Trailing Boom on Fungicides Application on Wheat, Bean and Soybean

This study aimed to determine the influence of air-assisted and trailing boom technologies on fungicide applications to control diseases incidence and severity on wheat, bean and soybean. The experiments were conducted in three different sites in the Campos Gerais (PR) region in a completely randomized blocks design. In the wheat crop season of 2011, the treatments were: i) control (no fungicide application on the plants); fungicide spray with ii) nozzles in conventional ground boom sprayer; iii) nozzles in trailing boom; and iv) nozzles in conventional boom sprayer + trailing boom simultaneously. In the bean and soybean crop season of 2011-12, we added an extra treatment of boom with air-assisted sprayer, since the farmers had this technology available. We conclude that at the area under the disease progress curve (AUDPC), the diseases controlled with fungicides presented lower severity and incidence compared with the control treatment for all the crops evaluated. The fungicide spraying technology aggregated to air-assisted and trailing boom did not differ from the conventional boom sprayer for disease control and yield components of wheat, beans and soybeans

The response of carbon assimilation and storage to long‐term drought in tropical trees is dependent on light availability

Whether tropical trees acclimate to long‐term drought stress remains unclear. This uncertainty is amplified if drought stress is accompanied by changes in other drivers such as the increases in canopy light exposure that might be induced by tree mortality or other disturbances. Photosynthetic capacity, leaf respiration, non‐structural carbohydrate (NSC) storage and stomatal conductance were measured on 162 trees at the world's longest running (15 years) tropical forest drought experiment. We test whether surviving trees have altered strategies for carbon storage and carbon use in the drier and elevated light conditions present following drought‐related tree mortality. Relative to control trees, the surviving trees experiencing the drought treatment showed functional responses including: (a) moderately reduced photosynthetic capacity; (b) increased total leaf NSC; and (c) a switch from starch to soluble sugars as the main store of branch NSC. This contrasts with earlier findings at this experiment of no change in photosynthetic capacity or NSC storage. The changes detected here only occurred in the subset of drought‐stressed trees with canopies exposed to high radiation and were absent in trees with less‐exposed canopies and also in the community average. In contrast to previous results acquired through less intensive species sampling from this experiment, we also observe no species‐average drought‐induced change in leaf respiration. Our results suggest that long‐term responses to drought stress are strongly influenced by a tree's full‐canopy light environment and therefore that disturbance‐induced changes in stand density and dynamics are likely to substantially impact tropical forest responses to climate change. We also demonstrate that, while challenging, intensive sampling is essential in tropical forests to avoid sampling biases caused by limited taxonomic coverage.Publicado online em 29 set. 2020

High-resolution genetic map and QTL analysis of growth-related traits of Hevea brasiliensis cultivated under suboptimal temperature and humidity conditions

Rubber tree (Hevea brasiliensis) cultivation is the main source of natural rubber worldwide and has been extended to areas with suboptimal climates and lengthy drought periods; this transition affects growth and latex production. High-density genetic maps with reliable markers support precise mapping of quantitative trait loci (QTL), which can help reveal the complex genome of the species, provide tools to enhance molecular breeding, and shorten the breeding cycle. In this study, QTL mapping of the stem diameter, tree height, and number of whorls was performed for a full-sibling population derived from a GT1 and RRIM701 cross. A total of 225 simple sequence repeats (SSRs) and 186 single-nucleotide polymorphism (SNP) markers were used to construct a base map with 18 linkage groups and to anchor 671 SNPs from genotyping by sequencing (GBS) to produce a very dense linkage map with small intervals between loci. The final map was composed of 1,079 markers, spanned 3,779.7 cM with an average marker density of 3.5 cM, and showed collinearity between markers from previous studies. Significant variation in phenotypic characteristics was found over a 59-month evaluation period with a total of 38 QTLs being identified through a composite interval mapping method. Linkage group 4 showed the greatest number of QTLs (7), with phenotypic explained values varying from 7.67 to 14.07%. Additionally, we estimated segregation patterns, dominance, and additive effects for each QTL. A total of 53 significant effects for stem diameter were observed, and these effects were mostly related to additivity in the GT1 clone. Associating accurate genome assemblies and genetic maps represents a promising strategy for identifying the genetic basis of phenotypic traits in rubber trees. Then, further research can benefit from the QTLs identified herein, providing a better understanding of the key determinant genes associated with growth of Hevea brasiliensis under limiting water conditions

Anthelmintic activity of nanoencapsulated carvacryl acetate against gastrointestinal nematodes of sheep and its toxicity in rodents.

Abstract: The objective of this study was to evaluate the efficacy of carvacryl acetate (CVA) and nanoencapsulated CVA (nCVA) on gastrointestinal nematodes of sheep. The CVA was nanoencapsulated with chitosan/gum arabic and the efficacy of nanoencapsulation (EE), yield, zeta potential, nanoparticle morphology and release kinetics at pH 3 and 8 were analyzed. Acute and subchronic toxicity were evaluated in rodents and reduction of egg counts in the faeces (FECRT) of sheep. The sheep were divided into four groups (n = 10): G1, 250 mg/kg CVA; G2, 250 mg/kg nCVA; G3, polymer matrix and G4: 2.5 mg/kg monepantel. EE and nCVA yield were 65% and 57%, respectively. The morphology of the nanoparticles was spherical, size (810.6±286.7 nm), zeta potential in pH 3.2 (+18.3 mV) and the 50% release of CVA at pHs 3 and 8 occurred at 200 and 10 h, respectively. nCVA showed LD50 of 2,609 mg/kg. CVA, nCVA and monepantel reduced the number of eggs per gram of faeces (epg) by 57.7%, 51.1% and 97.7%, respectively. The epg of sheep treated with CVA and nCVA did not differ from the negative control (P>0.05). Nanoencapsulation reduced the toxicity of CVA; however, nCVA and CVA presented similar results in the FECRT. [Atividade anti-helmíntica do acetato de carvacrila nanoencapsulado sobre nematoides gastrintestinais de ovinos e toxicidade em roedores]. Resumo: O objetivo deste trabalho foi avaliar a eficácia do acetato de carvacrila (ACV) e do ACV nanoencapsulado (nACV) sobre nematóides gastrintestinais de ovinos. O ACV foi nanoencapsulado com quitosana/goma arábica e foi analisada a eficácia de nanoencapsulamento (EE), o rendimento, potencial zeta, morfologia das nanopartículas e cinética de liberação em pH 3 e 8. Foram avaliadas as toxicidades aguda e subcrônica em roedores e a redução da contagem de ovos nas fezes (RCOF) de ovinos. Os ovinos foram divididos em quatro grupos (n = 10): G1, 250 mg/kg ACV; G2, 250 mg/kg de nACV; G3, matriz polimérica e G4: 2,5 mg/kg de monepantel. A EE e o rendimento de nACV foram de 65% e 57%, respectivamente. A morfologia das nanopartículas foi esférica, tamanho (810,6±286,7 nm), potencial zeta no pH 3,2 (+18,3 mV) e a liberação de 50% de CVA nos pHs 3 e 8 ocorreu às 200 e 10 h, respectivamente. nACV apresentou DL50 de 2.609 mg/kg. ACV, nACV e o monepantel reduziram a contagem de ovos por grama de fezes (opg) em 57,7%, 51,1% e 97,7%, respectivamente. A contagem de opg de ovelhas tratadas com ACV e nCVA não diferiu do controle negativo (P>0,05). O nanoencapsulamento reduziu a toxicidade do AVC; no entanto, nACV e ACV apresentaram resultados semelhantes na RCOF

Impairment of the Plasmodium falciparum Erythrocytic Cycle Induced by Angiotensin Peptides

Plasmodium falciparum causes the most serious complications of malaria and is a public health problem worldwide with over 2 million deaths each year. The erythrocyte invasion mechanisms by Plasmodium sp. have been well described, however the physiological aspects involving host components in this process are still poorly understood. Here, we provide evidence for the role of renin-angiotensin system (RAS) components in reducing erythrocyte invasion by P. falciparum. Angiotensin II (Ang II) reduced erythrocyte invasion in an enriched schizont culture of P. falciparum in a dose-dependent manner. Using mass spectroscopy, we showed that Ang II was metabolized by erythrocytes to Ang IV and Ang-(1–7). Parasite infection decreased Ang-(1–7) and completely abolished Ang IV formation. Similar to Ang II, Ang-(1–7) decreased the level of infection in an A779 (specific antagonist of Ang-(1–7) receptor, MAS)-sensitive manner. 10−7 M PD123319, an AT2 receptor antagonist, partially reversed the effects of Ang-(1–7) and Ang II. However, 10−6 M losartan, an antagonist of the AT1 receptor, had no effect. Gs protein is a crucial player in the Plasmodium falciparum blood cycle and angiotensin peptides can modulate protein kinase A (PKA) activity; 10−8 M Ang II or 10−8 M Ang-(1–7) inhibited this activity in erythrocytes by 60% and this effect was reversed by 10−7 M A779. 10−6 M dibutyryl-cAMP increased the level of infection and 10−7 M PKA inhibitor decreased the level of infection by 30%. These results indicate that the effect of Ang-(1–7) on P. falciparum blood stage involves a MAS-mediated PKA inhibition. Our results indicate a crucial role for Ang II conversion into Ang-(1–7) in controlling the erythrocytic cycle of the malaria parasite, adding new functions to peptides initially described to be involved in the regulation of vascular tonus