MGIDI‐Based Multivariate Selection in Tomato: Integrating Yield, Fruit Quality, and Genetic Resistance

Tomato ( Solanum lycopersicum L.) is one of the most economically important vegetable crops worldwide, requiring genotypes that combine high yield, fruit quality, and pathogen resistance. However, the multivariate nature of these traits makes simultaneous selection a major challenge in breeding programs. Therefore, the present study evaluated 40 F ₁ tomato hybrids derived from a partial diallel involving 13 inbred lines carrying different combinations of resistance genes (RGs). The experiment was conducted under greenhouse conditions using a randomized complete block design with four replications to identify superior genotypes through the multitrait genotype–ideotype distance index (MGIDI). Fifteen agronomic and fruit quality traits were evaluated, and deviance analysis revealed significant genetic variability for all of them, with heritability estimates ranging from 0.588 to 1.000. Multicollinearity among variables was reduced by removing three highly correlated traits. Correlation and principal component (PC) analyses revealed important associations among fruit size, weight, and quality attributes, as well as negative relationships between yield and chemical traits. Factor analysis grouped the variables into four factors representing dimensions associated with fruit size, genetic resistance, and quality parameters. The innovative integration of phenotypic information and the number of RGs into the MGIDI index enabled the identification of 12 superior hybrids, with H11, H21, and H36 showing the best overall performance. The greatest genetic gains were obtained for fruit firmness (FF; 17.953%), number of RGs (15.882%), and average fruit weight (14.682%), resulting in a cumulative total genetic gain of 68.443%. These findings demonstrate the effectiveness of the MGIDI index for multivariate selection and identify promising hybrids for advancement in tomato breeding programs, supporting the development of cultivars that combine high yield, superior fruit quality, and broad‐spectrum genetic resistance to multiple diseases.