EFFECT OF FLURIDONE ON CHLOROPHYLL, CAROTENOID AND ANTHOCYANIN CONTENT OF HYDRILLA

Hydrilla (mature and young plants) were exposed to 0.05, 0.5, 5.0, and 50 ppb of fluridone for 2, 4, 6, 8 and 12 wk and monitored for change s in chlorophyll, carotenoid and anthocyanin content. Fluridone decrea sed carotenoid and chlorophyll content of mature hydrilla plants. As f luridone exposure times and rates increased, chlorophyll and carotenoi d content decreased concomitantly. Regardless of time, 50 ppb fluridon e reduced carotenoid and chlorophyll content by 80 to 95%. In younger plants, 50 ppb fluridone lowered carotenoids and chlorophyll by at lea st 50 and 65%, regardless of time, respectively. Fluridone at 50 ppb c aused an increase in anthocyanin content (5X the control) in mature hy drilla but did not affect anthocyanin content in young hydrilla. Howev er, both plant types became pink in color after exposure to fluridone. Apparently, anthocyanins were simply unmasked after chlorophyll photo oxidation in young hydrilla while an increase in anthocyanin biosynthe sis occurred in the mature plants. The differential response in anthoc yanin content of hydrilla to fluridone could be related to physiologic al stage of development and/or light intensity.