UV RADIATION AS AN EXPLOITABLE AND DIVERSE TOOL IN THE REGULATION OF CROP QUALITY AND YIELD

Responses of red leaved lettuce (Lactuca sativa) to ‘cross-over’ style treatments of different UV radiation (280-400 nm) environments were studied under both field (polytunnel) and controlled environment (supplementary UV lighting) conditions. Under field conditions, initial propagation in the presence of UV radiation and follow on growth, or ‘cropping’ under low or no UV environments increased leaf weight ratio (LWR) and net assimilation rate (NAR), and decreased leaf area ratio (LAR) of lettuce plants. In addition, plants transferred from a UV inclusive environment to a UV depleted environment exhibited significantly increased leaf dry weight and decreased root dry weight following transfer, whereas plants propagated and cropped under a no UV environment throughout also exhibited increased leaf dry weight, but displayed significantly higher root dry weight than plants exposed to a UV-inclusive environment. In controlled environment (CE) conditions, increased net photosynthesis was observed in those plants exposed to UV-B radiation during the propagation stage. Exploitation of such UV-mediated changes in plant growth and physiology during different phases of crop production could improve the long-term performance of transplant crops such as lettuce.