Bio-efficacy of Crude Leaf Extracts of &lt;i&gt;Eucalyptus globulus&lt;/i&gt; Against &lt;i&gt;In vitro&lt;/i&gt; and &lt;i&gt;In vivo&lt;/i&gt; Growth of Chocolate Spot (&lt;i&gt;Botrytis fabae&lt;/i&gt; Sard.) of Faba Bean (&lt;i&gt;Vicia faba&lt;/i&gt; L.)

Addisu Tegegn Tola,Meseret C Egigu ,Bekele Hundie Egdu

doi:10.11648/j.plant.20160405.12

Abstract

It is widely known that faba bean (Vicia faba L.) is seriously attacked by the fungal disease, chocolate spot, caused by Botrytis fabae resulting in a yield loss ranging from 50 to 100%. Even though synthetic fungicides are used as one of the effective options for the control of plant diseases, the environmental hazards and economic unfeasibility associated with them necessitate the search for relatively safe natural products. This study was initiated to evaluate the antifungal potential of crude extracts of leaves of Eucalyptus globulus, against in vitro and in vivo growth of Botrytis fabae. In the in vitro experiment, antifungal assay was set up using different concentrations of the crude extracts. In vivo experiment was conducted in the field by planting a faba bean variety, Shallo, (EH011-22-1) and selected plants from each plot were used for extract application and subsequent data collection. Laboratory experiment showed that, compared to the control, extracts obtained from each solvent managed to produce statistically significant (p <0.05) inhibition of mycelial growth. Based on the minimum concentration, inhibition from methanol extract (42.2%) significantly varied from that of ethanol (26.3%). Nevertheless, aqueous extract was nearly statistically the same to that of methanol. On the other hand, at maximum concentration (40%), a maximum inhibition percent of 83.7, which was nearly double of that produced by aqueous extract, was recorded from ethanol extract treated plates. Field experiment has shown that the use of ethanol extract of Eucalyptus globulus produced an efficacy of about 58.4%. Number of flowers aborted, number of tillers per m2, number of pods per plant, number of seeds per pod and hundred seeds weight were affected due to the disease suppression effect of the three extracts. However, there was quantitative variation in yield though no statistically significant difference was observed. The result of this study showed that extracts of the tested plant species have natural fungitoxic potential and showed a promising future for the development of safe natural alternative fungicides used for the control of Botrytis fabae after further pertinent tests and screening of the active principles.

Highlights

Ethiopia is considered to be the secondary center of diversification of faba bean [4, 39, 42], which occupies an approximate area of 459, 183.5 ha with a total annual production of about 697,798.4 t [8]
Among faba bean fungal diseases, Chocolate spot, which is caused by Botrytis fabae (Sard.) is the most widespread and highly destructive disease causing a yield loss ranging roughly from 34 - 61% on susceptible cultivars in Ethiopia [15]
E. globulus is revealed in this study that it is a promising plant species in vitro and in vivo whose natural potential should be exploited after further detailed physicochemical studies

Summary

Introduction

Ethiopia is considered to be the secondary center of diversification of faba bean [4, 39, 42], which occupies an approximate area of 459, 183.5 ha with a total annual production of about 697,798.4 t [8]. The country is among the major faba bean producing Nations in the World; taking the second place next to China [11, 12, 39].The crop is a valuable source of cheap protein for the poorest part of the population who cannot afford animal protein [30]. In spite of the fact that these advantages are obtained from the crop, its yield in Ethiopia is substantially lower than the World average. Growth of Chocolate Spot (Botrytis fabae Sard.) of Faba Bean (Vicia faba L.). Among faba bean fungal diseases, Chocolate spot, which is caused by Botrytis fabae (Sard.) is the most widespread and highly destructive disease causing a yield loss ranging roughly from 34 - 61% on susceptible cultivars in Ethiopia [15]. The disease is found to be severely affecting yield wherever it occurs provided that susceptible host and conducive environmental factors prevail [15, 31]

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Results

Conclusion