Seed discontinuous hydration does not benefit germination, but improves drought tolerance of Triplaris gardneriana seedlings

The discontinuous seed hydration enables the acquisition of tolerance to environmental stresses, causing a stress imprint. It may modify metabolic patterns and lead to improved stress responses. This study aims to evaluate the effects of discontinuous hydration on germination and on seedling growth of Triplaris gardneriana Wedd. under intermittent drought. The seeds have gone through cycles (0, 1, 2 and 3) of hydration and dehydration (HD). The seedlings produced were subjected to water deficit (daily watering and intervals of seven and fourteen days between watering). Seed germinability parameters and, relative growth rate (RGR) of seedling, leaf area, dry matter yield and leaf relative water content (RWC) were evaluated. The HD cycles did not benefit germination, but two HD cycles induced a better biomass accumulation and increased leaf area in seedlings under moderate water deficit, while three HD cycles promoted an increase in RGR and influenced the RWC values. Severe stress affects seedling growth, but subjection to HD cycles minimizes the deleterious effects of drought, suggesting discontinuous hydration acts leading stress imprint in plants.

Seed discontinuous hydration does not benefit germination, but improves drought tolerance of Triplaris gardneriana seedlings

The discontinuous seed hydration enables the acquisition of tolerance to environmental stresses, causing a stress imprint. It may modify metabolic patterns and lead to improved stress responses. This study aims to evaluate the effects of discontinuous hydration on germination and on seedling growth of Triplaris gardneriana Wedd. under intermittent drought. The seeds have gone through cycles (0, 1, 2 and 3) of hydration and dehydration (HD). The seedlings produced were subjected to water deficit (daily watering and intervals of seven and fourteen days between watering). Seed germinability parameters and, relative growth rate (RGR) of seedling, leaf area, dry matter yield and leaf relative water content (RWC) were evaluated. The HD cycles did not benefit germination, but two HD cycles induced a better biomass accumulation and increased leaf area in seedlings under moderate water deficit, while three HD cycles promoted an increase in RGR and influenced the RWC values. Severe stress affects seedling growth, but subjection to HD cycles minimizes the deleterious effects of drought, suggesting discontinuous hydration acts leading stress imprint in plants.(AU)

Flooding avoidance Triplaris gardneriana Wedd. (Polygonaceae): growth and morpho-anatomical aspects / Evitação do alagamento em Triplaris gardneriana Wedd. (Polygonaceae): crescimento e aspectos morfo-anatômicos

The aim of this study was to analyze the effect of flooding in Triplaris gardneriana Wedd, cultivated in drained soil (control) and in flooded condition. The experiment was developed in a greenhouse, using plants with 90 days after the emergency. The response to treatment was evaluated at 0, 30, 60 and 90 days. Growth measurements were made, such as biomass allocation, relative growth rate (RGR). Adventitious roots were not measured only observed, as well as the development of hypertrophied lenticels. The RGR was continuously reduced along the 90 days in flooding conditions for the roots, stem and leaves, compared to control. The flooding of the substrate caused alterations such as: increasing of the cortex width and diameter of the central cylinder of root and increasing the diameter of the vessel element of the root and stem. Results show that T. gardneriana remains under stress when submitted to flooding. Therefore, the production of structures as lenticels, aerenchyma and adventitious roots, structures related to the avoidance of this type of stress, were key factors for the maintenance and survival of T. gardneriana.(AU)

O objetivo deste trabalho foi analisar o efeito do alagamento em Triplaris gardneriana Wedd, cultivadas em condições de solo drenado (controle) e solo alagado. O experimento foi desenvolvido em casa de vegetação, utilizando-se plantas com 90 dias após a emergência. As respostas ao tratamento foram avaliadas para os períodos de 0, 30, 60 e 90 dias. Foram feitas medidas de crescimento, como alocação de biomassa, taxa de crescimento relativo (TCR). Raízes adventícias não foram medidas, apenas observadas, assim como o desenvolvimento de lenticelas hipertrofiadas. A TCR foi continuamente reduzida durante os 90 dias em condições de inundação para as raízes, o caule e as folhas em relação ao controle. O alagamento do substrato provocou alterações anatômicas como aumento da largura do córtex e do diâmetro do cilindro central da raiz e aumento do diâmetro dos elementos de vaso do caule e da raiz. Nossos resultados indicam que T. gardneriana permanece em estresse quando submetida a inundações. No entanto, a produção de estruturas relacionadas à evitação deste tipo de estresse foi chave para a manutenção e sobrevivência de T. gardneriana.(AU)

Insect herbivores of Coccoloba cereifera do not select asymmetric plants.

Fluctuating asymmetry (FA) represents small, random variations from the symmetric bilateral pattern, and it is a frequently used measurement of plant and animal stresses. Some studies have shown a relationship between FA and herbivory, suggesting that FA might be a reliable indicator of plant quality and plant susceptibility to herbivore attack. In this study, we investigated the relationship between leaf FA of Coccoloba cereifera Schwacke (Polygonaceae) and the pattern of attack by the scale insect Abgrallaspis cyanophylly Signoret (Hemiptera: Diaspididae). Thirty individuals of C. cereifera were marked and followed during 2007 in southeastern Brazil, and all leaves of three shoots per plant were sampled, numbered, and categorized as young, mature, or senescent. We measured right and left widths of all leaves after digitizing the images to determine levels of FA for each leaf sampled per plant. Individuals of A. cyanophylli were counted using a stereoscope in the laboratory to determine infestation levels. Leaves of C. cereifera exhibited true patterns of FA, as shown by the normal distribution of asymmetry values. We observed high variation in attack rates by A. cyanophylly among C. cereifera individuals, with 43.3% of plants with no insects, whereas others exhibited up to 23,000 insects. No statistically significant relationship was observed between variation in FA and variation in A. cyanophylli among plants. These results suggest that FA cannot be used as an indicator of plant quality and susceptibility to herbivore attack but suggest that herbivores themselves might act as plant stressors.

Fructification phenology as an important tool in the recovery of iron mining areas in Minas Gerais, Brazil.

'Canga' is a name given to the ferruginous rocky fields that can be found in the 'Quadrilátero Ferrífero' of Minas Gerais, Brazil. The endemism and species richness make them areas of special biological importance, regarded as high-priority for conservation. Nevertheless, they are being threatened by intense mining activity. Aiming to understand more about this flora, this study was performed in order to determine the maturation or dispersal period of the fruits of four Canga species, Alibertia vaccinioides K.Schum. (Rubiaceae), Coccoloba acrostichoides Cham. (Polygonaceae), Miconia sellowiana Naudin (Melastomataceae), and one probable new species of Calyptranthes Sw. (Myrtaceae). Although fruit maturation or dispersal tended to occur at the end of the dry season, some asynchrony was observed in these species, with food sources being available during most of the year. This shows that these species have the potential to attract animals the whole year round, and planting them for the recovery of iron mining areas may increase the community's self-regeneration capacity, leading to a more successful restoration process.

Fructification phenology as an important tool in the recovery of iron mining areas in Minas Gerais, Brazil / Fenologia da frutificação como importante ferramenta na recuperação de áreas de mineração de ferro em Minas Gerais, Brasil

"Canga" is a name given to the ferruginous rocky fields that can be found in the "Quadrilátero Ferrífero" of Minas Gerais, Brazil. The endemism and species richness make them areas of special biological importance, regarded as high-priority for conservation. Nevertheless, they are being threatened by intense mining activity. Aiming to understand more about this flora, this study was performed in order to determine the maturation or dispersal period of the fruits of four Canga species, Alibertia vaccinioides K.Schum. (Rubiaceae), Coccoloba acrostichoides Cham. (Polygonaceae), Miconia sellowiana Naudin (Melastomataceae), and one probable new species of Calyptranthes Sw. (Myrtaceae). Although fruit maturation or dispersal tended to occur at the end of the dry season, some asynchrony was observed in these species, with food sources being available during most of the year. This shows that these species have the potential to attract animals the whole year round, and planting them for the recovery of iron mining areas may increase the community's self-regeneration capacity, leading to a more successful restoration process.

Canga é um nome dado para os campos rupestres ferruginosos encontrados no Quadrilátero Ferrífero de Minas Gerais. O endemismo e riqueza de espécies os tornam uma área de importância biológica especial, considerada prioritária para conservação. Além disso, tem sido submetida à intensa atividade mineradora. Este estudo objetivou determinar as épocas de maturação/dispersão de frutos de quatro espécies de ocorrência na canga, Alibertia vaccinioides K. Schum. (Rubiaceae), Coccoloba acrostichoides Cham. (Polygonaceae), Miconia sellowiana Naudin (Melastomataceae) e de uma provável espécie nova de Calyptranthes Sw. (Myrtaceae). Apesar da maturação/dispersão dos frutos ter apresentado uma tendência de ocorrer no final da estação seca, foi constatada uma assincronia do evento entre essas espécies, com disponibilidade de alimento aos animais frugívoros ao longo de grande parte do ano. O plantio dessas espécies para recuperação de áreas ferruginosas similares degradadas pela mineração poderá atrair fauna durante todas as estações, aumentando o potencial de autorregeneração da comunidade e o consequente sucesso no processo de restauração.