Ecophysiological response of Eucalyptus camaldulensis to dust and lead pollution

Background: Air and soil pollution are among the main concerns in urban areas worldwide, and dust and heavy metals are major contributors to environmental pollution. Lead (Pb) is a highly toxic heavy metal that badly affects human health as well as plant's survival and growth. Vegetation can play an important role in ameliorating the effects of these pollutants. Eucalyptus camaldulensis is well adapted and cultivated throughout a wide range of urban environments from temperate to tropical climates. Methods: A 90 days experiment was conducted to investigate the effects of lead (Pb) and dust pollution on the growth performance of young E. camaldulensis plants. Four months old seedlings were treated with a factorial combinations of Pb (0,10 and 20 mg/l applied in irrigation) and dust levels (0,5 and 10 g applied on foliage). Results: All morphological traits (root length, shoot length, stem diameter) and biomass (root and shoot, fresh and dry mass) of E. camaldulensis were significantly reduced when exposed to higher Pb and dust levels. The highest Pb treatments exhibited greater Pb accumulation in plant roots (23.54 ± 1.61 mg/kg), shoots (15.53 ± 1.98 mg/kg), and leaves (13.89 ± 1.49 mg/kg). Dust load on leaves was greater (72.78 ± 8.1 mg/cm2) for those treatments with higher dust and Pb additions compared to the control (16.11 ± 2.0 mg/cm2). Chlorophyll content was greater at the start of the experiment (68.78 ± 0.74 mg.g-1FW) and progressively decreased over time consistently with the increase of Pb and dust levels applied. Conclusions: The results of the experiment, suggest that E. camaldulensis could be successfully grown in minimum to moderate Pb and dust polluted urban environments.

Selecting Biomonitors of Atmospheric Nitrogen Deposition: Guidelines for Practitioners and Decision Makers

Environmental pollution is a major threat to public health and is the cause of important economic losses worldwide. Atmospheric nitrogen deposition is one of the most significant components of environmental pollution, which, in addition to being a health risk, is one of the leading drivers of global biodiversity loss. However, monitoring pollution is not possible in many regions of the world because the instrumentation, deployment, operation, and maintenance of automated systems is onerous. An affordable alternative is the use of biomonitors, naturally occurring or transplanted organisms that respond to environmental pollution with a consistent and measurable ecophysiological response. This policy brief advocates for the use of biomonitors of atmospheric nitrogen deposition. Descriptions of the biological and monitoring particularities of commonly utilized biomonitor lichens, bryophytes, vascular epiphytes, herbs, and woody plants, are followed by a discussion of the principal ecophysiological parameters that have been shown to respond to the different nitrogen emissions and their rate of deposition.

Root and Shoot Response to Nickel in Hyperaccumulator and Non-Hyperaccumulator Species

The soil–root interface is the micro-ecosystem where roots uptake metals. However, less than 10% of hyperaccumulators’ rhizosphere has been examined. The present study evaluated the root and shoot response to nickel in hyperaccumulator and non-hyperaccumulator species, through the analysis of root surface and biomass and the ecophysiological response of the related aboveground biomass. Ni-hyperaccumulators Alyssoides utriculata (L.) Medik. and Noccaea caerulescens (J. Presl and C. Presl) F.K. Mey. and non-hyperaccumulators Alyssum montanum L. and Thlaspi arvense L. were grown in pot on Ni-spiked soil (0–1000 mg Ni kg−1, total). Development of root surfaces was analysed with ImageJ; fresh and dry root biomass was determined. Photosynthetic efficiency was performed by analysing the fluorescence of chlorophyll a to estimate the plants’ physiological conditions at the end of the treatment. Hyperaccumulators did not show a Ni-dependent decrease in root surfaces and biomass (except Ni 1000 mg kg−1 for N. caerulescens). The non-hyperaccumulator A. montanum suffers metal stress which threatens plant development, while the excluder T. arvense exhibits a positive ecophysiological response to Ni. The analysis of the root system, as a component of the rhizosphere, help to clarify the response to soil nickel and plant development under metal stress for bioremediation purposes.

Ecophysiological response of Astronium fraxinifolium (Anacardiaceae) in degraded and non-degraded brazilian Cerrado

Plants native from Cerrado generally have peculiar characteristics that allow tolerating water and nutritional stress. Astronium fraxinifolium is a Anacardiaceae tree of from Brazilian Cerrado. The aim of this research was to characterize A. fraxinifolium leaves morphophysiologically, in order to recognize characteristics related to acclimatization of the species in different soil conditions. Two populations of A. fraxinifolium were sampled in different study areas, A1 (Degraded Soil) and A2 (“Undegraded Soil”). Nitrogen compounds, total carbohydrates, chlorophyll, nutritional content, stomatal density and gas exchanges were quantified, comparing the areas. A high number of stomata was observed on the abaxial surface of A. fraxinifolium leaves, with a higher density occurring in A1 individuals. The values of chlorophyll and boron content were significantly higher in A2 plants. It’s possible that the lowest concentration of boron in A1 plants is related to chlorophyll production. Regardinf the other analysis, there weren’t significant differences between the areas. The results show that this species undergoes changes in production of chlorophyll, but liquid photosynthesis isn’t impaired, considering the low chlorophyll content in A1 being compensated by the higher stomatal density. Thus, these changes may be the result of acclimating this species to different environmental conditions to which it’s exposed.

Interrelation of Ecophysiological and Morpho-Agronomic Parameters in Low Altitude Evaluation of Selected Ecotypes of Sweet Potato (Ipomoea batatas [L.] Lam.)

Sweet potato is a crop with a wide capacity to adapt to adverse conditions. To study the tolerance of the sweet potato to a low-altitude environment, 34 genotypes comprising three groups from different altitude conditions ranging from 18–599, 924–1298, 1401–2555 meters above sea level were evaluated. These genotypes were evaluated through ecophysiological parameters: net photosintetic rate (Pn), stomatal conductance (GS), transpiration (E), leaf internal CO2 (ICO2), vapor pressure deficit (VPD) and leaf internal temperate (LT). sSubsequently, water use efficiency (WUE) and carboxylation efficiency index (CEI) were estimated. Simultaneously, morpho-agronomic characterization of the genotypes was conducted including descriptors and morpho-colorimetric parameters. A wide ecophysiological variability was found among genotypes from high, intermediate and low altitudes, when those were evaluated under low altitude conditions. The genotypes that presented major soil coverage efficiency and leaf size showed greater Pn, WUE and CEI, and Low VPD and E, aspects that benefited the ability to form roots the under low-altitude environment. The altitudinal origin of the genotypes influenced the ecophysiological response under low altitude conditions. The capacity of certain sweet potato genotypes to tolerate low altitude conditions were due to to different mechanisms, such as certain morphoagronomic traits that allowed them to adjust their physiological processes, especially those related to photosynthesis.

Frequency distribution of foliar nickel is bimodal in the ultramafic flora of Kinabalu Park (Sabah, Malaysia)

Background and Aims The aim of this study was to test the frequency distributions of foliar elements from a large dataset from Kinabalu Park (Sabah, Malaysia) for departure from unimodality, indicative of a distinct ecophysiological response associated with hyperaccumulation. Methods We collected foliar samples (n = 1533) comprising 90 families, 198 genera and 495 plant species from ultramafic soils, further foliar samples (n = 177) comprising 45 families, 80 genera and 120 species from non-ultramafic soils and corresponding soil samples (n = 393 from ultramafic soils and n = 66 from non-ultramafic soils) from Kinabalu Park (Sabah, Malaysia). The data were geographically (Kinabalu Park) and edaphically (ultramafic soils) constrained. The inclusion of a relatively high proportion (approx. 14 %) of samples from hyperaccumulator species [with foliar concentrations of aluminium and nickel (Ni) >1000 μg g–1, cobalt, copper, chromium and zinc >300 μg g–1 or manganese (Mn) >10 mg g–1] allowed for hypothesis testing. Key Results Frequency distribution graphs for most elements [calcium (Ca), magnesium (Mg) and phosphorus (P)] were unimodal, although some were skewed left (Mg and Mn). The Ni frequency distribution was bimodal and the separation point for the two modes was between 250 and 850 μg g–1. Conclusions Accounting for statistical probability, the established empirical threshold value (>1000 μg g–1) remains appropriate. The two discrete modes for Ni indicate ecophysiologically distinct behaviour in plants growing in similar soils. This response is in contrast to Mn, which forms the tail of a continuous (approximately log-normal) distribution, suggestive of an extension of normal physiological processes.