EFFECT OF TOMATO FRUIT PEDICEL TEMPERATURE ON FRUIT EXPANSION PREDICTED BY A MODEL BASED ON PEDICEL CONDUCTIVITY

Abstract

In a model of tomato fruit expansion which has been proposed recently (Bussieres, 2002), the water import in the fruit is based on the values of various parameters of the stem, the fruit pedicel, the fruit calyx and the fruit. In this model, one important parameter is the fruit pedicel phloem conductivity: based on literature data, this model has found phloem conductivity to be an increasing function of the fruit size, probably due to the increasing size of elements of the sieve tubes in the pedicel phloem. As the conductivity of a tube in which a liquid flows increases when the liquid viscosity decreases, and as the viscosity decreases when the temperature increases, a positive effect of the temperature of fruit pedicel on fruit expansion has to be inferred. Therefore, the model of fruit expansion was used to calculate the difference in the fruit mass changes over time due to a difference in the temperature of the fruit pedicel. When temperature was 30°C rather than 18°C, fruit mass was found to be only higher over the first weeks after pollination, whereas final fruit mass was only slightly changed. These predictions will have to be confirmed by further measurements.