Effects of Phosphorus and Sulfur Nutrition on Soluble Sugars and Growth in Clitoria Ternatea

Effects of P and S on growth and regrowth were assessed in a greenhouse trial in which Clitoria was grown through three cuttings on a deficient soil with a factorial combination of 4 levels of P and 3 levels of S. Phosphorus deficiency caused stunting, flowering delay, and a rusty appearance of leaflets. Sulfur deficiency caused stunting and chlorosis. With successive cuttings, P deficiency became less severe and S deficiency more severe. Nodulation, observed at the end of the trial, was influenced more by S than by P. Maximal nodulation was achieved with the highest S level, at any of the highest three P levels. Root and stubble dry weight, and food reserves evaluated by etiolated regrowth and by soluble sugar in roots and stubble, responded positively to both P and S, and correlated with each other and with shoot growth preceding the final cutting. For maximal etiolated regrowth, the S requirement was higher than the P requirement.