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new UV-B lighting system controls powdery mildew of strawberry

Kanto, T., Matsuura, K., Ogawa, T., Yamada, M., Ishiwata, M., Usami, T., Amemiya, Y.
Acta horticulturae 2014 no.1049 pp. 655-660
Sphaerotheca, aluminum, anthocyanins, beta-glucanase, chalcone isomerase, disease resistance, energy, fertigation, fruit quality, fruits, genes, lamps, leaves, naringenin-chalcone synthase, pathogens, phenylalanine ammonia-lyase, powdery mildew, soil, strawberries, ultraviolet radiation
We have produced a new UV-B lighting system comprising a UV-B florescent lamp, a reflective aluminum plate, a timer, and a control board. UV-B radiation induces resistance to strawberry against pathogens, especially powdery mildew (Sphaerotheca aphanis var. aphanis). We demonstrated control of powdery mildew with UV-B radiation in soil culture and in drip fertigation. The lighting system was suspended from the ceiling at intervals of 5 m in a line in the middle of a vinyl house. The lamp height was ca. 2 m above the strawberry plants. Strawberry plants were radiated using UV-B fluorescent lamps daily during 9:00-15:00. Plants received light energy of ca. 2-7 kJ m-2 d-1. The lighting system suppressed powdery mildew. Control was 100% at best. UV-B radiation induced transcription of strawberry genes associated with disease resistance, such as phenylalanine ammonia lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), β-1,3-glucanase, and osmotin-like protein. Furthermore, production of antifungal substances was induced in leaves. UV-B radiation also made strawberry fruits more red than the control, reflecting the accumulation of anthocyanin in fruits. Consequently, the new UV-B lighting system prevents powdery mildew of strawberry and improves fruit quality.