Abstract
Nonthermal plasma (NTP), or cold plasma, has shown many advantages in the agriculture sector as it enables removal of pesticides and contaminants from the seed surface, increases shelf life of crops, improves germination and resistance to abiotic stress. Recent studies show that plasma treatment indeed offers unique and environmentally friendly processing of different seeds, such as wheat, beans, corn, soybeans, barley, peanuts, rice and Arabidopsis thaliana, which could reduce the use of agricultural chemicals and has a high potential in ecological farming. This review covers the main concepts and underlying principles of plasma treatment techniques and their interaction with seeds. Different plasma generation methods and setups are presented and the influence of plasma treatment on DNA damage, gene expression, enzymatic activity, morphological and chemical changes, germination and resistance to stress, is explained. Important plasma treatment parameters and interactions of plasma species with the seed surface are presented and critically discussed in correlation with recent advances in this field. Although plasma agriculture is a relatively new field of research, and the complex mechanisms of interactions are not fully understood, it holds great promise for the future. This overview aims to present the advantages and limitations of different nonthermal plasma setups and discuss their possible future applications.
Highlights
Plasma is the fourth fundamental state of matter [1]
Increased enzyme activity was found only in older seedlings from seeds treated with Nonthermal plasma (NTP), with an increase in superoxide dismutase (SOD) activity in the roots and ascorbate peroxidase (APX) activity in the shoots, while there were no detectable changes in the seeds right after the NTP treatment
According to Mildažienė et al [38], there was no difference in germination and seedling growth between seeds exposed to vacuum and the untreated seeds, there was a noticeable change in the auxin/cytokinin ratio
Summary
Plasma is the fourth fundamental state of matter [1] It is a mixture of electrons, positively charged ions, radicals, gas atoms, molecules (in excited or basic state) and photons from a range of energies including ultraviolet (UV) and vacuum ultraviolet (VUV) radiation [2,3]. In a nonequilibrium plasma or nonthermal plasma (NTP) the excitation, dissociation or ionization of molecules is more effective than increasing the average kinetic energy by heating, resulting in lower temperatures of the heavy particles in comparison to the electron temperature. The present knowledge enables the prediction of possible influences of NTP on seeds in terms of germination and growth, stress resistance, DNA change, transfer of traits to the generation, enzyme activity, phytohormones and, to some extent, optimization by the choice of the plasma treatment conditions [21,22,23,24]. There is already some evidence of the positive effects of NTP
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