Suchergebnisse

This study was aimed at testing the integrated use of a natural biostimulant based on seaweed (Ascophyllum nodosum) and plant (alfalfa and sugarcane) extracts and reduced dosages of the conventional synthetic fungicide Imazalil (IMZ) to manage postharvest rots of orange fruits. The following aspects were investigated: (i) the effectiveness of postharvest treatment with natural biostimulant alone or in mixture with IMZ at a reduced dose against green mold caused by Penicillium digitatum; (ii) the differential expression of defense genes in orange fruits treated with the natural biostimulant both alone and in combination with a reduced dose of IMZ; (iii) the persistence of the inhibitory activity of both biostimulant and the mixture biostimulant/IMZ against green mold; and (iv) the residue level of fungicide in citrus peel when applied alone or in combination with the biostimulant. Treatments with the chemical plant resistance-inducer potassium phosphite, alone or with a reduced dose of IMZ, were included for comparison. The mixture of natural biostimulant and IMZ at a low dose consistently reduced the incidence and severity of fruit green mold and induced a significant increase of the expression level of β-1,3-glucanase-, peroxidase (PEROX)-, and phenylalanine ammonia-lyase (PAL)-encoding genes in fruit peel, suggesting that the natural biostimulant elicits a long-lasting resistance of citrus fruits to infections by P. digitatum. Interestingly, the residual concentration of IMZ in fruits treated with the biostimulant/fungicide mixture was significantly lower than that of IMZ in fruits treated only with the fungicide at the same dose and by far below the threshold values set by the European Union. This study laid the foundations for (i) conceiving a practical and more eco-friendly alternative to the conventional postharvest management of green mold of citrus fruits, based almost exclusively on the use of synthetic fungicide IMZ, alone or mixed with potassium phosphite and (ii) providing a better insight into the ...

[Contact] The large quantity of high-quality asteroseismic data that have been obtained from space-based photometric missions and the accuracy of the resulting frequencies motivate a careful consideration of the accuracy of computed oscillation frequencies of stellar models, when applied as diagnostics of the model properties. ; [Aims] Based on models of red-giant stars that have been independently calculated using different stellar evolution codes, we investigate the extent to which the differences in the model calculation affect the model oscillation frequencies and other asteroseismic diagnostics. ; [Methods] For each of the models, which cover four different masses and different evolution stages on the red-giant branch, we computed full sets of low-degree oscillation frequencies using a single pulsation code and, from these frequencies, typical asteroseismic diagnostics. In addition, we carried out preliminary analyses to relate differences in the oscillation properties to the corresponding model differences. ; [Results] In general, the differences in asteroseismic properties between the different models greatly exceed the observational precision of these properties. This is particularly true for the nonradial modes whose mixed acoustic and gravity-wave character makes them sensitive to the structure of the deep stellar interior and, hence, to details of their evolution. In some cases, identifying these differences led to improvements in the final models presented here and in Paper I; here we illustrate particular examples of this. ; [Conclusions] Further improvements in stellar modelling are required in order fully to utilise the observational accuracy to probe intrinsic limitations in the modelling and improve our understanding of stellar internal physics. However, our analysis of the frequency differences and their relation to stellar internal properties provides a striking illustration of the potential, in particular, of the mixed modes of red-giant stars for the diagnostics of stellar interiors. ; Funding for the Stellar Astrophysics Centre is provided by The Danish National Research Foundation (Grant agreement No. DNRF106). The research was supported by the ASTERISK project (ASTERoseismic Investigations with SONG and Kepler) funded by the European Research Council (Grant agreement No. 267864). This research was supported in part by the National Science Foundation under Grant No. NSF PHY-1748958. VSA acknowledges support from VILLUM FONDEN (research grant 10118) and the Independent Research Fund Denmark (Research grant 7027-00096B). DS is the recipient of an Australian Research Council Future Fellowship (project number FT1400147). SC acknowledges support from Premiale INAF MITiC, from INAF "Progetto mainstream" (PI: S. Cassisi), and grant AYA2013-42781P from the Ministry of Economy and Competitiveness of Spain. AMS is partially supported by grants ESP2017-82674-R (Spanish Government) and 2017-SGR-1131 (General-itat de Catalunya). TC acknowledges support from the European Research Council AdG No 320478-TOFU and the STFC Consolidated Grant ST/R000395/1. SH received funding for this research from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no 338251 (StellarAges). AM acknowledges the support of the Government of India, Department of Atomic Energy, under Project No. 12-R&D-TFR-6.04-0600. DB is supported in the form of work contract FCT/MCTES through national funds and by FEDER through COMPETE2020 in connection to these grants: UID/FIS/04434/2019; PTDC/FIS-AST/30389/2017 & POCI-01-0145-FEDER-030389.