Effect of Dikegulac on Growth and Correlative Biochemical Changes in Leaves of Sunflower (Helianthus annuus L. cv. EC 68414)

Abstract

High concentrations of 500 µg/ml and 750 µg/ml of dikegulac (sodium 2,3: 4,6-di-O-isopropylidene-2-keto-L-gulonate) reduced plant height and retarded increase in leaf area of sunflower. Stem girth was increased in 100 µg/ml and 500 µg/ml but the highest concentration was found to be ineffective. Biochemical analyses showed that concomitant with DNA and RNA resynthesis chlorophyll, protein and carbohydrate synthesizing ability was not restored in two higher concentrations in treated leaves. Activity of degrading enzymes RNase and protease increased in two higher concentrations but increase of catalase activity after an initial fall suggested the tendency of revival of synthetic ability of treated leaves in these concentrations. Perpetuation of dikegulac effect in two higher concentrations in newly formed leaves was evident from biochemical analyses. Data suggested that the effect was more acute in such leaves and in fact, they could not achieve their normal synthetic ability even after passage of three weeks from the date of treatment.