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European Journal of Applied Sciences – Vol. 9, No. 3
Publication Date: June 25, 2021
DOI:10.14738/aivp.93.10207.
Otusanya, M. O. (2021). Role of Nitrogen and Iron in Tuber Phenol Content for Resistance to Infection and Better Storability in
Bounty-Fertilized Dioscorea Rotundata Variety Oniyere. European Journal of Applied Sciences, 9(3). 127-132.
Services for Science and Education – United Kingdom
Role of Nitrogen and Iron in Tuber Phenol Content for Resistance
to Infection and Better Storability in Bounty-Fertilized Dioscorea
Rotundata Variety Oniyere
Otusanya, M. O.
Formerly of Dept. of Crop Protection
College of Plant Science and Crop Production
Fed. University of Agriculture, Abeokuta, Ogun State, Nigeria
ABSTRACT
The role of nitrogen and iron in promoting phenol with its antimicrobial properties
for disease resistance with implication of better storability of yam tubers is
indicated in Dioscorea rotundata variety Oniyere fertilized with an 8-mineral
component fertilizer namely Bounty, in this study. The experiment was arranged in
RCBD (Randomized Complete Block Design) with 3 treatments and 3 replicates. The
treatment was bounty fertilizer at the rate 0, 0.6 and 1.2 ml l-1 applied at 3MAP
(months after planting), Tubers were harvested at 6MAP and analyzed for
proximate, phenol and mineral content. Another set was incubated with
Botryodiplodia theobromae for 2 weeks and then analyzed for phenol and proximate
content. Tuber Ca was comparable across treatments, whereas N, S, and Fe were
higher in the 0.6 and 1.2 ml l-1 Bounty-fertilized treatments than the control. P was
higher only in the 0.6 ml l-1 treatment than the control, whereas K and Mg were
higher in the control than the 0.6 ml l-1 treatment and in the 1.2 ml l-1 treatments
respectively. Phenol was higher in the 1.2 ml -1 treatment than the control. Calcium
which is the second highest (7% w/w) component in Bounty fertilizer was a mean
of 14.15 mg/100gdm in Oniyere tubers, which is only 7.73% of phenol content with
a mean value of 183.3 mg/100gdm. Calcium also had no significant correlation with
phenol. Dry matter and moisture remained unchanged after the incubation,
whereas crude fibre and fat increased by 93.6% and 39.47% respectively. Ash
increased only in the 1.2 ml l-1 treatment by 22.54% and remained unchanged in the
control and 0.6 ml l-1 treatment. Phenol remained unchanged after the incubation
in the 0.6 ml l-1 and 0 ml l-1 treatments but decreased in the 1.2 ml l-1 treatment.
However carbohydrate and crude protein decreased across the 3 treatments by
2.16% and 51.33% respectively. Correlation of r = -0.5786 between Calcium and
moisture indicates Ca will not promote moisture. Positive implication of low
moisture for longer tuber storage has been reported. Nitrogen (N) the highest
component (15% w/w) of bounty, had significant correlation with phenol and Fe, r
= 0.7921 and 0.9840 respectively, thus will enhance production of both tuber
phenol and tuber Iron. Fe correlated significantly with S (r = 0.9751) and Fe and S
will each in turn promote phenol, r = 0.7629 and 0.7978 respectively. Iron content
in Bounty fertilizer is 2% w/w compared to Nitrogen which is 15% w/w, whereas
Sulphur is not present in Bounty fertilizer. A future trial should involve analysis of
total phenolic compounds (not only phenol), as well as proximate and mineral
content, in a longer and time-related incubation of about six to eight weeks, so as to
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determine all factors contributing to longer and better (quality) storage of variety
Oniyere tubers.
INTRODUCTION
Yam (Dioscorea species) tuber quality is important both for the consumer, retailer and exporter
in the country of production as well as the importer in any nation. Preservation of tuber quality
is important as this underground tuber is a staple in all regions where it is produced. High
storage losses, has placed emphasis also on inputs to be established by systematic research,
that would be feasible/ affordable by small holder farmers. Calcium carbonate fertilization
along with N.P.K. has been reported to reduce infection by Aspergillus niger and Botryodiplodia
theobramae in long-term storage in two improved varieties of Dioscorea rotundata and
Dioscorea alata (Otusanya et al., 2016). Even higher reduction in infection by Botryodiplodia
theobromae has also been reported by the 8-mineral component fertilizer Bounty, in two local
white guinea yam varieties namely D. rotundata variety Efuru and Oniyere (Otusanya, 2018 a,
2018 b). Factors which confer resistance were investigated in this study in Dioscorea rotundata
variety Oniyere fertilized with Bounty, an 8-mineral component fertilizer.
MATERIALS AND METHODS
Source of Tubers and Fertilization
Tubers of Dioscorea rotundata var. Oniyere were harvested from a Yam Project plot of the
Teaching and Research Farms of DUFARMS (Directorate of University Farms), Federal
University of Agriculture (FUNAAB), Abeokuta, Ogun State in South West Nigeria. The
Experimental plot had been laid out in RCBD with 3 replications and 3 treatments of Bounty
fertilizer at the rates 0, 0.6 and 1.2 ml l-1 applied at 3MAP (months after planting). Bounty
fertilizer contains 8-minerals in the following composition: Calcium 7% w/w, N 15% w/w, Iron
2% w/w, Zn 2% w/w, Cu 0.5% w/w and B 0.025% w/w, MgO 0.5% w/w, Mn 1% w/w.
Harvest at 6MAP, tuber processing and Analysis
Tubers were harvested at 6 MAP and washed with tap water. They were dried under a low- speed fan on Laboratory benches in the Crop Protection Laboratory, FUNAAB. Triplicate
samples per treatment were then cut into thin slices and dried further for 3 days. The dried
chips were milled to powder with a high-powered mill at the Central Workshop of the College
of Engineering, FUNAAB. The milled samples were then transferred to the Biotechnology
Centre FUNAAB and the Biological Tetfund Laboratory FUNAAB for tissue analysis. Analysis of
proximate content of dry matter, moisture, ash, crude fibre, crude protein, fat and carbohydrate
was according to routine methods of the A.O.A.C. (1990). Phenol content and minerals content
analysis of Calcium, Nitrogen Magnesium, Potassium, Phosphorus, Iron and Sulphur were
carried out according to routine methods of the A.O.A.C. (1990).
Incubation of Tubers with Botryodiplodia theobromae and phenol and proximate content
analysis
A second set of the harvested tubers were cleaned free of soil with a soft cloth, surface sterilized
with 80% methylated spirit and inoculated with a 7-day old pure culture of Botryodiplodia
theobramae according to the method of Otusanya and Jeger (1996), for a 2 week incubation
period. Phenol and Proximate content analysis was done after the incubation with triplicate
samples per treatment, using routine methods of the A.O.A.C (1990).
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Otusanya, M. O. (2021). Role of Nitrogen and Iron in Tuber Phenol Content for Resistance to Infection and Better Storability in Bounty-Fertilized
Dioscorea Rotundata Variety Oniyere. European Journal of Applied Sciences, 9(3). 127-132.
URL: http://dx.doi.org/10.14738/aivp.93.10207
Data Analysis
Data obtained were analyzed using SAS 2000 version 9.1.3, and means separated with Tukey’s
(HSD) test. Pearson’s Correlation tests of all parameters was done also.
RESULTS
Mineral Content and Phenol in harvested tubers
N, S, and Fe were higher in the 0.6 and 1.2 ml l-1 Bounty fertilized tubers than the control,
whereas P was higher only in the 0.6 ml l-1 treatment than the control (Table 1). Mg was higher
in the control than the 1.2 ml l-1 treatment but the control was comparable with the 0.6 ml l-1
treatment. K was higher in the control than the 0.6 ml l-1 treatment, but the control was
comparable /similar with the 1.2 ml l-1 treatment. Ca was comparable across all treatments
(Table 1). Phenol was higher in the 1.2 ml l-1 treatment than the control, whereas the 0.6 ml 1-1
treatment was comparable with the control. Mean value for Ca, 14.15 mg/100gdm was only
7.73% of phenol which was 183.3 mg/100gdm (Table 1).
Proximate content and phenol in the uninoculated and the incubated tubers
Carbohydrate and crude protein decreased across the treatments in the incubated tubers.
Phenol decreased only in the 1.2 ml l-1 treatment, whereas there was no change in the 0.6 ml l- 1 treatment and the control. Crude fibre and fat increased across all treatments whereas Ash
increased only in the 1.2 ml l-1 treatment and did not change in the other two treatments (Table
2). Dry matter and moisture remained the same across treatments (Table 2).
Correlations between Minerals, Proximate content and Phenol
Only significant correlations in minerals, proximate and phenol content in the uninoculated
tubers are indicated in Tables 3 and 4. The following significant correlations were indicated as
shown in Tables 3 and 4, between Calcium and other minerals as well as between Calcium and
some proximate components: Ca and N, r = -0.6021; Ca and S, r = -0.6271; Ca and Fe, r = -0.7005;
Ca and Ash, crude protein, dry matter, carbohydrate, moisture, r = 0.9420, r = 0.8847, r = 0.5789,
r = -0.8547 and r = -0.5786 respectively. Carbohydrate had significant correlations with
moisture, ash, crude protein and dry matter, r = 0.7397, r = -0.9313, r = -0.9300 and r = -0.7401
respectively. There were significant correlations between Nitrogen, Phenol and some minerals
as follows: N and Phenol, r = 0.7921, N and Fe, r = 0.9840. Iron correlated significantly with
phenol and S, r = 0.7629 and 0.9751 respectively. Sulphur had significant correlation with
phenol r = 0.7978. Magnesium had significant correlations with phenol, P and K, r = -0.6823, r
= 0.7544 and r = 0.6507 respectively. Phosphorus correlated significantly with phenol, r = -
0.8080.
DISCUSSION
Mean tuber calcium content of 14.15 mg/100gdm is only 7.73% of mean tuber phenol of value
183.03 mg/100gdm in variety Oniyere. There was no correlation between Ca and Phenol. This
emphasizes the need for determining the relationship between Ca and total phenolic
compounds in a future trial because Calcium is implicated in phenolic compound synthesis
(Castaneda and Perez, 1996). Correlations indicate that Ca (which is present in Bounty fertilize- r, 7% w/w) may not promote moisture (r = -0.5786) and may not promote carbohydrate (r = -
0.8547). Low moisture has positive implication for longer yam (Dioscorea species) tuber
storage. (Frank and Kingsley, 2014), but carbohydrate is the energy providing proximate
component. Low carbohydrate will enhance higher ash, crude protein and dry matter, r = -
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0.9313, -0.9300 and -0.7401 respectively. The above may be responsible for dry matter being
unchanged across all treatments, as well as ash remaining unchanged in the control and 0.6 ml
l
-1 treatments.
It is worthy to note here, that Calcium had negative significant correlation with N, S and Fe, r =
-0.6021, -0.6271 and – 0.7005 respectively. But N which is the highest component (15% w/w)
in Bounty fertilizer will promote phenol and Fe, r = 0.7921 and 0.9840 respectively. Fe will also
promote S (r = 0.9751) and Fe and S will each in turn promote phenol r = 0.7629 and 0.7978
respectively.
Thus it is clear that N which is important for optimum yield along with K in Dioscorea species
(Diby et al., 2011) is also important for promoting phenol with its antimicrobial potential (for
increased resistance to rot pathogens) in stored yam tubers. A 2-week infection by
Botryodiplodia theobromae in Bounty-fertilized variety Oniyere was reported to be 43% lower
than that obtained in a Calcium carbonate-fertilized improved variety of White guinea yam,
Dioscorea rotundata TDR 131 (Otusanya, 2018b). A 2-week infection by Botryodiplodia
theobromae in Bounty-fertilized local white guinea yam, Dioscorea rotundata variety Efuru, was
also reported to be 63% and 23% lower than that obtained in the first and second year
respectively in the improved calcium carbonate- fertilized Dioscorea rotundata TDr 131
(Otusanya, 2018a). Leaf Nitrogen increased with Bounty-fertilization over the control and also
enhanced (in terms of positive correlation) the level of activity of the anticipin tannin,
contributing with phosphorus, iron and sulphur in lowering anthracnose severity to resistant
level in D. rotundata var. Efuru (Otusanya, 2018a).
References cited
A.O.A.C. 1990. Association of Official Analytical Chemists. Official Methods of Analysis. Washington D.C.
Castaneda, P. and Perez, L.M. 1996. Calcium ions promote the response of citrus lemon against fungal elicitors in
wounding. Phytochemistry 42, pp 595-598.
Diby, L.N., Hgaza, V.K., Tie, T.B., Carsky, R., Girardin, O. and Assa, A. 2011. Mineral nutrients uptake and
partitioning in Dioscorea alata and Dioscorea rotundata. Journal of Applied Biosciences, 38: 2531-2539.
Frank, O. and Kingsley, A. 2014. Proximate composition, physiological changes during storage and shelf life of
some Nigerian varieties of yam (Dioscorea species). Journal of Scientific Research and Reports 3(4): 553-562.
Otusanya, M. O. 2018a. Effect of mineral nutrition on anthracnose disease by Colletotrichum gloeosporioides Penz
and rot Botryodiplodia theobromae Pat in Dioscorea rotundata variety Efuru. Advances in Plants and Agriculture
Research 8 (4): 364-369.
Otusanya, M. O. 2018b. Mineral fertilizer effects on Anthracnose Disease caused by Colletotrichum
gloeosporioides Penz., tuber rot by Botryodiplodia theobromae pat. and yield in Dioscorea rotundata variety
Oniyere JOJ Horticulture and Arboriculture 2(1): 555580, pp 1-7.
Otusanya, M. O. and Jeger, M. J. 1996. Effect of Aspergillus niger on shoot emergence and vine development in
field-sown yams (Dioscorea spp.) and rot development under long-term storage conditions. International
Biodeterioration and Biodegradation 89-100.
Otusanya, M. O., Enikuomehin, O., Popoola, A., Adetunji, M., Kehinde, O., Okeleye, K., Latunde-Dada, O. and Amusa,
N. 2016. Effects of calcium fertilization on the susceptibility of Dioscorea species to the yam storage pathogens
Aspergillus niger van Tiegh and Botryodiplodia theobromae pat. Journal of Plant Physiology and pathology. 4.3 Doi:
10.4172/2329-1000155.
SAS 2000, Statistical Analysis System SAS/STAT. User’s guide version 9.1.3 Cary NC. SAS Inst. Incorporated.
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Otusanya, M. O. (2021). Role of Nitrogen and Iron in Tuber Phenol Content for Resistance to Infection and Better Storability in Bounty-Fertilized
Dioscorea Rotundata Variety Oniyere. European Journal of Applied Sciences, 9(3). 127-132.
URL: http://dx.doi.org/10.14738/aivp.93.10207
Table 1: Mineral content (mg/100 g dm) and phenol content (mg/100 g dm) in Bounty- fertilized tubers of Dioscorea rotundata variety ONIYERE at 6 months after planting
Bounty fertilizer
treatment ml l-1
Phenol Ca Mg K S N P Fe
0 163.37 b 13.94 b 25.20 a 60.25
ab
624.50 c 1017.50
c
65.72 b 0.92
c
0.6 181.01 b 14.05 b 24.34
ab
40.44 c 645.00 b 1106.00
b
65.82 a 0.97
b
1.2 204.70 a 14.46
ab
23.06 b 44.57 b
c
662.00 a 1124.33
a
61.12 d 0.99
a
Mean g183.03 14.15
Means in any column followed by a common letter are not significantly different at P = 0.05
Tukey’s (HSD) test
*Ca = 7.73% of phenol
Table 2: Proximate content (% dm) and phenol (mg/100gdm) in healthy Bounty-fertilized
tubers of D. rotundata var. Oniyere and those inoculated and incubated with B. theobromae for
14 days.
Treatment
of tubers
Dry
matter
Moisture Fat Ash Crude
fibre
Crude
protein
Carbohydrate Phenol
0 Fz 85.47
b
14.54 a 0.38 b 2.46 b 6.02 b 8.62 a 82.55 ab 163.37
b
0 Fz and BT 89.39
ab
10.61 ab 0.52 a 2.75 ab 11.79
a
4.22 b 80.72 c 171.49
b
0.6 Fz 86.33
ab
13.67 ab 0.35 b 2.46 b 5.99 b 8.60 a 82.61 a 181.01
ab
0.6 Fz and
BT
87.85
ab
12.15 ab 0.50 a 2.50 ab 11.79
a
3.99 b 81.22 bc 170.60
b
1.2 Fz 86.75
ab
13.25 ab 0.40 b 2.44 b 6.23 b 8.67 a 82.51 ab 204.69
a
1.2 Fz and
BT
91.50 a 8.49 b 0.56 a 2.99 a 11.73
a
4.40 b 80.39 c 165.61
b
% increase
or decrease
in
infected
tissue
39.47% 22.54% 93.6% 51.33% 2.16% 19.09%
Means in a column followed by the same letter are not significantly different at (P = 0.05)
(Tukey’s HSD test)
Fz = Fertilizer Bounty in ml l-1 , BT = Botryodiplodia theobromae
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Table 3: Significant Correlations ONLY of PHENOL and MINERALS in Bounty-fertilized D.
rotundata var. Oniyere at 6MAP
Ca Mg K N P S Fe Phenol
Ca -0.6021 -0.6271
Mg 0.6507 -0.7034 0.7544 -0.7411 -0.6823
K -0.8499 -0.8189
N 0.7921
P -0.8080
S 0.7978
Fe -0.7005 -0.7094 -0.8254 0.9840 0.9751 0.7629
Table 4: Significant Correlations ONLY of proximate content and Minerals in Bounty-fertilized
D. rotundata var. Oniyere at 6MAP
Moisture Ash Protein Dry matter Calcium
Dry matter 0.6704 0.8438
Moisture -0.6699 -0.8434
Ash 0.9206 0.6704
Carbohydrate 0.7397 -0.9313 -0.9300 -0.7401 -0.8547
Calcium -0.5786 0.9420 0.8847 0.5789