Divergencia genética entre progenies de Cordia trichotoma en una plantación mixta con Dalbergia nigra

Cordia trichotoma es una especie nativa que está siendo evaluada para diferentes sistemas forestales. El hecho de que los individuos empleados en las plantaciones posean algún grado de mejoramiento genético tiene muchas ventajas; para lograr este mejoramiento es fundamental la obtención de genotipos superiores, a fin de obtener un mejor rendimiento del producto final. El objetivo del presente estudio fue estimar la divergencia genética de progenies de C. trichotoma en dos diferentes condiciones de textura de suelo, por medio de caracteres fenotípicos. El diseño experimental fue bloques completos al azar, un árbol por parcela con 40 (área 1) y 34 (área 2) repeticiones, con espaciamiento de 3,0 m × 3,0 m. Los caracteres evaluados fueron: diámetro a altura del pecho, altura total de plantas, diámetro de cuello y altura del primer verticilo. Para estimar la divergencia genética y el agrupamiento de Tocher fue utilizado el método REML/BLUP. Las distancias entre las progenies en el área 1 fueron de 2,13 y 47,74 (17 y 15), en el área 2 las distancias entre las progenies fueron de 3,64 (9 y 15) y 48,28 (12 y 7). Las progenies formaron diez y cuatro grupos distintos (área 1 y área 2). Los caracteres que más contribuyeron para divergencia genética fueron diámetro a la altura del pecho-2016 (14,65%) área 1, y altura total de plantas-2014 (14,32%) área 2. Las progenies de C. trichotoma presentaron alta divergencia genética. En programas de mejoramiento, se recomienda el cruzamiento entre progenies de los grupos más divergentes para priorizar la ganancia con selección de los genotipos más productivos.

The Influence of CNC Turning with VBMT, RCMX, 3ER, and MGMN Type Indexable Inserts on West African Ebony/Diospyros Crassiflora, San Domingo Boxwood/Phyllostylon Brasiliense, Rio Rosewood/Dalbergia Nigra, Beechwood/Fagus Sylvatica, Oakwood/Quercus Robur, and Pinewood/Pinus Silvestris Surface Roughness

The current scientific literature lacks an adequate description of hardware used to machine timber. Traditional woodworking and metals fabrication consists of tungsten carbide (TC) inserts. In this work, the authors investigate the influence of cutting tool geometry on the resulting surface roughness of timber samples. A variety of wood types were used in these studies to provide broad information on the correlation between the cutting tools used and resulting surface morphology. The cutting tools were prepared on a computer numerical control (CNC) lathe and roughness average (Ra) and average maximum peak to valley height of the profile (Rz) parameters were measured by contact stylus. The tip radius of the TC inserts used was determined to be the most significant factor that impacted Ra and Rz. In summary, we found that the tip radius of the TC insert was inversely proportional to the roughness level, indicating that a flatter TC insert cutting end results in a smoother wood surface.

Heat Stress Affects the Physiological and Biochemical Quality of Dalbergia nigra Seeds in vitro

The jacaranda of Bahia (Dalbergia nigra (Vell.) Allemão ex Benth) is an endemic tree of a Brazilian neotropical biodiversity hotspot and is of great ecological and economic interest. Given the threat of extinction due to timber overexploitation and climate change, the present study aimed to analyze the physiological and biochemical quality of D. nigra seeds exposed to heat stress. The seeds were sown in a test tube containing woody plant culture medium, kept in a biochemical oxygen demand chamber at 45°C for 0, 24, 48, 72, and 96 hours, and then maintained in the same chamber at 25°C for 30 days. Physiological analyses of moisture, electrical conductivity, germination speed index, normal and abnormal seedlings, seedling length, root length, hypocotyl length, collar diameter, seedling and root dry mass, and Dickson quality index revealed a drop in germination and vigor with prolonged heat stress, dropping from 95% to 0% between 0 and 96 hours. This was accompanied by a reduction in the content of carbohydrates, lipids, and proteins. Therefore, the vigor and quality of seedlings is negatively influenced by exposure to heat stress at 45°C. Study Implications: Dalbergia nigra is a species of high economic interest due to its high-quality wood. In the face of climate change, it is necessary to understand the behavior of seeds under temperature above the ideal. The quality and vigor of seedlings produced in vitro at a temperature of 45°C are negatively affected with the increase in hours of heat stress. In addition, the contents of lipids, carbohydrates, and proteins present in the seed reserves show a sharp drop with heat stress. Ultimately, heat stress significantly affects seed biochemistry and subsequent seedling physiology.

The specific leaf area of forest species subjected to different degrees of shading did not differ when detached and full leaflets were compared

Studies of forest species under different environmental conditions are essential for enhancing our understanding of plant-environment relationships. Different light conditions interfere with the production of seedlings within forests, and this interference can be verified by assessing leaf area. However, several species have leaf compound that often contain numerous leaflets, which makes the direct measurement of leaf area difficult. This leads researchers to question whether these types of leaves should be separated for analysis or measured whole. Thus, the aim of this study was to analyse specific leaf area in whole leaves and detached leaflets of six forest species subjected to different levels of shading. The forest species assessed all produced compound leaves and included Schinus terebinthifolius Raddi (aroeira), Schinopsis brasiliensis Engl. (braúna), Dalbergia nigra (Vell.) Fr. All. ex Benth. (jacaranda-da-bahia), Chorisia speciosa A. St.-Hil (paineira), Caesalpinia peltophoroides Benth (sibipiruna) and Plathymenia reticulata Benth (vinhático). Each species was subjected to six different degrees of shading: 0% (full sun); 20; 40; 60; 80 and 90%. Sombrite netting was used to shade plants. The analysis of the specific leaf area was performed using two different methods, which included the analysis of separate leaflets and whole leaves. To analyse leaflet area,50 leaflets per plant were assessed three times, and six plants per treatment were assessed. To assess whole leaves, data were obtained from the whole leaves of six plants per treatment. This process was repeated for all aforementioned species. Data obtained from both analysis methods indicated that all species assessed were similarly affected by shade, and leaf area varied according to the level of shading. This similarity of data demonstrates that, for these species, it is not necessary to use complex methods to obtain specific leaf area measurements. Thus, determining specific leaf by measuring the entire leaf provides results that did not statistically differ from those obtained by measuring individual leaflets.

CONTROLLED-RELEASE FERTILIZER IN THE GROWTH OF Dalbergia nigra SEEDLINGS

For the realization of forest restoration projects, it is essential to produce native seedlings in quantity, also necessary that they present greater vegetative vigor and good nutritional status. In this context, the objective of this work was to analyze the growth and nutrition of phosphorus of Dalbergia nigra seedlings from two sources cultivated with doses of controlled-release fertilizer (CRF). The experimental design was in randomized blocks, arranged in a factorial scheme 2 x 4, referring to lots of two seed sources of D. nigra (Viçosa, MG and Linhares, ES) and four doses of CRF (0, 2, 4 and 8 kg m-3), with four replications and 126 seedlings per plot. At 60, 90 and 120 days after sowing, the seedlings were collected to measure the variables related to growth and nutrition. D. nigra seedlings from Linhares (ES) show better growth and dry matter production. It is recommended to dose 7.46 kg m-3 of controlled-release fertilizer for seedlings from Linhares (ES) and the dose 5.99 kg m-3 for those coming from Viçosa (MG), aiming to maximize the growth of production of seedlings of D. nigra. Increasing doses of controlled-release fertilizer allow greater accumulation of P in shoot shoots of D. nigra.