Insights into the formation of tomato quality during fruit development

Influence of the source-sink balance on the final quality of tomato was inv estigated in spring greenhouse production. Four treatments were compared di ffering by the fruit/leaf number ratio manipulated during either the cell d ivision or the cell elongation periods of the sixth truss. At maturity, qua lity was assessed through fruit colour, firmness, fresh weight, titratable acidity, refractive index, and contents of dry matter, reducing sugars, bet a -carotene, lycopene and C vitamin. beta -carotene and lycopene contents w ere correlated positively to each other, and negatively to fruit firmness. The refractive index, dry-matter and sugar contents were also positively co rrelated, but less under low competition during cell division. Fruit fresh weight was correlated with none of the qualitative parameters, and signific antly differed among fruits within the sixth truss; however this relied onl y on the difference between the first fruit and the following ones. Fruit c omposition did not vary among basal and tip fruits, but significantly depen ded on the fruit/leaf ratio. Low competition during the whole fruit develop ment promoted sugar, acid and carotenoid contents, indicating a general inc rease in fruit metabolism, though fruits were not significantly bigger. Dec reasing the competition during the cell elongation period tended to decreas e the fruit dry-matter content and increase the acid content, whereas affec ting the competition only during the cell division period hardly influenced the fruit composition. On the whole, results indicated that drastic remova l of fruits may have inhibited the source activity at a period of low sink demand. In contrast to fruit composition and fruit size, other physical qua lity traits (firmness and colour) were only slightly affected by the source -sink ratio.