Bio-Polymers in the World of Plasma: Effects of Cold Plasma on Seed Surface

Seeds can be considered as natural biopolymers. They are an essential source of nutrients for agriculture and food production. However, to gain optimal yield of important crops, many use pesticides and agrochemicals before, during, or/and after harvesting of crops. This represents a global threat to the environment, as its wide and common use can cause the resistance of pests to these chemicals and harmful effects on soil and the surrounding environment.

The non-thermal or “cold” plasma has been successfully used for treatment of various types of polymers and has recently shown great potential also in the field of agriculture. Many researchers have reported changes in hydrophilic properties of seed surface, increased water uptake and altered surface morphology, which was correlated with a selective etching of biopolymer matrix. Moreover, plasma treated seeds were showed improved growth and possible resistance to abiotic stress such as drought and salinity.

The objective of our experiment is to identify surface changes after cold plasma treatment, and the influence of changed seed morphology and chemistry. Different plasma treatments were applied on seeds of two winter wheat varieties. We examined and detected changes in the chemical composition of seed coat with X-ray photoelectron spectroscopy (XPS) and changes in hydrophilic properties of seed surface. Plasma treatment also affected the dynamics of water uptake of seeds. The XPS analysis detected the chemical changes on seed surface, depending on the mode of plasma exposure: either direct (glow) or indirect (afterglow) and time-dependent plasma exposure.