2020 Volume 19 Issue 1 Pages 7-12
The application of UV-B (Ultraviolet-B) to tomatoes (Solanum lycopersicum) cv. ‘House-momotaro’ and ‘Redore’ grown in forcing culture was investigated in order to induce resistance to disease and reveal any damage to yield. Irradiation with UV-B was performed every night between 11 pm and 2 am with an intensity of 2.30 to 12.56 μW・cm–2. As a result, the shrinkage of irradiated leaves, increase of the dry matter ratio of leaves and stems, and induction of burned fruits were observed in both cultivars. The UV-B irradiation of plants had no influence on the days from planting to blooming, fruit set ratio, or yield of fruits. Both an increase of brix and decrease of acidity were observed in fruit juices from irradiated plants. The UV-B irradiation had no effect on the fruit coloring or lycopene content of fruits.