Le voilier OceanoScientific Explorer Boogaloo : Une campagne péri-antarctique en 2017

L'utilisation de voiliers comme pourvoyeurs de données océanographiques et météorologiques de qualité scientifique a été testée dans le cadre du programme OceanoScientific et en particulier lors de la navigation péri-antarctique en solitaire du voilier OceanoScientific Explorer Boogaloo début 2017. Les caractéristiques du système et les données océanographiques recueillies (température, salinité, fluorescence de la chlorophylle A, pression partielle de dioxyde de carbone) sont présentées, illustrant le succès de l'approche, malgré quelques contraintes qui sont évoquées. Using sailing vessels to provide surface oceanographic and meteorological data for operational and scientific use has been promoted in the OceanoScientific programme. It has been tested during the circum-Antarctic sailing of the Explorer OceanoScientific Boogaloo in early 2017. The instrumentation, data acquisition, processing and transmission characteristics are described. Then, the ocean data collected (temperature, salinity, fluorescence of Chlorophyll-A, partial pressure of carbon dioxide) are presented, illustrating the success of the approach, but also some constraints that were encountered.

Mise en évidence, par la fluorescence de la chlorophylle, de la variabilité génotypique de la réponse à une contrainte hydrique chez le trèfle blanc (Trifolium repens) et l'ivraie vivace (Lolium perenne)

The genotypic variability of six interspecific neighbouring pairs of white clover (Trifolium repens L.) and perennial rye grass (Lolium perenne L.) has been examined in relation to chlorophyll fluorescence and leaf water content. Fluorescence was measured using wavelengths of 690 and 730 nm. The following indices of fluorescence were used: the fluorescence-decrease ratio at the two wavelengths (vitality index), their combination (adaptation index), and the ratio of the fluorescence intensities at 690 and 730 nm. The effect of the type of drought stress applied on leaf cutting and pot planted material was examined. The results show that the first two indices of fluorescence are precocious indicators of drought stress and that they allow to distinguish genetically close individuals. Fluorescence thus provides a mean of ranking genotypes of two species. Key words: fluorescence, vitality index, adaptation index, fluorescence ratio, relative water content.