PROGRESSO GENÉTICO PARA CARACTERES DE CRESCIMENTO, FORMA DO FUSTE E RESISTÊNCIA DA MADEIRA À PERFURAÇÃO EM Pinus maximinoi H.E. moore

Abstract

Although the species Pinus maximinoi H. E. Moore shows rapid growth and volumetric development, it also has high levels of genetic variability and source populations have deformations in the shaft, such as bifurcations and foxtailing. Thus, the main objectives of the present study were to assess the genetic control of growth characteristics, stem form factor, and wood resistance in a P. maximinoi progeny test as well as develop a selection index for genetic gains to establish a seedling seed orchard. The progeny test was established in the municipality of Telêmaco Borba, Paraná State, Brazil, with a randomized complete block design, containing 78 open pollinated progenies, in single plant plots, 20 repetitions, and a spacing of 2.5 x 3.0 m. Measurements of growth characteristics were taken at five years of age and included diameter at breast height (DBH, cm), height (ALT, m), volume (VOL, m3 ), stem form factor (FF), branch arrangement (DR), and wood resistance to drilling (RES). For FF and DR, a classification system was used with a ranking of 1 to 4. RES was obtained with the IML Resistograph®. A selection index (IS) was developed by grouping the BLUPs of the characteristics of interest to create a new index to select the best genetic materials. The estimated genetic variability for the progeny test indicates the possibility of obtaining genetic gains with selection. The coefficient of genetic variation ( %) CVg ranged from 14.42% for VOL to 4.11% for RES. The coefficient of narrow sense heritability 2 ( ) a h was high for height (0.55) and average for the other characteristics (DBH: 0.32; VOL: 0.42; RES: 0.42; FF: 0.33; and DR: 0.29). The IS was used to select the best individuals from the progeny test, which was transformed into a seedling seed orchard by thinning the poorer performing trees, providing estimated gains through selection for DBH of 11.6%, VOL of 11.68%, RES of 1.1%, and FF of 12.2%. The results show the existence of genetic variability and high levels of heritability for the evaluated traits, and as such there is the possibility of pronounced genetic gains in the seeds harvested from the seed orchard.