Interspecific Hybrid Compatibility and Seed Performance of Solanum lycopersicum × Solanum pimpinellifolium for Rootstock Breeding

Abstract

The use of grafted seedlings has become an important strategy in tomato production to overcome soil-borne diseases and various abiotic stresses. In recent years, tomato relatives have gained attention as valuable genetic resources for rootstock breeding due to their resistance traits and wide genetic diversity. Among these species, Solanum pimpinellifolium has been considered a promising donor for improving stress tolerance, adaptability, and seed vigor in cultivated tomato. This study aimed to determine the interspecific hybridization compatibility between Solanum lycopersicum lines and wild S. pimpinellifolium genotypes and to evaluate the germination and seedling emergence performance of the resulting hybrid seeds. Three S. lycopersicum lines were used as female parents and thirteen S. pimpinellifolium genotypes as male parents, resulting in 39 hybrid combinations. Hybridization success was evaluated based on fruit set rate, seed number per fruit, seed yield per fruit, and 100-seed weight. Additionally, germination and emergence tests were performed under two temperature conditions (24 and 27 °C) using three replicates of 30 seeds. Germination percentage, emergence percentage, and time to 50% emergence were determined. The obtained data were analyzed using analysis of variance in the R statistical environment, and mean comparisons were performed using Duncan’s multiple range test (p < 0.05). Fruit set rates among hybrid combinations ranged from 77% to 100%, indicating a generally high level of cross-compatibility between the parental genotypes. Seed number per fruit varied between 54 and 109, while seed yield per fruit ranged from 0.199 g to 0.607 g. Germination percentages were generally high under both temperature conditions, ranging from 85.3% to 100.0% at 24 °C and from 77.3% to 100.0% at 27 °C. In general, increasing temperature shortened the time to 50% emergence and accelerated seedling development. Some hybrid combinations, such as RSP14, RSP16, and RSP18, showed stable and high performance under both temperature conditions. Some hybrid combinations such as RSP14, RSP16, and RSP18 showed stable and high performance across both temperature conditions. Overall, the results demonstrated that interspecific hybridization between S. lycopersicum and S. pimpinellifolium can produce viable hybrid seeds with high germination and emergence performance. The identified superior combinations may serve as valuable genetic materials for future tomato rootstock breeding programs.