Plasma represents one out of the four fundamental states of matter and can be distinguished into thermal and non-thermal or cold plasma. In agriculture, cold plasma is used for seed treatment, as it can improve germination rate, seedling growth, seed wettability and increase crop yield with appropriate settings of plasma parameters, such as type of gas, strength and length of exposure. The higher wettability is due to the etching of the seed coat, thus increasing its hydrophilicity. In addition, it can affect gene expression, hormone synthesis, and resistance to biotic (pathogen) and abiotic stress (drought, salinity, heavy metals). In particular, the expression of genes encoding plant hormones changes, leading to an altered balance of plant hormones. Namely, the expression of gibberellic acid increases and the expression of abscisic acid decreases which also helps to overcome seed dormancy. Inactivation of pathogens (both bacteria, fungi and also viruses) and increased expression of resistant genes in plants (PR genes) can also occur. For this reason, cold plasma could in the future replace chemical agents intended for plant pest control. Most of the changes can be attributed to the action of reactive atomic and molecular species such as ROS and RNS which are an integral part of cold plasma.
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