Seasonal accumulation of ultraviolet-B screening pigments in needles of Norway spruce (Picea abies (L.) Karst.)

acide coumarique cell walls chemical composition clone clones composition chimique coumaric acids fisiologia vegetal flavonoide flavonoides flavonoids glucoside glucosides glucosidos irradiation pared celular paroi cellulaire picea picea abies pigment pigmentos pigments plant physiology radiation saison seasons