A study to examine the ageing behaviour of cold plasma-treated agricultural seeds

Abstract

Abstract Cold plasma (low pressure) technology has been effectively used to boost the germination and growth of various crops in recent decades. The durability of these plasma-treated seeds is essential because of the need to store and distribute the seeds at different locations. However, these ageing effects are often not ascertained and reported because germination and related tests are carried out within a short time of plasma-treatment. This research aims to fill that knowledge gap by subjecting three different types of seeds (and monomers): Bambara groundnuts (water), chilli (oxygen), and papaya (oxygen) to cold plasma-treatment. Common mechanisms found for these diverse seed types and treatment conditions were the physical and chemical changes induced by the physical etching and the cold plasma on the seeds and subsequent oxidation, which promoted germination and growth. The high glass transition of the lignin-cellulose prevented any physical restructuring of the surfaces while maintaining the chemical changes to continue to promote the seeds\ germination and growth. These changes were monitored over 60 days of ageing using contact angle, water uptake, electrical conductivity, field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS). The vacuum effect was also investigated to separate its effect from cold plasma (low pressure). This result provides a framework, understanding and confidence for anyone to scale up these low-pressure plasma; as well as later store and distribute the seeds to different locations for germination and growth.