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ABSTRACT

ABSTRACT.It is possible to determine the optimum time for permanence of vegetative propagules (mini-cuttings) inside a greenhouse for rooting, and this value can be used to optimize the structure of the nursery. The aim of this study was to determine the dynamics of adventitious rooting in mini-cuttings of three clones of Eucalyptus benthamii x Eucalyptus dunnii. Sprouts of H12, H19 and H20 clones were collected from mini-stumps that were planted in gutters containing sand and grown in a semi-hydroponic system. The basal region of the mini-cuttings was immersed in 2,000 mg L -1 indole-3-butyric acid (IBA) solution for 10 seconds. The rooting percentage of the mini-cuttings, the total length of the root system and the rooting rate per mini-cutting were also evaluated at 0 (time of planting), 7, 14, 21, 28, 35, 42, 49 and 56 days. We used logistic and exponential regression to mathematically model the speed of rhizogenesis. The rooting percentage was best represented as a logistic model, and the total length of the root system was best represented as an exponential model. The clones had different speeds of adventitious rooting. The optimum time for permanence of the mini-cuttings inside the greenhouse for rooting was between 35 and 42 days, and varied depending on the genetic material.Keywords: vegetative propagation, clonal forestry, organogenesis, mathematical modeling, rhizogenesis, clonal mini-garden. Dinamica de enraizamento adventício em miniestacas de Eucalyptus benthamii x Eucalyptus dunniiRESUMO. O tempo ideal de permanência de propágulos vegetativos (miniestacas) no interior da casa de vegetação para a rizogênese é possível de ser determinado matematicamente, o que pode otimizar as instalações do viveiro. O objetivo deste estudo foi determinar a dinâmica de enraizamento de miniestacas de três clones de Eucalyptus benthamii x Eucalyptus dunnii. Brotações dos clones H19, H12 e H20 foram coletadas de minicepas plantadas em canaletão com areia e cultivadas sob sistema semi-hidropônico. A região basal da miniestaca foi imersa em solução de 2.000 mg L -1 de ácido indolbutírico (AIB) por 10 segundos. A porcentagem de enraizamento de miniestacas, o comprimento total de raízes e a taxa de enraizamento por miniestaca foram avaliados a cada sete dias (0 -instante da estaquia, 14, 21, 28, 35, 42, 49 e 56 dias). Foram utilizadas as regressões logística e exponencial para a modelagem matemática da velocidade dos processos rizogênicos. O modelo logístico teve o melhor ajuste para o percentual de enraizamento, e o modelo exponencial para o comprimento total do sistema radicular. Os clones apresentaram diferentes velocidades de enraizamento. O tempo ideal de permanência das miniestacas dentro da casa de vegetação para o enraizamento está entre 35 a 42 dias, podendo variar em função do material genético.Palavras-chave: propagação vegetativa, silvicultural clonal, organogênese, modelagem matemática, rizogênese, minijardim clonal.

Origanum vulgare L is commonly known as a wild marjoram and winter sweet which has been used in the traditional medicine due to its therapeutic effects as stimulant, anticancer, antioxidant, antibacterial, anti-inflammatory and many other diseases. A reliable gene transfer system via Agrobacterium rhizogenes and plant regeneration via hairy roots was established in O. vulgare for the first time. The frequency of induced hairy roots was different by modification of the co-cultivation medium elements after infection by Agrobacterium rhizogenes strains K599 and ATCC15834. ). The frequency of shoot generation (85.18 %) was achieved in medium fortified with 0.25 mg/L −1 of BA. Shoots were placed on MS medium with 0.25 mg/l IBA for root induction. Roots appeared and induction rate was achieved after 15 days.

The objective of this work was to verify levels of tolerance in Anadenanthera colubrina seeds to water and salt stress simulated for polyethyleneglycol 6000 (PEG 6000), manitol and KCl. The seeds was collected from nine trees and stored in cold chamber at 5 ºC. For the evaluation of the germination under it water stress was used PEG 6000 solutions and manitol, and under salt stress solutions of KCl in different osmotic potentials: 0.0 Mpa (control), -0.6 MPa, -0.8 MPa, -1.0 MPa, -1.2 MPa and -1.4 Mpa. The seeds were made use in gerbox and placed in germination chambers, under constant light to the temperature of 25 ºC. The percentage and the germination speed index (GSI) were evaluated. The seeds of Anadenanthera colubrina showed moderate tolerance to the water stress simulated by PEG 6000. The percentage of germination was affected from -1.0 MPa, and the GSI from -0.6 Mpa. Manitol did not reveal efficient in the simulation of water stress, therefore it did not reduce the percentage of germination. Under it salt stress, simulated for KCl, the germination percentage was affected from the potential -1.2 MPa, characterizing a high limit of tolerance to this salt.