Effects of Hydrogen Peroxide on Organically Fertilized Hydroponic Lettuce (Lactuca sativaL.)

Hydroponic production typically uses conventional fertilizers and information is lacking on the use of organic hydroponic fertilizers. Development of biofilm is a common problem with organic hydroponics which can reduce dissolved oxygen availability to roots. One potential solution is the use of hydrogen peroxide, H 2 O 2 which can reduce microbial populations and decomposes to form oxygen. However, information is lacking on the impact of hydrogen peroxide on hydroponic crops. The aim of this study was to determine the effects of H 2 O 2 concentrations in deep water culture hydroponics by assessing how it affects plant size and yield in lettuce (Lactuca sativa L.) ‘Rouxai’. In this experiment, three different treatments consisting of a control without H 2 O 2 , and the application of 37.5 mg/L or 75 mg/L of hydrogen peroxide were added to aerated 4-L reservoirs that contained either organic (4-4-1) or inorganic nutrients (21-5-20), both applied at 150 mg·L -1 N. Three replicates for each treatment and each fertilizer were prepared resulting in a total of eighteen mini hydroponic containers each with one head of lettuce. When added to conventional fertilizers, concentrations of 37.5 mg/L and 75 mg/L of H 2 O 2 led to stunted growth or death lettuce plants. However, when 37.5 mg/L of H 2 O 2 was applied to organic fertilizers, the lettuce yield nearly matched that of the conventionally fertilized control, demonstrating that the application of H 2 O 2 has the potential to make organic hydroponic fertilization a more viable method in the future.