Biostimulant activity of two protein hydrolyzates in the growth and nitrogen metabolism of maize seedlings

Two protein hydrolyzate–based fertilizers (PHFs), one from alfalfa (AH) and one from meat flour (MFH), were studied chemically and biologically. AH and MFH revealed a different degree of hydrolysis and a different amino acid composition. The biostimulant activity was investigated using two specific and sensitive bioassays of auxins and gibberellins. Extracts of AH and MFH elicited a gibberellin‐like activity and a weak auxin‐like one. To improve our understanding of the biostimulant activity, AH and MFH were supplied to maize plants and their effect on growth and nitrate metabolism was studied. Both PHFs increased root and leaf growth and induced morphological changes in root architecture. Besides, the treatments increased nitrate reductase (NR) and glutamine synthetase (GS) activities, suggesting a positive role of the two hydrolyzates in the induction of nitrate conversion into organic nitrogen. Moreover, treatments enhanced GS1 and GS2 isoforms in maize leaves. The latter isoform, amounting to 5‐ to 7‐fold the level of the former, appears to be a superior form in the assimilation of ammonia. The high NR and GS activities together with the high induction of GS isoforms indicate a stimulatory effect of the two PHFs on the assimilation of nitrate. In addition, a role of amino acids and small peptides of the two PHFs is suggested in the regulation of the hormone‐like activity and nitrogen pathway.     

Molecular sequence data of Thecaphora frezii affecting peanut crops in Argentina

In Argentina, Thecaphora frezii is the causal agent of peanut smut, causing severe yield losses in peanut growing areas. In this work sequence data of the large ribosomal subunit (28S rDNA) of four T. frezii specimens from different production regions are provided. A fragment of about 650 bp was amplified by PCR from each of the isolates analyzed. The analysis of the sequences demonstrated 100 % identity among the four specimens and 92–96.3 % identity with sequences of other species of Thecaphora. This is the first study on molecular sequences of this pathogen.     

Heavy metals in soils and sedimentary deposits of the Padanian Plain (Ferrara, Northern Italy): characterisation and biomonitoring

Purpose

This contribution investigates agricultural soils and sedimentary deposits in the province of Ferrara (Padanian alluvial plain, Northern Italy) in order to: examine their genesis; to define the geochemical background of the area; and to evaluate the existence of anthropogenic contamination. Moreover, environmental risk related to the presence of potentially toxic heavy metals that can be transferred into agricultural products (and consequently bio-accumulated in the food chain) was also assessed.

Materials and methods

The analyses (reported in an extensive supplementary dataset) include XRD, XRF and ICP-MS assessment of bulk sediments, tests of metal extraction with aqua regia, as well as analyses of local agricultural products, i.e. biomonitoring which is important in the evaluation of element mobility.

Results and discussion

Based on the results, GIS-based geochemical maps were produced and local background levels were defined. This approach demonstrated that high concentrations of Cr and Ni is a natural (geogenic) feature of the local alluvial terrains, which in turn is related to the origin and provenance of the sediments, as confirmed by the lack of top enrichment in all of the investigated sites. Tests of metal extraction and analyses of agricultural products provide guidelines for agricultural activities, suggesting that extensive use of sewage sludge, industrial slurry and manure (that are often rich in metals) should be minimised.

Conclusions

The dataset reported in this paper shows that the agricultural terrains of the studied alluvial plain are not characterised by anthropogenic heavy metal pollution. In spite of the elevated natural background of Cr and Ni, most of the local agricultural products do not show significant evidence of bio-magnification. Exceptions are represented by forage grass (alfalfa) and corn (maize) that tend to uptake As and Ni, respectively. This demonstrates that in agricultural areas, a geochemical risk assessment must include both soil and plant investigations.     

Direct colloid osmometry in healthy New World camelids

Background: Direct colloid osmometry provides an objective assessment of the oncotic effects of crystalloid or colloidal fluid therapy, which is especially useful in monitoring fluid therapy of critically ill camelids due to their tendency toward nonspecific hypoproteinemia with increased risk of developing edema and ascites. Objectives: The aims of this study were to measure colloid osmotic pressure (COP) of alpacas and llamas, determine its correlation with concentrations of total protein (TP) and total solids (TS), as well as both albumin (A) and globulin (G) concentrations in the same model (A+G), and evaluate the effects of sample type and storage conditions on COP. Methods: Blood was collected from clinically healthy alpacas (n=23) and llamas (n=22) into heparin tubes. COP of fresh whole blood (COP_FB) and plasma (COP_FP) was determined using a membrane osmometer. For 20 alpacas, COP of refrigerated whole blood (COP_RB) and frozen plasma (COP_FrP) was also measured. Correlations between COP_FB and TS, TP, and A+G concentrations were assessed by simple and multiple regression analysis to model potential predictors. Results: Median COP_FB from alpacas (24.6 mmHg, range 19.3–28.1) was not significantly different from that of llamas (25.3 mmHg, range 22.5–33.7). Sample type or storage conditions did not affect COP. Measured COP had a strong positive linear correlation with TS, TP, and A+G concentrations in alpacas (r²=.7, .74, and .88, respectively). In llamas, COP correlated best with TS concentration (r²=.59), whereas correlation with TP and A+G concentrations was poor (r²=.19 and .25, respectively). Conclusion: COP can be measured using heparinized whole blood or plasma, either fresh or stored. Direct measurement is recommended whenever quantitative knowledge of COP is required in clinical or research setting. Further studies are needed to verify if the poor association of COP with TP found in this study can be generalized to llamas.     

Effects of dobutamine on cardiovascular function and oxygen delivery in standing horses

Dobutamine is routinely used to improve cardiovascular function in anaesthetized horses. However, dobutamine in conscious horses is insufficiently investigated. Ten research horses that were already instrumented for a preceding trial were included into the study. Cardiovascular variables were recorded and blood samples taken after instrumentation (Baseline), before starting dobutamine and after 10 min of dobutamine infusion (2 µg kg⁻¹ min⁻¹). A significant increase in systemic blood pressure, mean pulmonary artery pressure and right atrial pressure, and a decrease in heart rate were observed with dobutamine compared with baseline measurements. Arterial and mixed venous haemoglobin and oxygen content, as well as mixed venous partial pressure of oxygen increased. No significant changes in cardiac output, stroke volume, systemic vascular resistance, arterial partial pressure of oxygen, or oxygen consumption, delivery and extraction ratio were detected. Concluding, dobutamine increased systemic blood pressure without detectable changes in stroke volume, cardiac output or systemic vascular resistance in conscious horses.     

The effect of amino acids and amides on the regulation of nitrate uptake by wheat seedlings

Wheat plants grown hydroponically increased their nitrate uptake rate more than two‐fold after three days of N starvation. Exogenously supplied amino acids and amides had no effect on the nitrate uptake rate of plants well nourished in N. After three days of N starvation, however, some of the amino acids and amides supplied to plants inhibited up to 50% of the nitrate uptake rate. The most effective inhibitor was aspartic acid. Asparagine, glutamine or phenylalanine did not show any inhibitory effect. The percentage of inhibition was not increased by increasing the amino acid concentration, nor did the addition of mixed amino acids and amides increase the inhibition exerted by one amino acid alone. During the three days of N starvation, there was a decrease in the concentration of endogenous amino acids in the roots, but not all amino acids decreased their concentration at the same rate.

It is suggested that the endogenous levels of some amino acids may repress the nitrate uptake system in plants well supplied with N. During the development of the N deficiency, the concentration of these amino acid decreases, de‐repressing the nitrate uptake system.     

Neural networks in climate spatialization and their application in the agricultural zoning of climate risk for sunflower in different sowing dates

ABSTRACT

Sunflower is a species that is sensitive to local climate conditions. However, studies that use artificial neural networks (ANNs) to evaluate this influence and create tools such as agricultural zoning of climate risk (ZARC) have not been conducted for this species. Due to the importance of sunflower as a human food source and for biodiesel production, and also the necessity of conducting research to evaluate the suitability of this oleaginous species under different climatic conditions. Thus, we seek to construct a ZARC for sunflower in Brazil simulating sowing on different dates and using meteorological elements spatialized by ANNs. Climate data were used: air temperature (T), rainfall (P), relative air humidity (UR), solar radiation (MJ_m^?2_d^?1) and wind velocity (U²). Climatic regions considered suitable for the cultivation of sunflower had average annual values for T between 20 and 28°C, P between 500 and 1.500 mm per cycle, and soil water deficit (DEF) below 140 mm per cycle. A neural network is an efficient tool that can be used in spatialization of climate variables quickly and accurately. Sunflower sowing in the spring and summer are the ones that provide the largest suitable areas in southeastern Brazil, with 58.13 and 64.36% of suitable areas, respectively.     

Abundance of White-fronted Parrots and diet of an urban parrot assemblage(Aves:Psittaciformes)in a green Neotropical city

Urban ecosystems are evolutionarily recent novel environments acting as biodiversity filters.Psittacidae birds are considered successful urban adapters mainly d...     

Agriculturally intensified landscapes are associated with reduced body condition of lady beetles

Landscape Ecology - Agricultural intensification is contributing to a global species decline. Underlying mechanisms include toxic effects of pesticides on non-target organisms and reductions in...