Search

Alfalfa seeds were directly treated with corona discharge plasma radiation and compared with the control group, which was covered by a Petri dish, blocking the etching effect of ionic wind and thus simulating the effect of a non-uniform electric field. The results showed that corona discharge plasma radiation changed the chemical structure of the seed coat. The peak value of the Fourier transform infrared spectrum of the seed coat at 2 856 cm‒1 and 1 729 cm‒1 changed after treatment, indicating that the wax, lipids, and cellulose in the seed coat may have been degraded. Measurements of the seed floating rate and apparent contact angle in the treated seeds compared to the measurements in the control group indicated that corona discharge plasma radiation also improved the hydrophilicity of the alfalfa seeds. In the control group, the Petri dish cover effectively reduced the physicochemical etching by ionic wind; thus, it appears that ionic wind has a greater influence on the seed coat than does the non-uniform electric field. Scanning electron micrograph images showed that the etching of the seed coat in the treated seeds was severe; the cellulose of the seed coat was degraded, and the surface was cracked, which improved the water absorption capacity of the seed. The seedling height of the seeds treated with corona discharge plasma radiation increased significantly compared to that of the control group, indicating that the physicochemical etching of the ionic wind had resulted in a macroscopic biological effect. This study provides experimental data support for the analysis of surface modification and chemical structure composition of alfalfa seeds treated with corona discharge plasma radiation and also provides a basis for further study of the biological effect mechanism of the corona discharge field.