Water status, growth and calcium nutrition of apple trees in relation of bitter pit

Three different water status conditions (full watered, mild deficit and high deficit) were applied to cultivar 'Granny Smith' apple trees growing in pots during two periods of 4 weeks (last phase of fruit growth by cell division and middle phase of fruit growth by cell enlargement). In the first period, water deficit strongly reduced shoot, leaf and fruit growth, increased the calcium content in leaves and reduced the appearance of bitter pit in fruits. When applied in the second period, water deficit reduced leaf weight and fruit growth, increased the calcium content in leaves and reduced the appearance of bitter pit in fruits. Leaf sap osmolarity was lowered by the water deficit condition. These results are discussed with regard to patterns of diurnal water status in the differently watered trees.