Progress in the use of geospatial and remote sensing technologies in the assessment and monitoring of tomato crop diseases

With a growing global population and accelerating climatechange, systematic assessment and monitoring of crop diseases isurgently required to ensure food security and production.However, current dietary transitions inclined towards vegetablessuch as tomatoes are expected to increase while effective cropdisease monitoring and assessment methods are still limited.Therefore, a state-of-the-art review of progress in the assessmentand monitoring of tomato crop diseases using geospatial technol-ogies is presented. Results show that tomato crop diseases andtheir severity could be detected and discriminated from healthyones more effectively using various remote sensing systems.Furthermore, the recent advances in RS technologies have greatlyfacilitated its integration with climatic and topo-edaphic factors todetermine the possible drivers of disease infection

Crop Disease Detection Using Remote Sensing Image Analysis

Pest and crop disease threats are often estimated by complex changes in crops and the applied agricultural practices that result mainly from the increasing food demand and climate change at global level. In an attempt to explore high-end and sustainable solutions for both pest and crop disease management, remote sensing technologies have been employed, taking advantages of possible changes deriving from relative alterations in the metabolic activity of infected crops which in turn are highly associated to crop spectral reflectance properties. Recent developments applied to high resolution data acquired with remote sensing tools, offer an additional tool which is the opportunity of mapping the infected field areas in the form of patchy land areas or those areas that are susceptible to diseases. This makes easier the discrimination between healthy and diseased crops, providing an additional tool to crop monitoring. The current book brings together recent research work comprising of innovative applications that involve novel remote sensing approaches and their applications oriented to crop disease detection. The book provides an in-depth view of the developments in remote sensing and explores its potential to assess health status in crops

Antiviral and quality effects of chemical elictors and Cucumber Mosaic Virus (CMV) infection on tomato plants and fruits

Cucumber mosaic virus (CMV) has emerged as one of the most serious threats to tomato cultivation in Greece. In the present study the effects of Benzothiadiazoles (BTH) and pyraclostrobin against mechanically or aphid-transmitted CMV in tomato plants, of hybrid F1 Clodin, were investigated in greenhouse experiments. BTH was confirmed as capable of inducing systemic acquired resistance (SAR) in tomato seedlings against CMV, while pyraclostrobin was not. Responses to BTH application and/or CMV inoculation on Spanish tomato hybrid Delos (BTH, BTH+CMV, CMV treatments) were monitored during winter and spring season in Greece. In both seasons the SAR derived from BTH application suppressed CMV. BTH treatment presented increased plant growth, fruit size and marketable tomato yield compared to CMV and BTH+CMV treatments, whereas decreased compared to healthy control. CMV treatment caused the most severe stunting of tomato plants among the examined treatments and resulted in yield loss of marketable fruits, although the total fruit number was higher versus to other treatments. Cont/d.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

New Advances and Contributions to Forestry Research

New Advances and Contributions to Forestry Research consists of 14 chapters divided into three sections and is authored by 48 researchers from 16 countries and all five continents. Section Whither the Use of Forest Resources, authored by 16 researchers, describes negative and positive practices in forestry. Forest is a complex habitat for man, animals, insects and micro-organisms and their activities may impact positively or negatively on the forest. This complex relationship is explained in the section Forest and Organisms Interactions, consisting of contributions made by six researchers. Development of tree plantations has been man’s response to forest degradation and deforestation caused by human, animals and natural disasters. Plantations of beech, spruce, Eucalyptus and other species are described in the last section, Amelioration of Dwindling Forest Resources Through Plantation Development, a section consisting of five papers authored by 20 researchers. New Advances and Contributions to Forestry Research will appeal to forest scientists, researchers and allied professionals. It will be of interest to those who care about forest and who subscribe to the adage that the last tree dies with the last man on our planet. I recommend it to you; enjoy reading it, save the forest and save life

Morphological and chemical plant properties mediate host plant selection of whiteflies (Hemiptera: Aleyrodidae)

Whiteflies are among the most important pests causing severe damage to numerous cultivated and ornamental plants worldwide. The present dissertation comprises four studies and contributes to the knowledge of the host plant selection process by whiteflies. In the first study, host preferences were determined in dual choice tests for Aleyrodes proletella (L.), Bemisia tabaci (Genn.), and Trialeurodes vaporariorum (Westw.) on several host plants. On the one hand, this study extends the knowledge on the food spectrum of these economically important pests; on the other hand, the results highlight the host adaptation of whiteflies. The second study elucidated potential sources of host plant resistance against A. proletella, B. tabaci, and T. vaporariorum by recording their probing and feeding behaviour on two host plants each using the electrical penetration graph (EPG) method. It is concluded that whiteflies decide upon host plant acceptance by evaluation of multiple plant factors located in epidermal and/or mesophyll tissues of leaves as well as in the phloem sap of plants. Moreover, epicuticular leaf waxes are a key factor in the host selection process of A. proletella. It is hypothesized that constituents of the leaf surface wax act as stimulants promoting leaf penetration and phloem accession. The findings of this study shed light on the whitefly-host adaptation. The goal of the third study was to identify the role of epicuticular leaf waxes of several Brassica cultivars in the host selection process of A. proletella. For this purpose, dual choice tests were carried out on both waxy and dewaxed plant leaves as well as on Parafilm® treated with different leaf wax extracts. Also, life-history traits were monitored on waxy and dewaxed leaves, and the feeding activity of A. proletella was recorded on Parafilm® with and without leaf wax extracts. Scanning electron microscopy (SEM) imaging was used to visualize epicuticular leaf waxes on the plant surface. Finally, it was proved that leaf surface waxes of host plants promote feeding and act as phagostimulants. Although the wax compounds mediating host plant selection remain unknown, these findings offer breeding potential for resistant crop cultivars. In the fourth study, the influence of free phloem amino acids on the host plant selection of T. vaporariorum was investigated. Via liquid chromatography-mass spectrometry (LC-MS), the amino acid profiles in the phloem sap of six vegetable crops varying in their host plant attractiveness were analysed. Subsequently, stepwise multiple regressions of the relative amino acid compositions and the pre-determined host plant preferences were performed. To verify the contribution of single amino acids on host choice, dual choice tests on sucrose media with and without added single amino acids were carried out. Single amino acids play an active role in phagostimulation, whereas some amino acids exert strong inhibitory effects. This indicates that the dominant presence of such amino acids might reduce phloem sap uptake, thus contributing to host plant resistance towards T. vaporariorum. Overall, this research compared the host selection process of three whitefly species to identify their underlying mechanisms. It is hypothesized that the observed host selection strategies are the result of evolutionary adaptations between whiteflies and their host plants. Depending on the occupied ecological niche, species-specific host plant ranges of varying complexity were formed. Accordingly, the host selection process of the more specialised species A. proletella is particularly efficient by consideration of characteristic leaf surface wax stimuli. In contrast, host selection of the extreme generalists B. tabaci and T. vaporariorum is regulated by simple gustatory stimuli in order to take advantage of the host diversity they are offered. The findings of this research provide the basis for new approaches to optimizing breeding programs for whitefly resistant crops.Weiße Fliegen zählen zu den bedeutendsten Schädlingen, die weltweit erhebliche Schäden an zahlreichen Kultur- und Zierpflanzen verursachen. Die vorliegende Dissertation umfasst vier Studien und gibt Aufschluss über den Auswahlprozess von Wirtspflanzen durch Weiße Fliegen. In der ersten Studie wurden in Dual-Choice-Tests die Wirtspräferenzen von Aleyrodes proletella (L.), Bemisia tabaci (Genn.) und Trialeurodes vaporariorum (Westw.) für mehrere Wirtspflanzen bestimmt. Einerseits erweitert diese Studie den Kenntnisstand hinsichtlich des Nahrungsspektrums dieser wirtschaftlich bedeutenden Schädlinge, andererseits unterstreichen die Ergebnisse die Wirtsanpassung der Weißen Fliege. Die zweite Studie beleuchtete anhand der Aufzeichnung des Probe- und Nahrungsaufnahmeverhaltens von A. proletella, B. tabaci und T. vaporariorum an je zwei Wirtspflanzen potenzielle Quellen der Wirtspflanzenresistenz mittels der electrical penetration graph (EPG)-Methode. Die Ergebnisse lassen darauf schließen, dass Weiße Fliegen anhand der Bewertung mehrerer Pflanzenfaktoren, die sich sowohl in den epidermalen und/oder mesophyllischen Gewebsschichten der Blätter als auch im Phloemsaft der Pflanzen befinden, über die Akzeptanz einer Wirtspflanze entscheiden. Darüber hinaus stellen epikutikuläre Blattwachse einen Schlüsselfaktor im Wirtsselektionsprozess von A. proletella dar. Daraus lässt sich die Hypothese ableiten, dass Bestandteile des Blattoberflächenwachses als Stimulanzien wirken, die die Blattpenetration und das Erreichen des Phloems fördern. Die Ergebnisse dieser Studie beleuchten die Anpassung von Weißen Fliegen an ihre jeweiligen Wirtspflanzen. Das Ziel der dritten Studie war es, die Rolle epikutikulärer Blattwachse mehrerer Brassica-Sorten im Wirtsselektionsprozess von A. proletella zu identifizieren. Zu diesem Zweck wurden Dual-Choice-Tests an bewachsten und entwachsten Pflanzenblättern sowie mit Parafilm®, der mit verschiedenen Blattwachsextrakten behandelt wurde, durchgeführt. Außerdem wurden lebensgeschichtliche Parameter auf bewachsten und entwachsten Blättern ermittelt und die Nahrungsaufnahmeaktivität von A. proletella auf Parafilm® mit und ohne Blattwachsextrakten erfasst. Die Rasterelektronenmikroskopie (REM) wurde zur Visualisierung epikutikulärer Blattwachse auf der Pflanzenoberfläche eingesetzt. Schließlich wurde nachgewiesen, dass Blattoberflächenwachse der Wirtspflanzen die Nahrungsaufnahme fördern und als Phagostimulans wirken. Obwohl die Wachsverbindungen, die die Selektion von Wirtspflanzen bestimmen, unbekannt bleiben, bieten diese Erkenntnisse Potenzial für die Züchtung resistenter Kultursorten. In der vierten Studie wurde der Einfluss von den im Phloemsaft befindlichen freien Aminosäuren auf die Wirtspflanzenselektion von T. vaporariorum untersucht. Mittels Flüssigchromatographie mit Massenspektrometrie-Kopplung (LC-MS) wurden die Aminosäureprofile im Phloemsaft von sechs Gemüsekulturen analysiert, die sich hinsichtlich ihrer Wirtspflanzenattraktivität unterschieden. Anschließend wurden schrittweise multiple Regressionen unter Einbezug der relativen Aminosäure-Zusammensetzungen und den zuvor bestimmten Wirtspräferenzen durchgeführt. Um den Beitrag einzelner Aminosäuren in Bezug auf die Wirtswahl zu verifizieren, wurden Dual-Choice-Tests auf Saccharosemedien mit und ohne Zusatz einzelner Aminosäuren durchgeführt. Einzelne Aminosäuren spielen eine aktive Rolle bei der Phagostimulation, während einige Aminosäuren starke hemmende Effekte ausübten. Dies deutet darauf hin, dass die dominante Anwesenheit solcher Aminosäuren die Aufnahme des Phloemsaft reduziert und damit zur Resistenz von Wirtspflanzen gegenüber T. vaporariorum beiträgt. Insgesamt wurde im Rahmen dieser Forschungsarbeit der Auswahlprozess dreier Arten Weißer Fliegen miteinander verglichen, um die ihnen zugrunde liegenden Mechanismen zu identifizieren. Es wird postuliert, dass die beobachteten Wirtsselektionsstrategien das Ergebnis von evolutionären Anpassungen zwischen Weißen Fliegen und ihren Wirtspflanzen sind. Entsprechend der jeweiligen besetzten ökologischen Nische bildeten sich artspezifische Wirtspflanzenspektren von unterschiedlicher Komplexität. Demzufolge gestaltet sich der Wirtsselektionsprozess der spezialisierteren Art A. proletella durch die Berücksichtigung charakteristischer Reize, welche von Blattoberflächenwachsen ausgehen, als besonders effizient. Im Gegensatz dazu wird das Wirtswahlverhalten der extremen Generalisten B. tabaci und T. vaporariorum von einfachen gustatorischen Reizen gesteuert, um die sich ihnen bietende Wirtsvielfalt auszunutzen. Die Ergebnisse dieser Forschung bilden die Grundlage neuer Ansatzpunkte für die Optimierung von Züchtungsprogrammen für Nutzpflanzen, die gegen Weiße Fliegen resistent sind

Artificial Neural Networks in Agriculture

Modern agriculture needs to have high production efficiency combined with a high quality of obtained products. This applies to both crop and livestock production. To meet these requirements, advanced methods of data analysis are more and more frequently used, including those derived from artificial intelligence methods. Artificial neural networks (ANNs) are one of the most popular tools of this kind. They are widely used in solving various classification and prediction tasks, for some time also in the broadly defined field of agriculture. They can form part of precision farming and decision support systems. Artificial neural networks can replace the classical methods of modelling many issues, and are one of the main alternatives to classical mathematical models. The spectrum of applications of artificial neural networks is very wide. For a long time now, researchers from all over the world have been using these tools to support agricultural production, making it more efficient and providing the highest-quality products possible

Effects of different cooling methods on microclimate and plant growth in greenhouses in the tropics

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Whitefly resistance in tomato: from accessions to mechanisms

Tomato (Solanum lycopersicum) is affected by a wide range of biotic stresses, of which Bemisia tabaci is one of the most important.Bemisia tabaci affects tomato directly through phloem sap feeding, and indirectly through its ability to be the vector of a large number of viruses. Different methods are available for whitefly control, and although several biological control agents are used against whiteflies in greenhouse cultivation, chemical control still is an essential component in open field tomato production. Breeding for host plant resistance is considered as one of the most promising methods in insect pest control in crop plants, and especially it is a promising alternative in whitefly control. Resistance to whiteflies was found in several wild relatives of tomato like Solanum peruvianum, S. pennellii, S. habrochaites, S. lycopersicum var. cerasiforme, S. pimpinellifolium andS. galapagense. In spite of previous breeding efforts, whiteflies are still a problem in tomato cultivation. The aim of my research was to identify and understand resistance mechanisms targeting specific stages of the whitefly life cycle in order to provide breeders with tools for developing whitefly resistant varieties. I assessed the natural variation and whitefly resistance in Solanum galapagense and S. cheesmaniae, two wild tomato species endemic to the Galapagos Islands. Previously, Solanum galapagense and S. cheesmaniae were classified as two species based on a morphological species concept, but with molecular markers no clear separation could be made. So far, only a limited number of accessions/populations of S. galapagense and S. cheesmaniae have been evaluated for insect resistance and therefore it was unknown if the insect resistance coincides with the morphological species boundaries. Neither was there any knowledge about the relation between geographical and climatic conditions today on the Galapagos and the occurrence of the two species. We characterized twelve accessions of S. galapagense, 22 of S. cheesmaniae, and as reference one of S. lycopersicum for whitefly resistance using no-choice experiments. Whitefly resistance was found in S. galapagense only and was associated with the presence of relatively high levels of acyl sugars and the presence of glandular trichomes of type I and IV.It is likely that a minimum level of acyl sugars and the presence of glandular trichomes type IV are needed to achieve an effective level of resistance. Genetic fingerprinting using 3316 polymorphic SNP markers did not show a clear differentiation between the two species endemic to the Galapagos. Acyl sugar accumulation as well as the climatic and geographical conditions at the collection sites of the accessions did not follow the morphological species boundaries. Altogether, our results suggest that S. galapagense and S. cheesmaniae might be considered as morphotypes rather than two species and that their co-existence is likely the result of selective pressure. Plants possess several resistance mechanisms acting at different time points during the interaction with herbivorous insect. Before any contact with the insects, plants emit an array of volatile organic compounds that can act as attractant or repellent of insects.Bemisia tabaci use a set of plant-derived cues in the process of host plant selection. It recognizes mainly monoterpenes (p-cymene, γ-terpinene and β-myrcene, α-phellandrene) and sesquiterpenes (7-epizingiberene and R-curcumene). Previously the line FCN93-6-2, which was derived from a cross between a susceptible tomato cultivar (Uco Plata INTA) and S. habrochaites (FCN3-5) was proved to be non-preferred by the greenhouse whitefly Trialeurodes vaporariorum. We identified chemical cues produced by FCN93-6-2 and S. habrochaites that can affect the preference of the whitefly B. tabaci as well as the potential chromosomal region(s) of S. habrochaites harbouring the genes involved in the preference. Two S. habrochaites accessions (CGN1.1561 and in FCN3-5) and the line FCN93-6-2 were non-preferred by B. tabaci when the whiteflies could get in direct contact with the plant and also when the whiteflies were offered olfactory cues only. The non-preference was independent of trichome type IV and of the presence of methyl-ketones but associated to the presence of monoterpenes in lower concentrations. Functional validation of the candidate metabolites and of the different introgressions is still needed. Once the insect has landed on a plant, another set of resistance mechanisms enter into action. We have described a 3.06 Mbp introgression on top of Chromosome 5 (OR-5) from the wild tomato species S. habrochaites (CGN1.1561). For the identification of OR-5, we went from the selection of specific F2 plants to the development of F2BC4S1 and F2BC4S2 families. This introgression was sufficient to reduce whitefly fecundity without an evident effect on whitefly survival. The identification of mechanisms exclusively affecting whitefly fecundity and independent of trichomes type IV opens new doors for resistance breeding to whiteflies that may be especially interesting in greenhouse cultivation combination with natural enemies of the whitefly. As an additional layer of defences, plants can perceive stress signals and respond to them in a specific way through induction of their immune system. This induction can also be triggered by exposing the plants to priming agents like hormones, some xenobiotic chemicals, like benzothiadiazole (BTH), β-aminobutyric acid (BABA), and sugars. Although the effect of priming agents was shown in laboratory and field studies, little is known about the effect of the genetic background of tomato on the extent of the priming, e.g. do genotypes varying in their level of resistance to insects and pathogens respond in the same way to a priming agent. We assessed the effect of selected priming agents on the effectiveness of natural defence in tomato. A set of no-choice and choice bioassays was conducted using tomato genotypes varying in their level of basal resistance to Bemisia tabaci and pathogens. We observed that whitefly survival and oviposition were not affected by the priming treatment in no-choice assays. Overall, in choice assays, fructose treated plants were more preferred by whiteflies than control plants. A genotype specific effect of priming was seen for the line FCN93-6-2. On this tomato line, JA and BABA applications decreased the number of whiteflies, e.g. making them less preferred. In this thesis, I have gone from the screening of wild relatives of tomatoes to in depth characterization of resistance mechanisms. I have identified resistance mechanisms targeting specific stages of the whitefly life cycle, thus providing new tools for breeding durable whitefly resistance in tomato.</p

Annual report, 1961-62.

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