Plasma agriculture based on quantitative monitoring of reactions between fungal cells and atmospheric-pressure plasmas
- PDF / 748,669 Bytes
- 10 Pages / 612 x 792 pts (letter) Page_size
- 102 Downloads / 150 Views
Plasma agriculture based on quantitative monitoring of reactions between fungal cells and atmospheric-pressure plasmas Masafumi Ito1,Takayuki Ohta1, Keigo Takeda2, 1 Department of Electrical and Electronic Engineering, Faculty of Science and Technology, Meijo University 1-501 Shiogamaguchi, Tenpaku-ku, Nagoya 468-8502, Japan 2 Department of Electrical Engineering and Computer Science, Graduate School of Engineering, Nagoya University Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan ABSTRACT A high-density non-equilibrium atmospheric pressure plasma (NEAPP) applied for inactivating fungal spores of P. digitatum is introduced as an environmentally safe and rapidinactivation method. The contributions of ozone, ultra violet (UV) radiation and ground-state atomic oxygen in the NEAPP on the inactivation of the spores are evaluated using colony count method. The absolute densities of ozone were measured by using ultraviolet absorption spectroscopy. The ozone density increased from 2 to 8 ppm with an increase in the distance from the plasma source, while the inactivation rate decreased. The inactivation rate of plasma was evaluated to be thousand times higher than that of an ozone generator using the integrated number density of ozone. In addition, it was clarified that the contribution of UV radiation to inactivation was not dominant for P. digitatum inactivation by NEAPP by filtering the active species using quartz plate. From these results, we can speculate that the inactivation efficiency of reactive oxygen species (ROS) will be larger than those of others. In order to investigate the effect of ground-state atomic oxygen as one of ROS, the inactivation of P. digitatum spores using an oxygen radical source that employs a high-density atmospheric-pressure O2/Ar plasma. The absolute O density was measured to be 1.4×1014 and 1.5×1015 cm–3 using vacuum ultra violet absorption spectroscopy (VUVAS) using a microdischarge hollow cathode lamp. The behaviors of the O densities as a function of O2/(Ar+O2) mixture flow rate ratio correspond to that of the inactivation rate. This result indicates that ground-state atomic oxygen is concluded to be the dominant species that causes inactivation. INTRODUCTION In agricultural fields and plant protection stations, pesticides are sprayed to protect crops from various insects and viruses. Fungi, such as Aspergillus or Penicillium, contaminate foods, such as cereals, fruits, vegetables, meats [1]. However, residual agricultural chemicals (e.g., thiabendazole, imazalil, and ortho-phenylphenol) are harmful to the human body and the environment [2]. Moreover, methyl bromide is an effective and widely used pesticide. In 2005, however, it was prohibited under the "Montreal Protocol on Substances that Deplete the Ozone Layer" because of its high ozone depletion potential. NEAPPs (low-temperature), as well as low-pressure plasmas, were applied to inactivations, and showed promise as a very effective system that causes minimal damage to crops, foods, seeds, humans, and the environment. Microorganisms, s
Data Loading...
