Mise en eacute;vidence, par la fluorescence de la chlorophylle, de la variabiliteacute; geacute;notypique de la reacute;ponse agrave; une contrainte hydrique chez le tregrave;fle blanc (Trifolium repens) et l'ivraie vivace (Lolium perenne)

摘要

The genotypic variability of six interspecific neighbouring pairs of white clover (Trifolium repensL.) and perennial rye grass (Lolium perenneL.) has been examined in relation to chlorophyll fluorescence and leaf water content. Fluorescence was measured using wavelengths of 690 and 730ensp;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 730ensp;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.