Effect of immersion time of cultch on spatfall of the scallop Argopecten purpuratus (Lamarck 1819) in the Marine Reserve at La Riconada, Antofagasta, Chile

A pilot program to evaluate the feasibility of collecting juvenile (seed) scallops using Japanese technology was carried out from October 2001 to April 2002 in the Marine Reserve at La Rinconada, Antofagasta, Chile. The continuous presence of larvae in waters in the reserve allowed for collection of 400–15,340 spat per collector and showed the high reproductive capability of local scallops and the relationship between numbers of larvae in the water and amount of spatfall. Highest rates of settlement were proportional to high numbers of umbone larvae in the water at >5000 larvae m⁻³ when collectors were first immersed. Absence of a relationship between larval numbers and postlarval settlement with trophic factors such as chlorophyll and particulate organic matter in the water suggests that productivity was not limited by these factors. Harvest of spat from collectors immersed for four and five months had recovery efficiencies of 5.5% and 59.4% compared with settlement in collectors after immersion for one month. Cohort analyses of recovered spat suggested that settlement occurred over the lengthy immersion period and was due to the continuous presence of larvae in the water. The loss of a high percentage of spat over the 4–5 immersion period compared with settlement in the first month can be attributed to intraspecific competition of spat density and growth as well as clogging of the collectors by sediment and marine fouling that impeded a flow of water through the nets.     

Maize resistance to northern corn leaf blight is potentiated by nickel

Northern corn leaf blight (NCLB), caused by Exserohilum turcicum, is one of the most devastating diseases affecting maize yield worldwide. A foliar spray of nickel (Ni) to potentiate maize resistance against NCLB was investigated by examining alterations in the photosynthetic apparatus (leaf gas exchange and chlorophyll [Chl] a fluorescence parameters), production of ethylene and reactive oxygen species as well as activities of defence and antioxidant enzymes. Mycelial growth of E. turcicum was inhibited by Ni in vitro. Inoculated plants sprayed with Ni exhibited higher foliar Ni concentration, reduced NCLB symptoms, and lower concentrations of malondialdehyde and hydrogen peroxide. In inoculated leaves of plants not sprayed with Ni, concentrations of Chl a, Chl b, and carotenoids were lower and the photosynthetic apparatus was impaired at the biochemical level due to high NCLB severity. The activities of antioxidant enzymes were not affected by Ni, except an increase in glutathione reductase activity for noninoculated plants sprayed with Ni. High lipoxygenase and polyphenoloxidase activities, lower ethylene production, as well as elevated production of phenolics and lignin helped decrease NCLB severity in the leaves of Ni-sprayed plants.     

Remanence du parathion et du methylparathion dans tubercules de pomme de terre et dans le sol a la suite de traitements du sol

Résumé On présente les résultats des recherches effectuées pendant 4 ans, sur la persistence du parathion et du méthylparathion dans les tubercules de pomme de terre et dans le sol, à la suite des traitements du sol avec des préparations en poudre. On a effectué des déterminations pour la récolte de la même année et pour celle de l'année suivante, c'est-à-dire 6 mois et respectivement 18 mois après le traitement.En général, les résidus accumulés dans les pommes de terre ont varié entre 0,08 et 0,44 ppm. Le dépôt résiduel accumulé pendant 6 mois dans les pommes de terre présente des valeurs voisines de celles accumulé et après un intervalle de 18 mois.La quantité de substance toxique présente dans le sol au moment de la récolte a été de 3 à 6 fois plus grande que celle trouvée dans les tubercules récoltés du même sol, et elle a varié entre 0,27 et 0,58 ppm.

---

Summary During 4 years, investigations have been carried out on parathion and methylparathion residues in potato tubers and in soil, following soil treatments with dust preparations. Determinations were made for the crop of the same year, as well as for that of the next year, i.e. 6 months and 18 months after the treatment, respectively. In all cases, except in one year, the residues which accumulated in potatoes 6 months later, had values close to those of the residual deposit accumulated after 18 months.At harvesting, the amount of toxicant available in the soil was 3 to 6 times larger than that found in potato tubers harvested on the same soil, and varied between 0.27–0.58 ppm.No evident differences between the amounts of parathion and methylparathion residues were found, and this suggests that the same degradation factor acts on both compounds.The precipitations played an important role; thus in years with low precipitations, the toxicant deposits increased in the soil and, implicitly, also in the tubers.

---

Zusammenfassung Es werden die Ergebnisse einer vierjährigen Forschungsarbeit über die Verweildauer von Parathion und Methylparathion in der Kartoffelknolle und im Boden nach Bodenbehandlungen mit Stäubemitteln zusammengefaßt. Die Rückstandsanalysen wurden am Erntegut desselben Jahres, das heißt 6 Monate nach der Behandlung, und am Erntegut des nächsten Jahres, also 18 Monate nach dem Zeitpunkt der Behandlung, durchgeführt.Mit Ausnahme eines einzigen Jahres erreichte der Rückstand in der Kartoffelknolle in allen Fällen Werte zwischen 0,08 und 0,44 ppm. Die nach 6 Monaten in den Knollen festgestellten Rückstandswerte unterscheiden sich von den nach 18 Monaten nachgewiesenen nur unwesentlich.Im Boden wurden zur Zeit der Ernte drei- bis sechsmal höhere Rückstandswerte gefunden als in Knollen. Dieselben variierten zwischen 0,27 und 0,58 ppm.Die Rückstandswerte für Parathion und für Methylparathion zeigten keine deutlichen Unterschiede. Dies läßt auf die Einwirkung der gleichen Abbaufaktoren für beide Verbindungen schließen. Eine besondere Bedeutung unter den Klimafaktoren kam den Niederschlägen zu. In Jahren, in denen diese gering waren, wurden größere Rückstandswerte im Boden und auch in den Kartoffelknollen festgestellt.

     

Structure-antifungal activity relationship of cinnamic acid derivatives

A structure-antifungal activity relationship (SAR) study of 22 related cinnamic acid derivatives was carried out. Attention was focused on the antifungal activities exhibited against Aspergillus flavus, Aspergillus terreus, and Aspergillus niger. (E)-3-(4-methoxy-3-(3-methylbut-2-enyl)phenyl)acrylic acid (16) exhibited antifungal activity against A. niger, comparable to that of miconazole and a significant antifungal effect against A. flavus and A. terreus as well. A structure-activity relationship (SAR) study of related cinnamic acid derivatives has allowed a model to be proposed for the recognition of the minimal structural requirements for the antifungal effect in this series.