Methods for Simultaneous Evaluation of Productivity, Adaptability and Genotypic Stability in Eucalyptus grandis Progeny Trials in the State of Sao Paulo

Abstract

The estimated Harmonic Mean for Genetic Values (MHVG), Relative Performance of Genetic Values (PRVG) and the Harmonic Mean of Relative Performance of Genetic Values (MHPRVG) were used as measures to provide and facilitate the interpretation of genotypic stability and adaptability of Eucalyptus grandis W. Hill ex Maiden. The different criteria were applied as alternatives to the simulation of selection for productivity, stability, adaptability, as well as for the joint value of these attributes together. The estimates were generated by using the mixed model, assuming genetic effects to be random. The software SELEGEN-REML/BLUP was used to evaluate progeny trials and to estimate statistical parameters. The best trees to be used in seedling and clonal orchards were identified. Fifty three half-sib families from three Australian provenances were tested in the municipalities of Mogi Guaçu, Boa Esperança do Sul and Caçapava, in the State of São Paulo. Compact family blocks designs were used, involving variable numbers of replicates, with six-trees linear plots, in a 3 x 2 m spacing. Two types of data transformation were tried in order to evaluate their efficiency in the reduction of the genetic, environmental and phenotypic variances. MHVG, PRVG and MHPRVG statistics proved to be useful in simulations for the selection of individuals with the attributes considered, providing options for choosing strategies and criteria by considering different values for the estimated genetic gains. The joint analysis of experiments in different locations confirmed that substantial gains can be obtained in DBH through individual selection based on their genetic values. This can be achieved by either thinning the trial, which leads to the formation of a seedling seed orchard or vegetative propagation of the best individuals, in order to establish a clonal seed orchard. The genetic correlation between locations indicated that a single selected population and a single clonal seed orchard will suffice to represent all test locations. This mean a substantial saving at this stage of the tree improvement program. Genetic variability was achieved with the moderates values obtained from individual heritability, in the narrow sense, for growth in DBH in the three locations studied. The adoption of selection strategies and criteria proposed here will result in a selected population (seedling seed orchard) with two hundred individuals of the highest genetic value, while maintaining an adequate effective family number and producing gains in DBH in the order of 12.89 % to 24.33 % over the overall experimental mean. The selection of twenty individuals of thehighest breeding values to establish a clonal seed orchard can produce between 17.18 % and 50.95 % gains in DBH over the experimental mean. The selection of the best twenty individuals for the establishment of a seedling seed orchard can produce between 22.40 % and 82.16 % gains in DBH over the experimental mean.