Endogenous cytokinins from developing ‘Shamouti’ orange fruits derived from leafy and leafless inflorescences

Abstract

Purified extracts of developing fruits of “Shamouti’ orange, derived from leafy and leafless inflorescences, showed two paper chromatographic zones of cytokinin activity by the Amaranthus bioassay. The first zone corresponded to R f 0.0–0.3 and the second to R f 0.6–0.9. Sephadex LH-20 fractionation of the cytokinin extracts tentatively showed the occurrence of zeatin and zeatin-riboside. Irrespective of the origin of fruit, highest cytokinin levels were obtained at petal fall (Stage I) and markedly declined thereafter. Levels appeared to be relatively higher in fruit from the leafy than in fruit from the leafless inflorescence type. The involvement of cytokinins in fruit set and growth is discussed.