ACCURACY OF GENETIC PARAMETERS ESTIMATION AND PREDICTION OF GENOTYPIC VALUES IN EUCALYPTUS USING DIFFERENT PLOT TYPES

ABSTRACT A suitable experimental design should control the environmental effect and be capable of discriminating genotypes. Two clonal tests of Eucalyptus were planted side by side in a randomized block design with the same 32 treatments under two different plot designs. The first trial was designed with five plants per plot (linear plot, LP) and six block replicates at a spacing of 3 x 2 m. The second trial was designed with one plant per plot (single-tree plot, STP) and 30 block replicates also at a spacing of 3 x 2 m. Diameter at breast height (dbh), height (h), and individual volume (vol) were measured at five years of age. The STP design presented broad-sense heritabilities values of 0.23 for h and 0.41 for vol, which were higher than those found for the LP design (0.12 for h and 0.22 for vol). The ratio between the standard error and the estimated genotypic variance ( S g ^ ) was lower for the three evaluated traits in the STP trial. The correlations between the genetic values were positive and of high magnitude, ranging from 0.87 (h) to 0.91 (vol), but there were many differences between the two designs with regard to the ranking of clones. The STP presented better discriminant power according to the biplot analysis, as well as more accurate and reliable estimates.