Growth and yield recovery in strawberry plants under autotoxicity through electrodegradation

Summary The appropriate timing and intensity of electro-degradation (ED) of nutrient solution to recover strawberry autotoxicity in closed hydroponic system was investigated during spring 2010 in glasshouse of Experimental Research Center for Biological Resources Science,Shimane University. In growth chamber bioassay, growthof strawberry plantlets were inhibited greatly in non-renewed nutrient solution due to the accumulation of autotoxic root exudates compared to nutrient solutionrenewed weekly (control). Plants grown in non-renewednutrient solution electro-degraded weekly intervals also showed growth inhibition whereas biweekly ED improved its growth. This growth inhibition in weekly ED nutrient solution was found to be attributed by the degradation Fe-EDTA (about 10%) and low concentration of Ca 2+ in culture solution. Electrolysis durations were evaluated in without plant experiments. It was found that low pH (3.13) and increased temperature were two major constraints for longer ED duration(24 h). Therefore, considering electric voltage, electricalconductivity (EC) and pH, shorter ED duration (2 h) was selected for further experiments. 2 h ED treatment of nutrient solution certainly can save energy and be feasible for greenhouse applications. In greenhouse, strawberry plants were grown in Wagner's pot hydroponic system where nutrient solutions were eitherrenewed four weekly or not-renewed entirely. The non-renewed nutrient solutions were electro-degraded either biweekly or four weekly. Growth and yield of strawberry plants was decreased in non-renewed nutrient solution and its biweekly ED treatment but it was improved in non-renewed nutrient solution when ED applied at four weeks intervals. It was found that fruit yield of strawberry plant was completely recovered (∼99%) in non-renewed nutrient solution with ED at every four weeks, whereas, in our previous study the recovery was 71% compared to renewed nutrient solution. Therefore, we recommend application of ED to non-renewed nutrient solution for 2 h at every four weeks intervals to avoid autotoxicity in strawberry in a closed hydroponic system.