Anatomical changes induced by cluster illumination in blueberry fruit ( <i>Vaccinium corymbosum</i> L.) and their impact on water economy

Blueberry fruits were located in full shade (complete darkness), partial shade (16% full sun) and light exposed (100% full sun) conditions. An inversely proportional relationship between the growth rate of the fruit and its relative water content was clear in fully shaded fruits, with an increase in the shaded fruits transpiration rate during ripening having been recorded. The pedicels of light-exposed fruits showed greater development of phloem tissue than those of fully shaded fruits. The structure of the stomata was modified in the fully shaded fruits, with a decrease in the size of the subsidiary cells. The epidermis of exposed and partially shaded fruits presented a profuse layer of epicuticular wax at maturity, which was almost absent in fully shaded fruits. Throughout blueberry fruit development, the deficiency of solar radiation induced anatomical changes that, in turn, affected water economy.