Etude de l’influence du traitement plasma de type Glidarc sur la conservation et la germination des semences de maïs

Abstract

The gliding arc discharge (Glidarc) generates a non-thermal plasma at atmospheric pressure. A water solution exposed to the plasma is plasma activated water (PAW) and used in this work for the improvement of physico-chemical (pH, conductivity, STD, [NO ], [H O ]) 3 - 22 2 and biomass parameters in the field. In the process, maize seeds of the ATP (Acid Tolerance Population) variety were sown on an area of 64.4 m and then watered with tap water and plasma activated water for 300 and 900 seconds. Leaf width, crown diameter, chlorophyll content and physico-chemical parameters had higher values in plants watered with 300 s, 900 s of PAW compared to the control. We have highlighted the acidifying properties of activated water resulting from the presence of the NO• radical in the discharge which, when in contact with air, leads to the successive formation of nitrites and then nitrous and nitric ions in solution. We then studied the effect of the Glidarc plasma of humid air in spatial post-discharge mode (gas transfer) on the maizeseedsbyinvestigating early germination and the effect on potentially harmful maize pathogens. At first sight, the surface of the seeds treated for 900 s changed color and became darker than that of the control seeds. Scanning Electron Microscopy (SEM) analysis showed no change for seeds treated at 300 s, but significant changes for higher exposure (900 s) revealed by the change in the etched/eroded surface of the starch caryopsis, which resulted in water holes and large channels. The pathogenicity test by fungal infection led to a degree of 58% for untreated seeds, 6.7% and 13.3% for seeds treated for 300 and 900 s respectively, thus a significant reduction of the fungal load when the seeds were pre-treated. Next, germination rate and early growth parameters were evaluated. The results showed that under laboratory conditions, these parameters increased from 4.6 to 17.4% for germination rate, from 5.8 to 36.7% for shoot length and from 1 to 12.9% for root length. In addition, Fourier transform infrared (FTIR) spectroscopy showed no change in the bonding between atoms after plasma treatment, but revealed surface activation due to lipid removal. This application could contribute to the fight against food insecurity in Cameroon and worldwide by improving the sanitary quality of the seed without chemical additives