Divergência fenotípica em variedades do gênero Schizolobium por caracteres biométricos e fisiológicos

Abstract

The genus Schizolobium has a species that was divided into two varieties: Paricá belonging to the Amazon rainforest and Guapuruvu belonging to the Atlantic Forest, both of ecological and silvicultural importance due to the quality of the wood. Because they are values-aggregating strains, information on the physiological mechanisms that regulate the metabolism of plants in a particular environment, it becomes important to establish their level of adaptation. The objective of this study was to compare the physiological and growth characteristics of young paricá and guapuruvu plants and to analyze the possible differences between the two varieties in terms of tolerance to drought when submitted to water deficit. 2) to evaluate the phenotypic divergence by means of biometric and physiological characters in varieties of the genus Schizolobium by the UPGMA method and Tocher optimization method with the use of Euclidian distance as a measure of dissimilarity. The results showed that the growth analysis through the physiological indices were efficient to identify differences in the initial growth of Schizolobium plants and the physiological characteristics of gas exchanges were negatively affected by water stress in both varieties during the days of stress. The results evidenced the formation of two groups by the UPGMA method and by the Tocher method for the biometric characters. The guap-75 genotype was the most divergent because it had a higher dry mass of the stem and a larger dry mass of the root of the others. There was a divergence between the methods for the physiological characters being possible to form 5 groups by the Tocher optimization method, where the guap-01 and par-043 access form individual groups with one access in each group, and the UPGMA hierarchical method formed two groups, group one with 3 accesses par-43, par-22 and par-54 and group two with the other accesses. The genotypes of paricá (Pari-022, pari-043 and pari-054) have a slightly higher photosynthesis rate than the guapuruvu accessions, with values of 13.38 mmol CO m²s¹, 14.26 mmol CO m²s¹, and 15 , 37 mmol CO m²s¹, respectively.