FisMat2017 - Submission - View

Abstract's title: Reduction of microbial contamination and improvement of germination of sweet basil (Ocimum basilicum L.) seeds via Surface Dielectric Barrier Discharge
Submitting author: Paolo Ambrico
Affiliation: CNR NANOTEC
Affiliation Address: via Amendola 122/D 70126 Bari
Country: Italy
Oral presentation/Poster (Author's request): Oral presentation
Other authors and affiliations: Paolo. F. Ambrico1*, Milan Šimek,2,1, Massimo Morano3, Rita M. De Miccolis Angelini4, Angelantonio Minafra5, Pasquale Trotti4, Marianna Ambrico1, Václav Prukner2, Francesco Faretra4 1 Consiglio Nazionale delle Ricerche, Istituto di Nanotecnologia, via Amendola 122/D, 70126 Bari, Italy 2 Academy of Sciences of the Czech Republic, Institute of Plasma Physics v.v.i., Department of Pulse Plasma Systems, Za Slovankou 1782/3, 18200 Prague, Czech Republic 3 Centro di Ricerca, Sperimentazione e Formazione in Agricoltura "Basile-Caramia", Via Cisternino, 281, 70010 Locorotondo, Bari, Italy 4 Department of Soil, Plant and Food Sciences, University of Bari ALDO MORO, via G. Amendola 165/A, 70126 Bari, Italy 5 Consiglio Nazionale delle Ricerche, Istituto di Protezione Sostenibile delle Piante, via Amendola 122/D, 70126 Bari, Italy

Basil seeds were treated by a surface dielectric barrier discharge driven in the humid air by an amplitude modulated AC high voltage to avoid heat shock. In order to avoid direct contact of seeds with microdischarge filaments, the seeds to be treated were placed at sufficient distance from the surface discharge. After treatment, the seeds were analyzed in comparison with control samples for their microbial contamination as well as for the capability of germination and seedling growth. Moreover, chemical modification of seed surface was observed through the elemental Energive Dispersive X-ray analysis and wettability tests. We found that treatment applied at 20% duty cycle (effective discharge duration up to 20 sec) significantly decreases microbial load without reducing the viability of the seeds. On the other side, seedlinggrowth was considerably accelerated after the treatment, and biometric growth parameters of seedlings(total length, weight, leaf extension) considerably increased compared to the controls. Interestingly, Scanning Electron Microscopy images taken for the different duration of treatment revealed that seed radicle micropylar regions underwent significant morphological changes while the coat was substantially undamaged. Inside the seed, the embryo seemed to be well preserved while the endosperm body was detached from the epithelial tegument. A total of 9 different genera of fungi were recovered from the analyzed seeds. Scanning Electron Microscopy images revealed that conidia were localized especially in the micropylar region, and after plasma treatment, most of them showed substantial damages. Therefore, the overall effect of the treatment of naturally contaminated seeds by reactive oxygen and nitrogen species produced by plasma and the consequent changes in surface chemistry and microbial load can significantly improve seed vigor.