INFLUENCE OF ANION PROPORTIONS IN THE NUTRIENT SOLUTION ON TIPBURN INCIDENCE IN STRAWBERRY PLANTS IN SOILLESS CULTIVATION

Tipburn incidence was evaluated in ‘Camarosa’ and ‘Candonga’ strawberry plants grown in perlite by varying the anion proportions in the nutrient solution during 2005-2006 under greenhouse. Six nutrient solutions with different proportions of NO₃^-, PO₄H^2- and SO₄^2- were studied, maintaining constant both cation proportions and the total ionic concentration (30.2 meq L^-1). Concentrations of these anions varied from 9.0 to 12.8, 0.9 to 4.7, and 0.75 to 2.65 mM L^-1, respectively. Interactions between cultivars and solutions were not significant for any of the parameters studied. The anion proportions had no influence on yield parameters. Both the percentage of leaves with tipburn and tipburn severity per leaf were the highest with intermediate levels of sulphates and phosphates and low levels of nitrates. ‘Candonga’ not only produced the highest yield and fruit weight, but also the lowest tipburn incidence.