Changes in growth and reproductive phenology of Allagoptera arenaria (Arecaceae) under climate change scenarios.

Climate change has led to shifts in phenology in many species distributed widely across taxonomic groups. It is, however, unclear how we should interpret these shifts without some sort of a yardstick. We assessed climate change effects on Allagoptera arenaria, a acaulescent palm, using open top chambers (OTCs) and rain gutters in the field to mimic expected temperature and rainfall changes in this area. In a coastal environment (restinga), using open top chambers (OTCs) and rain gutters in the field to mimic expected temperature and rainfall changes in this area, 40 A. arenaria individuals were selected and randomly allocated to four treatments: control (C), 25% rainfall increase (P), 2 °C temperature increase (T), and 2 °C temperature plus 25% rainfall increase (TP). For 2 years, every two weeks, we measured changes in growth and reproduction phenology to assess whether this species altered allocation patterns in response to new environmental conditions. Increases in aboveground biomass were higher in the TP than in the T treatment, which in turn had more reproductive cycles throughout the experimental period. We conclude that temperature increases may shorten the reproductive cycle of A. arenaria.

Photosystem II Performance of Coffea canephora Seedlings after Sunscreen Application.

In the conilon coffee tree, the stress caused by high light can reduce the photosynthetic rate, limit the development and also reduce the yield of beans. Considering that the quality of a sunscreen spray can influence photosynthetic performance, the goal was to understand the iterations between the quality of the spray and the variation of the chlorophyll a fluorescence when applying sunscreen on conilon coffee trees. The parameters coverage, volumetric median diameter, density, droplet deposition, and the variation of the chlorophyll a fluorescence were evaluated. The nozzle and application rate factors did not show direct effects in the physiological responses of the plants. Plants with no sunscreen application showed high values of energy dissipation flux. The photosystem II (PSII) performance index and PSII photochemical maximum efficiency indicate that the use of sunscreen for plants promotes better performance of photosynthetic activity and that it provides photoprotection against luminous stress, regardless of the application rate and spraying nozzle; however, we recommend using the application rate of 100 L ha-1 and the cone jet nozzle type because they provide lower risks of product loss due to runoff.

Anatomical and physiological responses of Aechmea blanchetiana (Bromeliaceae) induced by silicon and sodium chloride stress during in vitro culture.

Salt stress is one of the most severe abiotic stresses affecting plant growth and development. The application of silicon (Si) is an alternative that can increase the tolerance of plants to various types of biotic and abiotic stresses. The objective was to evaluate salt stress's effect in vitro and Si's mitigation potential on Aechmea blanchetiana plants. For this purpose, plants already established in vitro were transferred to a culture medium with 0 or 14 µM of Si (CaSiO3). After growth for 30 days, a stationary liquid medium containing different concentrations of NaCl (0, 100, 200, or 300 µM) was added to the flasks. Anatomical and physiological analyses were performed after growth for 45 days. The plants cultivated with excess NaCl presented reduced root diameter and effective photochemical quantum yield of photosystem II (PSII) (ΦPSII) and increased non-photochemical dissipation of fluorescence (qN). Plants that grew with the presence of Si also had greater content of photosynthetic pigments and activity of the enzymes of the antioxidant system, as well as higher values of maximum quantum yield of PSII (FV/FM), photochemical dissipation coefficient of fluorescence (qP) and fresh weight bioaccumulation of roots and shoots. The anatomical, physiological and biochemical responses, and growth induced by Si mitigated the effect of salt stress on the A. blanchetiana plants cultivated in vitro, which can be partly explained by the tolerance of this species to grow in sandbank (Restinga) areas.

Mangroves as traps for environmental damage to metals: The case study of the Fundão Dam.

This essay is a conceptual framework for testing the causal mechanisms of system degradation by metals in the mangrove ecosystem. The Fundão Dam collapse caused massive damage to the marine environment on the Southern Atlantic and Brazilian coast, reaching various kilometers from its origin, becoming a source of contamination. Along this Brazilian coast are vast mangrove areas with high biodiversity, different geomorphology, and distinct ecological functioning. These mangroves support fisheries' productivity in the Tropical South Atlantic, in connection with Abrolhos Reef. Brazil does not have a protocol to monitor environmental damage in this ecosystem, and we proposed to develop a way to identify the impact and quantify it. Along the estuaries, to assess the damage, the plots were demarked in three regions: the upper, middle, and lower estuary, and in both types of forest: fridge and basin. Samples of sediment and leaves were collected bi-monthly to evaluate metal concentrations, especially iron and manganese, the most abundant metals in Fundão Dam. The monitoring also evaluated the forest structure, dynamics of the crabs' population, and flora productivity. First-year monitoring identifies a high concentration of iron or manganese in the sediment above the NOAAs' recommendation in all the estuaries. The concentration of Fe and Mn in sediment varies seasonally in magnitude, concentration, and types of metals between estuaries, sectors, and forests. The behavior of biological indicators in the presence of metals (type and concentration) differed between fauna and flora species. The monitoring recognized that the tailings mining from Fundão Dam impacted all estuaries by different magnitudes and persistence. These differences are due to geomorphology diversity, climate, and oceanographic influences.