Inheritance of elastic and viscoelastic components of tomato firmness derived from intra- and interspecific genetic backgrounds

• Published in: Journal of the American Society for Horticultural Science Vol. 130; no. 4; pp. 598 - 604
• Main Authors: Stommel, J.R, Abbott, J.A, Campbell, T.A, Francis, D
• Format: Journal Article
• Language: English
• Published: 01.07.2005
• Subjects: elasticity (mechanics); environmental factors; firmness; food quality; general combining ability; genetic variation; genotype; hybrids; inheritance (genetics); Maryland; measurement; Ohio; Solanum cheesmaniae; Solanum lycopersicum var. lycopersicum; specific combining ability; tomatoes; vegetable crops; viscoelasticity; Maryland; Ohio
• ISSN: 0003-1062; 2327-9788
• DOI: 10.21273/JASHS.130.4.598

Fruit firmness is a key quality component of tomatoes (Lycopersicon esculentum Mill.) for fresh-market and processed product applications. We characterized inheritance of firmness in processing tomato germplasm developed from interspecific L. esculentum Mill. x L. cheesmanii f. minor (Hook. f.) C.H. Mull. and intraspecific L. esculentum crosses. Although firmness is a key quality attribute of tomato, there is no standard method for measuring it. We measured the elastic portion of firmness by compression (compression F(max)) and puncture (puncture F(max)), and the viscoelastic portion by force-relaxation. The experimental design incorporated six genotypes in a complete 6 x 6 diallel. Compression F(max) and force measurements recorded at 0.5, 1.0, 5.0, and 10.0 seconds of relaxation were strongly related to each other, while relaxation parameters (A, B, C) describing relaxation curve shape were generally independent. Compression F(max), relaxation curve parameter A, and puncture F(max) were significantly different among hybrids. Significant differences between Maryland and Ohio environments were evident for compression F(max) and relaxation curve parameter A. The patterns of firmness means differed among firmness measurement methods, namely for compression F(max) and puncture F(max), indicating that they measure different aspects of tomato fruit firmness. Soft-fruited parents generally exerted a negative effect on compression F(max), whereas firm-fruited parents most often exerted a positive effect on compression F(max). The force required for fruit compression best approximated subjective assessment of fruit firmness. Force required for fruit puncture was subject to a significant environmental x hybrid influence in the genotypes evaluated. Shape of the force relaxation curve (i.e., parameter A) was not predictive of relative fruit firmness. General combining ability (GCA) and specific combining ability were both significant with GCA being the principal source of genetic variation. In agreement with combining ability estimates, narrow-sense heritability estimates for compression F(max) and puncture F(max) were relatively high.