Genetic Diversity of Lolium perenne L. in the Response to Temperature During Germination and Heterotrophic Growth

The global environment is changing with increasing temperature, CO₂ and precipitation. Because these factors are the most important deriving, force influencing specie growth and development. Grassland productivity has positively correlated with less annual temperature, annual precipitation and growing season length then, it has increased in recent decades but the average annual genetic gain is different between temporary and permanent. Lolium perenne L is the most important perennial grass specie sown in temperate agriculture. Differences in germination and relative growth rate of the radicle and shoot have also been observed between populations. The main objective of this study was to analyse the genetic diversity of this L. perenne in response to temperature during germination and initial heterotrophic growth. Four wild populations and two varieties of L. perenne were evaluated. They were grown in chambers at constant temperature ranging from 5 to 40˚C with 5˚C increments in the dark. Relative growth rate of the radicle and relative growth rate of the shoot were observed of eight populations at 8 controlled temperatures from 5 to 40˚C. It was observed that, within specie, the response of populations to temperature shows high variability and significant differences. No germination was observed at 40˚C for any of the 8 populations. Heterotrophic growth of the 8 populations was affected by temperature. The growths of the axes were negligible or lethal at 40˚C. Response curves of relative growth rate of the axis were asymmetric bell-shaped.

Significant interactions between temperature and population were detected for germination and heterotrophic growth. This variability could be exploited to breed new varieties adapted to the new environmental conditions induced by the global climate change.