Effects of Cultivation Method, Growing Season and Cultivar on the Ascorbic Acid Content of Tomato Fruit

Abstract

This study was conducted to clarify the ascorbic acid content of tomato fruits varing with cultivation methods, growing seasons and cultivars with special reference to the effect of light conditions.
Long term harvest cultures (sown in August and harvested up to the 11th and 15th clusters) were performed by soil and water culture. In both cultures the ascorbic acid content in fruits was low in lower clusters and remarkably high in the uppermost 4 clusters. There were little differences in the fruit constituents between soil and water culture, but the ascorbic acid content of fruits in low clusters was lower than that of soil grown plants. This was considered to be due to the fact that the larger stem and leaves in water culture easily shaded the lawer cluster fruits.
Seeds were sown monthly on the 20th day throughout the year to study the influence of growing season on the ascorbic acid content of fruits. Plants were grown by water culture and detopped above the third cluster. Ascorbic acid content was lowest in the fruits of August-sown crop, then it gradually increased and become highest in the fruits of the next April-sown crop.
Comparisons were made between European cultivars (‘Best of All’, ‘Money Maker’: red-orange and small fruit type) and Japanese cultivar (‘FTVNR-3’: pink and large fruit type). Plants were grown twice a year (in summer and winter) by water culture using two concentrations of nutrient solution. In winter crop the ascorbic acid content of ‘FTVNR-3’ went down to about 1/2 of summer crop, but the fruits of European cultivars kept about the same level as in summer crop.
From the results obtained, the relations between light condition and ascorbic acid content of tomato fruits were discussed.