Peer Review #1 of "Multi-walled carbon nanotubes produced after forest fires improve germination and development of Eysenhardtia polystachya (v0.1)" [peer_review]

A Saracino
2020 unpublished
Background. Multi-walled carbon nanotubes (MWCNTs) are nanoparticles with countless applications. MWCNTs are typically of synthetic origin. However, recently, the formation of MWCNTs in nature after forest fires has been documented. Previous reports have demonstrated the positive effects of synthetic MWCNTs on the germination and development of species of agronomic interest; nevertheless, there is practically no information on how synthetic or natural MWCNTs affect forest plant development. In
more » ... nt development. In this report, based on insights from dose-response assays, we elucidate the comparative effects of synthetic MWCNTs, amorphous carbon, and natural MWCNTs obtained after a forest fire on Eysenhardtia polystachya plant. Methods. E. polystachya seeds were sown in peat moss-agrolite substrate and conserved in a shade house. Germination was recorded daily up to 17 days after sowing, and plant development (manifested in shoot and root length, stem diameter, foliar area, and root architecture parameters) was recorded 60 days after sowing. Results. The treatments with natural MWCNTs accelerated the emergence and improved the germination of this plant, thus while no treated seeds achieve 100% of germination within 16 th day, seeds supplemented with natural MWCNTs at doses of 20 μg/mL achieve the above percentage within the 4 th day. Natural MWCNTs also promoted fresh and dry biomass in all applied treatments, specially at doses of 40 μg/mL where natural MWCNTs significantly promoted leaf number, root growth, and the dry and fresh weights of shoots and roots of seedlings. Seeds supplemented with doses between 20 and 40 μg/mL of amorphous carbon achieving 100% of germination within the 6 th day; however, seeds supplemented either with doses of 60 μg/mL of the above carbon or with synthetic MWCNTs at all the tested concentrations could achieve at most 80 % and 70% of germination respectively within the 17 days. Finally, neither treatments added with amorphous carbon nor those added with synthetic MWCNTs, showed significant increases in the fresh and dry biomass of the tested plant. Likewise, the survival of seedlings was reduced between 10-20 % with 40 and 60 μg/mL of amorphous carbon, and with synthetic MWCNTs in all the doses applied was reduced at 30% of survival plants. Conclusions. These findings indicate that MWCNTs produced by wildfire act as plant growth promoters, contributing to the germination and development of adapted to fire-prone conditions species such as E. polystachya. Abstract 17 Background. Multi-walled carbon nanotubes (MWCNTs) are nanoparticles with 18 countless applications. MWCNTs are typically of synthetic origin. However, recently, the 19 formation of MWCNTs in nature after forest fires has been documented. Previous 20 reports have demonstrated the positive effects of synthetic MWCNTs on the 21 germination and development of species of agronomic interest; nevertheless, there is 22 practically no information on how synthetic or natural MWCNTs affect forest plant 23 development. In this report, based on insights from dose-response assays, we elucidate 24 the comparative effects of synthetic MWCNTs, amorphous carbon, and natural 25 MWCNTs obtained after a forest fire on Eysenhardtia polystachya plant. 26 Methods. E. polystachya seeds were sown in peat moss-agrolite substrate and 27 conserved in a shade house. Germination was recorded daily up to 17 days after 28 sowing, and plant development (manifested in shoot and root length, stem diameter, 29 foliar area, and root architecture parameters) was recorded 60 days after sowing. 30 Results. The treatments with natural MWCNTs accelerated the emergence and improved the 31 germination of this plant, thus while no treated seeds achieve 100% of germination within 16 th 32 day, seeds supplemented with natural MWCNTs at doses of 20 μg/mL achieve the above 33 percentage within the 4 th day. Natural MWCNTs also promoted fresh and dry biomass in all 34 applied treatments, specially at doses of 40 μg/mL where natural MWCNTs significantly 35 promoted leaf number, root growth, and the dry and fresh weights of shoots and roots of 36 seedlings. Seeds supplemented with doses between 20 and 40 μg/mL of amorphous carbon 37 achieving 100% of germination within the 6 th day; however, seeds supplemented either with 38 doses of 60 μg/mL of the above carbon or with synthetic MWCNTs at all the tested 39 concentrations could achieve at most 80 % and 70% of germination respectively within the 17 40 days. Finally, neither treatments added with amorphous carbon nor those added with synthetic PeerJ reviewing PDF | (Manuscript to be reviewed 41 MWCNTs, showed significant increases in the fresh and dry biomass of the tested plant. 42 Likewise, the survival of seedlings was reduced between 10-20 % with 40 and 60 μg/mL of 43 amorphous carbon, and with synthetic MWCNTs in all the doses applied was reduced at 30% of 44 survival plants. 45 Conclusions. These findings indicate that MWCNTs produced by wildfire act as plant 46 growth promoters, contributing to the germination and development of adapted to fire-47 prone conditions species such as E. polystachya. 48 49
doi:10.7287/peerj.8634v0.1/reviews/1 fatcat:z2d7b7mtvfce3nydt3nz65ez6i