Inhibition of Canker Disease in Selected Citrus Plant by Gelonium multiflorum Extract

Abstract

Inhibition of Xanthomonas campestris pv. Citri : the pathogenic bacteria that caused canker disease in citrus plant were studied in lemon leaf by Gelonium multiflora extract. The antimicrobial activity was examined and antioxidant activities of the extracts were compared with ascorbic acid by scavenging effect with 2, 2- diphenyl-2-picrylhydrazyl radical (DPPH). Finally, the extracts were inhibited of canker disease in lemon leaves growing in the greenhouse. Dichloromethane extract of bark was purified by silica gel column with the solvent mixture of dichloromethane:methanol in polarity order from less polar to more polar. The purified fraction with 1:1 ratio at 400 – 500 mg L -1 followed by the ratio 1:9 (dichloromethane:methanol) purified from stem extracts at 500 mg l -1 provided the inhibition activities against Xanthomonas campestris pv. Citri . The diameters of clear zone were 20 and 15 mm, respectively. Purified fraction from stem eluted with 1:9 and 3:7, dichloromethane:methanol and purified fraction from bark eluted with 4:6, dichloromethane:methanol provided antioxidant activities with DPPH but lower than ascorbic acid. Purified dichloromethane: methanol; 1:9 ) at 700 mg L -1 completely inhibited the growth of Xanthomonas campestris pv. Citri . Moreover, purified fraction of bark with dichloromethane:methanol; 2:3 ) at 500 mg L -1 partially inhibited. All purified fractions (from column chromatography) of bark extract presented higher inhibition activities against Xanthomonas campestris pv. Citri than stem extracts of Gelonium multiflora . Keywords — Inhibition; Xanthomonas campestris pv. Citri ; canker disease; Gelonium multiflora ; antioxidant activities