Alcohol insoluble solid content (AIS) of tomato fruits was found to be highly correlated with viscosity. The correlation coefficient values, based on 12 cultivars, were r = 0.97 for AIS of whole fruit extracted with 50% ethanol and r = 0.94, extraction with 75% ethanol. The correlation of AIS with viscosity was high for outer pericarp, r = 0.93, and inner pericarp, r = 0.78, but low for locular contents, r = 0.18. A principal component analysis indicated that fruit size, shape and firmness, total solids, proportion of outer and inner pericarp, and locular contents were not highly associated with either AIS or viscosity. Their consequences for a breeding program are discussed.

Segregation for alcohol insoluble solids (AIS) in F2 and first backcross generations from a cross with ‘VF109’ and ‘Campbell 146’ as high and low parents, indicated 2 gene-pairs controlling AIS. Broad-sense heritability estimate for AIS was 84%, of which 62% was due to additive and 22% due to non-additive gene action. AIS had high phenotypic correlation with viscosity. The genotypic correlation was also high (rG = 0.89). The relative selection efficiency (RSE) of indirect selection, using AIS as a secondary character, was estimated to be 114% of the direct selection. Thus AIS may be useful as a secondary character for indirect selection of increased juice viscosity of tomatoes.

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