Drought effect on water relations and fruit yield in highbush blueberries

摘要

The effects of (i) a drought cycle on key physiological processes, and (ii) moderate or strong water deficits on yield and harvest index were investigated in Vaccinium corymbosum cv. Bluecrop growing in France. Water potential, metabolism, transpiration, photosynthesis and stem diameter variations were surveyed during a drought cycle and after rehydration (experiment 1). Two week-long dry periods (moderate and strong water deficits) occurring at different phenological stages (fruit growth, maturation and after picking) were analysed in relation to fruit yield (experiment 2). V. corymbosum was highly sensitive to water deficit (as water potential decreased, stomata closed and photosynthesis decreased). The rapid decrease in stomatal conductance efficiently restricted water loss and reduced metabolism. V. corymbosum exhibited a good recovery capacity after rehydration. The most critical stage for the application of water stress was during fruit growth. Water stress occurring between late May and late June strongly affected fruit production by decreasing fruit size. To assure high yield, V. corymbosum should be watered regularly.