Dormancy,a critical trait for weed success in crop production systems

Agricultural practices exert selective forces on weed populations. As these practices change over time, weed adaptive traits also evolve, allowing weeds to persist in the new environment. However, only weeds having individuals showing the trait with adaptive significance will be able to cope with these changes, thus allowing a sub‐population to be selected for persistence. In addition, changes in agricultural practices can select new weed species showing functional traits with characteristics adaptive to the modified system. Seed dormancy has long been recognized as a trait with enormous adaptive value to adjust weed biology to cropping systems. In this paper, we illustrate with examples of success and failure, the value of seed dormancy as a functional trait to cope with long‐term changes in crop production systems. We show that successful outcomes are mostly related to the existence of sufficient variability for the functioning of physiological mechanisms that control dormancy characteristics as influenced by the agricultural environment. Presented examples illustrate how knowledge about the relationship that exists between agricultural practices and their selective pressure on seed dormancy can be instrumental in predicting changes in weed biotype dormancy characteristics or foreseeing the appearance of new weed species in future agricultural scenarios. © 2019 Society of Chemical Industry     

Stereological analysis of metanephros from domestic cat (Felis catus,Linnaeus 1798) embryos and fetus

Kidney diseases are the most common illness for cats with a prevalence seven times higher than in dogs. Metanephros is the last of three renal systems to be formed during the embryonic period, which then becomes the permanent kidney. The current work aimed to analyse the morphology and to quantify the structures present in the development of metanephros from domestic cat (Felis catus) embryos and foetuses. For this purpose, the evaluation of the biometric parameters of metanephros from cat embryos and foetuses was performed in addition to the quantification of renal corpuscles and volume of cortical and medullary layers by stereological analysis. The evaluated biometric parameters were weight, width, height, thickness and volume. The values of the measured biometric parameters increased throughout the gestational stages. The quantity of renal corpuscles gradually increased following the embryo-foetal development, mainly during the middle of the gestational stage. It was during this phase that morphologically, a complete corticomedullary division was observed. Although the difference in the quantity of renal corpuscles between the middle and the end of the gestational stages was not statistically significant, there was an increase in the volume of the medullary layer and a decrease in the volume of the cortical layer between these two stages. These findings suggest that the metanephros presents a progressive growth with the renal corpuscles following this development until the middle of the gestational stage. Starting from this phase, the differentiation of the corticomedullary layers can be seen with a significant increase in the medullary layer.     

Growth and Feed Utilization of the Tilapia Hybrid Oreochromis mossambicus×O. niloticus Cultured at Different Salinities under Controlled Laboratory Conditions

Abstract.— Growth and feed utilization of the tilapia hybrid Oreochromis mossainbicus × O. niloticus cultured at different salinities under controlled laboratory conditions were studied for 2 mo. Fish (2.32 g mean initial weight) were grown in 113-L aquaria at salinities of 0.5, 17 and 32 ppt at a density of 20 fish per tank. Mean specific growth, food conversion, and food consumption were determined at each salinity. There was no significant difference ( P > 0.05) in growth among the treatments, although feed conversion and feed consumption were significantly improved (P ≤ 0.05) when fish were grown at 17 and 32 ppt.     

Carbon Fixation and Partitioning in Coffee Seedlings Infested with <Emphasis Type="Italic">Pratylenchuscoffeae</Emphasis>

The objective was to study CO₂ fixation and photoassimilate partition in coffee (Coffea arabica) seedlings infested with the lesion nematode Pratylenchus coffeae. Seedlings infested with 0, 1000 and 8000 Pratylenchus coffeae nematodes were exposed to ¹⁴CO₂ and the incorporation and distribution of radioactivity were followed in the roots, stems and leaves. Fresh mass, pigments, soluble sugars, sucrose and specific radioactivity of sucrose in the plant parts were determined. At the highest level of infestation almost all the parameters were significantly changed showing the carbon fixation in the leaves and partitioning to the roots were decreased. Since lesion nematodes are not sedentary and do not form feeding sites that could be characterised as metabolic sinks, it is suggested that their damage is more readily expressed by the leaves, through a reduction in photosynthesis and phloem transport.     

A financial analysis of treatment strategies for Trypanosoma evansi in the Brazilian Pantanal

The Brazilian Pantanal is a 138 000 km² tropical seasonal wetland located in the center of South America bordering Bolivia and Paraguay. The Pantanal contains approximately 1100 cattle ranches, 3 million cattle, 49 000 horses and a unique diversity of wildlife. Cattle ranching is the most important economic activity in the Pantanal. This study explores the direct financial impacts of the adoption of seven treatment strategies for the control of Trypanosoma evansi in the Brazilian Pantanal. T. evansi adversely affects the health of the horse population in the region. Horses are indispensable to the cattle ranching industry in the Pantanal. Estimated costs include risk of infection, costs of diagnosis, alternative treatments, collecting animals for treatment, and costs of animal losses. The estimated total cost of T. evansi to the Pantanal region's cattle ranchers is about US$2.4 million and 6462 horses/yr. Results indicate that one preventive and two curative treatment strategies are financially justifiable. The best available technology for the treatment of T. evansi from an economic perspective is a curative treatment employed year-round. This treatment represents an annual net benefit of more than US$2 million or US$1845/ranch and spares about 5783 horses. It represents an annual net benefit of over US$200 000 and 600 horses relative to the currently most widely adopted strategy.     

Microbial metabolism of fenoxaprop-ethyl

Fenoxaprop-ethyl was found to be metabolized by a mixed microbial population isolated from a leachate from a landfill. Fenoxaprop acid and 6-chloro-2(3H)-benzoxazolone were detected as metabolic products in the culture broths. It was shown that the microbial population could utilize fenoxapropethyl as a source of carbon and nitrogen, but the presence of an additional source of carbon increased the metabolism rate.     

Germination in Optimal Conditions as Effective Strategy to Improve Nutritional and Nutraceutical Value of Underutilized Mexican Blue Maize Seeds

Plant Foods for Human Nutrition - Germination of grains is a bioprocess of emerging interest to improve nutritional and nutraceutical profile of cereals in a natural way. The aim of this work was...     

Organic Matter Removal on Oxide Determination in Oxisols Via Portable X-ray Fluorescence

Many factors can influence the results obtained by portable X-ray fluorescence analysis (pXRF). The effect of soil organic matter on pXRF results is not satisfactory understood. Thus, we conducted this study to verify the effect of organic matter removal on oxide determination by pXRF in Oxisols. To obtain soil material with different organic matter contents and maintaining the same elemental composition from soil minerals, six contrasting Oxisols were heated in a muffle furnace for 30 min at the following temperatures (°C): 100; 200; 300; 400; 500 and 600. After heating, the soil samples were scanned using a pXRF Bruker® S1 Titan LE model (Dual Soil mode) for 60 s and the contents of SiO₂, Al₂O₃, Fe₂O₃, TiO₂, P₂O₅, and MnO were recorded. The soil organic matter presence underestimated the pXRF results for lightest oxides (Si and Al) compared to heaviest oxides (Fe, Ti, and Mn). These oxides are important for tropical soils classification and for many soil-related studies and pXRF technology has been a useful tool for soil chemical characterization. Our findings contribute to more suitable use of pXRF highlighting the possible effect of organic matter.