Opportunities and challenges of using non-thermal plasma treatments in soilless cultures: experience from greenhouse experiments
In laboratory studies, or under growth chamber conditions, non-thermal plasma (NTP) treatments have shown potential to improve the performance of greenhouse productions in terms of crop sustainability. Nevertheless, the effects of NTP treatments applied to real (i.e., commercial or semi-commercial) growing conditions have not been well understood yet. Time of exposure, treatment intensity and efficient equipment are some aspects that need attention for successful commercial applications. In this work, a prototype greenhouse was realized to test NTP devices in soilless culture against a standard (i.e., untreated control) greenhouse environment. Two cultivars of Salanova® lettuce (green and red) were used as test plants and transplanted in two successive cultivation cycles starting from autumn 2018. Plants were fertigated in a closed-loop system with 1) standard nutrient solution as control treatment, and 2) nutrient solutions treated by bubbling NTP-air into the main reservoir, where the nutrient solution was prepared, or directly in the recirculation tanks, at different rates. Air was also continuously treated in the NTP greenhouse. Electrical conductivity, pH, N-NO3 concentration in the recirculated nutrient solution and crop water uptake were monitored daily during the cultivation. Plant yield, tissue mineral content, leaf pigments and polyphenols were measured at harvest. Plants treated at low rate showed no effect on produce yield and quality and tissue characteristics while showed increased crop water use efficiency compared with the control plants. NTP treatments applied at high rates reduced the risks for fungal attacks, decreased nitrate accumulation into leaf blades and increased anthocyanin content in the red variety although significant reductions in yield were observed. This work highlighted the potentialities of NTP treatments but also gave some insights on the risks and technical aspects that should be addressed for suitable applications of such devices in soilless cropping.
Cannazzaro, S., Di Lonardo, S., Cacini, S., Traversari, S., Burchi, G., Pane, C., Gambineri, F., Cursi, L. and Massa, D. (2021). Opportunities and challenges of using non-thermal plasma treatments in soilless cultures: experience from greenhouse experiments. Acta Hortic. 1321, 259-266
closed-loop systems, leafy vegetables, lettuce, nitrate accumulation, nutrient solution disinfection, protected cultivation, water use efficiency