Response of Lippia sidoides to different irrigation depths

Evaluating the response of medicinal plants to irrigation is not very common, especially when they are native species with economic potential, such as the Lippia sidoides. Thus, this study aimed at evaluating the Lippia sidoides response, by using the Ky coefficient, and growth, under different irrigation depths. The coefficients were determined from the dry matter and essential oil yields. The experiment used a randomized blocks design, with treatments consisting of seven irrigation depths (0.5, 0.75, 1.0, 1.2, 1.4, 1.65 and 1.9 of the Eto), with three replications. The ETo was evaluated by using the Penman-Monteith method and the ETr according to the soil water balance. Growth was determined by measuring the stem diameter and height, at 35, 56, 77, 98 and 119 days after transplanting. At 120 days of cultivation, samples were collected to determine the dry matter and essential oil yields. The plant responded to water deficit with coefficients above 1.0, for both dry matter and essential oil yields. Growth was positively affected by irrigation, reaching higher values for stem diameter and height when the highest irrigation depths were used

Use of light-emitting diode (LED) in the physiology of cultivated plants – review

The objective of this study was to demonstrate the effects of the use of LED bulbs in the physiology of cultivated plants. Light-emitting diodes (LEDs) have been proposed as a light source for controlled environments or in plant growth chambers, since they have desirable characteristics for plant development. The development and physiology of plants are strongly influenced by the environment light spectrum provided by the LEDs, among which we can mention the blue, red, green, and their combinations. The blue light, for example, is responsible for a number of important photomorphogenetic features in plants, including stomatal control. Studies indicate that the red wavelength is efficiently absorbed by the pigments present in the plants, since its wavelength is very close to the absorption peak of chlorophyll. The relevance of green light responses is based on the assumption that there are situations in nature that the plant may find conditions of increased green radiation in its growing environment. LED bulbs offer many advantages as radiation sources for plants, but there are difficulties that delay their implementation for applications in the plant cultivation. With the advancement of technologies, the characteristics and performance of LED bulbs, as a source of radiation for plants, tend to be improved. However, this efficiency varies among the light spectra and the species. Thus, the advancement in the use of LEDs in the protected cultivation of cultivated plants is linked to specific physiological responses of each species

Crescimento inicial de Dalbergia nigra (Vell.) Allemão ex. Benth. (Fabaceae) e Chorisia speciosa A.St.-Hil (Malvaceae) sob diferentes níveis de sombreamento

A produção de mudas florestais, seja com finalidade econômica ou conservacionista, depende de conhecimentos relacionados ao crescimento e desenvolvimento vegetal. O estudo de uma planta em diferentes condições ambientais permite definir e aprimorar formas de cultivos mais adequadas. No trabalho, objetivou-se avaliar o crescimento de mudas de Dalbergia nigra (jacarandá caviúna) e Chorisia speciosa (paineira) cultivadas em casas de vegetação sob diferentes níveis de sombreamento, com o intuito de determinar o sombreamento mais adequado ao crescimento e relacionar suas respostas ao contexto ecológico. As sementes das espécies foram germinadas e cultivadas em casas de vegetação nas condições de 0, 22, 50, 70, 84 e 91 % de sombreamento. As variáveis analisadas foram altura de plantas, diâmetro do colo, área foliar total e a relação altura/diâmetro, sendo coletados os dados aos 30, 60, 90 e 180 dias após a emergência. As mudas de jacarandá caviúna tiveram maior altura, diâmetro do colo e área foliar nos tratamentos com sombreamento intermediários (50%, 70% e 84% de sombra) e apresentou características de espécies tolerantes a sombra e de estágios mais avançados de sucessão, se aproximando de espécies secundárias tardias a clímax. Por outro lado, as mudas de paineira apresentaram melhor crescimento no tratamento sem sombra (0%) e nos tratamentos com sombreamentos leves (20 e 50%), com características de espécies heliófitas em etapas iniciais de sucessão e aproximando-se de plantas pioneiras a secundárias iniciais

Resistance Mechanisms of Peltophorum dubium (Sprengel) Taubert Submitted to Flood Conditions

ABSTRACT Peltophorum dubium (Sprengel) Taubert seedlings were submitted to 60 days of flooding, with and without Ca+. During this period, growth, root anatomy and chlorophyll content were analyzed. The relative growth rates (RGR) of roots and shoots were higher in non-flooded plants. The flooded treatments, with and without Ca+, have affected the roots growth but did not affect the shoot and the stem diameter. The anatomy analysis showed thickening of the sclerenchyma in 15 and 60 days in the flooded treatments with and without Ca+, and the vessel diameter was smaller at 45 days. The chlorophyll content differed, however it was not statistically significant. The results indicate that Peltophorum dubium as candidate specie for reforestation in areas subjected to continuous flooding for up to 60 days, since no mortality was observed