Genetic variability of silvicultural traits in opened-pollinated progenies of Balfourodendron riedelianum (Engler)

Abstract

The fragmentation of natural forests has reduced the size of the populations of many tree species around the world. Because of this, it is essential to adopt strategies for ex situ conservation of the remaining populations to ensure the perpetuation of the genetic resources. Thus the aim of this study was to estimate the genetic parameters for the traits: tree height, diameter at breast height (DBH), stem form, forking, volume of wood and survival in a provenance and progeny test of Balfourodendron riedelianum. The field trial was established at the Pederneiras Experimental Station, Forestry Institute of the State of Sao Paulo. The experimental design was a compact family block, with 46 open-pollinated progenies originating from three natural populations (13 progenies from Alvorada do Sul-PR, 16 from Galia-SP and 17 from Bauru-SP), six replicates and five plants per subplot, spaced at 3 x 3 m. The test was assessed at the age of 27 years and estimates of genetic parameters were obtained using the method of additive univariate linear mixed model REML/BLUP. Significant differences were detected by the likelihood ratio test in the analysis of deviance of provenances for all traits. The coefficient of heritability at progeny means level varied from moderate to high for all traits (0.38 to 0.63), indicating that much of the phenotypic variation among the progenies tested is of genetic origin. This suggests the possibility of improving the means of the offspring of the trees of this population through the selection among progenies. The proportion of selection of 60% of the trees, for the DBH trait using the index of multi-effect, showed small gains at provenance levels. The results also suggest that the seeds collected in the proposed seed orchard will cause small increase in the DBH mean due to the low estimates of the genetic gains.