EFFECT OF FLURIDONE ON PLANT DEVELOPMENT AND STRESS-INDUCED ABA ACCUMULATION IN Vicia Faba L. PLANTS

The effect of fluridone on the growth of plants and drought stressinduced abscisic acid (ABA) accumulation were studied in mature leaf tissue of Vicia faba L. plants grown under different light intensity. Drought stress was induced by allowing the leaves to lose 12% of fresh weight. Treatment of Vicia plants (grown at high light intensity – 600μmol.m-2.s-1) with 10μmoles fluridone caused a considerable decrease in the rate of growth and bleaching of the plants. Fluridone fully blocked stress-induced ABA accumulation. Plants grown under low light intensity (40μmol.m-2.s-1) had diminished level of ABA after impossition the leaves to dehydration. Fluridone treatment reduced the level of ABA in unstressed as well as dehydrated leaves. The accumulation of ABA in 21-day-old green Vicia plants was considerably reduced when they were exposed to dark periods (24h, 48h, and 72h) just before the impossition of stress. Twenty four hours after dark treatment dehydration of these leaves resulted in a 3 fold decrease in stress-induced ABA accumulation. Seventy two hours after dark treatment the level of stress-induced ABA was approximately equal to the prestressed values. Fluridone-treated plants failed to accumulate ABA when water stressed. The presented results are discussed in term with the role of light and fluridone on stress-induced ABA accumulation.