2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/13611We have studied the spectral evolution of stellar populations in function of their heavy element content and star formation, using Geneva and Padova stellar track sets, both covering a number of metallicities, and Kurucz grid of stellar atmospheres. The general trend is the progressive growth of absorption and decline of flux towards shorter, UV-wavelengths, with increasing metallicity, and increase of infrared flux. Our models help to quantify given theoretically quite obvious effect. Presented results of integration of flux in different regions indicate, that with a change of metallicity from Z=0.001 to Z=0.04 total amount of radiation energy emitted in the shortest wavelength region by a stellar population during its lifetime diminishes typically by a factor ~10, with the corresponding typical increase in the infrared about 1.5-2 times. These numbers are quite independent on the actual IMF slope values under the assumption of identical slopes.4 pages, LATEX, with 1 encapsulated figure. To appear in: "The Stellar Content of Local Group Galaxies", IAU Symp. 192, published in ASP Conference Series, ed-s P. Whitelock and R. CannonAstrophysicstext