We review new trends of agricultural applications of atmospheric‐pressure plasmas for decontaminating agricultural products and enhancing seed germination and growth of plants and beneficial microorganisms. We classify the decontamination techniques into three kinds of treatments, which are gas‐phase, in‐liquid, and plasma‐activated liquid treatments, and introduce recent studies mainly after 2010, discussing the inactivation mechanism of microorganisms in each treatment. Likewise, we categorize the enhancement techniques into the same three kinds of treatments, and introduce the growth enhancements in detail, discussing the mechanisms and future prospects.

This paper reports on the correlation between gas flow and plasma behaviour in the outflow of a micro-atmospheric pressure plasma jet operating in helium using both 2D optical imaging and Schlieren photography. Schlieren photography shows that the helium outflow changes from laminar to turbulent conditions after distances between 20 and 50 mm from the nozzle. Above a flow rate of 1.4 slm, the length of the laminar region decreases with increasing flow rate. However, by contrast the visible plasma plume increases in length with increasing flow rate until its extension just exceeds that of the laminar region. At this point, the plasma becomes turbulent and its length decreases. Exposing polystyrene (PS) samples to the plasma jet significantly alters the water contact angle in a defined area, with the hydrophobic PS surface becoming more hydrophilic. This modification occurs both with and without direct contact of the visible glow on the surface. The radius of the treated area is much larger than the width of the visible jet but much smaller than the area of the turbulence on the surface. The treated area reduces with increasing nozzle–substrate distance.

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