PHENOTYPIC CHARACTERIZATION OF SEED PROGENY OBTAINED FROM IN VITRO CUCUMBER REGENERANTS

Abstract

Cucumber ( Cucumis sativus L.) is a major vegetable crop facing continuous challenges regarding genetic narrowness and pathogen susceptibility. Traditional breeding approaches often face challenges in combining high productivity with resistance to multiple diseases. This study aimed to comprehensively evaluate the phenotypic and biometric characteristics of new inbred lines obtained through in vitro regeneration and compare them with those of the long-established cultivar Gergana. Experiments were conducted under greenhouse conditions during 2025 and 2026. Six stabilized seed progenies from in vitro regenerants were evaluated for yield, fruit traits, and resistance to downy and powdery mildew under natural infection backgrounds. Data were analyzed using Tukey's HSD test, Principal Component Analysis (PCA), and Ward's clustering method. Significant phenotypic divergence was observed. Line 105/3-1 demonstrated the highest average yield of 8649.6 kg/da, significantly outperforming cv. Gergana (5538.4 kg/da), while showing the lowest infection index for both downy and powdery mildew. Multivariate analysis clustered the genotypes into three distinct groups based on nine morphological and phytopathological variables. The results indicated that in vitro regeneration combined with targeted pedigree selection can be a useful approach for generating and selecting heritable phenotypic variation in cucumber. Line 105/3-1 represents a valuable elite parental component for future heterosis breeding programs.