Advantages and Limitations of Surface Analysis Techniques on Plasma-Treated Arabidopsis thaliana Seeds

Alexandra Waskow,Alan Howling,Ivo Furno

doi:10.3389/fmats.2021.642099

Abstract

Surface characterization of plasma-treated seeds has made significant progress over the last decade. Most papers in the literature use scanning electron microscopy (SEM) and contact angle goniometry to investigate surface modifications. However, very few papers address the chemical modifications to the seed coat after plasma treatment. Here, a summary of the methods used to analyze plasma-treated seeds is presented, such as SEM, contact angle goniometry, energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). The results obtained on Arabidopsis thaliana Col-0 seeds and the limitations of these techniques are discussed. An experiment was designed in order to compare the relative advantages and limitations of these surface analysis techniques by investigating the separate effects of plasma, heat, and ozone on A. thaliana seeds.

Highlights

Biological applications of low temperature, non-thermal plasmas have recently become widespread from medicine, environmental remediation, and sterilization, to agriculture
Ozone and heat are applied as separate treatments and compared to the plasma treatment in an effort to identify the individual effect of each component on the seed. We show that it seems to be a synergy of the plasma effects, and not its individual components, which is responsible for any modifications to the seeds
As pointed out by Mildaziene et al (2016), this may depend on the seed position and whether it is in direct contact with the surface or close to the plasma

Summary

INTRODUCTION

Biological applications of low temperature, non-thermal plasmas have recently become widespread from medicine, environmental remediation, and sterilization, to agriculture. In addition to SEM, energy-dispersive X-ray spectroscopy (EDX) has been used on plasma-treated seeds, for example, by Cui et al (2019) on Arabidopsis seeds They observe an increase of O concentration from approximately 38% to 45% and a decrease of C concentration from 62% to 55% in the untreated and plasma-treated seeds, respectively, indicating the oxidation of carbon. Many authors over the last decade observed increased hydrophilicity following Bormashenko et al (2012) who improved the wettability of lentil, beans and wheat seeds with an air plasma treatment. Velichko et al (2019) compared an argon plasma jet in open air with an atmospheric air dielectric barrier discharge (DBD) in terms of germination and contact angle of plasma-treated wheat grains. All treatments were performed directly on the seeds initially spread uniformly over the SDBD

RESULTS AND COMPARISON

CONCLUSION

DATA AVAILABILITY STATEMENT