Influence of genotype and truss position on reproductive traits in tomato (Solanum lycopersicum L.) under open-field conditions

Abstract

This study investigated the reproductive performance of seven tomato genotypes grown under open-field conditions during the 2024 season at the Institute of Field and Vegetable Crops, Novi Sad, Serbia. The experimental material consisted of four indeterminate genotypes (Novosadski jabučar, Pegaz, Dunavski rubin, and breeding line V14) and three determinate genotypes (Alparac, Bačka, and Knjaz) selected from the Institute's breeding collection. Plants were established in a randomized block design with five replications, using 30 plants per variant. Reproductive traits: flower number, fruit number, fruit-set percentage, average fruit weight and average fruit yield per truss, were recorded across the first four flowering trusses. Fruit number and fruit set declined consistently toward higher trusses across all genotypes, indicating physiological limitations associated with assimilate allocation. Truss position accounted for the majority of variation in fruit number (82.2 %) and fruit set (87.0 %), whereas genotype was the primary determinant of average fruit weight (82.7 %). Significant genotype × truss interactions were observed for all traits, highlighting differential genotypic responses along the plant axis. The results demonstrate that fruit quantity is strongly influenced by intra-plant positional and environmental factors, whereas fruit size is largely under genetic control. These findings emphasize the importance of integrating truss-level physiological considerations with genotypic selection in tomato breeding programs. The study provides practical guidance for selecting genotypes with stable reproductive performance and improved yield potential under variable field conditions.