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Thesis (M.Sc. (Agronomy)) -- University of Limpopo, 2019 / Smallholder farmers are usually confronted with severe climatic conditions during summer growing seasons on production fields that are generally characterized by poor soil fertility and consequent low crop yields. Conservation agriculture could be a feasible local practice under such conditions to ensure a more sustainable and environmentally friendly system for cultivating crops. A rainfed field experiment was conducted at two diverse agroecological sites, Syferkuil and Ofcolaco during 2017 growing season in the Limpopo Province of South Africa to evaluate production, and symbiotic activities in soybean (Glycine max (L.) Merrill) and also to validate the performance of the Agricultural Production System Simulator (APSIM) model in simulating soybean biomass accumulation and grain yield under tillage and mulch practices. The experiment was established as a randomized complete block design in a split-plot arrangement with tillage (till and no-till) as the main plot treatment and four rates of grass mulch (0, 3, 6 and 9 tons ha-1) as the sub-plots treatment. The APSIMSoybean model was used to validate the result for simulated biomass and grain yield for the tillage practices at different mulching rates. A greenhouse experiment was also conducted during the 2017/2018 growing season to enhance the understanding of undulation potential in the selected soybean cultivar together with other cultivars. The greenhouse experiment was laid out in a randomized complete block design (RCBD) with four replications. Three soybean cultivars, commercial cultivar Donmario 8.6IRR (sourced from Agricol), Dundee commercial cultivar and Ibis 2000 (both sourced from Agricultural Research Council) were evaluated for their growth, phenological development, and symbiotic activities. Soybean growth was significantly (p≤0.001) affected by tillage at Syferkuil but not at Ofcolaco with the tilled soil having more pronounced growth than no-till at the former. Addition of mulch resulted in improved soybean growth relative to the control at both localities. Tillage and mulch as well as their interactive effects on soil moisture was significant at Syferkuil. Across tillage practices mulch application exhibited the highest moisture content than the control plots. At Ofcolaco tillage and mulch significantly (p≤0.001) affected soil water content but not the interaction effect, with more moisture recorded under the no-tilled condition and mulch application rate of 9 t ha-1 Soybean shoot and root nitrogen content was not influenced by tillage but was responsive (p≤0.001) to mulch application at both sites. The application of 9 t ha-1 mulch increased the shoot nitrogen content compared to the control plants at both locations. Soybean biomass and grain yield were also significantly influenced by tillage and mulch at Syferkuil but not at Ofcolaco (p≤0.001). A significant interaction effect of tillage and mulch (p≤0.001) on biomass and grain yield was also observed at Syferkuil but not Ofcolaco. At Syferkuil, higher biomass and grain yield was observed under the tilled condition when mulch at the rates of 6 and 9 tons were applied whereas, at Ofcolaco, soybean biomass and grain yield was higher under mulch application than the control with mulch application of 9 tons ha-1 at this location having the highest biomass and grain yield. The results of the APSIM model simulation showed the simulated biomass and grain yield to have a positive relationship. Hence, APSIM model can be used to guide alternate management practices to improve soybean production in the Limpopo Province. Findings from the greenhouse trial revealed that soybean cultivars significantly (p≤0.001) vary in symbiotic activities, growth, and physiological development. Across the cultivars, Ibis 2000 was superior in all studied parameters whereas Donmario, the cultivar used in the field trial was generally inferior among the three. KEYWORDS: Cultivars, Grain yield, Soybean, / Department of Science and Technology (DST) and National Research Foundation (NRF)

Le phoma (Phoma macdonaldii / Leptosphaeria linquistii) et le phomopsis (Phomopsis / Diaporthe helianthi) sont deux champignons pathogènes majeurs du tournesol. Dans un contexte d’objectif de réduction de la lutte chimique, une meilleure compréhension des interactions peuplement-agents pathogènes-environnement-conduite de culture est nécessaire. Des essais menés au champ et en serre à Auzeville en 2010 et 2011 ont permis de décomposer les effets de la conduite de culture du tournesol sur l’apparition et le développement des deux maladies. Les variables clés de l’architecture des plantes en peuplement et du microclimat, modifiées par la conduite de culture (choix variétal, densité de semis, fertilisation azoté, irrigation) ont été décrites et mises en relation avec les composantes de la maladie. Ainsi, pour le phomopsis, le rôle déterminant du microclimat résultant du niveau de développement de la couverture foliaire lors des phases initiales d’infection a été confirmé. La taille des feuilles et le diamètre des tiges sont des caractères déterminants de la progression des dégâts sur feuille et tige. Les conséquences des attaques de phomopsis sur feuille en termes de mécanismes de nuisibilité ont été analysées finement et modélisées. Pour le phoma, le rôle du statut nutritionnel azoté dans la progression des attaques sur tige et collet a été confirmé. La fonction régulatrice du phoma vis-à-vis des attaques de phomopsis sur feuille a été quantifiée. Sur le plan de la modélisation, plusieurs approches ont été menées : (i) Evaluation de la qualité prédictive d’Asphodel, modèle épidémiologique prévoyant les émissions de ascospores de Phomopsis ; application à différentes conduites de culture et extension au phoma pour la partie inoculum primaire ; (ii) développement d’un modèle prédictif de l’incidence du phoma prenant en compte les effets climatiques, microclimatiques et agronomiques ; (iii) proposition d’une modélisation conceptuelle des interactions plante-agent(s) pathogène(s)-environnement-conduite de culture. Ce travail pourra, à terme, contribuer à la conception de stratégies de gestion des principales maladies du tournesol, à l’échelle de la parcelle ou du territoire. / Phoma (Phoma macdonaldii / Leptosphaeria linquistii) and phomopsis (Phomopsis / Diaporthe helianthi) are two major sunflower fungal diseases. In a context of reduction of pesticides, a better understanding of the interactions between crop canopy, pathogens, environment and cropping practices is needed. Field and greenhouse experiments set up at Auzeville in 2010 and 2011 allowed to dissect the impact of sunflower crop management on disease appearance and development. Key variables of plant architecture and microclimate, modified by cropping practices (variety choice, sowing density, nitrogen fertilization, irrigation) were described and related to disease components. Thereby, for phomopsis, the key role of microclimate resulting from the level of development of leaf area during the initial stages of infection was confirmed. Leaf length and stem diameter are key characters for necrosis progression on leaf and stem. The impact of phomopsis leaf infection in term of damage mechanism was analysed and modelled. For phoma, the effect of nitrogen nutrition status on necrosis progression on stem and stem base was confirmed. The regulatory function of phoma towards phomopsis leaf infection was quantified. In terms of modelling, several approaches were developed: (i) evaluation of the predictive quality of Asphodel, an epidemiological model predicting Phomopsis ascospore release; application to different cropping practices and extension to phoma for primary inoculum; (ii) development of a predictive model for phoma incidence taking into account the climatic, microclimatic and agronomic effects; (iii) proposal of a conceptual model of the interactions between crop canopy, pathogens, environment and cropping practices. This study could contribute to the design of integrated management strategies for the main sunflower diseases, at field or at territory scale.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniversitet, 2004. / Härtill 4 uppsatser.

Submitted by Carolina Rabal Biasetto null (carolinarabal@yahoo.com.br) on 2016-05-18T19:36:08Z No. of bitstreams: 1 Tese_Doutorado_Carolina_Rabal_Biasetto_2016.pdf: 15348096 bytes, checksum: 59245cf961f6aaf1a999156f53853b5d (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-05-20T18:01:57Z (GMT) No. of bitstreams: 1 biasetto_cr_dr_araiq_par.pdf: 1896284 bytes, checksum: 8b4dcb25761fe239f657abc24e10c1e7 (MD5) / Made available in DSpace on 2016-05-20T18:01:57Z (GMT). No. of bitstreams: 1 biasetto_cr_dr_araiq_par.pdf: 1896284 bytes, checksum: 8b4dcb25761fe239f657abc24e10c1e7 (MD5) Previous issue date: 2016-04-27 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A capacidade biossintética dos fungos endofíticos, aliado aos estudos químico e biológicos relatados para Eugenia brasiliensis, motivou a idealização do projeto, a prospecção química, biológica e enzimática em fungos endofíticos associados a folhas, caules e frutos saudáveis de Eugenia brasiliensis e a avaliação do co-cultivo e epigenética em Xylaria cubensis, Diaporthe sp. e Colletotrichum sp., na obtenção de novas substâncias. O isolamento dos fungos endofíticos, resultou em dezessete linhagens de fungos endofíticos, sendo estes cultivados em escala reduzida em meio líquido de batata e dextrose (PDB) e Czapek, a 25 oC, sob modo estático para obtenção dos respectivos extratos brutos em AcOEt. A avaliação metabólica destes extratos foi realizada por CCDC, HPLC-DAD e RMN de 1H, como também a potencialidade enzimática e biológica pela avaliação das atividades antifúngica, anticolinesterásica e citotóxica, sendo que estes extratos demonstraram ser promissores. A prospecção inicial conduziu a seleção de três fungos endofíticos identificados como Xylaria cubensis (Eb_caH_5), Diaporthe sp. (Eb_caS_4), e Colletotrichum sp. (Eb_frmH_1), os quais foram cultivados (escala ampliada) em PDB para isolamento e determinação/elucidação estrutural dos metabólitos secundários. O estudo de Xylaria cubensis, resultou no isolamento de 8 substâncias, sendo da classe dos nucleosídeos, dicetopirazinas, isocumarinas e citocalasinas. De Diaporthe sp. foi isolado e identificado 8 substâncias: duas dicetopiperazinas, ácido nitropropiônico, uracila, tirosol, zygosporina D, pirrolidona (inédita) e alternariol. Colletotrichum sp. resultou no isolamento de 6 substâncias, sendo três dicetopiperazinas, além das substâncias N-(2-feniletil)acetamida, N-acetiltriptamina e metanoato de 2-hidroxibutila 3-indol (inédita). Todas as classes de substâncias produzidas por estes fungos endofíticos apresentam diversas atividades biológicas relatadas na literatura. Destaca-se a atividade fitotóxica da citocalasina D frente a coleóptilos de trigo superior ao herbicida comercial GOAL®. Para verificar a influência na produção metabólica de Xylaria cubensis, Diaporthe sp. e Colletotrichum sp., utilizou-se estratégias como o co-cultivo em meio sólido (PDA) e líquido (PDB) e a epigenética (escala reduzida), nas quais os endófitos mostraram produção metabólica diferente em relação à produção das monoculturas e na ausência do modulador epigenético ácido hidroxâmico suberoilanilida (SAHA), respectivamente. As ferramentas estatísticas, como PCA (Análise de componentes principais) e PLS-DA (Análise discriminante com calibração multivariada por mínimos quadrados parciais) permitiram uma rápida identificação e localização dos perfis metabólicos dos co-cultivos comparados às monoculturas. Estes dados contribuem para o conhecimento dos perfis metabólicos, biológicos e enzimáticos dos fungos endofíticos isolados de Eugenia brasiliensis, bem como suas interações com o hospedeiro. / The biosynthetic capacity of endophytic fungi, allied chemical and biological studies reported to Eugenia brasiliensis motivated the idealization of the project, prospection chemical, biological and enzymatic in endophytic fungi associated with healthy leaves, stems and fruits from Eugenia brasiliensis and evaluation co-culture and epigenetic in Xylaria cubensis, Diaporthe sp. and Colletotrichum sp., in obtaining new substances. The isolation of endophytic fungi resulted in seventeen endophytics fungi, these being cultivated in small scale on potato dextrose broth (PDB) and Czapek at 25 °C under static mode to obtain the corresponding crude extracts in AcOEt. The metabolic evaluation of these extracts was performed by CCDC, HPLC-DAD and 1H NMR, also enzymatic and biological potential were performed by antifungal, cytotoxic, and anticholinesterase activities, and these extracts have shown promise. The preliminary prospection led to the selection of three endophytic fungi identified as Xylaria cubensis (Eb_caH_5), Diaporthe sp. (Eb_caS_4) and Colletotrichum sp. (Eb_frmad_1) which were cultivated (larger scale) in PDB for isolation and determination or structural elucidation of secondary metabolites. The study of Xylaria cubensis resulted in the isolation of eight substances, as follows: nucleoside, diketopiperazines, isocoumarins and cytochalasins class. From Diaporthe sp. was isolated and identified eight substances, as follows: two diketopiperazines, nitropropionic acid, uracil, tyrosol, zygosporin D, pyrrolidone (unpublished) and alternariol. Colletotrichum sp. resulted in the isolation of six substances, three diketopiperazines, besides the substances N-(2-phenylethyl) acetamide, Nβ-acetyltryptamine and 3-hydroxybutan-2-yl-1H-indol-3-ylacetate (unpublished). All classes of substances produced by these endophytic fungi present several biological activities reported in the literature. Noteworthy is the phytotoxic activity of cytochalasin D against wheat coleoptile higher than commercial herbicide GOAL®. To verify the influence on the metabolic production of Xylaria cubensis, Diaporthe sp. and Colletotrichum sp., used strategies such as the co-culture on solid (PDA) and liquid medium (PDB) and epigenetic (small scale), in which endophytes showed an interesting and different metabolic production when compared with the production of monocultures and the absence of epigenetic modulator SAHA, respectively. The statistical tools, such as PCA (Principal component analysis) and PLS-DA (discriminant analysis with multivariate calibration partial least squares) allowed quick identification and location of the metabolic profiles of the co-culture compared monocultures. These data will contribute to the knowledge of the metabolic profiles, biological and enzymatic of endophytic fungi isolated from Eugenia brasiliensis and their interactions with host. / CNPq: 140980/2012-1

Submitted by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-08-23T17:16:50Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese - Manoel Feitosa Jeffreys.pdf: 4154773 bytes, checksum: 90fd1c343f946032e9481145081f1652 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-08-23T17:17:08Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese - Manoel Feitosa Jeffreys.pdf: 4154773 bytes, checksum: 90fd1c343f946032e9481145081f1652 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2017-08-23T17:17:31Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese - Manoel Feitosa Jeffreys.pdf: 4154773 bytes, checksum: 90fd1c343f946032e9481145081f1652 (MD5) / Made available in DSpace on 2017-08-23T17:17:31Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese - Manoel Feitosa Jeffreys.pdf: 4154773 bytes, checksum: 90fd1c343f946032e9481145081f1652 (MD5) Previous issue date: 2016-07-20 / FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas / This work aimed to study the chemical extracts of Piranhea trifoliata and your endophytes (PICRODENDRACEAE) and its potential antimicrobial tests, antioxidant and antimalarial. The leves it was collected in Volta Grande of Xingú, Altamira, PA (collect 1) and Lake of Catalão, Manaus, AM (collect 2 e 3). The dried specimen’s it was deposited in the herbarium of the Federal Institute of Amazonas (IFAM) with record numbers 10653 and 10654. The collected material was dried and pulverized. The collect 1, was extracted by dichloromethane (DCM), methanol (MeOH) and water (H2O). The collect 2 and 3 was extracted by hexane, methanol and water. The preliminary phytochemical analysis of leaves and fungi showed that dichlorometane and hexane extracts contain terpenes and methanolic extracts contain phenolic compounds. The broths from fungi showed that diclorometânica phase (DCM) contain terpenes, and phase of Ethyl Acetate (AcOEt) contain terpene and phenolic compounds. The phytochemical study of the leves led to the isolation of: Friedelan-3-one (I), 30-hydroxy-friedelan-3-one (II), Lupeol (III), the mixture of β -Sitosterol and Stigmasterol steroids (IV and V), hydroxycoriatin (VI), the mixture of α and β-amyrin (VII and VIII ), 7- hydroxy-6-methoxy-coumarin (IX), 7,4 ''' dymethylamentoflavone (X), methyllonyflavna 3'-O-(XI) and purification of the 28-hydroxy-friedelan-3-one (XIV). The phytochemical study of the Diaporthe hongkongensis, fungi, led to the isolation of (3-oxociclobutil) 2-methyl-1- hydroxi metilciclopenta -2,4- diene carboxylate (XII) and 9-amino-7- (2,5,7-triazabicyclo [2.2.1] hept-3-yl)-2,3,6- trioxi-1-azabicyclo [3.2.2] nona-4,8-diene-4- carbaldehyde (XIII) both isollated of the first time. All compound were identified by 1H, 13C NMR, 2D and mass espectra data. The antioxidant activity, shoed the MeOH extract of leaves from collection 2, was equivalent with 1,15 and 1,13, the H2O phase showed 2,8 and 4.,51 (DPPH• and Fe3+) were considered significant. The antibacterial activity the DCM phase of leaves of collectes 2 and 3 and the EtOAc phase of collection 1, showed CIM and CMB found was 500/mL against Aeromonas hydrophila and Flavobacterium columnare. The aqueous phase of collection 1 showed CIM and CMB found was 1000 μg/ml against Flavobacterium columnare and Pseudomonas fluorescens. The mycelial extracts of fungi 4 and 6, tested with methodology to inhibition halo, showed medium activity, 1 cm, against Aeromonas hydrophila and Klebsiella pneumoniae. The DCM and EtOAc phases of metabolite broth of the fungu 4, showed activity with halo of 1 and 1,2 cm. The antimalical activity. The antimalarial activity showed that hexane and MeOH extracts of leves of the collection 3, showed IC50 of 1,51 and 1,77 mg/mL when compared to the standard. The MeOH extract of fungi 4, showed 6,89 of parasitaemia being significant. The activity by isolated compound sowed CIM of 73,58% to the compound X and 71,75% to the compound XI against Klebsiella pneumoniae . / O presente trabalho teve como objetivo realizar o estudo químico e biológico das folhas de Piranhea trifoliata e de seus fungos endofíticos (Picrodendraceae) e realizar a avaliação do seu potencial frente aos ensaios antimicrobiano, antioxidante e antimalárico. As folhas foram coletadas na Volta Grande do Xingú, Altamira, PA (coleta 1) e no lago do Catalão, Manaus, AM (coletas 2 e 3). A coleta 1 foi extraída com diclorometano, metanol e Água, e as coletas 2 e 3 foram extraídas com hexano, metanol e água. Parte do material das coletas 2 e 3 foi também processada para a obtenção dos fungos endofíticos e estes foram extraídos com diclorometano e acetato de etila. A análise fitoquímica preliminar das folhas e dos fungos mostrou que os extratos diclorometânicos e hexânico possuem terpenos e os extratos metanólicos apresentam substânciastos fenólicas. Os caldos metabólitos dos fungos mostraram que a fase diclorometânica (DCM) possui terpenos, e a fase de acetato de etila (AcOEt) possui indícios de terpenos e substâncias fenólicas. O estudo fitoquímico das folhas levou ao isolamento da Friedela-3-ona, 30-hidroxi-friedelan-3-ona, Lupeol, a mistura dos esteróides β-sitosterol e Estigmasterol, hidroxicoriatina, a mistura de α e β–amirina, 7-hidroxi-6-metoxi-cumarina, 7,4’’’ dimetilamentoflavona, 3’-O- metilloniflavna e a 28-hidroxi-friedelan-3-ona. Já o estudo fitoquímico do fungo Diaporthe hongkongensis, levou ao isolamento de (3-oxociclobutil) metil1-hydroxi-2 metilciclopenta-2,4-dieno carboxilato e 9-amino-7-(2,5,7-triazabiciclo[2.2.1]hept-3-il)-2,3,6-trioxi-1-azabiciclo [3.2.2] nona-4,8-dieno-4-carbaldeido ambas inéditas. Todas as substânciais foram identificadas por RMN de 1H e de 13C, mono e bidimensionais e espectrômetro de massas. Quanto à atividade antioxidante, o extrato MeOH das folhas da coleta 2, apresentou equivalência de 1,15 e 1,13, a fase H2O apresentou 2,8 e 4,51 (DPPH e Fe3+) sendo considerados significativos. A atividade antibacteriana mostrou que a fase DCM das folhas das coletas 2 e 3 e a fase AcOEt da coleta 1, apresentaram CIM e CMB de 500 μg/mL frente às bactérias Aeromonas hydrophila e Flavobacterium columnare. A fase aquosa da coleta 1, apresentou CIM e CMB de 1000 μg/mL frente às bactérias Flavobacterium columnare e Pseudomonas fluorescens. Os extratos miceliais dos fungos 4 e 6, testados pela a metodologia do halo de inibição, apresentaram média atividade, 1 cm frente às bactérias Aeromonas hydrophila e Klebsiella pneumoniae. As fases DCM e AcOEt do caldo metabólito do fungo 4 mostraram-se ativas com 1 e 1,2 cm de halo. A atividade antimalárica mostrou que os extratos hexânicos e MeOH das folhas da coleta 3 apresentaram IC50 de 1,51 e 1,77 μg/mL quando comparado com o padrão. O extrato MeOH do fungo 4 apresentou 6,89 de parasitemias sendo significativo. Ao testar as substâncias isoladas frente as bactérias, observou-se a CIM de 73,58% em X e 71,75% em XI frente a bactéria K. pneumoniae.

Orientador: Angela Regina Araujo / Resumo: Os fungos endofíticos, representam uma fonte promissora na descoberta de produtos naturais. Estes endófitos têm se revelado pela alta capacidade na produção de diversas classes de metabólitos secundários com uma ampla variedade de atividades biológicas, tais como: antimicrobiana, citotóxica, antioxidante, ansiolítica e inseticida. Estas observações motivaram o desenvolvimento do presente estudo, o qual visou a prospecção química e biológica dos fungos endofíticos associados à Platonia insignis Mart. O isolamento dos fungos endofíticos resultou em dezoito linhagens puras, sendo estes cultivados em meio líquido de MDB, para obtenção dos respectivos extratos brutos. Estes foram avaliados quanto ao perfil químico e biológico, os quais demonstram ser promissores para produção de substâncias bioativas. A prospecção inicial conduziu a seleção de dois fungos endofíticos, identificados como Diaporthe hongkongensis e Phyllosticta elongata para desenvolvimento do trabalho. Duas abordagens foram aplicadas a fim de verificar a influência da composição nutricional frente a produção metabólica de D. hongkongensis e P. elongata: cultivo em meio de MDB e cultivo em meio sólido de milho. O estudo de D. hongkongensis, cultivado em MDB, resultou no isolamento de uma dicetopiperazina, ariletilamida, acetiltriptamina e o acetato de metila-[2-oxo-2-(feniletilamino)], sendo o primeiro relato de isolamento deste composto como produto natural. Do cultivo deste endófito, em meio de milho, foram isolado... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Endophytic fungi represent a promising source for the discovery of natural products. These endophytes have been shown to be highly capable of producing various classes of secondary metabolites with a wide variety of biological activities such as antimicrobial, cytotoxic, antioxidant, anxiolytic and insecticide. These observations motivated the development of the present study, which aimed at the chemical and biological prospecting of endophytic fungi associated with Platonia insignis Mart. The isolation of endophytic fungi resulted in eighteen pure strains, which were cultivated in liquid medium of PDB, to obtain the respective crude extracts. These extracts were evaluated for chemical and biological profile, which show promise for bioactive substances production. The initial prospecting led to the selection of two endophytic fungi, identified as Diaporthe hongkongensis and Phyllosticta elongata to develop the work. Two approaches were applied to verify the influence of nutritional composition on the metabolic production of D. hongkongensis and P. elongata: cultivation in PDB medium and cultivation in solid corn medium. The study of D. hongkongensis grown in PDB resulted in the isolation of a diketopiperazine, arylethylamide, acetyltryptamine and methyl [2-oxo-2- (phenylethylamino)] acetate, being the first report of isolation of this compound as a natural product. From the cultivation of this endophyte in corn medium, alternariol, a fatty acid ester and four steroids, which ... (Complete abstract click electronic access below) / Doutor

Le principali anomalie evidenziate nelle nocciole avariate riguardano la presenza di macchie necrotiche, imbrunimenti interni rilevati inseguito al taglio dei frutti e la presenza di marciumi parziali o totali su di essi con conseguente riduzione del prodotto disponibile sul mercato e ingenti perdite economiche. Sulla base di quanto premesso, lo scopo principale di questa tesi è stato quello di identificare e caratterizzare l'agente causale/i dei difetti del nocciolo e di definire un protocollo di gestione del problema, secondo i principi IPM. È stata quantificata l'incidenza dei generi fungini isolati da nocciole provenienti da diverse aree geografiche (Caucaso e Turchia), raccolte in diversi anni e in diverse fasi di crescita della coltura. Diaporthe è stato identificato come il principale genere fungino associato ai difetti della nocciola, e la caratterizzazione molecolare ha confermato il ruolo predominante della specie D. eres. Sono state studiate le caratteristiche ecologiche di questo fungo e l'efficacia in vitro di fungicidi chimici e biologici per controllarne la crescita miceliale, lo sviluppo di picnidi e la formazione di cirri. I risultati ottenuti costituiscono una base per definire linee guida per la corretta gestione della coltura al fine di prevenire la comparsa del patogeno identificato e delle difettosità nelle nocciole / Defects on hazelnuts are responsible for a significant reduction in the availability of high-quality hazelnuts with profound economic impacts. A reduction in the occurrence of defects, based on the identification of causal agents and on their control, is critical to improve the quality of raw nut products and reduce yield losses. Based on this background, the main aim of this thesis was to identify and characterize the causal agent/s of kernel defects in hazelnuts and to define a management protocol, according to IPM principles. Defects affecting hazelnuts are cause of brown spots on the kernel surface and darkening/browning inside the kernel, visible after nuts are half-cut. The incidence of fungal genera in hazelnuts coming from different geographical areas (Caucasus and Turkey), collected in different years at different crop growth stages, was quantified. Diaporthe was identified as the main genus involved in hazelnut defects, and the molecular characterization confirmed the predominant role of D. eres. Its ecological needs were investigated, and the in vitro efficacy of chemical and biological fungicide were screened to control D. eres growth, pycnidial conidiomata development and cirrhi occurrence. This would be an essential tool for a sustainable crop protection approach in this economically important crop