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This study evaluated aspects of the pollen viability of the species Myrceugenia euosma (O. Berg) D. Legrand and Siphoneugena reitzii D. Legrand (Myrtaceae), both native trees with ornamental, medicinal and industrial potential. The study used different concentrations of sucrose to determine pollen viability in vitro and through colorimetric tests with specific dyes (Lugol, carmine acetic, and tetrazolium chloride – TTC – 0.1 and 0.05%). The two species also had their pollen stored for 30 and 90 days in freezers, refrigerators, and natural environments to check the best method for preserving their viability. The results showed that the highest average germination of M. euosma pollen was in a culture medium containing 30% sucrose. After 30 and 90 days of storage, pollen viability was significantly reduced, having preserved part of its potential only in the freezer. The pollen of S. reitzii had a higher average germination rate in a medium with 20% sucrose, but also showed a reduction in viability after 30 and 90 days of storage. The colorimetric tests showed that the pollen of both species responded to the dyes. However, the viability of Lugol and carmine acetic was considered to be overestimated in relation to the in vitro germination tests. Tetrazolium at 0.1% proved to be an alternative for checking the viability of S. reitzii pollen. It can be concluded that different concentrations of sucrose affect germination, and that storing pollen at a low temperature can preserve some of its viability in the short term.

ABSTRACT This study aimed to determine the main causes of low germination of Zanthoxylum rhoifolium Lam. (Rutaceae) seeds. Initially, the physical and physiological qualities were evaluated in seeds from four areas (lots) (Step I). Then, tests were performed (Step II) to determine physical dormancy (imbibition in water and methylene blue), physiological (germination test with scarification) and morphological (analysis of the embryo), in addition to histochemical analysis and (Step III) bioassay in aqueous and hydroalcoholic extracts. In Step I, a low germination was observed in all evaluated lots (≤ 1.0%); however, in the tetrazolium test, a high viability was verified for the Dois Vizinhos lot (88%). The lots showed differences in their physical aspects, with the predominance of seeds with damage. In Stage II, developed embryos were verified and there has no germination without the tegument. The methylene blue and histochemical test indicated the presence of an impermeable and thick tegmen. The bioessays with hydroalcoholic extracts indicated the presence of germination inhibitor(s). The main causes associated with low germination of Z. rhoifolium seeds are attributed to the combined dormancy due to an impermeable tegmen and some non-specific physiological dormancy, as well as the presence of damaged seeds. The seeds also contain germination inhibitors.

ABSTRACT: Plants use light as a source of energy in the process of photosynthesis. Different levels of luminosity cause physiological and morphological changes in the plant, and its success depends on its adaptation to these different levels. Light emitting diodes (LED) have been proposed as a light source in controlled environments. The present research evaluated physiological and morphological aspects in Eucalyptus benthamii (Myrtaceae) seedlings kept under different colors of LED lamps and submitted to water stress. The experiment was carried out in a completely randomized design, in which the treatments were defined as: T1 (control, with white light); T2 (blue light); T3 (red light) and T4 (mixed blue and red light). Red light resulted in the best response to most morphological variables in plant growth. In response to water stress, blue light LEDs resulted in a better seedling response, with slower reduction of photosynthetic rate and other variables. This may indicate the possibility of reducing water deficit damage in seedlings acclimated to blue light prior to field planting.

O araçá (Psidium cattleianum Sabine) é uma espécie frutífera nativa que possui importância econômica na indústria alimentícia e farmacêutica. Diante disto, há necessidade de produzir mudas de qualidade capazes de atender às demandas de mercado. Este trabalho teve como objetivo avaliar a influência do ambiente de crescimento e o uso do adubo de lenta liberação Osmocote® no desenvolvimento de mudas de araçá. Sementes de araçá foram coletadas em março de 2015 e germinadas. Depois de cerca de 90 dias, as mudas foram dispostas segundo os tratamentos que receberam. Os tratamentos consistiram em cinco doses de adubo (0; 3,0; 6,0; 9,0 e 12,0 g L-1) combinados com dois ambientes de viveiro (casa de vegetação e sombrite 50%) em esquema fatorial 5 x 2. Aos 210 dias avaliou-se altura de mudas (cm), diâmetro de colo (mm); peso seco de parte aérea e raiz (g) e índice de clorofila (SPAD). Houve interação dos fatores para a maioria das variáveis, com exceção do índice de clorofila. A dose intermediária do adubo implicou na melhor performance de crescimento de mudas em quase todas as ocasiões, assim como o ambiente sombreado. Para mudas de araçá, recomenda-se o uso de 6 mg L-1 de adubo e o uso de telado de sombrite para seu crescimento.

Objetivou-se compreender os ciclos reprodutivo e vegetativo de Campomanesia guazumifolia (Cambess.) O. Berg., monitorando os eventos fenológicos e correlacionando com dados climáticos da região de estudo. Foram utilizados dois métodos de avaliação, o Índice de Atividade e o Índice de Intensidade (Índice de Fournier). A fenofase de floração ocorreu entre os meses de outubro a dezembro, e março a abril, com picos de intensidade de Fournier em novembro. A frutificação ocorreu de dezembro a abril, sendo que dezembro foi o mês de maior intensidade de frutos. A espécie apresentou período de maior queda foliar entre março e setembro, com pico de intensidade em agosto, e o brotamento com pico em setembro. Foi observada correlação positiva entre as variáveis climáticas de temperaturas máximas e mínimas mensais e a frutificação, e correlação negativa entre temperaturas máximas e médias mensais e a queda foliar

ABSTRACT: The objective of this paper was to test the effects of water deficit, saturation and salinity in individuals of Toona ciliata. Seven treatments were tested: the control group, the complete suspension of irrigation, the permanent saturation of the pot soil and four doses of NaCl (50, 100, 200 and 400 µmol). The experimental design was completely randomized, with 8 repetitions in each treatment. Physiologic evaluations were carried out during the experiment, and morphologic evaluations at the end. The plants were responsive to the applied stresses comparatively to the control group. Reductions were observed in morphological and physiological variables in all treatments under stress. All individuals under stress recovered slightly in the end of the experiment, and began to sprout again, representing a probable adaptation to the conditions.