Replacement of peat by coir in Ranunculus asiaticus grown under different fertigation regimes and non-thermal plasma treatment

Coconut coir dust is finding broad application in the ornamental sector as peat substitute. However, deeper investigations are needed since its performances are variable and not always optimal for different plant species and growing conditions. The use of non-thermal plasma (NTP) in re-circulating nutrient solution appears a promising and sustainable strategy to enhance crop protection, decrease the use of sanitizers and pesticides, and increase yield and quality of ornamental productions. Nevertheless, only a few examples of NTP application on containerized crops under operational growing conditions are available, particularly in combination with different substrates and fertigation regimes. In this work the application of NTP was tested on the nutrient solution used for the production of Ranunculus asiaticus potted plants. The effect was assessed in growing plants using two substrates (both 50:50 v v^‑1): 1) peat:perlite, and 2) coconut coir dust:perlite, and with two levels of fertilization. Plants grown on coconut coir dust had lower total biomass and flower number. On the other hand, in terms of biomass and tissue nutrient content, R. asiaticus plants developed better at lower nutrient concentration than at the standard nutrient solution. NTP treatment increased the green biomass, while it did not improve the flower production. NTP-based sanitizing effects on the root zone, where the number of colony-forming units of fungi was significantly reduced, were only observed when using the standard nutrient solution.