Yield is a complex trait that is affected by several genetic and environmental factors. Yield is defined as the amount of the part
of interest that is harvested from a crop plant in a given area. We investigated the genetic basis of yield in an F2
derived from a cross between Solanum lycopersicum
L. and its most closely related wild species S. pimpinellifolium
found that average fruit weight, fruit diameter, and fruit length had a strong effect on yield. In addition, small effects on
yield due to soluble solids content and locule number were also observed. A total of 25 different significant quantitative trait
locus (QTLs) were detected for six traits (fruit length and diameter, fruit weight, yield, locule number, and Brix degrees).
The percentage of phenotypic variation associated with single QTLs ranged from 4.19% to 12.67%. A strong co-location of
QTLs among yield and fruit size traits was observed, suggesting that these QTLs play a role in the same expression process
controlling yield. We also realized that the effects of soluble solids content on yield could be due to direct effects of fruit
size QTLs linked to genes controlling soluble solids content. This result then may suggest that yield in tomato is mainly
formed by fruit size QTLs, whereas the remaining factors may play a complementary role in the expression of tomato yield.