Evaluation of the Use of Carbon Isotope Discrimination as a Selection Tool of Perennial Fodder Species for Temporary Pastures

Abstract

Estimation of the relationship between carbon isotope discrimination (Δ13C) in perennial fodder plants and various factors such as climate, fertilization and soil could contribute to a better selection and/or improvement of genotype of fodder species. Theoretical models of carbon isotope discrimination in plants indicate a linear relationship between Δ13C and CO2 partial pressures ratio (pi/pa) from the intercellular spaces (pi) of CO2 in leaves and from the atmosphere (pa). It is also known that between pi parameter and water-use efficiency (WUE) there is a negative correlation. Eight perennial fodder legume and grass mixtures were cultivated on three levels of fertilization in order to assess mixtures for pastures that can provide sustainable quantitative and qualitative yields. The species, which composed the mixtures, were also cultivated as pure crops on the same fertilization conditions. The results of this study indicated that in five of the six species, which composed the mixture with the highest yield, pi/pa values decreased while fertilization doses increased, most likely as a result of variation in water-use efficiency.