-population Banannaya 42, bred by V. Ya. Smolei at the Far Eastern experimental station of the All-Union Scientific Research Institute of Plant Breeding in the 1940s, as the starting material. We carried out a multi-year research on the selection of promising families belonging to this variety to increase yield, improve the uniformity of fruits and the main biochemical parameters.   Results. The breeding work conducted on the families of variety-population 945 in 2011-2022 resulted in the improvement of some economically important traits (the uniformity of fruit shape, yield, and biochemical parameters) compared to the started form. The eleven years of research allowed us to achieve high uniformity of fruit shape in the selection of the ninth year (PIP 2) – 90.0-90.7 % (increased by 34.9-36.0 %). The yield increased from 28.4 t/ha to 38.2-45.3 t/ha or by 34.5-59.5 %. The following biochemical parameters were improved through selection: the content of dry mater from 8.5 to 12.9 % or by 51.8 % on average, the content of sugars from 6.1 to 9.1 or by 49.2 %, the content of carotene from 1.7 to 3.8 or by 123.5 %, and the content of vitamin C from 9.6 to 21.1 or by 119.8 %. We selected the families of the same type from variety-population 945 (variety-population Banata) with improved and uniform economically important traits for submission to the State variety testing. The yield was 38.2-45.3 t/ha, fruits were heart-shaped, skin was greyish green, pulp was orange, and the content of sugars was 9.0-13.2 %. Large-fruited variety population Banata was included in the State register of breeding achievements admitted to use in the Russian Federation in 2024.

Fruit peel/pulp distribution of biologically active compounds is an important characteristic of plant physiology and the basis of zero waste production in agriculture. Among C. ficifolia, C. maxima and C. moschata the former showed the lowest dry matter content, especially in peel, similar peel and pulp values of antioxidant activity (AOA) and polyphenol content (TP), with the highest levels in fruit placenta. Peel carbohydrate profile of C. ficifolia fruit was characterized by lower levels of disaccharides compared to C. maxima and C. moschata peel and an opposite pattern of monosaccharides accumulation. The analysis of 25 elements content in Cucurbita peel and pulp, using ICP-MS, indicated that C. ficifolia fruit are characterized by significantly high concentrations of Sr, Si and I in pulp compared to the values of C. maxima and C. moschata. On the contrary, C. maxima and C. moschata were characterized by low concentration of pulp Mn. Highly significant positive correlations were recorded between Cr-Sr, Cr-Ca and CaSr (r=0.906; 0.939 and 0.974 respectively) and P-Cu (r=0.968). Despite C. ficifolia, does not contain carotenoids, it is highly valuable due to the high levels of Si, I, Cr and Ca in peel and pulp, which reveals new areas of its application.