Non-Thermal Plasma Treatment Influences Shoot Biomass, Flower Production and Nutrition of Gerbera Plants Depending on Substrate Composition and Fertigation Level

Low-temperature plasma as magic wand to differentiate between the good and the evil

Plasma is the fourth physical state of matter, characterized by an ionized gaseous mixture, after solid, liquid, and gas phases, and contains a wide array of components such as ions, electrons, radicals, and ultraviolet ray. Whereas the sun and thunder are typical natural plasma, recent progress in the electronics enabled the generation of body-temperature plasma, designated as low-temperature plasma (LTP) or non-thermal plasma since the 1990s. LTP has attracted the attention of researchers for possible biological and medical applications. All the living species on earth utilize water as essential media for solvents and molecular transport. Thus, biological application of LTP naturally intervenes water whether LTP is exposed directly or indirectly, where plasma-activated lactate (PAL) is a standard, containing H₂O₂, NO₂^- and other identified molecules. Electron spin resonance and immunohistochemical studies demonstrated that LTP exposure is a handy method to load local oxidative stress. Cancer cells are characterized by persistent self-replication and high cytosolic catalytic Fe(II). Therefore, both direct exposure of LTP and PAL can provide higher damage to cancer cells in comparison to non-tumorous cells, which has been demonstrated in a variety of cancer types. The cell death mode is either apoptosis or ferroptosis, depending on the cancer-type. Thus, LTP and PAL are expected to work as an additional cancer therapy to the established guideline protocols, especially for use in somatic cavities or surgical margins.

Effects of Nonthermal Plasma (NTP) on the Growth and Quality of Baby Leaf Lettuce (Lactuca sativa var. acephala Alef.) Cultivated in an Indoor Hydroponic Growing System

The aim of this research was to develop an effective protocol for the application of nonthermal plasma (NTP) technology to the hydroponic nutrient solution, and to investigate its effects on the growth and quality of baby leaf lettuce (Lactuca sativa var. acephala Alef.) grown in a hydroponic growing system (HGS) specifically designed for indoor home cultivation. Four HGSs were placed in separate growth chambers with temperature of 24 ± 1 °C and relative humidity of 70 ± 5%). Lettuce plants were grown for nine days in nutrient solutions treated with NTP for 0 (control) to 120 s every hour. Results of the first experiments showed that the optimal operating time of NTP was 120 s h−1. Fresh leaf biomass was increased by the 60 and 120 s NTP treatments compared to the control. Treating the nutrient solution with NTP also resulted in greater leaf content of total chlorophylls, carotenoids, total phenols, and total antioxidant capacity. NTP also positively influenced chlorophyll a fluorescence in Photosystem I (PSI) and photosynthetic electron transport. These results revealed that the NTP treatment of the nutrient solution could improve the production and quality of hydroponically grown baby leaf lettuce.

Combined effect of silicon and non-thermal plasma treatments on yield, mineral content, and nutraceutical proprieties of edible flowers of Begonia cucullata

Edible flowers are becoming popular as a nutraceutical and functional food that can contribute to human nutrition with high antioxidant molecules and mineral elements. While comparative studies between different flower species have been performed, less is known about the best agronomical practices to increase yield and nutraceutical proprieties of blooms. Silicon stimulates plant resistance against stress and promotes plant growth while non-thermal plasma (NTP) technology has been applied for the disinfection and decontamination of water, as well as for increasing plant production and quality. The application of silicon and NTP technology through nutrient solution and spraying was investigated in edible flowers given that the combination of these treatments may play a role in promoting their nutritional and nutraceutical proprieties. The treatments were applied on two varieties of Begonia cucullata Willd. (white and red flowers) to explore their effects on different flower pigmentations. Plants with red flowers showed higher nutraceutical proprieties than the white ones but yielded a lower flower number. While the NTP treatment did not improve flower yield and quality, the silicon treatment increased anthocyanins and dry weight percentage in red flowers. NTP treatment increased zinc concentration, while it decreased potassium, magnesium, and manganese, and increased silicon concentration in white flowers. The combination of silicon and NTP showed negative effects on some nutraceutical proprieties of red flowers thus highlighting that the two treatments cannot be combined in edible flower production. In conclusion, the positive effect of silicon use in edible flower production has been demonstrated while the NTP technology showed contrasting results and its use should be explored in greater depth, including a consideration of its role in biotic attack prevention and reduced chemical input.