Effect of fluazifop-butyl on the chlorophyll content, fluorescence and chloroplast ultrastructure of Elymus repens (L.) Gould. leaves

Summary Some aspects of the action of fluazifop‐butyl on the chlorophyll content, chloroplast functioning and chloroplast ultrastructure of Elymus repens are reported. Over a period of 0–12 days after spraying with 0.25 or 1.0 kg ha−1 of the herbicide, chlorophyll a and b contents of this susceptible plant decreased, progressing from the youngest to the more mature leaves. Newly formed tillers and the youngest expanding leaves exhibited a more severe type of chlorosis and were often found to be devoid of chlorophyll. A similar progressive decline of the chlorophyll content was observed in an experiment where leaf segments were floated in fluazifop‐butyl. Evidence of a rapid and significant alteration of the normal chlorophyll fluorescence of E. repens leaves treated with fluazifopbutyl was obtained. The herbicide, at a concentration range of 0.25–1.0 μg μ1−1, caused a significant loss of the fast fluorescence rise, fluorescence yield and, after 24 h, caused a total abolition of the fluorescence decay (PS decas). These results are discussed. Ultrastructural damage to chloroplasts was seen within 24 h after treatment with fluazifop‐butyl. This damage ranged from a partial to total disruption of the outer chloroplast envelope and a disorganization of the internal thylakoid system. Such Ultrastructural effects on chloroplasts were found to intensify up to about 6–7 days after spraying, by which time nearly all chloroplasts in tissue sections were affected to some degree. Résumé Effet du fluazifop‐butyl sur la teneur en chlorophylle, la fluorescence et l'ultrastructure des chloroplastes chez Elymus repens (L.) Gould. leaves Quelques aspects de l'action du fluazifop‐butyl sur la teneur en chlorophylle, le fonctionnement et l'ultrastructure des chloroplastes chez Elymus repens font l'objet de cet article. Sur une période de 0 à 12 jours après la pulvérisation de 0,25 ou 1 kg d'herbicide/ha, les teneurs en chlorophylle a et b de cette plante sensible décroissaient progressivement des plus jeunes feuilles vers les plus âgées Les nouveaux talles et les feuilles dernièrement sorties ont extériorisé un type de chlorose plus grave et ont souvent été trouvés comme étant dépourvus de chlorophylle. Une baisse progressive similaire de la teneur en chlorophylle a été observée dans une expérimentation où des segments de feuilles étaient plongés dans le fluazifop‐butyl. On a mis en évidence une altération rapide et significative de la fluorescence normale de la chlorophylle d