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European Journal of Applied Sciences – Vol. 10, No. 1

Publication Date: February 25, 2022

DOI:10.14738/aivp.101.11609. Otusanya, M. O. (2022). Seed-Borne Fungi Associated with Pepper (Capsicum Species) in Some States in Nigeria. European Journal

of Applied Sciences, 10(1). 199-209.

Services for Science and Education – United Kingdom

Seed-Borne Fungi Associated with Pepper (Capsicum Species) in

Some States in Nigeria

Otusanya, M. O.

ABSTRACT

Capsicum (Pepper: common name) species fruits are ground and utilized either

fresh or dried as an essential ingredient of sauce/soup in every region of Nigeria.

Seed health tests were carried out on thirty-one seed cultivars of Capsicum that is

Capsicum frutescens L. and Capsicum annuum L. from Kaduna, Benue and Oyo States

in Nigeria in this study. An initial mini-greenhouse project with some of the

cultivars resulted in Curly-top Virus symptoms disease. The latter disease which

had not been hitherto reported in Nigerian Capsicum cultivars necessitated the

grouping of the seeds into two sets of Nigerian/Indigenous Cultivars (in group one)

and Exotic plus less exotic cultivars in a second group. The Nigerian set made up of

eight cultivars was examined with and without surface-sterilization for mycoflora.

The design was completely randomized comprising five (5), replicates per cultivar

and 50 seeds in a cultivar replicate. The working sample was 250 seeds per cultivar

set up under an alternating cycle of 12hours Near ultra-violet light (NUV light) and

12hours darkness in an incubating room of 27 ± 2oC temperature. Incubation for

viability counts and associated fungi was for seven days. The Exotic plus less exotic

set had twenty-three cultivars, which were tested as the Nigerian Cultivars, without

surface-sterilization. Viability was over 30.00% only in eleven of the twenty-three

Exotic plus less exotic Cultivars, whereas there was none (over 30%) in the

indigenous or Nigerian Cultivar set. Three reasons adduced for the low turn-out in

germination are period of seed storage of six months or over, lack of seed treatment

and mixed infections possibly with viruses or nematodes. The genera Phoma,

Chaetomium, Penicillium, Rhizopus and Cladosporium with the former two

associated with all eight cultivars, were isolated from the un-sterilized

indigenous/Nigerian set and are considered to be surface contaminants. Twenty

fungi namely Aspergillus flavus, A. niger, A. ochraceus, A. wentii, Cercospora sp.,

Chaetomium sp., Colletotrichum sp., Curvalaria lunata, C. pallescens, Fusarium

equiseti, F. moniliforme, F. solani, Graphuinu sp., Macrophomina sp., Penicillium sp.,

Phoma sp., Rhizopus sp., Spegazzima sp., Stemphylium sp. and Verticillium sp. were

isolated from the un-sterillized Exotic plus less exotic cultivars set. Among the

twenty, Aspergillus flavus, Fusarium moniliforme and Phoma sp. were dominant as

they were associated with 22, 21 and 19 of the twenty-three cultivars respectively.

Overall mean infection of 13.55%, 8.06% and 5.23% were highest by A. flavus,

Colletotrichum sp. and Rhizopus sp. respectively and the three highest cultivar

replicate infections were 55.60%, 32.80% and 23.20% also by Aspergillus flavus,

Rhizopus sp. and Colletotrichum sp. in that order respectively. Seed-borne

saprophytes are reported to be economically important as they effect seed rot, seed

weight loss or seed germination reduction and ought to be excluded by adequate

seed treatment. Twelve fungi were associated and isolated from the eight surface- sterilized Indigenous/Nigerian cultivar set. They are Aspergillus flavus, A. niger, A.

tamari, Cochliobolus lunatus, Colletotrichum capsici, Corynespora casiicola,

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European Journal of Applied Sciences (EJAS) Vol. 10, Issue 1, February-2022

Services for Science and Education – United Kingdom

Curunlaria pallescens, Fusarium moniliforme, F. pallidoroseum, Macrophomina

phaseolina, Pithomyces chartarum and Thielavia terricola. Aspergillus flavus,

Fusarium moniliforme and Aspergillus niger were the three most frequently

occurring/dominant fungi as they were isolated from all eight, seven and six

cultivars respectively. However, overall mean infection was highest by Aspergillus

flavus 11.80%, second is Colletotrichum capsici 6.60% and third is Fusarium

moniliforme 3.20%. The two highest infections in any cultivar replicate also were

55.60% by Aspergillus flavus and 23.20% by Colletotrichum capsici, and in third

place is 15.20% by Aspergillus niger. Colletotrichum capsici and two other

Colletotrichum species gloeosporioides and acutatum are known to be the most

important economic fungal pathogens of Capsicum species in Nigeria and globally

causing ripe fruit rot and stem die-back. Seed-borne Fusarium species namely

moniliforme, solani and oxysporum and Verticillium species also contribute to high

pre-harvest losses (by damping-off of seedlings and witling of field plants) on

Pepper globally. The Aspergilli cause moulds on above-ground portions of pepper

plants and Macrophomina is known to be parasitic on leaves. Pithomyces chartarum

and Thielavia terricola have not been reported on Capsicum species and are

therefore new records on Capsicum seeds in Nigeria. Seed storage for planting

without adequate/appropriate seed treatment is to be discouraged in Nigeria;

because of low viability as in this study, and seedling failure/field epidemics/crop

failure. Fundings and extensive trials with Plant extracts, Oils and Biocontrol

microbes should also be underscored as necessary for seed treatment in place of

fungicides for health and environmental safety. Improved Seeds should also be

sought for as priority from approved Agencies/Seed Companies by farmers.

INTRODUCTION

Capsicum frutescens L. and Capsicum annuum L, (Pepper – common name) is traditionally

important as a main component of soup/stew/sauce in every region/ethnic group in Nigeria. It

is mixed with legume or cereal grains locally to preserve from spoilage/ward off insects and is

also medicinal.

Seed samples of thirty-one cultivars of Pepper were collected from Inst. Of Agric Res., Ahmadu

Bello University, Samaru Zaria (In Kaduna State, Nigeria), Yandev, Gboko (in Benue State,

Nigeria) and Teaching and Research Farms in University of Ibadan, Ibadan (in Oyo State,

Nigeria). Several cultivars were sown and then transplanted. Many of the Screen house potted

plants had yellowing symptoms and marked curling of the leaves, identified as the Curly-top

Virus disease at the Int. Inst. of Tropical Agric, Ibadan through Prof. Ekpo (personal

communication). Curly-top virus disease was reported on Mexican tomato as well as wild and

cultivated Mexican peppers namely Capsicum annuum L., C. chacoense Hunz, C. chinese Jacq. and

C. frutescens L. from Southern New Mexico (Bosland, 2000). The disease has also been reported

on Coastal tomato and pepper from Monterey and San Benito Counties in California (Koike and

Gilbertson, 2010). The cultivars were therefore separated into two sets of Indigenous/Nigerian

in one set and Exotic plus less exotic in a second set. The twenty-three cultivars which may be

said to be foreign or Exotic plus less exotic were examined for seed-borne fungi with the blotter

technique, without surface-sterilization. Seven cultivars of pepper grown in the states where

the seeds were sourced, and one foreign/exotic cultivar namely Cherry Sweet which has been

adopted by Nigerian pepper growers were put in the Indigenous/Nigerian cultivars set. They

were examined for seed-borne fungi using the blotter technique with and without surface- sterilization.

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Otusanya, M. O. (2022). Seed-Borne Fungi Associated with Pepper (Capsicum Species) in Some States in Nigeria. European Journal of Applied

Sciences, 10(1). 199-209.

URL: http://dx.doi.org/10.14738/aivp.101.11609

MATERIALS AND METHODS

Source of Seeds

Thirty-one Cultivars of Pepper, Capsicum species seeds were collected from the Inst. Of Agric.

Res., Ahmadu Bello University (Samaru), Zaria in Kaduna State of Nigeria, Yandev and Gboko in

Benue State of Nigeria, the National Inst. of Hort. Res., Ibadan in Oyo State and Teaching and

Res. Farms, University of Ibadan, also in Oyo State of Nigeria.

Preparation of Surface-sterilized Seeds

Seeds were surface-sterilized with 10% Sodium hypochlorite solution, and washed in three

changes of sterile distilled water. The Blotter technique was used to prepare the seeds for

Incubation and Examination (ISTA 1993). Four (4) layers of Whatman number 4 filter paper

were laid in sterile plastic 9 centimeter (9cm) petri-dishes. The dishes were flooded with sterile

distilled water and excess decanted. With a pair of sterile forceps, five surface-sterilized seeds

were placed in a row along the diameter of a petri-dish. Another set of seeds were placed in

another row at right angles to the first one, and so on until there were a total of 25 seeds placed

equidistant from one another in a petri-dish. The experiment was completely randomized

design. Selection of the seeds was random. Two plates each with 25 seeds represented a cultivar

replicate. Each cultivar had 5 replicates and a total of 250 seeds. Surface sterilization and

loading of petri-dishes was in a Lamina-hood. Petri-dishes were covered and placed under a

gadget supplying an alternating cycle of 12hours near ultraviolet light (NUV light) and 12 hours

darkness, in an incubating room with temperature of 27 ± 2oC. Incubation period was seven (7)

days.

Record of Surface Contaminants and Germination Count.

Loading of petri-dishes with unsterilized seeds was the same as for the sterilized seeds.

Incubation for the two sets of petri-dishes was 7 days. Germination count was taken on the 8th

day. Germination was the number of seeds that had germinated as a percentage of the total of

50 seeds in a replicate, and the final cultivar percentage germination was the total number of

seeds that were viable/germinated in a total of the 5 replicates of a cultivar. Surface

contaminants were recorded from the seeds that were not surface-sterilized.

Examination of Seeds

After a 7-day incubation period, seeds were examined with a Wild M5 Stereo-binocular

Microscope and a Compound binocular Microscope. Culturing of fungi from seeds as necessary

was done for confirmation of fungal identity by slide preparations and use of potato dextrose

agar. Identification was based on morphology/growth habit, reproductive structures such as

sexual spores and asexual spores (e.g. conidia) and special structures such as sclerotia, sterile

mycelia, etc, and with Identification guides namely the Illustrated Genera of Imperfect Fungi by

Barnett and Hunter (1998) and FUNGI by Vashista and Sinha (1998). Some of the fungal

identities were confirmed at the International Mycological Institute in Kew, Surrey England and

bear numbers between the range IMI 321688 to IMI 321718.

Estimates of Infection

Infection by a fungus was firstly taken as a Percentage of a cultivar replicate, and then as a

percentage of the total of 5 replicates in a cultivar, and also as a total of the cultivars examined.