Breeding for higher yield in tomato by yield dissection and quantitative trait loci for yield components

Summary

Yield improvement is an important target for plant breeding. Genomic regions (quantitative trait loci; QTLs) important for yield are identified by investigating the association between phenotype and genotype, however, this is often difficult. In this research, yield was dissected into yield component traits using a crop model. Yield component traits and their QTLs were examined to identify the most important traits and QTLs for improvement of tomato yield. Fruit size and the number of fruits showed a trade-off. Nevertheless, yield improvements could be more attributed to the number of fruits than fruit size, more attributed to total fruit dry weight than fruit water content, and more attributed to total plant biomass than harvest index. High total plant biomass lines were attributed to a high light interception and/or a high light use efficiency. Improving light use efficiency rather than light interception was a more straightforward way to improve yield. Combining QTLs for all photosynthesis-related traits predicted yield with good accuracy. This thesis demonstrates how to identify breeding strategies to improve yield by combining a crop model with QTLs.