Several species of Solanum produce secondary metabolites with antimicrobial activity. In
the present study, the inhibitory activity of Solanum chrysotrichum, S. erianthum, S. torvum
and S. rostratum against phytopathogenic Curvularia lunata was determined. Methanol extracts
from roots, stems, leaves and fruits were evaluated by the method of mycelial inhibition
on agar and the minimum inhibitory concentration (MIC) was determined on a liquid
medium. To increase the antimicrobial activity, the combined activity of the most active
extracts for each phytopathogen was also determined (a combination of intra and interspecies
extracts). The results showed that 12 of the 16 methanolic extracts of Solanum species
had antifungal effects against C. lunata. The extracts of S. rostratum and S. erianthum
developed the highest activity (~80% inhibition and 28.4 MIC μg . ml–1), even, equal to or
greater than, the reference fungicide. The mixture of the active extracts of S. chrysotrichum
and S. torvum increased their activity. Various extracts affected the macro and microscopic
morphology and most of them reduced the number of conidia of the fungus. This resulted
in the capacity to control the vegetative growth and reproduction of C. lunata, the causal
fungus of corn leaf spot disease.
The article presents a novel method that allows measurement of thermal conductivity that is based on Stefan-Boltzmann law. The developed method can be used to determine thermal conductivity of ceramic investment casting molds. The methodology for conducting thermal conductivity tests of ceramic material samples is presented. Knowledge of the value of thermal capacity and thermal conductivity as a function of temperature enables computer simulations of the process of cooling and solidification of liquid metal in a mold.