“DABROWICKA PRUNE” FRUIT QUALITY AS INFLUENCED BY CALCIUM SPRAYING

Abstract

The aim of this experiment was to examine the effect of spraying with different calcium (Ca) materials on prune (Prunus domestica L.) fruit quality. The experiment was conducted in 1996–1998 in Central Poland on ‘Dabrowicka Prune’ trees, grafted on Myrobalan seedlings (Prunus divaricata). Trees were planted in spring 1987 at a distance of 4×4 m on a sandy loam soil with low organic matter and high phosphorus (P), potassium (K), and magnesium (Mg) concentrations. Prune trees were five times sprayed with Ca using CaCl2, Wuxal Calcium, and Stopit materials. In each spray CaCl2, Wuxal Calcium, and Stopit materials were applied at rate of 5, 5, and 10 kg ha−1, respectively. The first spray was applied 10 days after full bloom and four next ones at 8-day intervals. Trees unsprayed with Ca served as control plots. The results showed that Ca sprays had no effect on prune fruit yield and mean fruit weight. Only spraying with Wuxal Calcium enhanced levels of nitrogen (N), Mg, and Ca in leaf and fruit tissues. At harvest, ‘Dabrowicka Prune’ fruit sprayed with Wuxal Calcium had higher soluble solid concentration and titratable acidity and were firmer and more resistant to infection by Monilinia spp. than control fruits. Spraying with the tested Ca materials had no influence on sensitivity of prune fruit to splitting. These results indicate that Ca sprays in plum orchards may be beneficial treatment improving fruit quality.