Calcium nutrition in relation to the occurrence of internal browning in Brussels sprouts

Abstract

Brussels sprouts, cv. Long Island, grown in sand cultures supplied with either normal or low-calcium nutrient solutions, were used to study the relationship between internal browning of sprouts and the calcium regime of the plants. The interaction of ammonium, magnesium, and potassium ions with calcium nutrition, and the susceptibility of four locally selected strains of Brussels sprouts to the disorder, were also investigated. No symptoms, in either the sprouts or the growing points, were found in plants grown under normal calcium nutrition, but each of the low-calcium treatments, irrespective of other cations, induced a significant amount of internal browning in sprouts. The incidence was greatest in the low-calcium high-magnesium, and least in the low-calcium high-ammonium treatments. Calcium deficiency symptoms of the growing points were most severe in the low-calcium high-magnesium treatment, and only this treatment significantly reduced plant yield. Internal browning occurred in the four strains when grown under the low-calcium high-magnesium treatment. Two strains (Bepi and original early) were more severely affected and developed symptoms earlier than the other two (Sartori and mid-season). However, the Sartori strain was the only one in which low calcium nutrition reduced yield. The calcium content in the sprouts decreased from the wrapper to the meristematic region. In leaves, the calcium content was highest in the leaf margin in all strains except mid-season. Low calcium nutrition greatly reduced the calcium content in sprouts and leaves.