The combining ability of new lines of cucumber for the main economically valuable traits

Relevance. To create heterotic cucumber hybrids, it is important to have a high general and specific combining ability of the initial material, which makes it possible to select valuable genotypes at an early stage of selection. Material and methods. The research was carried out in 2018-2020. at the Research Institute of Vegetable, Melon Crops and Potatoes, located in the Tashkent region of Uzbekistan (SRIVMC&P). Studied 6 accessions of cucumber. As a result of diallelic crosses, 36 hybrid combinations were obtained (p2). Hybridological analysis was carried out according to the first Griffing's method, including forward and backcrossing and the use of parental forms (p2). To determine the combining ability, conventional methodologies were used (1,15). Genetic-statistical analyzes were carried out using the MS Excel application package. Results. Studies have established that according to the traits "the number of days from seed germination to the opening of female flowers" and "the number of days until the technical ripeness of fruits" in all studied cucumber accessions, the ratio (σ 2ĝi<σ 2si) is observed, where the dominant role in the inheritance of this trait also belongs to genes with dominant and epistatic effects. The trait “number of fruits per plant” is controlled by dominant and epistatic gene effects (σ 2ĝi<σ 2si) in almost all cucumber accessions, and in the accession A-6 - by additive gene effects (σ 2ĝi <σ 2si). The phenomenon (σ 2ĝi <σ 2si) was noted for the trait "average fruit weight", where the expression of the trait is controlled by the dominant and epistatic effects of genes (σ 2ĝi <σ 2si) in three studied cucumber accessions (C-25/1, A-6 and A-9), and in the other three accessions, additive gene effects (σ 2ĝi <σ 2si) are more important in inheritance. The trait "productivity of one plant" is controlled by the dominant and epistatic effects of genes (σ 2ĝi <σ 2si) in the three studied cucumber accessions, and in the other three accessions (C-25/1, A-6 and A-9), genes play a special role for the expression of the trait with additive effects. Promising hybrid combinations with the best performance for their use as a initial material for breeding have been revealed.