USE OF REPEATED MEASURE, REPEATABILITY COEFFICIENT AND PATH ANALYSIS OF ARCHITECTURE TRAITS IN DWARF TOMATO GENOTYPES (Solanum lycopersicum L.)

Tomato (Solanum lycopersicum L.) is a pivotal vegetable crop, holding significant economic and social importance. Enhancing yield through the utilization of dwarf genotypes has proven successful across various crops. Dwarf tomato plants, characterized by their smaller canopy and upright posture throughout the growing season, mitigate fruit-soil contact, thereby improving fruit quality and enabling greater plant density per hectare. However, implementing early selection for plant morphological traits in tomato breeding programs presents challenges. These traits are inherently complex, often necessitating multiple evaluations to identify the optimal selection criteria. Consequently, such assessments are frequently overlooked. Moreover, understanding the correlations between these traits and their direct and indirect effects on the desired characteristics can enhance selection efficiency. This study aims to determine the optimal number of measurements (ONM) required for accurate evaluation by employing the repeatability coefficient and also, to create a path analysis (PA) to assess architectural trait correlations among tomato genotypes with determined growth. Fourteen tomato genotypes with determined growth were subjected to evaluation in randomized blocks with 10 replications. Measurements of plant height, leaf length, internode length, internode diameter, and canopy area were recorded at four distinct time points during the vegetative period: 15, 22, 29, and 36 days after transplantation. The one-way ANOVA was employed to estimate variance components, followed by the derivation of a genetic correlation matrix and repeatability coefficients. These metrics facilitated the subsequent path analysis and determination of the ONM, respectively. The genetic correlation matrix unveiled a robust association between canopy area and leaf length, with leaf length exerting the most substantial direct influence on canopy size in the path analysis. Among the evaluated traits, only height and leaf length demonstrated reasonable repeatability values, with 10 repetitions yielding a minimum 90% determination coefficient for all traits except internode length. Selective efficiency and heritability increased progressively with each measurement, with the most substantial gains observed up to the third measurement. Consequently, path analysis indicated that selecting for leaf length represents the most effective approach to reduce canopy area. Utilizing 10 repeated measurements can accurately determine the true genetic value of tomato plants during early selection for growth traits. In conclusion, this research provides valuable insights into the optimal measurement strategy for the early selection of growth traits in tomato breeding programs. The findings underscore the significance of leaf length as a key determinant of canopy size and recommend the use of 10 repeated measurements for precise assessment of tomato plants' genetic potential in early selection efforts.