Resumo O gênero Tibouchina apresenta aproximadamente 350 espécies, dentre elas, Tibouchina affinis fothergillae, Tibouchina heteromalla, Tibouchina moricandiana var. vinaceae e Tibouchina sellowiana. Por se tratarem de espécies nativas do Brasil, podem ser utilizadas para revegetação de áreas antropizadas, devido à característica pioneira. A presente pesquisa objetivou estudar a propagação vegetativa via miniestaquia, utilizando ácido indol butírico (AIB) e ácido fúlvico (AF), bem como realizar determinações bioquímicas e quantificar a produtividade de minicepas destas espécies. Os propágulos foram coletados de um minijardim clonal, nos meses de abril, junho, setembro e novembro/2017, confeccionados com 5+1 cm de comprimento, corte em bisel na base e reto no ápice, mantendo-se um par de folhas reduzidas à metade. As bases das miniestacas foram submetidas aos tratamentos: 0 mg L-1AIB/AF, 2000 mg L-1AIB, 2000 mg L-1AF e 2000 mg L-1AIB+AF. O experimento foi instalado utilizando-se tubetes de 53 cm³ com vermiculita, avaliados após 33 dias de permanência em casa de vegetação, considerando-se a porcentagem de enraizamento das miniestacas. O delineamento foi inteiramente casualizado, num esquema fatorial de 4x4 (quatro épocas de coleta x quatro tratamentos), conduzido individualmente/espécie. As espécies não responderam aos tratamentos com AIB/AF. Nas diferentes épocas de coleta dos propágulos, o enraizamento foi superior a 95% para todas as espécies em abril, setembro e novembro, exceto para Tibouchina sellowiana com 49% de enraizamento no mês de novembro, demonstrando o efeito direto das condições ambientais as quais as plantas matrizes estavam sujeitas, sob a rizogênese. Conclui-se que não há necessidade da aplicação de AIB/AF para a propagação vegetativa das diferentes espécies de Tibouchina, sendo viável o uso da técnica de miniestaquia. Visando a maior produtividade de miniestacas, recomenda-se coletar os propágulos em abril para Tibouchina affinis fothergillae e Tibouchina moricandiana var. vinaceae, em novembro para Tibouchina heteromalla e em junho para Tibouchina sellowiana.

Abstract Tibouchina gene showed approximately 350 species, among these, Tibouchina affinis fothergillae, Tibouchina heteromalla, Tibouchina moricandiana var. vinaceae, Tibouchina sellowiana, are native species of Brazil, were used for revegetation in anthropized areas, due to the pioneerinh chacacteristic. The present research aimed to study rhizogenic from the technique of plant propagation by minicutting with the use of indole-3-butyric acid (IBA) and fulvic acid (FA), biochemical determinations, in addition to the ministumps production. The minicuttings were sampled in april, june, september and november and prepared with 5+1 cm length, bevel cut at the base and straight in the apical portion, keeping two leaves reduced to half. The bases of the minicuttings were to put to different treatments: 0 mg L-1 IBA/FA, 2000 mg L-1 IBA, 2000 mg L-1 FA and 2000 mg L-1 IBA+FA. The installation was in tubes with 53 cm3 with vermiculite, evaluating after 33 days of stay in the greenhouse, analyzed the rooting percentage of minicutting. The experimental design was completely randomized in a factorial of 4x4 (4 sample x 4 treatments). Rooting was greater than 95% for all species in the samples held in april, september and november, except to Tibouchina sellowiana with 49% of rooting in the month of November, showing the direct effect of the environment under the rizogenic. Concluded was unnecessary supplementation with exogenous IBA and FA for technical minicutting of different Tibouchina species. The production of minicutting was viable in april for Tibouchina affinis fothergillae and Tibouchina moricandiana var. vinaceae, in november Tibouchina heteromalla and june Tibouchina sellowiana.

ABSTRACT We aimed to verify the morphophysiological changes in jaboticaba tree (Plinia peruviana (Poir.) Govaerts) saplings under shade gradient to improve knowledge on the appropriate light environmental conditions for the saplings production and field homogeneous or intercropping cultivation of this species. The saplings were grown under full sun and artificial shade levels (30%, 50%, and 80%). Growth, photosynthetic pigments, gas exchanges, chlorophyll fluorescence, and leaf anatomy characters were evaluated. Our results showed that jaboticaba tree saplings growth was improved under full sun and 30% of shade. Under 50% and 80% shade the saplings demonstrate phenotypic plasticity, such as larger and thinner leaves. Chlorophyll fluorescence, chlorophyll content, and quantum yield of photosystem II were higher under higher shade level, but the CO2 assimilation rate was not different between light conditions. These changes are typically found in shade-tolerant plants and is related to perform photosynthesis more efficiently in highly variable light conditions. Despite that, we recommend that cultivation be carried out under full sun or up to 30% shade to maximize jaboticaba tree saplings growth in nurseries and orchards.

Abstract Plinia cauliflora is an important Brazilian species that produces highly appreciated fruits, with a great potential of commercialization. However, the high cost of seedlings is a bottleneck for the expansion of commercial orchards. The present study aimed to investigate somatic embryogenesis as a propagation method for P. cauliflora using seeds as explants. To induce embryogenic mass (EM) and somatic embryo (SE) development we evaluated the supplementation of culture medium with different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D), combined or not with activated charcoal (AC). For the embryo maturation, we investigated the effects of AC, polyethylene glycol (PEG), Gelzan®, 6-benzylaminopurine and gibberellin supplementation. For the EM induction, the best results were obtained in MS culture medium supplemented with 300 μM 2,4-D and 1 g L-1 AC. During the first maturation phase, the supplementation of 30 g L-1 PEG improved the somatic embryo formation at the torpedo and cotyledonary stages, whereas the maturation treatments did not result in the conversion of the embryos into plantlets. The anatomical analysis showed that the 2,4-D presence for 60 days may have been deleterious for embryonic development. These results represent the first report of P. cauliflora somatic embryogenesis and its feasibility for mass propagation.

ABSTRACT. Grafting is an alternative method for the early production of Araucaria angustifolia seeds, and welding quality is essential for the success of the technique. The objective of this study was to create a classification of welding quality to estimate the percentage of scion survival. The patch and flute grafting techniques were used in a greenhouse and in the field. Survival was evaluated 270 days after grafting (DAG). At 60 DAG, observations of the graft connection region were made with the naked eye, classifying the connections into four welding classes. After 160 DAG, transverse cuts were performed on each class and visually and anatomically evaluated. Flute grafting presented higher initial survival (79%), but at 180 DAG, the survival rate of both techniques was similar (48% for flute and 41% for patch). There was greater scion survival for the class that had only two regions in contact with discontinuity in the bark. Stabilization of survival occurred after 180 DAG, regardless of the welding class. Visually, there were differences in welding quality; however, anatomically, all classes presented vascular connections. The visual welding quality assessment underestimated the percentage of scion survival. However, the vascular connection and development of parenchymatous tissue are promising for diagnosing grafting success.

ABSTRACT. Plinia peruviana is a species that is native to Brazil and is important due to the taste and medicinal properties of its fruits. Young leaves and split mature seeds were used as explants to initiate somatic embryogenesis to obtain a large number of plants in a short period of time. Leaf discs were cultured in MS medium containing various concentrations of 2,4-D (2,4-dichlorophenoxyacetic acid) or picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid). In the case of the mature seeds, various concentrations of glutamine, 2,4-D and a combination of auxin and BAP (6-benzylaminopurine) were tested for somatic embryogenesis induction. For somatic embryo maturation, several concentrations of PEG 6000 (polyethylene glycol; up to 90 g L-1) were tested. After 60 days of culture using leaf discs, callus formation occurred in all treatments, with the highest averages obtained with 10 μM 2,4-D. However, these calluses did not form somatic embryos. For the cultured seeds, the best treatment was the MS medium with 1,000 mg L-1 glutamine and 10 μM 2,4-D without BAP. The supplementation of 60 g L-1 PEG 6000 was sufficient to promote the maturation of the somatic embryos. Histological analyses of the calluses that were formed from leaf discs showed nonembryogenic characteristics. In contrast, the calluses that originated from mature seeds had small and round cells with little vacuolation, which are characteristics of embryogenic structures.

Abstract Titanium dioxide nanoparticles (TiO2NPs) are widely used and may impact the environment. Thus, this study used a high concentration of TiO2NP (1000 mg/L) to verify the defense mechanisms triggered by a plant system – an indicator of toxicity. Furthermore, this study aimed at completely characterizing TiO2NP suspensions to elucidate their toxic behavior. TiO2NPs were taken up by meristematic cells of Allium cepa, leading to slight inhibition of seed germination and root growth. However, severe cellular and DNA damages were observed in a concentration-dependent manner (10, 100, and 1000 mg/L). For this reason, we used the highest tested concentration (1000 mg/L) to verify if the plant cells developed defense mechanisms against the TiO2NPs and evaluated other evidences of TiO2NP genotoxicity. Nucleolar alterations and plant defense responses (i.e., increased lytic vacuoles, oil bodies and NP phase change) were observed in meristematic cells exposed to TiO2NP at 1000 mg/L. In summary, TiO2NPs can damage the genetic material of plants; however, plants displayed defense mechanisms against the deleterious effects of these NPs. In addition, A. cepa was found to be a suitable test system to evaluate the cyto- and genotoxicity of NPs.