EFEITO DE IBA E DE RIZOBACTÉRIA NO ENRAIZAMENTO DE MINIESTACAS DE ACÁCIA NEGRA

Black wattle is a forest species of great economic importance in the southern of Brazil. Researches for vegetative propagation methods to constitute clonal forests are effective to increase forest productivity. The goal of this work was to evaluate the action of compounds of root promotion in minicuttings of Acacia mearnsii as an alternative to vegetative propagation to the species. The experiment was conducted in July/2018 (winter season), with one negative control, two concentrations of indole butyric acid – IBA (2000 and 4000 mg L-1) and two concentrations of AzoTotal™ (100% e 50%), an inoculant containing Azospirillum brasilense bacterium. In the IBA treatments, the base of minicuttings remained immersed in hydroalcoholic solution 50% for 10 seconds and for the inoculant treatments during 15 minutes. The experiment took place in a greenhouse and after 45 days they were evaluated: the percentage of rooted minicutting; number of roots per minicutting; length of the three largest roots per minicutting; percentage of minicuttings with calluses; percentage of minicuttings survival; percentage of minicutting with budding and percentage of minicutting that kept the leaflets. There was significant difference between treatments considering rooted minicuttings, number of roots by minicutting, length of the three largest roots by minicutting, and there were not observed differences to the other variables analyzed. The use of IBA was more effective for the vegetative propagation process in this species.A acácia negra é uma espécie florestal de expressiva importância econômica na região sul do Brasil e a investigação de métodos de propagação vegetativa para constituição de florestas clonais é de grande valia para aumento da produtividade florestal. O objetivo deste trabalho foi avaliar a ação de promotores de enraizamento na miniestaquia de Acacia mearnsii como alternativa para a propagação vegetativa da espécie. O experimento foi conduzido no mês de julho/2018 (estação de inverno), com uma testemunha, duas concentrações de ácido indol butírico – IBA (2000 e 4000 mg L-1) e duas concentrações do inoculante AzoTotal® (100% e 50%) que contem a bactéria Azospirillum brasilense. Para os tratamentos com IBA, as bases das miniestacas permaneceram imersas em solução hidroalcoólica 50% durante 10 segundos e para o inoculante durante 15 minutos. O experimento foi conduzido em casa de vegetação e após 45 dias avaliou-se a porcentagem de miniestacas enraizadas, número de raízes por miniestaca, comprimento das três maiores raízes por miniestaca, porcentagem de miniestacas com calos, porcentagem de sobrevivência das miniestacas, porcentagem de miniestacas com brotação e porcentagem de miniestacas que mantiveram os folíolos. Houve diferença significativa entre os tratamentos para miniestacas enraizadas, número de raízes por miniestaca, e comprimento das três maiores raízes, não ocorrendo para as demais variáveis analisadas. A utilização de IBA mostrou-se mais eficaz para o processo de propagação vegetativa da espécie

FEASIBILITY OF EARLY Pinus taeda L. SELECTION TO ASSESS GROWTH VARIABLES IN PROGENY TEST

Forest species breeding programs require a long period-of-time for plants to reach the proper age to enable selecting superior genotypes, which is a critical factor in selection processes. Thus, the aims of the current study are to estimate genetic parameters in juvenile and adult plants (6, 10 and 20 years) in order to investigate genetic correlations between variables at different ages and at certain ages; as well as to determine whether it is possible performing efficient early selection in juvenile plants. The test was implemented in 1997; it comprised 120 progenies and followed a randomized block design, with five repetitions - linear plots comprised 5 plants at 2.5 m x 2.5 m spacing. DBH (cm), H (m) and VOL (m³) of all tested subjects were measured at the age of 6, 10 and 20 years. Variance components, genetic parameters, as well as genetic correlations between variables and between ages were estimated in Selegen REML/BLUP® software. Genetic parameter estimates have shown superiority at 10 years, in comparison to that estimated at 6 and 20 years. Variable ‘DBH’ has shown high genetic correlation to height (H) and volume (VOL), whereas DBH x VOL have shown high genetic correlation (0.98) in 10-year-old plants. With respect to genetic correlation between ages, 10-year-old plants have shown moderate correlation to 6- and 20-year-old plants. Early selection is indicated for 10-year-old plants, in 20-year cycles, since plants at this age have shown higher selection efficiency to predict gains in comparison to adult plants