Effects of the Rare Sugars D-psicose and D-tagatose on the Sugar Content and Incidence of Blossom End Rot in Tomato Grown Hydroponically with Salinity Treatment

Low sugar content of fruits in winter, and blossom end rot in summer, are serious problems in the production of tomato with high soluble solids content. In the present study, we investigated the effects of the rare sugars D-psicose and D-tagatose on the sugar content of fruits and incidence of blossom end rot during several cropping seasons. We determined a highly positive correlation between the sugar content and the cumulative solar radiation during the maturation period. Treatment with D-psicose resulted in an increase in the sugar content over every cropping season. It resulted in a reduction in the incidence of blossom end rot, a reduction in stomatal conductance, and an increase in the relative water content in summer. On the other hand, it resulted in an increase in the incidence of blossom end rot in winter and rainy season. Treatment with D-tagatose had no effect on the sugar content, incidence of blossom end rot, water potential, stomatal conductance, or relative water content. Our results indicate that treatment with D-psicose is advantageous for increasing the sugar content in winter and preventing the incidence of blossom end rot in summer.