Fruchtresistenz von Tomaten gegen P. infestans

Resistance of tomato fruits to Phytophthora infestans Late blight, caused by Phytophthora infestans (Mont) de Bary, is one of the important diseases in organic potato and tomato production. While some information on foliar disease resistance of tomatoes is available, virtually no information exists on the relation of leaf to fruit resistance. The central parameters of the infection chain, incubation and latency period were determined for 40 tomato varieties using three isolates of P. infestans. A total of 2858 fruits were drop inoculated in the lab and assessed daily for symptoms or sporulation for 16 days. There were significant variety by isolate interactions for incubation period, latency period and the interim time suggesting race specific interactions with tomato fruits. A Manteltest showed that the distance matrix of the isolate x variety interaction of leaf and fruit reactions were not correlated. Thus, it appears that fruit and leaf resistance are independent characters

Beziehung von Blatt- und Fruchtbefall mit Braunfäule bei Freilandtomaten

There is virtually no information available on the relationship between the reaction of tomatoes to Phytophthora infestans on leaves and fruits. Late blight and brown rot of tomatoes were assessed in outdoor conditions in 2005 on 15 tomato varieties and in 2006 for 41 varieties. Leaf disease expressed as area under the disease progress curve (AUDPC) and the proportion of healthy fruit of the total fruit were used as meas-ures. In 2005, the two varieties that were most susceptible to leaf blight produced the least healthy fruit while the most resistant variety produced the highest proportion of healthy fruit. However, for the varieties with more intermediate reactions to leaf blight there was great variation in the proportion of healthy fruit with an overall insignificant rank correlation for the two parameters (Spearman). The independence between leaf blight and brown rot was confirmed for the year 2006. While these data are an indica-tion that there is a need to assess leaf and fruit resistance independently, this will have to be done under controlled conditions or the fruit from the field has to be incu-bated after removal from the mother plants to determine if there were latent infections

Optimierung des Anbaus von Sojabohnen: Bestimmung des Vorfruchtwertes und der N2-Fixierleistung sowie Reduzierung der Bodenbearbeitung

Bisher sind die N2-Fixierung aus der Luft, die N-Salden (N2-Fixierung minus N-Abfuhr) und die Vorfruchtwirkung von Soja für Deutschland nicht beschrieben. Diese wurde in Feldversuchen auf einem konventionell und zwei ökologisch bewirtschafteten Standorten im Vergleich zu Körnererbsen untersucht. Die N2-Fixierung von Soja fiel um knapp 100 (ökologisch) und 40 (konventionell) kg ha-1 höher aus als die der Erbsen. Die N-Bilanz war zwischen Soja und Erbsen vergleichbar. Die Vorfruchtwirkung von Erbsen ist aufgrund eines höheren Ertrages in der Nachfrucht Weizen im ökologischen Landbau höher als die von Soja einzuschätzen. Im konventionellen Anbau unterschied sich dagegen die Leistung des nachfolgenden Weizens nicht. Soja passt auch aufgrund einer hohen Wirtschaftlichkeit sehr gut in die Fruchtfolgen. Im ökologischen Anbau erwirtschaftet sie im Fruchtfolgeausschnitt Körnerleguminose – Weizen einen um etwa ein Drittel höheren Deckungsbeitrag als Erbsen, im konventionellen konnte sie mit der Leistung von Körnermais mithalten. In einem dreijährigen Exaktversuch und in On-Farmversuchen wurde die Eignung von reduzierter Bodenbearbeitung im konventionellen Sojaanbau geprüft. Mit Mulchsaat und Strip-Till konnte Soja agronomisch und ökonomisch erfolgreich angebaut werden. Hingegen war die Direktsaat in gewalzten bzw. abgefahren Grünroggen mit 14,4 dt ha-1 im Ertrag niedriger und hatte einen erheblichen wirtschaftlichen Nachteil. Ferner konnte in Mulchsaat und Strip-Till auf die Applikation von Glyphosat vor der Saat ohne Ertragseinbußen oder einen höheren Unkrautbesatz verzichtet werden

Optimality-based Analysis of XCSF Compaction in Discrete Reinforcement Learning

Learning classifier systems (LCSs) are population-based predictive systems that were originally envisioned as agents to act in reinforcement learning (RL) environments. These systems can suffer from population bloat and so are amenable to compaction techniques that try to strike a balance between population size and performance. A well-studied LCS architecture is XCSF, which in the RL setting acts as a Q-function approximator. We apply XCSF to a deterministic and stochastic variant of the FrozenLake8x8 environment from OpenAI Gym, with its performance compared in terms of function approximation error and policy accuracy to the optimal Q-functions and policies produced by solving the environments via dynamic programming. We then introduce a novel compaction algorithm (Greedy Niche Mass Compaction - GNMC) and study its operation on XCSF's trained populations. Results show that given a suitable parametrisation, GNMC preserves or even slightly improves function approximation error while yielding a significant reduction in population size. Reasonable preservation of policy accuracy also occurs, and we link this metric to the commonly used steps-to-goal metric in maze-like environments, illustrating how the metrics are complementary rather than competitive

Vergleich der N2-Fixierungsleistung, der N-Bilanz und der N-Menge in den Ernteresiduen von Sojabohnen und Erbsen

Über eine Symbiose mit Knöllchenbakterien sind Sojabohnen und Erbsen dazu in der Lage Stickstoff aus der Luft zu fixieren. Zur Höhe der N2-Fixierungsleistung gibt es bereits einige Untersuchungen, für Sojabohnen vorwiegend aus Übersee. Allerdings ist die N2-Fixierungsleistung von vielen Faktoren abhängig, wie z. B. Temperatur, Niederschlagsmenge und –verteilung, Sorte, Bakterienstamm, Nährstoff­versorgung, Krankheits- und Schädlingsdruck. Daher war es ein Ziel des Projektes „Optimierung des Anbaus von Sojabohnen – Bestimmung des Vorfruchtwertes und der N2-Fixierungsleistung sowie Reduzierung der Bodenbearbeitung“, das von der Bundesanstalt für Landwirtschaft und Ernährung gefördert wurde, die N2-Fixierungsleistung unter den Bedingungen Süddeutschlands bei Sojabohnen und Erbsen zu schätzen. Sojabohnen und Erbsen haben in Süddeutschland eine N2-Fixierungsleistung, die im Bereich zwischen 80 und 288 kg Stickstoff je Hektar liegt. Sojabohnen haben in den meisten Jahren höhere N2-Fixierungsleistungen als Erbsen. Der rechnerische Anteil der N2-Fixierungsleistung an der N-Menge im Korn liegt bei den Sojabohnen fast immer höher als bei den Erbsen. Bei beiden Kulturen wird mehr Stickstoff über das Erntegut abgefahren, als zuvor fixiert wurde. Die N-Bilanz ist bei beiden Kulturen ebenfalls negativ. Jedoch befindet sich in den Ernteresiduen Stickstoff, den eine Folgekultur wie Winterweizen nutzen kann. Auch hier ist bei Sojabohnen die N-Menge höher als bei Erbsen

Dynamical phase transition for a quantum particle source

We analyze the time evolution describing a quantum source for noninteracting particles, either bosons or fermions. The growth behaviour of the particle number (trace of the density matrix) is investigated, leading to spectral criteria for sublinear or linear growth in the fermionic case, but also establishing the possibility of exponential growth for bosons. We further study the local convergence of the density matrix in the long time limit and prove the semiclassical limit.Comment: 24 pages; In the new version, we added several references concerning open quantum systems and present an extended result on linear particle production in the fermionic cas

Einfluss von Mischanbau mit Hafer, flacher Bodenbearbeitung und Biofumigationsbrassicaceen auf Beikrautbesatz, Erbsenkrankheiten und Erträge in der Fruchtfolge mit Winterweizen

Experiments were conducted to determine how tillage intensity, the use of biofumigation brassica cover crops and mixed cropping with oats affect the performance of organic peas with respect to weed pressure, diseases, and yield. Fields were either ploughed to a depth of about 15-20 cm or only to about 8 cm in late summer followed by either Sinapis alba (low glucosinolate (GSC) content), Raphanus sativus (medium GSC) or Brassica juncea (high GSC). Brassicas were mulched in fall right before flowering and incorporated in the top soil. In mixtures with oats seed rate for peas was as in pure stands, for oats it was 20 %. There was a dramatic spring drought in 2011 resulting in severe water stress for the peas in 2011. Weeds were significantly reduced by about 45 % by oats in both years. Neither tillage nor any of the brassica cover crops or mixing with oats had a significant effect on root disease severity of peas or the pathogen composition. In both years pea lower stems and roots were mostly infected by Phoma medicaginis. In 2011, about half of the infected plants were also infected by Mycosphaerella pinodes and up to 20 % with Ascochyta pisi. Pea yields were 2.2 t ha-1 and 2.1 t ha-1 in 2010 and 2011, respectively. Oat yields were 3.0 and 4.9 t ha-1, respectively. Mixing with oats reduced pea yields by 32 and 63 % in 2010 and 2011, respectively while the oats yielded about 45 % of the pure stands. Tillage did not affect yields, however, pea yields in plots that had been planted to R. sativus as cover crop were significantly reduced. Subsequent wheat yields in the rotation were significantly higher after peas and the pea-oat mixture than after oats alone

Effekte von Kompostapplikationen auf Fußkrankheiten und Grünmasseertrag von Wintererbsen

Abstract: Effects of compost applications on foot diseases and biomass yield of winter peas. A field experiment was conducted to assess the effects of compost applications on the growth and health of winter peas from September 2009 to May 2010. A total of 5 t DM ha-1 of a 12 month old yard waste compost were applied in plots that were either uninoculated or inoculated with Phoma medicaginis grown on infested oat kernels. The control treatment received no compost and was left uninocu-lated. Main plots received all four treatments and were replicated four times. Compost slightly reduced the incidence of Mycosphaerella pinodes and Phoma medicaginis in March and the foot disease severity in May. Overall fresh matter production was significantly reduced by inoculation. These reductions were compensated by compost applications. There was great variation among main plots in the performance of the peas. Where peas performed poorly in the controls (i.e. low fresh matter yield) com-posts improved the performance considerably. Where performance was high, there were no more additional benefits of adding compost to the system

Genetische Variation in der Resistenzinduktion gegenüber Phytophthora infestans bei Tomaten

There are numerous instances in which induced plant resistance responses (IR) have been demonstrated. However, before IR can be made use of in practice it is important to understand as much as possible the ecology and genetics of the inducing agents and their interactions with plants and pathogens. Effects of host genetic background were tested with thirteen tomato varieties and two isolates of Phytophthora infestans. Isolate effects on inducibility were tested with six varieties and six pathogen isolates. Leaf disks of plants that had been treated with BABA (DL-3-aminobutyric acid) or water were inoculated seven days later with 20 µl sporangial solutions of 5*104 sporangia ml-1. All experiments were repeated three times with six replications each. Disease reductions due to induction ranged from 43 to 100% and were independent of the susceptibility of the variety to the isolates when not induced. The interactions between isolate and variety with respect to inducibility were highly significant