Predicting seed admixture in maize combining flowering characteristics and a Lagrangian stochastic dispersion model

The seed purity problem has received very low attention in maize coexistence studies, and has not been considered in prediction tools that simulate pollen flow and out-crossing between maize fields. To fill this gap we developed the Seed Admixture Model (SAMETH) able to predict seed admixture dispersion combining flowering characteristics (pollen shed, silks exertion) with a Lagrangian stochastic dispersion model. The model was tested with a dataset obtained from 20 fields in 2007 and in 2008, whose seeds were mixed with 1% of a homozygous blue-kernelled hybrid. The model was first calibrated with data from 6 fields and then validated with the data from the remaining 14 fields. Moreover, a sensitivity analysis was performed to test the consequences of different pollen quantities released by the admixture and the commercial hybrids. The measured seed admixture ranged from 0.7% to 6% and the model was able to simulate the seed admixture with r² = 0.83. The sensitivity analysis showed that the model was sensitive to the absolute released pollen quantities but it was still able to predict seed admixture rather accurately. Because of its reliability, the model could become a useful tool for case study scenarios that involve seed admixture and for which field implementations would be too complex and time-consuming.     

„VitiMeteo Plasmopara“ – Prognosemodell zur Bekämpfung von Plasmopara viticola (Rebenperonospora) im Weinbau

Downy mildew, caused by Plasmopara viticola, is the most important disease of European grapevine (Vitis vinifera) in humid climates. On the basis of weather data the forcasting model “VitiMeteoPlasmopara” calculates the most important steps of the life cycle of downy mildew. A growth model for the simulation of leaf development is integrated in the pure forcasting model for downy mildew. “VitiMeteoPlasmopara” was elaborated by the Swiss Research Station ACW, Changins-Wädenswil and the State Institute of Viticulture and Enology Freiburg in Germany. Since 2003 the system is scientifically tested in Switzerland and Baden-Württemberg and applied in practice. Once or twice a day, the actual results of the forecasting system are visualised on the Internet. “Vitimeteo Plasmopara” is used to forecast downy mildew in Switzerland and in the south of Germany (Baden Württemberg), comprising approx. 42,000?ha of grapevine (15,000?ha CH, 27,000?ha D), and about 100 weather stations located in the area. The forecasting system is widely used by both advisory service and growers. It has proven a very useful tool to estimate the epidemiological situation and it allows the definition of spray intervals in relation with the epidemics. The open structure of the database allows the use and the integration of weather data into any other expert software moduls to forecast the development of other fungal diseases, pests or completely other models, for example irrigation models. “VitiMeteo Growth ”, a vine growth model, “VitiMeteo Insects”, a model for pests and “VitiMeteo DataGraph”, a software to analyze and present weather data, are already developed. The expert software moduls are summarized under designation “VitiMeteo Suite”.     

On the use of phloem sap δ¹³C as an indicator of canopy carbon discrimination

In this study we measured δ13C in various carbon pools along the basipetal transport pathway in co-occurring Pinus pinaster and Acacia longifolia trees under Mediterranean climate conditions in the field. Overall, species differences in photosynthetic discrimination resulted in more enriched δ13C values in the water-conserving overstory P. pinaster relative to the water-spending understory invasive A. longifolia. Post-photosynthetic fractionation effects resulted in differences in δ13C of water-soluble organic matter pools along the plant axis with progressive depletion in δ13C from the canopy to the trunk (～6.5‰ depletion in A. longifolia and ～0.8‰ depletion in P. pinaster). Regardless of these fractionation effects, phloem sap δ13C in both terminal branches and the main stem correlated well with environmental parameters driving photosynthesis for both species, indicating that phloem sap δ13C has potential as an integrative tracer of changes in canopy carbon discrimination (Δ13C). Furthermore, we illustrate that a simple model based on sap flow estimated canopy stomatal conductance (G(S)) and phloem sap δ13C measurements has significant potential as a tool for estimating canopy-level carbon assimilation rates.     

Growth and survival of termite-piped Eucalyptus tetrodonta and E. miniata in northern Australia: Implications for harvest of trees for didgeridoos

The most common canopy trees in the savannas of northern Australia, Eucalyptus tetrodonta and E. miniata are also two of the most common species harvested to make didgeridoos, the traditional musical instrument of northern Australian Aboriginal peoples now experiencing high demand from international markets. Most of the trees of the area naturally have hollow cores, or pipes, due to termite activity, but little is known of the relationships of the cores to size of tree, tree growth or survival. In a wooded savanna of northern Australia, 267 individual trees with known growth and survival rates were cored to determine degree of termite-piping. Generalized linear modelling and multi-model inference showed that frequency of piping increased with diameter (dbh) tree for E. tetrodonta, but >85% of E. miniata trees were piped regardless of dbh. Growth (dbh increment) and survival (4-year) were size-dependent. Survival of both species decreased strongly with degree of piping (pipe ratio). For any given diameter, the growth rate of E. miniata trees was independent of pipe ratio, but for E. tetrodonta trees decreased strongly with pipe ratio. From modelled data, a 10-cm tree with pipe ratio of 0.60 was very vulnerable, growing at 0.0 cm year⁻¹ with 46% survival rate, whereas a 40-cm tree, even with large pipe ratios (0.80), grew 0.05 cm year⁻¹ with 98% survival rate. Traditional methods of tree harvesting remove only those smaller hollow trees that are already suffering low growth rates and are likely to die before reaching maturity, whereas current large-scale commercial methods also remove trees with higher growth and survival rates—those trees most likely to contribute to sustainable tree populations. Incorporating traditional selection and harvest methods into current commercial operations would help ensure longevity of this source of livelihood for indigenous peoples of the region.     

Mapping the environmental limitations to growth of coastal Douglas-fir stands on Vancouver Island, British Columbia

Coastal Douglas-fir (Pseudotsuga menziesii spp. menziesii (Mirb.) Franco) occurs over a wide range of environmental conditions on Vancouver Island, British Columbia. Although ecological zones have been drawn, no formal spatial analysis of environmental limitations on tree growth has been carried out. Such an exercise is desirable to identify areas that may warrant intensive management and to evaluate the impacts of predicted climate change this century. We applied a physiologically based forest growth model, 3-PG (Physiological Principles Predicting Growth), to interpret and map current limitations to Douglas-fir growth across Vancouver Island at 100-m cell resolution. We first calibrated the model to reproduce the regional productivity estimates reported in yield table growth curves. Further analyses indicated that slope exposure is important; southwest slopes of 30 degrees receive 40% more incident radiation than similarly inclined northeast slopes. When combined with other environmental differences associated with aspect, the model predicted 60% more growth on southwest exposures than on northeast exposures. The model simulations support field observations that drought is rare in the wetter zones, but common on the eastern side of Vancouver Island at lower elevations and on more exposed slopes. We illustrate the current limitations on growth caused by suboptimal temperature, high vapor pressure deficits and other factors. The modeling approach complements ecological classifications and offers the potential to identify the most favorable sites for management of other native tree species under current and future climatic conditions.     

Fertiliser and irrigation effects on wood density at various heights for <Emphasis Type="Italic">Pinus radiata</Emphasis>

This study examined the combined effect of 19-years of nitrogen fertilisation and irrigation on the basic density along the stems of Pinus radiata (D.Don). The sample trees came from two treatments in the Biology of Forest Growth experiment: the control (C no treatment) and the irrigated and liquid fertilised (IL irrigated from age 10 to 29, liquid fertilised from ages 10 to 17). The mean basic density at breast height in the IL trees was significantly less (P < 0.05) than the C trees (430 and 471 kg m⁻³, respectively). However, the mean density of the entire bole was not significantly different. Basic density decreased with height, with the density near the tips of the trees being only 80% of the density at breast height for both treatments. The relative rate of the decrease was different between treatments. The density of the C trees decreased steadily with height while the IL trees held a relatively constant density for about half their total height. The results show the importance sampling at several different heights when considering the effects of various treatments on wood basic density in Pinus radiata.     

Evaluation of non-chemical seed treatment methods for the control of Phoma valerianellae on lamb’s lettuce seeds

Journal of Plant Diseases and Protection - The aim of the present study was to identify seed treatment methods for eradicating Phoma valerianellae from lamb`s lettuce seeds in organic vegetable...     

Potentiation of the Cytotoxic Activity of Copper by Polyphosphate on Biofilm-Producing Bacteria: A Bioinspired Approach

Adhesion and accumulation of organic molecules represent an ecologically and economically massive problem. Adhesion of organic molecules is followed by microorganisms, unicellular organisms and plants together with their secreted soluble and structure-associated byproducts, which damage unprotected surfaces of submerged marine structures, including ship hulls and heat exchangers of power plants. This is termed biofouling. The search for less toxic anti-biofilm strategies has intensified since the ban of efficient and cost-effective anti-fouling paints, enriched with the organotin compound tributyltin, not least because of our finding of the ubiquitous toxic/pro-apoptotic effects displayed by this compound [1]. Our proposed bio-inspired approach for controlling, suppressing and interfluencing the dynamic biofouling complex uses copper as one component in an alternative anti-fouling system. In order to avoid and overcome the potential resistance against copper acquired by microorganisms we are using the biopolymer polyphosphate (polyP) as a further component. Prior to being functionally active, polyP has to be hydrolyzed to ortho-phosphate which in turn can bind to copper and export the toxic compound out of the cell. It is shown here that inhibition of the hydrolysis of polyP by the bisphosphonate DMDP strongly increases the toxic effect of copper towards the biofilm-producing Streptococcus mutans in a synergistic manner. This bisphosphonate not only increases the copper-caused inhibition of cell growth but also of biofilm production by the bacteria. The defensin-related ASABF, a marine toxin produced by the sponge Suberites domuncula, caused only an additive inhibitory effect in combination with copper. We conclude that the new strategy, described here, has a superior anti-biofilm potential and can be considered as a novel principle for developing bio-inspired antifouling compounds, or cocktails of different compounds, in the future.     

Die Rolle der Mietenlaus (Hyperomyzus tulipaellus Theob.) im Seuchenzyklus der Vergilbungskrankheit derBeta-Rüben (Beta-Virus 4,Corium betae Holmes)

Zusammenfassung 1. Zweijährige vergleichende Feldinfektionsversuche mitM. p. undH. t. bestätigen die Ansicht, daß auchH. t. im Freiland als Überträger des Vergilbungsvirus zu gelten hat und unter bestimmten Voraussetzungen im Seuchenzyclus des Vergilbungsvirus eine bedeutende Rolle spielt, während diese Art das Rübenmosaik kaum überträgt.2. Die Schädigung der Rüben nach erfolgreicherH. t.-Infektion war bedeutend geringer als in den Vergleichsversuchen mitM. p. Dieser Befund ergab sich durch Vegetationsbeobachtungen im Laufe des Sommers und durch Symptomstudien an den infizierten Pflanzen. Er wurde durch den Ausfall der Versuchsernten und -untersuchungen eindeutig bestätigt.3. Bei früher Infektion schädigteH. t. die Rüben nur etwa halb so stark wieM. p.; im Juli konnte praktisch keinH. t.-Schaden mehr gefunden werden; die Empfindlichkeit der Rüben gegenüberH. t. im Vergleich zuM. p. nahm also bedeutend rascher ab. Die stärkere Schädigung derM. p.-Rüben ließ sich auch in einem Dicksaftversuch nachweisen.4. Die Ergebnisse werden diskutiert. Da unter den Bedingungen Nordwesteuropas gerade dann die Gefahr zahlreicher Infektionen durchH. t. besteht, wenn die Rüben sehr empfindlich sind, ist damit zu rechnen, daß in der Praxis auchH. t. zu merklichen Ertragsverlusten führen kann. Durch den Ausfall der Versuche wird die Ansicht über die verhängnisvolle Rolle der Futterrübenmieten für das Auftreten der Vergilbungskrankheit entscheidend unterstützt.     

Methioningehalt und Eiweißqualität von Blattpflanzen in Abhängigkeit von der Stickstoffdüngung

Zusammenfassung Beim Feldsalat und beim Spinat wurden mit steigenden N-Gaben unter den gegebenen Bedingungen sowohl in Klimakammer-Versuchen in Mitscherlichgefäßen (Glassand + 1 % Torfmull), als auch in 10 m² großen Betonkasten-Parzellen auf N-bedürftigem Geisenheimer sandigen Lehmboden folgende Ergebnisse erzielt:1. An Feldsalat (Valerianella olitoria L.), der in einer Klimakammer mit 2 Lichtstufen kultiviert wurde, konnte am Ertragsverlauf gezeigt werden, daß die N-Wirkung mit höherer Lichtintensität steigt. Rohprotein- und Reineiweißgehalte des Feldsalates ließen bei den Versuchen mit steigenden Stickstoffgaben einen charakteristischen, flach S-förmig ansteigenden Kurvenverlauf sowie einen absinkenden Relativen Eiweißgehalt (Eiweiß-N in % Gesamt-N) und einen steilen Abfall der Eiweißqualität (EAS-Indices nach B. L.Oser) erkennen. Fast alle essentiellen Aminosäuren wiesen mit steigenden N-Gaben und bei höherer Lichtintensität einen ansteigenden Kurvenverlauf auf. Die Werte für Histidin und Tryptophan veränderten sich dagegen kaum. Als einzige essentielle Aminosäure fiel Methionin mit steigenden N-Gaben bis zum Erreichen des Höchstertrages ab.Bei höherer Lichtintensität erhöhten sich die Werte der EAS-Indices und die Methioningehalte deutlich gegenüber den entsprechenden bei geringerer Lichtintensität. Analoge Befunde beim Kopfschluß (Kohlkopf, Kopfsalat) gegenüber freier Blattentfaltung werden diskutiert.2. Im wesentlichen wurden diese Ergebnisse durch Freilandversuche an Spinat (Spinacia oleracea L.) mit steigenden N-Gaben (Kalkammonsalpeter) bestätigt.Wurde jedoch der Spinat in jungem, noch nicht voll entwickeltem Zustand geerntet, beobachteten wir ein Absinken der Methioningehalte und der EAS-Indices erst bei hohen N-Gaben (180 kg N/ha).3. Der Methionin-Stoffwechsel in Pflanzen wird unter Berücksichtigung unseres heutigen Wissens und vorliegender Ergebnisse diskutiert.

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Summary Fertilizer-experiments with rising amounts of N in growth rooms (Mitscherlich pots; glass sand + 1 % peat muld) as well as in open air (concrete plots, size 10 m²) on Geisenheim sandy loam, deficient in nitrogen, gave the following results:1. Cornsalad (Valerianella olitoria L.), cultivated in a growth room with 2 degrees of light intensity showed a higher effect of N — as regard yield — when light intensity rose. Crude protein and protein in cornsalad increased in a characteristic way (S-shaped curve), on the other hand relative protein contents (protein-N in % of total N) as well as protein quality (EAA-Index) decreased. All essential aminoacids — except Histidine and Tryptophane, which did not change considerably — increased with higher amounts of Nitrogen and light intensity. The only aminoacid, which showed a distinct decrease, until the highest amount of yield has been attained, was Methionine.This aminoacid as well as the EAA-Indices decreased when light intensity decreased. We found similar effects when vegetables, as cabbage and head lettuce, formed heads.2. About the same results gave a couple of open air experiments with Spinach (Spinacia oleracea L.) in concrete plots. Rising amounts of Nitrogen (Calcium ammonium nitrate) caused the same effect on Methionine and on protein quality. If the Spinach was yielded very young, only high amounts of Nitrogen resulted in a decrease of Methionine and of protein quality.3. The metabolism of Methionine in plants, as it is known at present is discussed in view of our findings.

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Résumé La mâche et l'épinard ont été cultivés avec des doses croissantes d'azote, aussi bien dans des chambres climatisées, en pots de Mitscherlich (sable de verre et 1 % de tourbe fine), qu'en parcelles de 10 m² dans des compartiments de beton remplis d'une argile sableuse de Geisenheim très pauvre en azote.Voici les résultats obtenus:1. La mâche (Valerianella olitoria L.) cultivée dans une chambre climatisée à deux niveaux d'éclairement, a montré une reponse au taux de N fonction croissante de l'éclairement (jugée d'après le rendement). Les courbes donnant les taux de protides totaux, et les taux de protéines vraies en fonction des taux croissant de fumure azotée, présentent une forme en S caractéristic, le taux relatif de protéines (N des protéines % de N total), ainsique la qualité des protides totaux (indice d'aminoacides essentiels d'aprèsOser) sont des fonctions décroissantes des taux de fumure. Presque tous les aminoacides essentiels se rencontrent à des taux croissant lorsque le taux de N de la fumure croît, et lorsque l'éclairement augmente. Par contre, les taux d'histidine et de tryptophane se modifient à peine. Parmi tous les aminoacides essentiels, seule la méthionine diminue lorsque le taux de N de la fumure croît, et cela jusqu'au maximum de rendement.Par contre, lorsque l'éclairement augmente, les valeurs de l'indice d'aminoacides essentiels, les taux de methionine augmentent. Des faits analogues avaient été observés dans la formation d'une pomme (chou pommé, salade pommée); les plantes en rosette ont des indices plus élevées que les plantes pommées.2. Les mêmes résultats sensiblement ont été obtenus sur l'épinard (Spinacia oleracea L.) cultivé en plein air sur divers compartiments bétonés. Des doses croissantes d'azote dans la fumure (nitrate d'ammonium et de calcium) ont eu sur le taux de méthionine, sur l'indice d'aminoacides, le même effet déprimant. Si l'épinard est récolté très jeune, seules des doses très élevées d'azote ont un effet déprimant sur méthionine et qualité protéique.3. Le métabolisme de la méthionine tel qu'il est présentement connu chez les végétaux, est discuté à la lumière des faits observés ici.

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mit 9 Fig.