Growth of apical and lateral buds of papaw (<i>Carica papaya</i>, L.) as affected by nutritional and hormonal factors

Abstract

SummaryStudies were made of nutritional and hormonal factors affecting shoot and callus growth from apical and lateral bud explants of Carica papaya. Both high concentrations of minerals and the addition of 10 μM riboflavin to the culture medium reduced callus growth and improved shoot growth and quality. The promotion of shoot growth by cytokinin was greatly reduced when riboflavin was absent. Increasing auxin concentration reduced shoot growth; however this effect was removed when riboflavin was added. Six auxins (IAA, IBA, NAA, NOA, pCPA and 2,4-D) and five cytokinins (kinetin, 2iP, zeatin, PBA and BAP) were applied individually over a range of concentrations and the resultant growth was observed and recorded. Best shoot growth occurred when 1 μ mol l−1 of both NAA and BAP were added to a modified de Fossard et al. (1974) basal medium. High concentrations of auxin in the medium caused deformed shoot growth, whereas high concentrations of BAP and PBA caused excessive callus production.