Early Selection Potential of Gmelina arborea Roxb. Clones Based on Physiological Correlations of Their Nursery-Field behavior

The development of superior genetic materials points out the need to identify parameters for early selection of superior genotypes. The aim of this research was to identify possible correlations between young-adult materials, based on their photosynthetic capacity determined in five genotypes evaluated at nursery and 15-months-old field stages. Light response curves and gas exchange were generated. Physiological behaviors of five clones were assessed, both at rooted mini-cuttings stage and at 15-months old field stage, where 5 trees (ramets) per clone in each of both stages were evaluated. The water use efficiency in nursery (WUE-N) reported positive and moderate to strong correlations for all genotypes, with respect to Pn-F (net photosynthesis in field) and WUE-F. The same parameter in the field (WUE-F) correlated moderately and directly with P n-F (r = 0.5), whereas Gs-F and E-F was inversely and strongly correlated (r = -0.66 and r = -0.82 respectively). The chlorophyll content in rooted mini-cuttings leaves (Cloro-N) correlated directly with Pn-F, which suggests that a measurement of chlorophyll content could identify genotypes with a higher net photosynthesis later on in the field. These results evidence the possibility of early selection of G. arborea superior genotypes using physiological parameters.