Inheritance of Viscosity Potential in Tomato1

Inheritance of the viscosity potential of tomato ( Lycopersicon esculentum Mill.) fruits was studied using parents and F 1 , BCP 1 , BCP 2 , and F 2 progeny from the crosses VF145-7879 × VF109 and VF145-7879 × 9039-M. Differences in viscosity from both crosses were controlled by 3 or fewer genes. In the VF145-7879 × VF109 cross there was bimodal distribution of BCP 1 and F 2 progeny which supports relatively simple inheritance. Partition analysis of the VF145-7879 × 9039-M cross supported the view that 3 or fewer genes were involved in viscosity difference. The heritability estimates were high for both crosses (0.75 and 0.68) and analysis of genetic variance showed that additive genic effects were most important. In the VF145-7879 × VF109 cross there was small, but significant, additive × dominance interaction whereas in the VF145-7879 × 9039-M there was no interaction but there were dominance effects. Study of the heritabilities of 5 components of the alcohol-insoluble solids did not clarify the genetic analysis of viscosity potential. Possible effects of competition for photosynthate on the genetic analysis are discussed.