Effect of light on Powdery Mildew in greeenhouse tomato (Solanum lycopersicum 'Espero')

摘要

Powdery mildew caused by Oidium neolycopercisi is one of the most destructive diseases ingreenhouse tomato and has been an increasing problem in Norwegian greenhouse tomatoindustry. Due to the favourable environment and the lack of resistance varieties, they areextremely aggressive in greenhouse tomato. We do not want to use fungicides are frequentlyused to treat the tomato for powdery mildew. The most common fungicides are sulphurs. Aswe do not want to use these kinds of fungicides because they can be harmful to the humanhealth and biological control agents, there is a need for alternative preventing measures thatwill be economical. Light regulation is one of the possible strategies that can be used inmanagement of powdery mildew in greenhouse tomato production. In this study, the effect oflight, lighting duration and its intensity on powdery mildew severity of tomato wereexamined under growth chamber conditions.The powdery mildew susceptible tomato plants cv.Espero was inoculated by sprayingconidial suspension prepared from 7-10 days old powdery mildew inoculum. Inoculatedplants were exposed to different light treatment. Among the different lighting treatmentinoculated plants exposed to 16 hours of daily lighting supplied by red light emitting diode(LEDs) shows significantly low level of severity on inoculated plants as well as no disease innon-inoculated plants compared to all other treatments. In the combination of HPS and LED,the powdery mildew severity has no significance after 18 days inoculation. However, tomatoplants exposed to 16 hours of daily red light treatment showed symptoms of leaves in palegreen colour with downward curling. Further total dry weight of above ground plant partssignificantly low in plants grown under red light compared with rest of treatment. The resultshowed that the application of only red light has very limited potential in powdery mildewdisease management in practice. Further research in combination with different spectral quality is necessary.