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1.
Sci Total Environ ; 698: 134154, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31505342

RESUMO

Water scarcity, nutrient-depleted soils and pollution continue to be a major challenge worldwide and these are likely to worsen with increasing global populations particularly, in urban areas. As a result, environmental and public health problems may arise from the insufficient provision of sanitation and wastewater disposal facilities. Because of this, a paradigm shifts with regard to the sustainable management of waste disposal in a manner that could protect the environment at the same time benefits society by allowing nutrient recovery and reuse for food production is required. Hence, the use of urban wastewater for agricultural irrigation has more potential, especially when incorporating the reuse of nutrients like nitrogen and phosphorous, which are essential for crop production. Among the current treatment technologies applied in urban wastewater reuse for agriculture, hydroponic system is identified as one of the alternative technology that can be integrated with wastewater treatment. The integration of hydroponic system with municipal wastewater treatment has the advantage of reducing costs in terms of pollutants removal while reducing maintenance and energy costs required for conventional wastewater treatment. The efficiency of a hydroponic system with regard to municipal wastewater reuse is mainly linked to its capacity to allow continuous use of wastewater through the production of agricultural crops and the removal of pollutants/nutrients (nitrogen and phosphorus), resulting to increased food security and environmental protection. Moreover, the suitability of hydroponic system for wastewater treatment is derived from its capacity to minimize associated health risks to farmers, harvested crop and consumers, that may arise through contact with wastewater.


Assuntos
Agricultura/métodos , Hidroponia , Verduras/crescimento & desenvolvimento , Eliminação de Resíduos Líquidos , Irrigação Agrícola , Conservação dos Recursos Naturais , Produtos Agrícolas , Fazendeiros , Nitrogênio , Fósforo , Saneamento , Tecnologia , Águas Residuárias , Água , Purificação da Água
2.
J Sci Food Agric ; 100(2): 453-464, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31487397

RESUMO

Operative planning in agricultural production has historically had the objective of improving yields and quality. Sowing, cropping, and harvesting are usually treated independently, and waste and the sustainability of operations are generally not integrated into operational planning methodologies for agricultural production. This study shows the need to have a clear and precise methodology to minimize waste in agricultural production systems to ensure sustainability. This need is addressed with a novel methodological guide to minimizing waste in agricultural operations, crop maintenance, and harvesting. The proposed methodology is founded on the use of lean manufacturing as a waste-management tool. Lean manufacturing principles allow agricultural operations and the variables that represent wastes to be identified, mathematical models to be built, constraints to be defined, and the cost of waste to be illustrated, as well as its minimization through an objective function. To guide implementation, we propose a conceptual model to explain the construction of a mathematical model that represents the development of decision variables on agricultural operations with the elements to consider and the constraints and theoretical proposal of the necessary objective function. The proposed conceptual model and the constructed methodology constitute a novel development within agricultural production systems that could be used by decision makers and farmers. © 2019 Society of Chemical Industry.


Assuntos
Agricultura/métodos , Resíduos/análise , Agricultura/economia , Modelos Teóricos , Resíduos/economia
3.
An Acad Bras Cienc ; 91(3): e20180578, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31596389

RESUMO

The aim of this study was to determine how often rural farmers in a watershed use no-tillage systems combined with crop rotation, contour farming and agricultural terraces. The study area was Paraná Watershed III (PB3) in the western region of Paraná State, and data from the 2006 Agricultural Census of the Brazilian Institute of Geography and Statistics were used. A frequency distribution analysis of farms as a function of the no-tillage (NT) area was conducted in combination with a cluster analysis of soil and water conservation practices (adoption of crop rotation, contour farming and agricultural terrace practices). The results showed that the farms in PB3 adopt adequate soil and water conservation practices, with 73% adopting NT combined with at least 2 other conservation practices; however, agricultural terracing was found to be the most neglected practice in the region. In addition, based on the soil and water conservation practices in the watershed, 5 groups of farms were identified, the worst of which, those located in the municipalities that mainly neglect conservation practices, live in areas with highly erodible soils.


Assuntos
Agricultura/métodos , Conservação dos Recursos Naturais/métodos , Produtos Agrícolas , Solo/química , Brasil , Água/análise , Abastecimento de Água
4.
Plant Dis ; 103(12): 3093-3100, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31613191

RESUMO

In Nebraska, rotation of soybean (Glycine max) fields to corn (Zea mays) is a major practice to manage the soybean cyst nematode (SCN; Heterodera glycines). However, factors associated with SCN population density decline during corn rotation are not clearly defined. This study addresses that question using a modeling approach. Seventy-nine fields were sampled in 2009, 2010, and 2011 to determine SCN population densities (eggs/100 cm3 of soil) before and after rotation. After rigorous field screening and model testing and validation, the regression model Log(Pf)^=-2.3360+0.8368LogPi+0.4333pH was developed, where Log Pf is the natural log of SCN eggs at the end of the rotation year, Pi is the population density before rotation, and pH is the soil pH. Model goodness-of-fit was assessed through residual analysis, information criteria, and other remedial measures. Model overdispersion was 1.04. Validation in a 50 and a 75% random sample from the original data set showed little change in model regression coefficients, standard errors, and associated significance, confirming model fit and performance. The model indicates that for one-unit increase in soil pH, SCN Pf is expected to increase by 53.7% at constant Pi, and correspondingly, a 10% change in Pi will result in about 8.3% change in Pf at constant soil pH. The model suggested that SCN population levels before corn rotation and soil pH are major determinants of observed SCN population density reduction after annual corn rotation in Nebraska. This model has potential for use in SCN risk analysis and in predicting SCN population decline after corn rotation in the state.


Assuntos
Agricultura , Nematoides , Solo , Zea mays , Agricultura/métodos , Animais , Nebraska , Nematoides/fisiologia , Doenças das Plantas/parasitologia , Doenças das Plantas/prevenção & controle , Densidade Demográfica , Análise de Regressão , Rotação , Solo/parasitologia , Zea mays/crescimento & desenvolvimento , Zea mays/parasitologia
5.
Plant Dis ; 103(12): 3101-3107, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31613192

RESUMO

Phytophthora cinnamomi is an ecologically and agriculturally significant plant pathogen. Early and accurate detection of P. cinnamomi is paramount to disease prevention and management. In this study, a loop-mediated isothermal amplification (LAMP) assay utilizing a new target gene Pcinn100006 identified from genomic sequence data was developed and evaluated for the detection of P. cinnamomi. This Pcinn100006 LAMP assay was found highly specific to P. cinnamomi. All 10 tested isolates of P. cinnamomi yielded positive results, whereas 50 isolates belonging to 16 other Phytophthora species, Globisporangium ultimum, and 14 fungal species lacked detection. This assay was 10 times more sensitive (100 pg in a 25-µl reaction mixture) than a conventional PCR assay (2 ng in a 50-µl reaction mixture) for detecting the genomic DNA of P. cinnamomi. In addition, it detected P. cinnamomi from artificially inoculated leaves of Cedrus deodara. Moreover, detection rates of P. cinnamomi using environmental DNAs extracted from 13 naturally infested rhizosphere samples were 100% in the Pcinn100006 LAMP assay versus 46% in the conventional PCR assay. Considering its higher accuracy and shorter time span, this Pcinn100006 LAMP assay is a promising diagnostic tool to replace conventional PCR-based and culture-dependent assays for screening of P. cinnamomi in regions at risk of infection or contamination.


Assuntos
Agricultura , Genoma de Protozoário , Técnicas de Amplificação de Ácido Nucleico , Phytophthora , Agricultura/métodos , Phytophthora/genética , Doenças das Plantas/parasitologia , Plantas , Rizosfera , Sensibilidade e Especificidade
6.
Plant Dis ; 103(12): 3117-3128, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31634034

RESUMO

Globodera pallida is a major nematode pest of potato (Solanum tuberosum) and is of great economic importance for the potato industry. Assessing potato yield loss caused by the Idaho G. pallida population under field conditions was not performed due to its quarantine status in Idaho, where it is prohibited by regulatory statutes to grow potato in any infested fields. The experimental data came from three trials that were conducted under greenhouse conditions. A predictive risk model analysis was performed to: (i) determine the effect of the Idaho population of G. pallida on potato yield; (ii) estimate reproduction rate from different initial nematode densities; and (iii) simulate potato yield losses in Idaho field conditions by integrating the coefficients of potato yield into the SUBSTOR-DSSAT crop simulation model. Experiments were conducted under greenhouse conditions using five initial G. pallida soil infestation levels (0, 10, 20, 40, and 80 eggs/g soil). The coefficients of potato yield achieved under each initial nematode density were integrated into the SUBSTOR-DSSAT potato growth simulation model. The model showed that tuber weight reached a maximum yield of 96 ton/ha in noninfested soil. Based on the greenhouse trials, the model predicted a minimum yield of 12 and 58 ton/ha in trial 1 and trial 2/3 respectively, when initial nematode density was 80 eggs/g soil. In trial 1, tuber weight was significantly reduced by 44% at 40 eggs/g soil and by 87% at 80 eggs/g soil, and 20% at 40 eggs/g soil and by 39% at 80 eggs/g soil in trial 2/3. The outputs of this study should facilitate common understanding between regulators, policymakers, and potato growers on the challenges and opportunities for controlling this economically important pest in Idaho.


Assuntos
Agricultura , Modelos Biológicos , Solo , Solanum tuberosum , Tylenchoidea , Agricultura/métodos , Animais , Idaho , Solo/parasitologia , Solanum tuberosum/parasitologia , Tylenchoidea/fisiologia
7.
Plant Dis ; 103(12): 3172-3180, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31657996

RESUMO

Real-time loop-mediated isothermal amplification (LAMP) assays for the detection of sporangia of the causal pathogen of late blight, Phytophthora infestans, and spores of the main causal pathogen of early blight, Alternaria solani, were developed to facilitate the in-field detection of airborne inoculum to improve disease forecasting. These assays were compared with an existing real-time PCR assay for P. infestans and a newly developed real-time PCR assay for A. solani. Primers were designed for real-time LAMP of P. infestans and A. solani. The specificity of the P. infestans real-time LAMP assay was similar to that of an existing real-time PCR assay: DNA of P. infestans was consistently amplified as was DNA of the taxonomically closely related species Phytophthora mirabilis, Phytophthora phaseoli, and Phytophthora ipomoea; no amplification of DNA from the potato pathogens Phytophthora erythroseptica or Phytophthora nicotianae occurred. Real-time LAMP and PCR assays were developed for A. solani, and the specificity was compared with an existing conventional PCR assay. Importantly, the A. solani real-time LAMP and PCR assays did not amplify the species Alternaria alternata. However, cross-reactivity with Alternaria dauci was observed with the real-time PCR assay and Alternaria brassicae with the real-time LAMP assay. The sensitivity of all assays for the detection of DNA extracted from sporangia/spores of the target pathogens was evaluated. The P. infestans real-time LAMP assay reliably detected 5 pg of DNA, equivalent to ∼1 sporangia per reaction. By comparison, 20 fg of DNA was detectable with the existing real-time PCR assay. In the case of A. solani, real-time LAMP detected 4.4 pg of DNA, equivalent to ∼1 spore per reaction, and real-time PCR detected 200 fg of DNA. In-field air samplers were deployed in two trial plots planted with potato: one infected with P. infestans, and the other infected with A. solani. Four additional samplers were located in commercial potato fields. Air samples were taken through the season, and detection of airborne inoculum of P. infestans and A. solani with both real-time PCR and LAMP was assessed.


Assuntos
Alternaria , Técnicas de Amplificação de Ácido Nucleico , Phytophthora infestans , Reação em Cadeia da Polimerase em Tempo Real , Medição de Risco , Agricultura/métodos , Alternaria/genética , Phytophthora infestans/genética , Medição de Risco/métodos , Solanum tuberosum/parasitologia , Esporângios/genética , Esporos de Protozoários/genética , Esporos de Protozoários/isolamento & purificação
8.
Plant Dis ; 103(12): 3031-3040, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31638863

RESUMO

Bacterial diseases of onion are reported to cause significant economic losses. Pantoea allii Brady, one of the pathogens causing the center rot on onions, has not yet been reported in Canada. We report the pathogenicity of P. allii on commercially available Canadian green onions (scallions). All P. allii-inoculated plants, irrespective of the inoculum concentration, exhibited typical leaf chlorotic discoloration on green onion leaves, which can reduce their marketability. Reisolation of P. allii from infected scallion tissues and reidentification by sequencing and phylogenetic analyses of the leuS gene suggest that the pathogen can survive in infected tissues 21 days after inoculation. This is the first report of P. allii as a potential pathogen of green onions. This study also reports the development and validation of a TaqMan real-time PCR assay targeting the leuS gene for reliable detection of P. allii in pure cultures and in planta. A 642-bp leuS gene fragment was targeted because it showed high nucleotide diversity and positively correlated with genome-based average nucleotide identity with respect to percent similarity index and identity of Pantoea species. The assay specificity was validated using 61 bacterial and fungal strains. Under optimal conditions, the selected primers and FAM-labeled TaqMan probe were specific for the detection of nine reference P. allii strains by real-time PCR. The 52 strains of other Pantoea spp. (n = 25), non-Pantoea spp. (n = 20), and fungi/oomycetes (n = 7) tested negative (no detectable fluorescence). Onion tissues spiked with P. allii, naturally infested onion bulbs, greenhouse infected green onion leaf samples, as well as an interlaboratory blind test were used to validate the assay specificity. The sensitivities of a 1-pg DNA concentration and 30 CFU are comparable to previously reported real-time PCR assays of other bacterial pathogens. The TaqMan real-time PCR assay developed in this study will facilitate reliable detection of P. allii and could be a useful tool for screening onion imports or exports for the presence of this pathogen.


Assuntos
Agricultura , Cebolas , Pantoea , Reação em Cadeia da Polimerase em Tempo Real , Agricultura/métodos , Canadá , Genes Bacterianos/genética , Cebolas/microbiologia , Pantoea/classificação , Pantoea/genética , Pantoea/patogenicidade , Filogenia , Virulência
9.
Environ Monit Assess ; 191(10): 609, 2019 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-31486904

RESUMO

A study was performed to determine whether self-rooted grafting decreases cadmium (Cd) accumulation in post-grafting soybean (Glycine max (Linn.) Merrill) generations. Pot experiments were performed using ungrafted (UG) seedlings, self-rooted grafting from the same soybean seedling (SG), self-rooted grafting from two soybean seedlings at the same growth stage (TG), and self-rooted grafting from two soybean seedlings at different developmental stages (DG). Growth and Cd accumulation in three post-grafting soybean generations were assessed. In the SG treatment, only the second post-grafting generation had increased shoot biomass and only the first post-grafting generation shoots had decreased Cd contents. The seed Cd content, soluble protein content, and antioxidant enzyme activity were not significantly affected in three post-grafting generations. In the TG and DG treatments, shoot biomass, soluble protein content, and antioxidant enzyme activities were increased, and the shoot and seed Cd contents were decreased in three post-grafting generations. The seed Cd contents in the first, second, and third post-grafting generations were 15.00%, 9.46%, and 12.44%, respectively, lower in the TG than UG treatments. The seed Cd contents in the first, second, and third post-grafting generations were 32.73%, 27.03%, and 32.22%, respectively, lower in the DG than UG treatments. Different grafting methods promoted growth and decreased Cd accumulation to different degrees in three post-grafting generations. Grafting seedlings at different developmental stages had the strongest effects.


Assuntos
Agricultura/métodos , Cádmio/metabolismo , Poluentes do Solo/metabolismo , Soja/crescimento & desenvolvimento , Soja/metabolismo , Biomassa , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/metabolismo , Plântula/crescimento & desenvolvimento , Plântula/metabolismo , Sementes/metabolismo
10.
Ying Yong Sheng Tai Xue Bao ; 30(9): 3145-3154, 2019 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-31529890

RESUMO

The combination of field trial and indoor incubation experiment were conducted to examine the long-term effects of one-time application of bio-organic fertilizer on soil organic carbon (C) components, organic C mineralization, and enzyme activity in cucumber continuous cropping. Compared with CK, bio-organic fertilizer application significantly increased the content of soil organic C, activated C pool, slow-release C pool and inert C pool during four continuous cucumber planting seasons. With the increases of the number of consecutive crops, the proportion of soil inert carbon gradually increased. After four continuous seasons of cucumber planting, the cumulative and daily mineralization rate of soil organic C in the bio-organic fertilizer treatment increased by 17.3%-31.0% and 7.8%-43.0%, respectively. In the stage of cucumber ripening, bio-organic fertilizer application increased the activities of continuous soil urease, catalase, sucrose and neutral phosphatase by 10.5%-62.1%, 4.8%-25.5%, 3.9%-21.4% and 4.6%-66.4%. The activities of those four enzymes increased with the increases of the application amount of organic fertilizer. Results from the correlation and path analysis showed that the activity of the four enzymes were significantly correlated with the dynamics of organic carbon components in soil cucumber continuous cropping process. Soil urease and invertase activities significantly affected organic carbon mineralization during the continuous cropping process of cucumber. Application of bio-organic fertilizer could increase soil organic carbon content and enzyme activity, improve inert carbon ratio of soil organic carbon pools, cumulative and mineralization rate of organic carbon in continuous cropping process, thereby enhance soil carbon sequestration capacity.


Assuntos
Agricultura/métodos , Cucumis sativus/crescimento & desenvolvimento , Fertilizantes , Carbono , Solo , Microbiologia do Solo
11.
An Acad Bras Cienc ; 91(3): e20180066, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31508663

RESUMO

Despite its economic importance, the microclimate in soybean canopies has not yet been studied in detail. Such a study can yield valuable information regarding the interaction of a crop with its environment. In this context, the aim of this study was to evaluate the solar radiation dynamic and yield responses for each canopy strata for two soybean cultivars with determined and undetermined growth habits. A field study was conducted during the 2013/2014 and 2014/2015 growing seasons in the city of Frederico Westphalen, Rio Grande do Sul, Brazil. The cultivar NA6411, with a determinate growth habit, presented a greater interception of radiation in the middle and lower canopies strata which results in higher soybean yield when compared to the cultivar TEC6029, and thus, can be recommended for cultivation in crop production systems. The contribution of the middle and upper canopy strata to the total yield formation was greater than that observed in the lower canopy strata due to the greater interception of solar radiation by these strata. To increase soybean yields, new studies regarding the microclimatic conditions of the soybean canopy should be developed to improve the maximum potential yield of the new soybean cultivars.


Assuntos
Microclima , Soja/crescimento & desenvolvimento , Soja/efeitos da radiação , Luz Solar , Agricultura/métodos , Brasil
12.
Sci Total Environ ; 692: 1165-1174, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31539948

RESUMO

The management system of soils and nitrogen application can cause impacts on the N2O emissions produced by the agricultural sector. In the establishment of practices of greenhouse gas mitigation for this sector, the objective of this study was to evaluate the effect of soil tillage, with and without N fertilization, on N2O emissions from Oxisols under rainfed maize in the Brazilian Cerrado region. The managements were of monoculture maize under conventional tillage (CT) and no-tillage (NT), with (1) and without (0) application of N fertilizer (0 and 257 kg N ha-1). From November 2014 to October 2015, gas emissions were measured. The soil and climate variables were measured and related to the N2O fluxes. In the N-fertilized treatments, N2O fluxes were higher (P < 0.01), ranging from -21 µg m-2 h-1 to 548 µg m-2 h-1 N2O under conventional tillage and from -21 µg m-2 h-1 to 380 µg m-2 h-1 N2O under no-tillage, compared with -6 to 93 µg m-2 h-1 N2O from systems without N application. There was a combined effect of mineral N and water-filled pore space for most N2O fluxes. The emission factors of N2O during maize cultivation were lower than the standard factor (1%) established by the International Panel of Climate Change. During the plant crop cycle, 30% less N2O was emitted from the N-fertilized no-tillage than from the conventional tillage. For the total cumulative N2O (crop cycle + fallow), the N2O emissions from NT1 and CT1 were not different, but 10× higher than those from the respective crops without N fertilization. To the emissions per unit of grain yield, CT1 and NT1 emitted 769 and 391 mg N2O kg-1 grain produced, respectively, and NT1 was most efficient in fertilizer-into-product conversion. Under maize cultivation, the soil acted as N2O source, regardless of the management.


Assuntos
Agricultura/métodos , Poluição do Ar/prevenção & controle , Fertilizantes , Gases de Efeito Estufa/análise , Dióxido de Nitrogênio/análise , Zea mays/crescimento & desenvolvimento , Poluição do Ar/estatística & dados numéricos , Brasil , Solo
13.
Sci Total Environ ; 692: 1223-1233, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31539953

RESUMO

Several circulation models are forecasting climate changes in the Mediterranean region. Accordingly, it is expected that water scarcity in the region will be higher with drastic shifts of hydrological and erosive watershed responses. In Tunisia, wheat yields have been variable over the years and are lower than the potential yields. In response, the adoption of conservation agriculture (CA), introduced into Tunisia in 1999 to help adaptation to climate change, has resulted in a substantial reduction in agricultural productivity. CA areas increased from 52 ha in 1999 to 14,000 ha in 2015. Using a modelling approach, the present paper evaluates the potential of CA to adapt wheat-based-systems to climate change in Tunisia. The Agricultural Production Systems Simulator (APSIM) model was used to predict the effect of tillage (conventional tillage [CT] vs. zero-tillage [ZT] and soil residue retention [ZT-RR]) on wheat productivity and soil fertility. Two contrasting locations in Tunisia were studied; one semi-arid (Kef) and one sub-humid (Bizerte). Results showed that the sustainable production of durum wheat under climate change conditions in Tunisia is possible through the adoption of CA practices (ZT and ZT-RR) in both sub-humid and semi-arid areas. In fact, mulching (residue retention) is more effective than CT (under semi-arid and sub-humid conditions) in enhancing wheat yield (15%), water use efficiency (18% and 13%) and soil organic carbon accumulation (0.13 t ha-1 year-1 and 0.18 t ha-1 year-1). It is also more effective for soil resilience - preventing water erosion (1.7 t ha-1 year-1 and 4.6 t ha-1 year-1 of soil loss). The present study allowed identification of 260,000 ha as priority areas for CA adoption; this represent one-third of the total cereal area in Tunisia. Appropriate evaluation of the benefits of CA on sustainable agricultural intensification would provide more arguments for effectively supporting CA adoption in Tunisia.


Assuntos
Agricultura/métodos , Mudança Climática , Conservação dos Recursos Naturais , Triticum/crescimento & desenvolvimento , Tunísia
14.
Plant Dis ; 103(11): 2857-2864, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31524084

RESUMO

Assessments of Fusarium crown rot are often made in field trials inoculated with Fusarium pseudograminearum or F. culmorum. Factors affecting the efficiency of two inoculation procedures were evaluated. Pulverized Fusarium-colonized wheat plus oat grain inoculum mixed with the wheat seed caused more seedling damping-off compared with equal rates of colonized whole millet seeds placed 2 cm above the wheat seed. Both inoculation systems increased the incidence and severity of crown rot. The efficiency of F. pseudograminearum-colonized millet seed inoculum was not reduced when wheat seed was treated with difenoconazole. Crown rot in inoculated plots became greater when starter fertilizer was applied with or below the wheat seed and when soil below the wheat seed was disrupted by a seed drill with an opener that creates a groove or trench directly below the seed. No biologically important associations were detected between whiteheads and other measures of crown rot, grain yield, or grain test weight. The millet seed inoculation system was the most efficient for wheat production systems in the semiarid U.S. Pacific Northwest.


Assuntos
Agricultura , Fusarium , Microbiologia do Solo , Triticum , Agricultura/métodos , Noroeste dos Estados Unidos , Doenças das Plantas/prevenção & controle , Triticum/microbiologia
15.
Plant Dis ; 103(11): 2804-2811, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31524095

RESUMO

Sorghum anthracnose (Colletotrichum sublineola) reduces grain yield up to 50% but suggested management tactics have not yet been developed for the mid-Atlantic United States, where warm, wet conditions favor disease. Under factorial arrangement, five fungicides plus a nontreated control and four application timings were compared for foliar anthracnose control, yield, and profitability of fungicide use in grain sorghum over eight site-years in Virginia and North Carolina. Anthracnose severity was rated at the hard dough stage, and grain yield was determined at harvest. Every percent increase in disease severity resulted in yield losses of 27 to 85 kg/ha. Pyraclostrobin and pyraclostrobin plus fluxapyroxad reduced anthracnose (P < 0.01), and three applications resulted in less disease and greater yield compared with single applications (P < 0.01). However, three applications exceed the labeled maximum application for the fungicides and are not economical. Among single applications, boot or flowering timings reduced disease, and flowering applications resulted in the overall greatest yield. Results suggest that when disease onset occurs at or prior to boot, a single application of pyraclostrobin-containing fungicide at or just prior to flowering reduces anthracnose, protects yield, and increases income. However, when disease is absent or severity is low prior to flowering, fungicide application may not be profitable.


Assuntos
Agricultura , Colletotrichum , Fungicidas Industriais , Doenças das Plantas , Sorghum , Agricultura/métodos , Colletotrichum/efeitos dos fármacos , Fungicidas Industriais/farmacologia , North Carolina , Doenças das Plantas/prevenção & controle , Sorghum/microbiologia , Tempo , Virginia
16.
Plant Dis ; 103(11): 2764-2770, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31490090

RESUMO

Fusarium wilt (Fusarium oxysporum f. sp. lycopersici), root-knot nematodes (Meloidogyne spp.), and purple nutsedge (Cyperus rotundus L.) are among the most damaging soilborne pests for tomato (Lycopersicon esculentum Mill.) production in the southeastern United States. Allyl isothiocyanate (allyl ITC) was evaluated as a potential fumigant alternative for control of soilborne pathogens, nematodes, and weeds. Shank- or drip-injected allyl ITC at rates ranging from 221 to 367 kg ha-1 exhibited excellent performance, reducing the recovery of total F. oxysporum from treated soils. Shank- or drip-injected allyl ITC at 367 kg ha-1 provided equivalent control of C. rotundus compared with 1,3-dichloropropene + chloropicrin and metam potassium, respectively. Totally impermeable film (TIF) did not further reduce the recovery of F. oxysporum and various nematodes from soil treated with allyl ITC compared with virtually impermeable film (VIF). However, TIF mulch significantly improved C. rotundus control versus shank- or drip-injected allyl ITC treatments under VIF mulch. Overall, allyl ITC is an effective methyl bromide alternative against F. oxysporum, C. rotundus, and plant-parasitic nematodes Criconemella spp. and Hoplolaimus spp. in plasticulture tomato production.


Assuntos
Agricultura , Lycopersicon esculentum , Controle de Pragas , Agricultura/métodos , Animais , Cyperus/efeitos dos fármacos , Fusarium/efeitos dos fármacos , Isotiocianatos/farmacologia , Lycopersicon esculentum/microbiologia , Lycopersicon esculentum/parasitologia , Controle de Pragas/métodos , Solo/parasitologia , Microbiologia do Solo , Sudeste dos Estados Unidos , Tylenchoidea/efeitos dos fármacos
17.
Food Chem ; 301: 125170, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31398671

RESUMO

The technological and polyphenolic parameters of grapes for juice processing obtained from successive harvests were studied in semi-arid tropical viticulture. Red grapes "BRS Violeta" and "Isabel Precoce" were harvested during the same year and analyzed based on a multivariate approach that included climatic variations. The grapes were marked by variations in flavonoid compounds, particularly anthocyanins. Temperature, global radiation, air velocity and evapotranspiration rates were associated with higher accumulation of bioactive polyphenols in grape berries and juices. The temperatures in February were associated with higher antioxidant activity in grape peels, while the highest thermal amplitude in August and November favored the accumulation of anthocyanins up to 564 mg kg-1. Flavanols and procyanidin compounds were more abundant in seeds when the maximum thermal amplitude was 13.8 °C. The climatic data together with the polyphenolic results point out useful information about appropriate periods for harvesting grapes with high phenolic content in tropical areas.


Assuntos
Agricultura/métodos , Sucos de Frutas e Vegetais/análise , Frutas/química , Vitis/química , Antocianinas/análise , Biflavonoides/análise , Brasil , Catequina/análise , Flavonoides/análise , Qualidade dos Alimentos , Fenóis/análise , Polifenóis/análise , Proantocianidinas/análise , Clima Tropical
18.
Food Chem ; 301: 125295, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31387038

RESUMO

Raspberry fruits are a perfect source of polyphenols, including flavonols, anthocyanins. Some experiments have indicated that organic fruits contain more bioactive compounds than conventional fruits. The aim of this study was therefore to analyse and compare the concentration of bioactive compounds in organic vs. conventional raspberries and to determine the effects of harvest time and cultivar. Three cultivars of raspberry ('Laszka', 'Glen Ample' and 'Glen Fine') that were harvested in summer and one 'Polka' cv. that was harvested in autumn time from organic and conventional cultivation methods were used in the experiment. The contents of dry matter and polyphenols in the fruits were determined. The organic samples contained significantly more dry matter, phenolic acid and flavonoids, including myrycetin, quercetin, luteolin and quercetin-3-O-rutinoside. Harvest time was an important factor in raspberry fruit quality.


Assuntos
Agricultura/métodos , Polifenóis/análise , Rubus/química , Antocianinas/análise , Fazendas , Flavonoides/análise , Frutas/química , Agricultura Orgânica/métodos , Fatores de Tempo
19.
Plant Dis ; 103(10): 2612-2623, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31408402

RESUMO

Symptoms of Fusarium crown rot of wheat include premature death of inflorescens (whiteheads), lesions on subcrown internodes, and rotting of crown tissue and lower stem internodes. Each symptom type is influenced by a different set of environmental conditions. Whiteheads are the easiest symptom to quantify and are frequently reported in the Pacific Northwest U.S.A. The objective of this research was to examine factors associated with whitehead expression and relationships with wheat yield and test weight. Incidence of whiteheads differed for inoculations with different isolates of F. pseudograminearum and F. culmorum, and over years due to weather factors. Whiteheads became less as planting dates for winter wheat were delayed until after September, and incidence was increased with increasing nitrogen application rate. Dates of initial and greatest expression of whiteheads differed among cultivars, which was associated in part with the cultivar heading date. Whiteheads were not correlated with subcrown internode lesions or browning of crown tissue. Whiteheads were also not correlated with grain test weight. Whiteheads were sometimes negatively associated with grain yield, but that relationship was variable and could not be considered a reliable, recurrent, or accurate measure of crown rot severity. These results indicate the need for caution in reporting whiteheads as a sole indicator of cultivar susceptibility to Fusarium crown rot.


Assuntos
Agricultura , Fusarium , Doenças das Plantas , Triticum , Agricultura/métodos , Grão Comestível/microbiologia , Fusarium/fisiologia , Noroeste dos Estados Unidos , Doenças das Plantas/prevenção & controle , Triticum/microbiologia
20.
Sci Total Environ ; 685: 1139-1151, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31390704

RESUMO

Water saving techniques, such as alternate wetting and drying (AWD), are becoming a necessity in modern rice farming because of climate change mitigation and growing water use scarcity. Reducing water can vastly reduce methane (CH4) emissions; however, this net climate benefit may be offset by enhanced carbon dioxide (CO2) emissions from soil. The main aims of this study were: to determine the effects of AWD on yield and ecosystem C dynamics, and to establish the underlying mechanistic basis for observed trends in net ecosystem C gain or loss in an Italian rice paddy. We investigated the effects of conventional water management (i.e. conventionally flooded paddy; CF) and AWD on biomass accumulation (aboveground, belowground, grain), key ecosystem C fluxes (net ecosystem exchange (NEE), net primary productivity (NPP), gross primary productivity (GPP), ecosystem respiration (ER), autotrophic respiration (RA), heterotrophic respiration (RH)), and soil organic matter (SOM) decay for four common commercial European rice cultivars. The most significant finding was that neither treatment nor cultivar affected NEE, GPP, ER or SOM decomposition. RA was the dominant contributor to ER for both CF and AWD treatments. Cultivar and treatment affected the total biomass of the rice plants; specifically, with greater root production in CF compared to AWD. Importantly, there was no effect of treatment on the overall yield for any cultivar. Possibly, the wetting-drying cycles may have been insufficient to allow substantial soil C metabolism or there was a lack of labile substrate in the soil. These results imply that AWD systems may not be at risk of enhancing soil C loss, making it a viable solution for climate change mitigation and water conservation. Although more studies are needed, the initial outlook for AWD in Europe is positive; with no net loss of soil C from SOM decomposition, whilst also maintaining yield.


Assuntos
Agricultura/métodos , Conservação dos Recursos Hídricos/métodos , Oryza/crescimento & desenvolvimento , Biomassa , Ecossistema , Europa (Continente)
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