Variations in photosynthetic, anatomical, and enzymatic leaf traits and correlations with growth in recently selected Populus hybrids

Abstract

Several photosynthetic, anatomical, and enzymatic leaf traits were studied on 1- and 2-year-old fast growing Populus clones representing interspecific hybrids of P. deltoides, P. trichocarpa, and P. maximowiczii. Growth performance of the clones was studied with container-grown plants and for 5 years in the field. Considerable variation in photosynthetic, anatomical, and enzymatic leaf traits was found, but variation in growth differences among the clonal groups was minimal. Photosynthetic photon flux density saturated net photosynthesis of 1-year-old container-grown plants was significantly correlated with shoot height growth, but none of the other leaf traits measured showed a significant correlation with any of the growth characteristics. Clonal groups could be segregated by taxonomic and genetic affinities with hierarchical clustering and principal component analysis. Although enzymatic and biochemical traits (area leaf weight, ribulose-bisphosphate carboxylase and phosphoenolpyruvate carboxylase activities, protein content) and adaxial stomatal frequency can be used to discriminate among clonal groups, no significant regression of these leaf traits on growth performance was observed.