Sesame (Sesamum indicum L.) ethanolic extracts effect on Fusarium oxysporum f. sp. sesami

Abstract

One of the most important constraint in Venezuela sesame production is the incidence of the soil-borne fungus Fusarium oxysporum f. sp. sesami, which causes the disease called fungus wilt. A control option is to use plant extracts. The objective of this research was to evaluate the effect of sesame root and stem extracts of the three sesame cultivars Fonucla, INIA and UCLA295 on the growth of Fusarium oxysporum f. sp. sesami, It was evaluated by means of the record of in vitro growth in ELISA microplates cells in presence of 0.2 mL of sesame root or stem extracts. Each treatment (root and stem extracts of each sesame cultivar was replicated 24 times. Each cell contained 0.2 mL of spore suspension (200 conidia mL-1) in potato dextrose broth and one of the treatments. Optical density was recorded each 12 h during 192h. Root extracts had the trend of inhibiting fungus growth, however only extracts coming from cultivar INIA had statistical differences (P<0.05); it inhibited up to 25% of fungus growth. On the contrary, stem extracts had the trend of stimulating fungus growth, but only INIA cultivar had a significant effect (P<0.05) as compared to the control treatment, reaching to promote up to 20% of growth. These results display difference in biochemical composition of root and stem metabolites in sesame. This situation is desirable because it indicates genetic diversity in the sesame defense strategies against the fungus, and it could be taken into account for designing sesame breeding programs against biotic stress.

Keywords

• conidias
• densidad óptica
• hongo del suelo
• raíz
• tallo