Abstract
Seasonal changes in the water-soluble Ca concentration in the distal half of fruit tissue and the blossom-end rot (BER) incidence in relation to the fruit growth rate were examined in the medium-sized fruit tomato cultivar ‘Cindy Sweet’, which is less susceptible to BER than large-sized fruit tomato cultivars. The rate of BER incidence was higher in the plants fed low Ca solutions, 1/4Ca and 1/8Ca, compared to those fed Enshi standard solution in both spring and autumn cropping. It was significantly higher in plants grown in spring than in autumn. The water-soluble Ca concentration in the distal half of fruit tissue was negatively correlated with the BER incidence and was significantly lower in spring than in autumn. A marked increase in the incidence of BER was observed as the water-soluble Ca concentration in the distal half of fruit tissue decreased below 0.2 μmol・g−1FW. This value was similar to our previous findings on the large-sized fruit tomato cultivar ‘House Momotaro’. The fruit growth rate was 3-fold higher in the fruits from plants grown in spring, with its higher temperature and solar radiation, than in autumn. There was a significant negative correlation between the rate of fruit growth and water-soluble Ca in the tissue of the distal half of fruit. These results suggested that the vigorous fruit growth can lead to BER disorder by potentially causing the dilution of water-soluble Ca in fruit tissue and increased Ca demands for rapid fruit enlargement.
