Effect of different doses of UV-C on visual appearance and chlorophyll fluorescence parameters of lettuce

Application of UV-C on fruits and vegetables postharvest aims to delay their decay, increase their resistance against pathogens and improve their nutritional quality. Nevertheless, effect of UV-C varies not only with applied dose, but also with species of plants. Therefore, it is necessary to test different doses of UV-C in order to select a suitable dose that does not disturb conservation of plant product. This work is organized as follows: first, we applied different doses of UV-C on leaves of lettuce once a day for a week; second, we monitored indicators of stress using a Handy PEA, and finally we visually evaluated the appearance of leaves. Specifically, monitoring visual appearance of leaves shows that only plants receiving a dose of 0.85 kJ.m−2have an appearance identical to control plants. In spite, plants exposed to doses of 1.71 kJ.m−2and 3.42 kJ.m−2have leaves with many necrotic spots starting from the third day. Owing to their aggressiveness, doses 1.71 and 3.42 kJ.m−2cannot be maintained for the rest of our experiences, whereas 0.85 kJ.m−2appears to represent a suitable dose.