How do two lupinus species respond to temperature along an altitudinal gradient in the venezuelan andes?

Abstract

Temperature determines plant formations and species distribution along altitudinal gradients. Plants in the high Andes, through different physiological and morphological characteristics, respond to freezing night and high daytime energy inputs which occur anytime of the year. The main objective of this study to characterize day and night temperature related responses of two Lupinus species with different ranges (L. meridanus, 1,800-3,600 and L. eromonomos, 3,700-4,300 m of altitude). Are there in night low temperature resistance mechanisms between the species along the gradient? How do species respond, in terms of optimum temperature for photosynthesis, to increasing altitude? Lupinus shows frost avoidance, in contrast to L. eromonomos, which tolerates freezing at higher altitudes. temperature for photosynthesis decreases along the gradient for both species. Maximum 02 assimilation rates were higher in L. meridanus, while L. eromonomos showed decreasing 02 assimilation rates the higher altitude. In most cases, measured daily leaf temperature is always within the 80 % of optimum for . L. meridanus7 upper distribution limit seems to be restricted by cold resistance mechanisms, L. eromonomos7 to a combination of both cold resistance and to 02 assimilation responses at higher.