PROTECTIVE EFFECT OF OLIVE POLYPHENOLS ON WATERMELON AGAINST FUSARIUM OXYSPORUM F. SP. NIVEUM INFECTION

Abstract

The inhibitory activity of polyphenolic compounds extracted from olive leaves was tested against F. oxysporum f. sp. niveum growth. Results showed phenolic and alcoholic extracts inhibited fungal growth by 70.6% and 66.75%, respectively, at 4000 ppm concentration. Olive leaves powder inhibited the growth by 47.50%. All treatments increased watermelon germination percentage after 7 days when scored 85% and 100% at 0.4% and 0.8% olive leaf powder concentrations, respectively. Alcoholic treated seeds at 4000 ppm scored 90% compared to pathogenic fungus treatment with 25% germination percent. Whereas the germination percentages were 90% and 100%, respectively for fungicide (Bltanol) and healthy control (untreated) treatments. All treatments could protect watermelon seedlings for continuous 35 days after planting.  The phenolic extract showed the highest vigour index values when scored 1616.7 and 1821.6 at the concentrations of 4000 and 8000 ppm, respectively. Whereas, alcoholic extract and olive leaf powder at scored 1332 and 1102.5 at concentration 8000 ppm and 0/8% respectively, compared to the pathogenic fungal and the fungicidal treatments with 360.5 and 896.8, respectively. These results indicated the effectiveness of the olive leaf extract in fungal growth inhibition. This study confirmed the presence of antifungal active substances in olive leaves against pathogenic fungi.