POSTERS: Cultural control
Red and blue LEDs used for horticulture lighting can suppress sporulation of Peronospora belbahrii, the causal organism of basil downy mildew
Jaimin Patel - Lighting Research Center, Rensselaer Polytechnic Institute. Leora Radetsky- Lighting Research Center, Rensselaer Polytechnic Institute, Mark Rea- Lighting Research Center, Rensselaer Polytechnic Institute
Continuous broad- as well as narrow-band spectra have been shown to suppress sporulation of many downy mildew pathogens. However, the suppressing effects of intermittent light at night, to save electric energy, using commonly available narrow-band blue (?max = 458 nm) and red LED (?max = 670 nm) horticultural lighting systems have never been demonstrated. Sporulation inhibition of Peronospora belbahrii (the casual pathogen of basil downy mildew) was studied using blue and red LEDs at two irradiances (12 and 60 µmol /m2/s) for two intermittent-lighting protocols (three 1.3-h light pulses and one 4-h light pulse), and a continuous 10-h lighting protocol, as well as a control. A nighttime dose of 2.20 mol /m2/night of continuous blue or red light was able to inhibit basil downy mildew sporulation by nearly 100%. For doses (0.17 – 0.87 mol/m2/night) that did not completely suppress sporulation, continuous light exposures through the night were always more effective than the tested intermittent light exposures. In general, at equal intermittent doses between 0.17 – 0.87 mol/m2/night that did not completely suppress sporulation, red light was slightly more inhibitory than blue light.