Calcium concentration in tomato fruits in relation to the incidence of blossom-end rot

Abstract

Tomato fruits (CV. Grosse Lisse) were grown in sand cultures irrigated with nutrient solutions containing either normal- (120-160 p.p.m. Ca) or low-calcium (40 p.p.m. Ca) levels. Data were collected from the first five trusses, and restricted to fruits arising from the first three flowers of each truss. A greater yield of fruit and fewer fruit affected by blossom-end rot (BER) were produced by the normal than the low calcium treatment. Irrespective of treatment or BER incidence, the calcium concentration was higher in the stem end than the calyx end, and the concentrations of calcium and potassium were greater in trusses 1 and 2 than 4 and 5. BER affected the largest fruit in the normal, but the smallest in the low calcium treatment. Within the same trusses affected fruit had a lower calcium concentration in the stem end than did healthy fruit. For all fruits the ranges in calcium percentage (on dry basis) recorded were : Healthy fruits-stem end 0.086-0.029, calyx end 0.057-0.018 ; affected fruits-stem end 0.072-0.022, calyx end 0.045-0.020. Differences in magnesium and potassium concentrations in stem or calyx ends between healthy and affected fruits were recorded. The K: Ca ratio was higher in affected fruits, but the incidence of BER was unrelated to the Mg : Ca ratio. For both calcium and magnesium the stem end : calyx end concentration ratio was lower in affected than healthy fruit.