The influence of light upon glycoalkaloid and chlorophyll accumulation in potato tubers (Solanum tuberosum L.)

Glycoalkaloid and chlorophyll concentrations within tuber tissue of three potato cultivars (Desiree, King Edward and Kerrs Pink) were measured following 15 days continuous illumination (250 mu mol m(-2) s(-1) photosynthetically active radiation). Comparisons were made of the influence of four light sources: fluorescent tube type warm white, high pressure sodium, and high and low pressure mercury light. There were significant differences between cultivars in their rates of glycoalkaloid and chlorophyll accumulation. Glycoalkaloid and chlorophyll accumulation were markedly influenced by light source, with exposure to sodium and fluorescent light promoting higher glycoalkaloid and chlorophyll accumulation compared with exposure to high and low pressure mercury light. In virtually all cases, glycoalkaloid and chlorophyll concentrations within tuber tissue increased steadily over time with no indication of cessation when exposed to light. Exposure to light altered ratios of alpha-chaconine:alpha-solanine but did not significantly influence ratios of chlorophyll a:chlorophyll b. Results demonstrated a strong relation between glycoalkaloid and chlorophyll accumulation in response to light. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.