Effect of light intensity on methylxanthine contents of Ilex paraguariensis A. St. Hil.

Mate (Ilex paraguariensis A. St. Hil.) is a shade-tolerant species, frequently cultivated on agroforestry systems or even in monoculture. Secondary metabolism of mate includes the methylxanthines, caffeine and theobromine. Shading could alter the quantitative profile of these compounds in the plant, and since the secondary chemistry of mate is decisive to determine the quality of raw material, the caffeine and theobromine content under different light intensities were investigated. Artificial shading obtained by a nylon screen and natural shading produced by other trees were tested. Methylxanthines content was increased with the reduction of light, but only in the low light intensity treatment. A negative correlation was found between biomass accumulation and methylxanthines content. But the total methylxanthines yield per plant was not altered. (c) 2006 Elsevier Ltd. All rights reserved.