Manganese deficiency of kiwifruit(Actinidia chinensisPlanch.)

Abstract

Manganese deficiency as indicated by visual symptoms and low tissue manganese concentrations was associated with large reductions in the number and total weight of fruit per vine in a commercial kiwifruit orchard. The mean weight per fruit and the percentage of fruit of exportable size were not affected. Fruit from manganese deficient vines had a slightly higher mean total solids content after 121 days storage at 0.5° to 1°C than fruit from healthy vines, but fruit firmness was not reduced by the disorder. Variations in the severity of leaf symptoms, leaf and fruit manganese concentration, and fruit yield were associated with variation in the pH of the surface soil within the range 6.8 to 7.3. Maximum yields of fruit were associated with pH values 3.5 μg g^–1 dry matter in the fruit and >33 μg g^–1 dry matter in youngest fully expanded leaves on aerial canes. DTPA extraction of air‐dried samples of surface soil did not provide a useful guide to plant‐available manganese.