Response of hydroponic baby lettuce to UV-B radiation exposure during the growing period

Abstract

Lettuce (Lactuca sativa L.) has a nutritional contribution comparable to other vegetables. It is produced in soil and hydroponics systems, outdoors or indoors, and in some cases, with the management of radiation. UV-B radiation exposure can influence the functional quality of vegetables and is becoming more frequent. Cultivars Kristine RZ and Versaï RZ were exposed to four radiation doses: UV-B0 (0 μW·cm-2), UV-B16 (16 μW·cm-2), UV -B33 (33 μW·cm-2) and UV-B58 (58 μW·cm-2), during 30 min for 10 days. Lettuce leaves were harvested twice. The leaf area of 'Versaï RZ' was not affected by radiation in the first harvest, while the high doses (33 and 58 µW·cm-2) reduced the leaf area of 'Kristine RZ' between 15-30 %, respectively. The radiation did not significantly impact the percentage of dry matter and the color parameters. However, functional compounds were affected. In general, the cv. Kristine RZ responded positively to the dose of 16 µW·cm-2 while 'Versaï RZ' to 58 µW·cm-2. An increase in the content of functional compounds was also observed in 'Versaï RZ' in the second harvest, and a reduction in the levels measured in 'Kristine RZ' indicated a different adaptation to UV-B radiation that must be studied individually.