LED Grow Lights Alter Sorghum Growth and Sugarcane Aphid (Hemiptera: Aphididae) Plant Interactions in a Controlled Environment

Abstract

Normal growth and production of plant tissues requires water, carbon dioxide, nutrients, and light. Light-emitting diodes (LED) are being used increasingly as a substitute for fluorescent or incandescent light sources in greenhouse horticulture because of their small size, durability, wavelength specificity, long operating life, and efficiency in offering photosynthetically active radiation at lowered energy costs compared to conventional lights. However, studies conducted to test the effects of these lights reveal that spectral properties of light-emitting diodes can have dramatic effects on plant morphology, nutrient uptake, and pathogen development when plants are grown under the incorrect light spectrums. We grew sorghum plants under a light-emitting diode grow panel, and compared it to plants grown under conventional fluorescent lighting within identical environmental chambers. Light-emitting diode lighting resulted in deleterious sorghum growth with fewer true leaves formed, reduced plant height, lower chlorophyll content, and an unusual pink to purple coloration of the plant tissue when compared to sorghum grown under conventional lighting. All 4 of the different sorghums grown under light-emitting diodes had 2× the amount of biomass measured as dry weights for upper (stems and leaves) and lower (root mass) when compared to the conventional lighting. When sorghums were infested with sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), both light sources supported a similar number of aphids but plants grown under light-emitting diodes had higher damage ratings than those under conventional lights for both known resistant and susceptible sorghums. For future trials, sorghum should not be grown using the light-emitting diode lights when assessing host-plant resistance to aphid infestation.