EFFECT OF TEMPERATURE ON GLYCOALKALOID AND CHLOROPHYLL ACCUMULATION IN POTATOES (SOLANUM-TUBEROSUM L CV KING-EDWARD) STORED AT LOW PHOTON FLUX-DENSITY, INCLUDING PRELIMINARY MODELING USING AN ARTIFICIAL NEURAL-NETWORK

Potato tubers (cv. King Edward) were stored at 5, 10, 20, and 25 degre es C for up to 8 days in either low light (12 mu mol of photons m(-2) s(-1), photosynthetically active photon flux density) or darkness. Tub ers were half-buried in potting compost to prevent light reaching the entire tuber surface. After 0, 2, 5, and 8 days samples were analyzed for photosynthetic pigment and glycoalkaloid content. Temperature clea rly affected the accumulation of chlorophylls, with 20 degrees C causi ng maximal greening. The buried surface of tubers exposed to light als o greened, although accumulating only 15-40% of the chlorophyll found in the upper, exposed tissues. However, there was no effect of the tem perature or light exposure regimes employed on glycoalkaloid concentra tions. Using this data, an artificial neural network was used to produ ce a preliminary model of the greening process. It was found that this closely resembled the actual results and could estimate intermediate data. It is concluded that there is no biosynthetic link between the l ow light-induced accumulation of chlorophyll and glycoalkaloids in thi s commercially important potato cultivar under the conditions describe d.