  The study investigates the potential of Plasma-Activated Water (PAW) as a
nitrogen supplement in hydroponic cultivation (HS-N+PAW), specifically focusing
on radish seed germination and plant growth. PAW, produced using a dielectric
barrier discharge pencil plasma jet using air as plasma forming gas, is
compared against conventional hydroponic solution (HS) and hydroponic solution
without nitrogen (HS-N). PAW treatment completely eliminates microbial growth
in seeds. Radish plants cultivated with HS-N+PAW display approximately 30% and
3% longer roots compared to those grown with HS-N and HS, respectively, with
shoot length increasing by ~16.5% (HS-N) and <1% (HS). Root weight sees a
substantial increase of ~51% with HS-N+PAW compared to HS-N, while the increase
with HS is not significant. Similarly, shoot fresh weight sees a notable
increase of 50% (HS-N) and 10% (HS). In terms of biochemical composition,
radish roots show a significant increase of approximately 15.3% in soluble
sugar concentration with HS-N+PAW compared to HS-N. Protein concentration in
radish leaves increases by ~5.1% and ~19.0% with HS-N+PAW compared to HS-N and
HS, respectively. Heightened soluble sugar and protein concentrations in
HS-N+PAW-grown plants, indicating enhanced metabolic activity and nutrient
uptake. However, variations in chlorophyll and carotenoid concentrations in
leaves among different growth media are statistically insignificant. H2O2
concentration root and shoot remains consistent across growth media,
electrolytic and phenolic leakage, along with antioxidant enzyme activities,
exhibit differential responses, underscoring the impact of growth conditions on
plant stress responses.
