Factor analysis, stepwise regression and path coefficient analyses of yield, yield-associated traits, and fruit quality in tomato

Breeding of tomato (Solanum lycopersicum L) with a focus on yield has indirectly led to reductions in flavor. Development of tomato genotypes with high quality and yield needs efficient tools to monitor trait association in breeding. The objective of the work was to combine simultaneous selection for yield and quality in elite segregating populations of tomato breeding using multivariate methods. Eighty-three tomato lines (S3) were produced, using the modified pedigree method, from crossings of commercial hybrids. Factor analysis determined five hidden factors, which justified 68.62% of variation. The first factor, with the highest percent of justified variance, was effective for fruit yield. The second factor with the most coefficients was effective for fruit quality. The third factor, with extensive, positive, coefficients for fruit length, fruit diameter, and pericarp thickness, was effective for fruit characterization. The fourth factor, with the most factorial load over number of fruit per cluster and high negative weight, was effective for durability of flowers. The fifth factor was affected by number of flowers per cluster, and vitamin C and total soluble solids content. In triplot analysis partially inbred lines 75, 76, 77, and 78 had high values of the first factor and was effective for high performance. The most important traits, based on stepwise regression, were number of fruit per line, single fruit weight, fruit diameter and pericarp thickness. Path analysis indicated number of fruit per line and single fruit weight had the highest positive direct effect on yield and direct selection for these traits is possible. Based on their high positive loading for factors 1 and 3, that had relation to fruit yield and moderate loading for factor 2, where maturity index was negative, partially inbred lines 75 and 78 can be used for subsequent tomato breeding. In tomato, important traits for yield include single fruit weight, fruit length and diameter, and pericarp thickness and titratable acidity must be considered simultaneously to maintain flavor.