Maintaining the Flow: Maintenance Service Provision in the Alto Río Lerma Irrigation District, Mexico

Through irrigation management transfer inMexico poorly functioning governancemechanisms for maintenance were replaced.New actors, new roles, and newresponsibilities in the maintenance ofMexican irrigation systems wereestablished. This article analyzes themaintenance service delivery mechanisms inthe Alto Río Lerma Irrigation District(ARLID), to evaluate if and how theinstitutional arrangements establishedthrough management transfer ensure adequateservice provision. After presenting themain actors currently involved inirrigation maintenance, the rules andregulations underlying the servicerelationships between the actors involvedin maintenance in ARLID are analyzed. Thisis done by detailing how theserelationships are formally organized, howthey work in practice, and which incentivesexist for the service providers to providean efficient service and for the servicerecipient to pro-actively participate inservice provision. We conclude that the newinstitutional framework for maintenanceservice provision is quite coherent andthat the governance mechanisms that havebeen established work well, especiallythose between the farmers and theirorganizations. This has led to improvedmaintenance services.     

Methodische untersuchungen zur Sekundärauswertung von Sortenversuchen Bezüglich der Ertragsstabilität von Sorten mit Hilfe der Ökoregression

In Sortenversuchen sind die Wechselwirkungen Sorten × Orte meist sehr groß und die Mittelwertdifferenzen somit wenig aussagekräftig.

Es wird empfohlen, Landessortenversuche über Landesgrenzen hinweg sekundär regressionsanalytisch auszuwerten, um die Reaktionen von Sorten auf die unterschiedlichen Wachstumsbedingungen der Orte zu erkennen. Auf Aspekte der Auswertung wird näher eingegangen. Die Auswertungsergebnisse der sekundären Auswertung sind für Pflanzenzüchter und Landwirte gleichsam relevant.     

Eine Anordnung zur Messung kleiner Sauerstoffaustauschraten photosynthetisierender Algen bei geringen Lichtintensitäten

Zusammenfassung Es wird eine Meßanordnung zur amperometrischen Registrierung der relativen Nettosauerstoffaustauschrate mittels einer membrangeschützten Platinelektrode beschrieben, die besonders für die Verwendung kleiner Versuchsobjekte (einzelliger Algen und isolierter Chloroplasten) geeignet ist. Die hohe Empfindlichkeit ermöglicht die Analyse von Sauer-stoffaustauschraten unter Verwendung monochromatischen Lichtes relativ hoher spektraler Reinheit. Die gute Stabilität des Elektrodenpotentials läßt eine große Verstärkung des Meßwertes und eine direkte Registrierung des Anstiegs der relativen Sauerstoffaustauschrate zu.

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Summary An amperometric device is described for the registration of relative oxygen exchange rates of small particles such as algae or isolated chloroplasts. The high sensitivity of the electrode according to the Clark-type make possible the application of monochromatic light with small half band wides for examination of photosynthetic reactions. The employed Ag/AgO-reference electrode has a very stable potential and allows a high amplification necessary for direct registration of the oxygen exchange rate derivatives. Some examples are given for registrated exchange rates.

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RADIOGRAPHIC ANATOMY OF THE CRIBRIFORM PLATE (LAMINA CRIBROSA)

The radiographic appearance of the cribriform plate was investigated in 16 canine cadaver heads. The cribriform plate appeared as a "V"-shaped multilinear bone-opaque stripe in the caudal nasal region in projections perpendicular to the hard palate in 6 dogs with a skull index between 50.00 and 54.00. In 9 dogs with a skull index between 55.40 and 74.40, the cribriform plate had a more "C"-shaped and sharp appearance. In vertically oblique projections with an obliquity greater than 20 degrees, the cribriform plate lost its sharp outline and finally (40 degrees) disappeared. In lateral projections the cribriform plate appeared as a "C"-shaped interrupted bone-opaque stripe in all 16 dogs. In more brachycephalic dogs frontal bone structures superimposed on the cribriform plate on ventrodorsal and dorsoventral views and accentuated the radiographic appearance of the plate. Vertically oblique views separated both structures to produce two lines.     

Restoration and stress relief through physical activities in forests and parks

A field survey assessed the restorative effects of visiting an urban forest and a city park in Zurich, Switzerland. Respondents rated their headaches, level of stress, and how balanced they felt both prior to visiting the outdoor location and at the time of being interviewed. Suffering from headaches and stress decreased significantly, and feeling well-balanced increased significantly. The recovery ratio for stress was 87%, and the reduction in headaches was 52%, in terms of the possible improvements on five-point rating scales. With respect to feeling well-balanced, the observed changes amounted to 40% of the possible enhancement. Positive effects increased with length of visit, and individuals practising sports (e.g., jogging, biking, playing ball) showed significantly higher improvements than those engaged in less strenuous activities (e.g., taking a walk or relaxing). These findings support previous research on how exercise in green spaces promotes well-being and recovery from stress.     

Molecular characterization of the incitant of cowpea bacterial blight and pustule, Xanthomonas campestris pv. vignicola

Strains of Xanthomonas campestris pv. vignicola (Xcv), isolated from cowpea leaves with blight or minute pustules and collected from various geographic areas, were selected on the basis of pathological and physiological features. All strains were analyzed for genotypic markers by two methods: ribotyping with EcoRI endonuclease, and RFLP analysis with a plasmid probe (pthB) containing a gene required for pathogenicity from Xanthomonas campestris pv. manihotis. Ribotyping revealed a unique pattern for all the strains that corresponded to the previously described ribotype rRNA7. Based on polymorphism detected by pthB among Xcv strains, nine haplotypes were defined. The observed genetic variation was independent of the geographic origin of the strains and of pathogenic variation. Some haplotypes were widely distributed, whereas others were localized. In some cases, we could differentiate strains isolated from blight symptoms and pustules according to haplotypic composition. However, in most cases, no significant differences were observed. Our results and the previous pathogenic and biochemical characterizations suggest that the strains isolated from leaves with blight symptoms or minute pustules belong to the same pathovar. We provide information on pathogen diversity that can be used to identify and characterize resistant germplasm.     

Studies on the effect of deltamethrin sprays on the numbers of epigeal predatory arthropods occurring in arable fields

The effect of spraying winter rape and winter wheat with deltamethrin on the numbers of epigeal Carabidae, Staphylinidae and Linyphiidae caught in pitfall traps was studied in Northern Germany in 1980 and 1981. Two experiments were performed with each crop, deltamethrin being sprayed at 7.5 g a.i. ha^?1 in 300 litres of water in springtime on rape, and in midsummer on wheat. Sprayed plots were rectangles of 2 and 3 ha; unsprayed plots were squares of 0.5 ha each (two replicates). Ten pitfall traps were placed per replicate at least 3 weeks before spraying and were left for at least 3 weeks after spraying, the traps being emptied weekly. Beneficial Carabid species which have been shown already to have an economic significance, were rare during this study, but four other species (three of them were autumn breeders) were not affected by deltamethrin. At the spraying dates the autumn breeders were hidden in the soil as pupae. Three Staphylinid species, studied in only one experiment each, appeared to be strongly reduced in numbers by deltamethrin. The Linyphiid spiders were affected most heavily by deltamethrin sprayed in spring or in midsummer; the initial mortality of more than 92% lasted longer than 4 weeks, and an adverse effect was still significant in winter wheat 6 weeks after spraying. Overall, deltamethrin appears to have a broad spectrum effect concerning the epigeal predatory arthropods.     

Einige neue Erkenntnisse über die Bionomie der europäischen Monochamus-Arten (Col. Cerambyc.)1)

Ohne ZusammenfassungVortrag gehalten beim ersten Südtiroler Entomologentag in Dietenheim, 22. September 1970.I 39042 Brixen, Prov. Bozen/Italien, Rienzdamm 38