Buffelgrass (Pennisetum ciliare) land conversion and productivity in the plains of Sonora, Mexico

Bufflelgrass (Pennisetum ciliare syn. Cenchrus ciliaris) is an African grass that has been widely introduced in subtropical arid regions of the world to improve rangelands for cattle production. However, it can have a negative effect on the diversity of native plant communities. Buffelgrass was introduced to Sonora, Mexico in the 1970s as a means to bolster the cattle industry. “Desmonte,” the process by which native desert vegetation is removed in preparation for buffelgrass seeding, alters the land surface such that buffelgrass plots are easily detectable from aerial and Landsat satellite images. We estimated the extent of conversion to buffelgrass in a 1,850,000 ha area centered on Hermosillo, from MSS and TM images from 1973, 1983, 1990 and 2000. We then compared the relative above-ground productivity of buffelgrass to native vegetation using Normalized Difference Vegetation Index values (NDVI) from Landsat and Moderate Resolution Imaging Spectrometer (MODIS) satellite sensor systems. Buffelgrass pastures have increased from just 7700 ha in 1973 to over 140,000 ha in 2000. Buffelgrass pastures now cover 8% of the land surface in the study area. Buffelgrass pastures have lower net primary productivity, estimated by MODIS NDVI values, than unconverted desert land. The desmonte process removes trees and shrubs, while the buffelgrass plantings are often sparse, leading to an apparent net loss in net primary production from land conversion. We recommend that the desmonte process be discontinued until its efficacy and safety for native ecosystems can be established, and that a comprehensive plan for preserving biodiversity while accomodating economic development be established for this region of the Sonoran Desert in Mexico.     

Temporal variation in breeding,foraging and bird sanctuary visitation by a Southern African Population of great white pelicans Pelecanus onocratalus

Temporal variation in visitation, breeding and foraging during 1977–1978 at a breeding site and a proclaimed bird sanctuary are described for a southern African population of great white pelicans Pelecanus onocratalus. Foraging activity and sanctuary visitation were at low levels during the austral winter (May–August). The pelicans bred at only one site, Dassen Island (33° 25t?, 18° 12′ E), in three major waves in spring and summer (September–March), coinciding with periods of high visitation and foraging activity at Rondevlei Bird Sanctuary (34° 04′S, 18° 30′ E), an important foraging and roosting site within the range of the population. Temporal variation in these aspects of pelican biology is influenced by the fluctuating availability of suitable foraging habitat and fish prey. Water depth and rainfall, those environmental factors which appear to affect the availability of foraging habitat and fish prey, were correlated strongly negatively with measures of pelican foraging activity and sanctuary visitation during 1977–1978. They were also negatively correlated with measures of sanctuary visitation calculated for a 22-year period. Therefore, these factors may have influenced patterns of foraging and visitation of this great white pelican population over the long term.     

Effects of Two Energy-Restricted Diets Containing Different Fruit Amounts on Body Weight Loss and Macronutrient Oxidation

The consumption of specific foods in energy-restricted diets may affect the weight loss process. The purpose of this research was to evaluate whether obese women following two hypocaloric diets with distinct fruit content differ in weight loss and metabolic responses. Fifteen obese women were included, who were randomly assigned to follow a low or a high-fruit energy-restricted diet for 8 weeks. The main outcome variables were weight and fat losses. Metabolic measurements concerning macronutrient oxidation were also assessed by using ¹³C labelled fructose and indirect calorimetry. The induced weight loss was similar for both diets (6.9 ± 2% vs. 6.6 ± 2%, p = 0.785). Both experimental diets similarly improved the lipid plasma profile in the participants, but the cholesterol fall was higher in obese subjects receiving the diet containing more fruit. No statistical differences in lipids carbohydrates and ¹³C labelled fructose utilisation were observed, but protein oxidation was differently affected by the experimental diets. The compensatory effects of the associated fibre/fructose intake may explain the lack of a specific effect of the fruit amount on hypocaloric diets designed to weight loss, although the increased fibre content from enriched fruit diets may be involved in the favourable effects on cholesterol plasma levels.     

Interpreting vegetation indices

Remotely sensed spectral vegetation indices are widely used and have benefited numerous disciplines interested in the assessment of biomass, water use, plant stress, plant health and crop production. The successful use of these indices requires knowledge of the units of the input variables used to form the indices, and an understanding of the manner in which the external environment and the architectural aspects of a vegetation canopy influence and alter the computed index values. Although vegetation indices were developed to extract the plant signal only, the soil background, moisture condition, solar zenith angle, view angle, as well as the atmosphere, alter the index values in complex ways. The nature of these problems are explored both in an empirical and in a theoretical sense, and suggestions are offered for the effective use and interpretation of vegetation indices.     

Assessment of the Potential Cyto�CGenotoxicity of the Nonsteroidal Anti-Inflammatory Drug (NSAID) Diclofenac on the Zebra Mussel (Dreissena polymorpha)

A battery of eight biomarkers was used on the freshwater bivalve Dreissena polymorpha in order to evaluate potential sub-lethal effects of the nonsteroidal anti-inflammatory drug diclofenac (DCF; 2-[(2,6-dichlorophenyl)amino]phenylacetic acid). By an in vivo approach, mussels were exposed for 96 h to increasing concentrations (0.3, 1, and 2 nM) of DCF perfectly comparable with current surface water levels. We determined the single cell gel electrophoresis assay, the apoptotic frequency (DNA Diffusion assay), the micronucleus test (MN test), and the lysosomal membrane stability (Neutral Red Retention Assay) in mussel hemocytes. Moreover, the activity of catalase, superoxide dismutase, glutathione peroxidase, and the phase II detoxifying enzyme glutathione S-transferase was measured in the cytosolic fraction extracted from a pool of entire bivalves to reveal possible alterations of the oxidative status of exposed specimens. The biomarker battery pointed out a negligible cyto- and genotoxicity on zebra mussel hemocytes since only a slight decrease of lysosomal membrane stability from baseline levels was measured at the end of exposures at the highest concentration (2 nM). In addition, environmental concentrations of DCF seem to have a negligible effect on the activities of antioxidant and detoxifying enzymes.     

Antioxidant Activity in the Zebra Mussel (Dreissena polymorpha) in Response to Triclosan Exposure

The biocide triclosan (TCS, 5-chloro-2-(2,4-dichlorophenoxy)phenol) is commonly used in several personal care products, textiles, and children??s toys. Because the removal of TCS by wastewater treatment plants is incomplete, its environmental fate is to be discharged into freshwater ecosystems, where its ecological impact is largely unknown. The aim of this study was to determine the effect of TCS on the antioxidant enzymatic chain of the freshwater mollusk zebra mussel (Dreissena polymorpha). We measured the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), as well as the phase II detoxifying enzyme glutathione S-transferase (GST) in zebra mussel specimens exposed to 1 nM, 2 nM, and 3 nM TCS in vivo. The mussels were exposed for 96 h, and the enzyme activities were measured every 24 h. We measured clear activation of GST alone at all three dose levels, which shows a poor induction of the antioxidant enzymatic chain by TCS. CAT and SOD were activated only at 3 nM, while GPx values overlapped the baseline levels.     

Correlations between disease severity,glucosinolate profiles and total phenolics and Xanthomonas campestris pv. campestris inoculation of different Brassicaceae

Many Brassicaceae species are economically important crops and Xanthomonas campestris pv. campestris (Xcc), the causal agent of black rot, is considered one of the most important necrotrophic plant bacterial diseases occurring worldwide on these and many other crops. Therefore identifying resistance mechanisms and genes is crucial. Researchers continue to investigate the role of phytochemicals (plant secondary metabolites) in protecting plants against diseases and pathogens. Glucosinolates (GLS), and more specifically their hydrolysis products, are known to have various biological effects including antimicrobial activity. From the positive results of initial in vitro studies with Xcc and other pathogenic bacteria new experiments were designed to evaluate the possible in planta role of GLS, and also phenolics, in the interaction with Xcc. The in planta studies, with various Brassicaceae seedlings, have shown a correlation between GLS profiles, and therefore the subsequent hydrolysis products, and the inhibition of Xcc growth. There were no significant correlations between Xcc infection and total phenolics. Positive correlations were found between specific and total GLS contents and the severity of disease. Further in vitro and in planta studies need to be performed to evaluate the role of GLS and other defense mechanisms in Xcc and other important bacterial infections of Brassicaceae crops.     

Relation of peel damage in citrus fruit to wind climate in orchard and its control

Peel damage originated by wind is the main abiotic cause of citrus fruit discards for export in Uruguay. Natural windbreaks such as Eucalyptus and Casuarinas have not been effective in reducing it. This research was carried out during three years in a citrus orchard situated in the coastal plain of Uruguay (35° SL). The purpose of this work was to study wind climate inside the orchard, fruit seasonal sensitivity, basal leaf effect on the onset and evolution of peel damage, and the efficiency of artificial windbreaks to reduce fruit discard of ‘Ellendale’ tangor. Average wind velocity in the orchard did not exceed 5 m s⁻¹. First peel scars were evident two weeks after petal fall and damaged fruit percentage importantly increased during the first stage of fruit growth. Low energy vortexes caused almost permanent friction between basal leaves and the developing fruitlets growing in their axil. Removal of the basal leaf decreased significantly wind damaged fruit. Natural wind flow modification through the use of semi-porous artificial windbreak nets (5 cm by 10 cm mesh) modified low energy vortexes and increased significantly the percentage of export quality fruit. We conclude that this type of net is more efficient than natural windbreaks or classical nets to reduce wind damage in citrus fruit.     

Colonization of <Emphasis Type="Italic">Arabidopsis</Emphasis> roots by <Emphasis Type="Italic">Trichoderma atroviride</Emphasis> promotes growth and enhances systemic disease resistance through jasmonic acid/ethylene and salicylic acid pathways

Trichoderma spp. are common soil fungi used as biocontrol agents due to their capacity to produce antibiotics, induce systemic resistance in plants and parasitize phytopathogenic fungi of major agricultural importance. The present study investigated whether colonization of Arabidopsis thaliana seedlings by Trichoderma atroviride affected plant growth and development. Here it is shown that T. atroviride promotes growth in Arabidopsis. Moreover, T. atroviride produced indole compounds in liquid cultures. These results suggest that indoleacetic acid-related indoles (IAA-related indoles) produced by T. atroviride may have a stimulatory effect on plant growth. In addition, whether colonization of Arabidopsis roots by T. atroviride can induce systemic protection against foliar pathogens was tested. Arabidopsis roots inoculation with T. atroviride provided systemic protection to the leaves inoculated with bacterial and fungal pathogens. To investigate the possible pathway involved in the systemic resistance induced by T. atroviride, the expression profile of salicylic acid, jasmonic acid/ethylene, oxidative burst and camalexin related genes was assessed in Arabidopsis. T. atroviride induced an overlapped expression of defence-related genes of SA and JA/ET pathways, and of the gene involved in the synthesis of the antimicrobial phytoalexin, camalexin, both locally and systemically. This is the first report where colonization of Arabidopsis roots by T. atroviride induces the expression of SA and JA/ET pathways simultaneously to confer resistance against hemibiotrophic and necrotrophic phytopathogens. The beneficial effects induced by the inoculation of Arabidopsis roots with T. atroviride and the induction of the plant defence system suggest a molecular dialogue between these organisms.     

Effect of pre-germination treatment with direct magnetic field exposure: a systematic review and meta-analysis

The search for ecological technologies that favour germination processes in agricultural and forestry seeds is a topic of interest as an environmentally friendly option. This study was a systematic review and meta-analysis to examine whether magnetic field direct exposure of seeds has a specific effect on germination. Using Scopus (2000–2020) and Web of Science (2000–2020) databases, a bibliographic search was carried out using the following expressions (pre-sowing AND seed AND magnetic) to filter the references in the title, abstract and keywords of the articles published. The calculation and declaration of the effect size was performed by comparing binary results through applying the Odds-Ratio register with a 95% confidence interval (CI). The random effects model was applied with the DerSimonian and Laird method. A total of 175 articles were found, of which only 26 were accepted for systematic review and meta-analysis. Three subgroups were established according to the magnetic field strengths. The subgroup corresponding to intensities between 1 and 50 mT presented an Odds-Ratio of 0.49 with a CI of (0.19, 0.79), Q (14)?=?24.77, p?=?0.04, indicating that the treatment had a significant effect. The remaining subgroups showed no significant effect. Likewise, the global meta-analysis revealed a significant effect in favour of the treatment, with an Odds-Ratio of 0.68, a CI of (0.41, 0.94), Q (28)?=?44.03, p?=?0.03. From the studies included in the meta-analysis, the results show a significant effect of seed direct exposure to magnetic fields that can be used to increase seed germination.