The influence of defoliation and moisture on the tannin and polyphenol contents of Portulacarcia afra.

Abstract

To determine whether tannin and total polyphenol contents of Portulacaria afra change owing to damage, different trees were subjected to three intensities of defoliation, namely, none, fifty and ninety per cent. In addition, the influence of an improved water supply through irrigation was determined. Results showed an initial increase followed by a decrease in the concentration of secondary metabolites after defoliation. Irrigation resulted in a decrease of the above-mentioned concentrations only in trees that were not defoliated. The results support the decrease of the above-mentioned concentrations only in trees that were not defoliated. The results support the theory of optimal defense and thus indicate that polyphenols are a possible cause of unpalatability in P. afra.

Keywords: afrikaans; bucklands; change; chemical defence; damage; defoliation; eastern cape; grahamstown district; irrigation; palatability; polyphenols; portulacaria afra; secondary metabolites; south africa; stress; tannin; trees; water supply