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European Journal of Applied Sciences – Vol. 10, No. 2
Publication Date: April 25, 2022
DOI:10.14738/aivp.102.11965. Sobowale, A. A., Ali, O. O., Oyewole, B. O., & Elum, C. G. (2022). Rot Fungi of Cucumis Sativus (Cucumber) and their Susceptibility
to Extracts of Moringa Oleifera Leaves and Allium Sativum Bulbs. European Journal of Applied Sciences, 10(2). 178-207.
Services for Science and Education – United Kingdom
Rot Fungi of Cucumis Sativus (Cucumber) and their Susceptibility
to Extracts of Moringa Oleifera Leaves and Allium Sativum Bulbs
Sobowale A. A.
Department of Botany, University of Ibadan, Ibadan, Nigeria
Ali O. O.
Department of Botany, University of Ibadan, Ibadan, Nigeria
National Horticultural Research Institute (NIHORT)
Idi Ishin, Ibadan, Nigeria
Oyewole B. O.
National Horticultural Research Institute (NIHORT)
Idi Ishin, Ibadan, Nigeria
Elum C. G.
National Horticultural Research Institute (NIHORT)
Idi Ishin, Ibadan, Nigeria
ABSTRACT
The fungitoxic capabilities of extracts of Moringa oleifera leaves and Allium sativum
bulbs against fungi associated with rot of Cucumis sativus L. (cucumber) was
investigated. The rotting fruits were purchased from some markets and isolation
and identification of pure cultures of fungi from the rotting cucumber fruits was
done using standard procedures. Leaves of M. oleifera and cloves of A. sativum were
procured and crude extracts (aqueous and ethanol) of the plant materials were
obtained following standard procedures. Fungitoxic abilities of leaves of the M.
oleifera and cloves of A. sativum extracts on the isolated fungi were evaluated in
vitro at concentrations of 25%, 50%, 75% and 100%. The interactive impacts of the
extracts on the isolated fungi was also evaluated. The experiment was carried out
in triplicates. All Petri plates were incubated at 28±2oC and observed for 7 days.
Diametric and radial growth measurement of the resulting fungi was taken at 24
hours intervals. Data were analysed using the GLM procedure of SAS (version 9.1).
Means were separated using DMRT (p≤0.05). Isolated fungi were identified as
Fusarium verticillioides, F. oxysporum and Colletotrichum orbiculare. Extract of M.
oleifera gave a better growth inhibition compared to that of A. sativum in the
individual assay. Combined extracts of A. sativum (50%) and M. oleifera (100%) as
well as A. sativum (75%) and M. oleifera (100%) gave better growth inhibition
compared to other treatment combinations. Both aqueous and ethanol extracts of
A. sativum and M. oleifera significantly (p≤05) inhibited mycelia growth of the
isolated fungi at different concentrations compared to control. The aqueous
extracts gave better growth inhibition compared to the ethanol extracts. Growth
inhibition of F. oxysporum was better than that of F. verticillibides, which in turn was
significantly better than that of C. orbiculare. Extracts from cloves of A. sativum and
leaves of M. oleifera can be said to possess fungitoxic potentials against fungi
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Sobowale, A. A., Ali, O. O., Oyewole, B. O., & Elum, C. G. (2022). Rot Fungi of Cucumis Sativus (Cucumber) and their Susceptibility to Extracts of
Moringa Oleifera Leaves and Allium Sativum Bulbs. European Journal of Applied Sciences, 10(2). 178-207.
URL: http://dx.doi.org/10.14738/aivp.102.11965
associated with rot of cucumber. Further work in the field will be needed before
credible assertions can be made on their fungitoxicity.
Keywords: Allium sativum, Moringa oleifera, Cucumis sativus phytotoxicity, interactions
INTRODUCTION
Cucumis sativus L. (cucumber) is a vegetable plant widely cultivated in the entire world
especially in Asia, Africa and South America. It is an annual monoecious creeping vine that bears
large leaves that form canopy over its cylindrical fruits (1). It is ranked the fourth most widely
cultivated vegetable in the world after tomato, cabbage and onion (2,3). It is grown in all the
agro-ecological zones of Nigeria. The savanna zone of Nigeria has the greatest potential for its
production due to moderate rainfall. However, research has proved that it can grow in some
southern parts of Nigeria that had moderate rainfall (4). The crop is grown under rain-fed
conditions in the rainy season, and grown using irrigation in the dry season (5).
It is rated a highly nutritive fruit containing many vitamins and minerals that make it a healthy
choice for consumption in various ways. It is an excellent source of vitamin C and A which are
antioxidants, as well as folate, manganese, molybdenum, potassium, sodium, silica, sulphur and
lesser amounts of vitamin B complex (4). It has been found to be of use to in the food, medical,
pharmacological, ethno-botanical and industrial sectors. It is reported to be useful in treating
ailments such as cancers, diabetics, skin irritations wounds, eczema, arthritis gout, gastric ulcer,
constipation, general debility, piles etc. (6, 7). It has been useful in the manufacture of different
products like soaps, lotions, shampoos and fragrances, etc. (8).
Postharvest diseases are reported to account for about 50% losses in fruits stored in poor
storage conditions especially under high humidity which pose a major problem to the
agricultural industries. Like many other fruits, cucumber is also susceptible to postharvest
diseases especially fruit rot caused by fungi under poor storage conditions. In Nigeria, fungi
constitute the major limiting factor to production of cucumber and are also mainly responsible
for their post-harvest rots. Emechebe and Shoyinka (9) reported that pathogenic fungi are
capable of causing up to 100% yield loss in crops. These fungal infections are as well known to
cause their mycotoxins contamination (10). Contamination of fruits by mycotoxins has been
documented to cause different health hazards both in man and animals.
The use of chemical fungicides for disease control continues to attract increasing public
concern. Biological control and use of botanicals as alternative to synthetic fungicides in the
management of postharvest pathogens including rot fungi have continued to gain attention.
Extracts of Moringa oleifera leaves and Allium sativum bulbs have been reported to have high
antimicrobial properties against several plant pathogens. This study therefore aimed to explore
the antimicrobial potential of these plants on the rot fungi of cucumber fruit.
MATERIALS AND METHODS
Sample collection
The experiment was conducted at the Plant Pathology Laboratory of the Department of Botany,
University of Ibadan, Nigeria. Diseased cucumber fruits with signs of rot were obtained from
four markets in Ibadan viz., Oje, Benjamin (at Eleyele), Ring road and Bodija. The diseased
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European Journal of Applied Sciences (EJAS) Vol. 10, Issue 2, April-2022
Services for Science and Education – United Kingdom
samples were packaged, labelled appropriately and taken to the laboratory for further research.
Leaves of Moringa oleifera were collected from National Horticultural Research Institute
(NIHORT) Ibadan, Oyo State while Allium sativum cloves were purchased from a market.
Isolation and identification of fungi
The cucumber fruits were rinsed thoroughly before surface sterilizing with 70% ethanol for
one minute. They were thereafter rinsed again in three changes of sterile distilled water before
blotting with filter paper. Diseased sections of the fruits were cut using a sterile scalpel and
inoculated directly (direct plating method) unto sterile Petri plates of Acidified Potato Dextrose
Agar (APDA). Incubation was done at 270C ± 20C for 7 days to allow growth of fungi associated
with the rotting. Resulting fungi were later sub-cultured to obtain pure cultures and later
identified using the method of Wantanabe (11).
Pathogenicity test
Healthy cucumber fruits were surface sterilized with 70% ethanol. Cylindrical plugs were cut
from each cucumber fruit using a sterile 5mm cork borer. Pure culture of each isolated fungus
was introduced into the holes in three replicates. The cylindrical plugs were placed back in the
holes and sealed with sterile petroleum jelly. The fruits were incubated at room temperature
(28±2oC) for 7 – 10 days while the control had no fungus. The cucumber fruits were examined
after 7 days to access and record the extent of rot and the pathogens were re-isolated from the
inoculated cucumber fruits.
Preparation of the plant extracts
Leaves of M. oleifera and clove of A. sativum were washed under running water, air dried for
weeks at room temperature and grounded into powdered form. The powdered samples were
added to different conical flasks containing the extraction solvent (sterile distilled water and
ethanol). For the aqueous plant extraction, dried plant materials were soaked in water for 24
hours, stirred every 2 hours, sieved with muslin cloth and further filtered using Whatman filter
paper. The aqueous filtrate was concentrated using a rotator evaporator at 500C. While for the
ethanol extraction, dried plant materials were soaked in ethanol for 72hours with constant
stirring every two hours after which solvent was collected using muslin bag. It was further
filtered using Whatman filter paper and filtrate was evaporated to dryness using a rotatory
evaporator set at 400C. The crude ethanol extract was further concentrated using a vacuum
oven set at 400C with a pressure of 700mmHg. After getting the crude extracts of each botanical,
0.25g of each extract was dissolved in 250ml of sterilized distilled water and it served as the
stock solution. Further dilutions were made to get the 25%, 50%, 75% and 100%, a modified
method of Akanmu et al., (12).
Antifungal potential of the plant extracts
One milliliter (1ml) of each prepared extract at different concentrations (25%, 50%, 75% and
100%) were aseptically dispensed into sterile Petri plates. About 15ml of sterilized Acidified
Potato Dextrose Agar (APDA) was poured into each of the Petri plates containing plant extracts.
The Petri dishes were swirled to allow for even distribution of the extracts within the plates. A
3mm cork borer was used to cut discs from each 7 day old actively growing culture of the
pathogens. Petri dishes without extract and with 1ml of ethanol dispensed served as control.
The treatments were done in three replicates and all plates were incubated at 28oC. Diametric