The implementation of biofungicides entails the use of plant extracts containing antifungal compounds to control diseases in plants. This study determined the potential of the Cinnamomum burmannii leaf extract as a biofungicide against anthracnose disease in chilli plants. The anthracnose disease is caused by the fungus Colletotrichum capsici. The crude extract of the C. burmannii leaves can inhibit the growth of the test fungi with an inhibition zone diameter of 2.2 cm and MIC of 0.5%. The acetone extract of the C. burmannii leaves can inhibit the growth of colonies, biomass and fungal spore germination. T4, inhibit the growth of colonies in rows by 46%. At the same concentrations of T4, the growth of the biomass and spores is inhibited by 87% and 86%, respectively. At the T5 and T6 treatments of the colonies, fungi biomass and spores cannot grow. The mechanism of the C. burmannii leaf extract can control fungi development by destroying the structure of fungal cell walls.
C. burmannii leaf extraction
The selected C. burmannii leaves of healthy, undamaged leaves in green colour. The leaves were chopped into small pieces and dried for three days at room temperature. Then, the leaves were blended until they were in powder form. The leaf powder was macerated in methanol at the ratio of 1:10 (w/v) for 48 hours. The filtrate was obtained by filtering through a gauze and the Whatman no. 2 filter paper. The crude extract was obtained by evaporating the filtrate using a vacuum rotary evaporator at 40 °C. The crude extract was used for further testing.
Results
The crude extract of C. burmannii leaves can inhibit the mycelia fungus (C. capsici) in vitro by using the PDA media with an inhibition zone diameter of 2.2 cm. This inhibition (2.2 cm) could be categorised as strong. The smallest inhibitory concentration (i.e. MIC) of the C. burmannii leaf extract was 0.5%. This finding indicates that the C. burmannii leaf extract is an extremely effective biofungicide and can control the chilli rot disease caused by the fungus C. capsici. The smaller the MIC of an extract is, the more effective the extract can be used as a biofungicide.The C. burmannii leaf acetone extract can inhibit the growth of test fungi colonies in vitro with the PDA media. Moreover, the C. burmannii leaf extract can inhibit the growth of test mushroom colonies. The T4 treatments from the C. burmannii leaf acetone extract can inhibit the radial growth of fungus colonies at 46% relative to the controls. The T5 and T6 treatments of C. burmannii leaf extract can kill fungal colonies. The mushroom colonies killed with the T5 and T6 concentrations were re-grown on the control media, and they were unable to grow or die. This finding indicates that the C. burmannii leaf extract is fungistatic at the 1% concentrations, but it is fungicidal at 1.25% and 1.5% concentrations. The extract concentration affects inhibitory activity at 94.7%. The C. burmannii leaf extract can be regarded fungistatic against the test fungus if the extract can inhibit mould growth and can be regarded fungicidal if the extract can cause death of the test fungus. These fungistatic and fungicidal properties can be determined by increasing or decreasing the concentration of the extract; thus, an effectiveness test on the test fungi was performed accordingly.
T4 treatments of the C. burmannii leaf extract inhibited the growth of the fungal biomass by 87%. Even the T5 and T6 treatments of the C. burmannii leaf extract inhibited the growth of the test fungal biomass by 100%; in other words, at these concentrations, the mushroom biomass cannot grow or die. The research on cinnamon extracts inhibiting the growth of the Fusarium oxysporum fungi, further causing a wilting disease in large chilli plants (Capsicum annum L.), has been reported in Egypt. The C. burmannii extract at 4% and 6% concentrations can inhibit the growth of the fungus F. oxysporum (1) and (2) by 64.8% and 100% and 61.8% and 100%, respectively. The best treatment was at 0.4%, as this concentration can inhibit the growth of mycelia and fungal spore germination by 83.2%.The T3, T4, T5 and T6 treatments inhibited the formation of fungal spores with successive concentrations at 69%, 86%, 100% and 100%.
Inhibiting the fungus growth C. capsici
C. burmannii leaf extracts can inhibit the growth of the fungus C. capsici, which attacks the chilli plants by damaging the fungal cell wall or by changing the cell wall structure. The damages on the fungal cell walls cause an imbalance of the components contained within and outside the cell. Cell contents will undergo lysis and eventually cause death of the fungal cells.
In the fungus without the treatment of cinnamon bark extracts, the surface morphology of the cell appeared smooth. By contrast, in the fungus with the extract treatment, the cell surface appeared damaged. The treatment with the A. calamus rhizome methanol extract in the test fungi showed shrinking hypha and conidia structures compared with those of the controls.
Reference:
Darmadi, A.A.K., Suriani, N., Darmayasa, I.D.A.B.G., Bagus, I.D.A., Suaskara, M.A.D.E., Gari, N.M. and Fudholi, A.H.M.A.D., 2021. Cinnamon leaf extract to control anthracnose disease on chilli plants in bali: a novel and new potential. International Journal of Pharmaceutical Research, 13(1).
