Impact of Sodium Hypochlorite Applied as Nutrient Solution Disinfectant on Growth, Nutritional Status, Yield, and Consumer Safety of Tomato (Solanum lycopersicum L.) Fruit Produced in a Soilless Cultivation

Soilless crop production is spread worldwide. It is a cultivating technique that enhances yield quality and quantity, thus contributing to both food safety and food security. However, in closed-loop soilless crops, the risk of spreading soil-borne pathogens through the recycled nutrient solution makes the establishment of a disinfection strategy necessary. In the current study, sodium hypochlorite was applied to the recycled nutrient solution as a chemical disinfectant to assess its impact on plant growth, leaf gas exchange, fruit yield, tissue mineral composition, and possible accumulation of chlorate and perchlorate residues in tomato fruits. The application of 2.5, 5, and 7.5 mg L-1 of chlorine three times at fortnightly intervals during the cropping period had no impact on plant growth or gas exchange parameters. Furthermore, the application of 2.5 mg L-1 of chlorine led to a significant increase in the total production of marketable fruits (total fruit weight per plant). No consistent differences in nutrient concentrations were recorded between the treatments. Moreover, neither chlorate nor perchlorate residues were detected in tomato fruits, even though chlorate residues were present in the nutrient solution. Therefore, the obtained tomatoes were safe for consumption. Further research is needed to test the application of chlorine in combination with crop inoculation with pathogens to test the efficiency of chlorine as a disinfectant in soilless nutrient solutions.