Oenocarpus distichus presents economic, ecological, and dietary potential for pulp market processed in natura. Germplasm conservation and genetic improvement depend on genetic divergence studies. The objective was to quantify genetic divergence in a native population of O. distichus genotypes based on fruit biometrics. The fruit length and width, fruit mass, pulp and seed, pulp and almond thickness, and pulp yield per fruit were evaluated. All fruit biometric characteristics of O. distichus palms show genetic variability. Genetic variations among genotypes are essential for predicting heredity and heterosis, which are essential for improving O. distichus production. Pulp yield and seed mass were negatively correlated. Almond thickness and pulp, seed mass and transverse diameter were positively correlated. Genetic distances between pair of genotypes ranged from 0.07 to 48.10 with three genetically distinct groups. The seed mass, almond thickness and transverse diameter contributed to genetic divergence. Heritability estimates the genetic control that can be obtained from O. distichus germplasm. Correlations between the variable pair reduce the evaluation effort and the resources to measure the genotype allocations in heterogeneous groups presenting high genetic variability. This makes it possible to select individuals for hybridization programs with F1 generation gains. Correlation and relative contribution networks, based on relationships graphical between fruit biometric characteristics, allow the variables selection with less effort and fewer measurements. O. distichus fruit biometric characters are efficient to quantify genetic divergence between genotypes.

Research highlights: We used Dijkstra Algorithm (DA) to define optimal allocation of yards in order to minimize total skid-trail’s distance in the Amazon Forest. DA minimized trails’ distances and associated transportation costs, leading to an even smaller value when the current planning was disregarded and suggesting the reduction of deleterious environmental externalities. Background and objectives: We sought to answer if it is possible to optimize distances and intrinsic costs in the management of Amazonian forests using DA. The objective was to minimize skid trails distances by best allocating yards using DA and to compare four scenarios of forest harvest planning in the Brazilian Amazon. Materials and methods: Tree census data from Gênesis-Salém Farm, state of Pará, Brazil, were used. The yards and roads located by Grupo Arboris (scenario 1) were compared to three alternative scenarios in terms of total skid distance, trails and road densities, and skidding costs for three successive harvests, seeking to minimize total skid-trails’ distance. Alternative scenarios were to keep the number of yards within work units (WU) and place them in the edge of existing roads (scenario 2); keep the number of yards within each WU (scenario 3); and place 23 yards, disregarding the current planning (scenario 4). Results: Total skid-trail’s distance, number of trees above optimal extraction distance and densities of skid trails and roads were smaller in scenarios 2, 3, and 4, compared to the current yard allocation (scenario 1). Scenario 4, with fewer restrictions, reduced skid-trails’ distances by 23%. Harvest costs decreased from scenario 1 to 4 in all three harvest cycles. Conclusions: DA allowed optimized distribution of yards and skid trails and generated efficient results for harvest planning. This reinforces the importance of optimized planning, which establishes satisfactory results in the effort to reduce costs and environmental impact keeping high efficiency.

The objective of this study was to quantify the accumulation of nutrients in the bark of four eucalyptus clones at 12 years-of-age, planted at different population densities, and the values were extrapolated to kg of nutrients per hectare. The experiment used randomized blocks in a 4 × 3 factorial design and three replications, with four Eucalyptus clones (2486, I182, I144, and GG100) planted at three population densities (416, 833, and 1111 trees ha^-1). The rigorous cubage of three trees per plot was performed by collecting discs of bark at the following heights: diameter at breast height (1.30 m), 0, 25, 50, 75, and 100% of the commercial height of the stem. The bark discs of each tree were grouped and used to determine N, P, K, Ca, Mg, and S content, in addition to the basic density. The volume and dry mass of bark per tree was estimated and the accumulation of nutrients per tree ha^-1 was estimated sequentially, for each population density. Analysis of variance and Tukey’s post-hoc tests verified that Ca showed the greatest accumulation in the bark, followed by N, K, S, Mg, and P. The increase in population density contributed to higher bark production and greater nutrient accumulation per hectare. However, this increase was not evident when comparing densities of 833 and 1111 trees ha^-1.

COMPORTAMENTO SILVICULTURAL DE ESPÉCIES FLORESTAIS EM ARRANJO PARA INTEGRAÇÃO PECUÁRIA FLORESTA

Grafting and growth retardants are commonly used in breeding programs to stimulate flower production. However, little is known about their effects on Brazilian tree species. The aim of this study was to investigate the vegetative and reproductive development of grafted tree seedlings treated with paclobutrazol (PBZ) and grown under greenhouse or outdoor conditions. Potted seedlings of Jacaranda mimosifolia, Handroanthus heptaphyllus, Swietenia macrophylla, Schinus terebinthifolius, Cariniana legalis, and Hymenaea courbaril were evaluated. Shoot number, length, and circumference as well as flower and fruit numbers were determined at 50 and 90 days after PBZ application. Data were subjected to analysis of variance, and means were compared by Tukey’s test (P ≤ 0.05). Growing conditions influenced the vegetative parameters of seedlings, especially after 90 days. J. mimosifolia and S. terebinthifolius responded positively to flowering induction, and their fruit and flower numbers differed between growing environments. Potted grafts of the six native tree species were successfully grown. Grafting and PBZ application induced early flowering in J. mimosifolia and S. terebinthifolius.