Avanço no programa de melhoramento de Eremanthus erythropappus (DC.) MacLeish: parâmetros genéticos e estratégias para conservação e seleção de progênies

Abstract

Despite recent advances in the knowledge of candeia (Eremanthus erythropappus), significant gaps still persist, especially in the areas of silviculture and genetic improvement. The species is noteworthy for its production of essential oil rich in alpha-bisabolol. In this context, the development of progeny tests represents a fundamental strategy for evaluating genetic variability, selecting superior genotypes, and defining conservation and breeding strategies. The study aimed to estimate genetic parameters and evaluate the efficiency of selection, with the goal of obtaining genetic material with the potential for future productive gains and maintaining genetic variability. The experiment was conducted in Baependi – MG, under a randomized complete block design, with five repetitions and six-plant plots, totaling 35 half-sib progenies and 1,050 individuals. Five years after planting, the variables of survival, height, diameter at breast height (DBH), and estimated wood volume were evaluated. Genetic analysis was performed using the REML/BLUP method, with the use of the SELEGEN software. Three selection intensities (15, 30, and 45%) were compared based on selection gains (GS) and effective population size (Ne). Significant genetic variability was observed for height and DBH, with additive genetic variance (Va) estimated at 0.38 and 1.35, respectively. Narrow-sense heritability (h2a) was 0.67 for height and 0.28 for DBH, indicating greater genetic control over the former variable. Selection accuracies (Acprog) were high, reaching 0.84 for height and 0.73 for DBH, which confirms the precision of the estimates. Individual genetic variation coefficients (CVgi%) of 10.90% for height and 11.33% for DBH indicate a good range of variation for selection. Considering a selection intensity of 30% within families, a genetic gain of 0.58 m for height and 0.74 cm for DBH was observed, while maintaining an effective size (Ne) of 75 and 72 individuals, respectively, which are adequate values to minimize risks of inbreeding. In the selection between families with the same intensity (30%), progenies P1, P2, P3, P4, P5, P6, and P13 stood out, showing superior simultaneous performance for height and DBH. It is concluded that the candeia genetic improvement program shows expressive advances, with the potential to generate superior materials and establish seed orchards. Selection strategies with moderate intensities allow for consistent genetic gains without compromising diversity, promoting the conservation of the species and expanding its sustainable use with long-term ecological and economic benefits.