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European Journal of Applied Sciences – Vol. 9, No. 3
Publication Date: June 25, 2021
DOI:10.14738/aivp.93.10209. Otusanya, M. O. (2021). Calcium Nitrate Fertilization Effect on Anthracnose Caused by Colletotrichum Gloeosporioides Penz., Tuber
Rot By Rhizopus Stolonifer Ehrenb. and Yield in Dioscorea Alata Variety Atoroku After Fallow. European Journal of Applied Sciences,
9(3). 143-155.
Services for Science and Education – United Kingdom
Calcium Nitrate Fertilization Effect on Anthracnose Caused by
Colletotrichum Gloeosporioides Penz., Tuber Rot By Rhizopus
Stolonifer Ehrenb. and Yield in Dioscorea Alata Variety Atoroku
After Fallow
Otusanya, M.O.
Formerly of Department of Crop Protection
College of Plant Science and Crop Production
Federal University of Agriculture, Abeokuta, Ogun State, Nigeria
ABSTRACT
Calcium nitrate soil amendment fertilization effects on anthracnose disease caused
by Collettrichum gloeosporioides, tuber rot by Rhizopus stolonifer and yield were
determined in Dioscorea alata variety Atoroku (a local variety from South West
Nigeria). The field design was RCBD (randomized complete block design) with 3
treatments and 3 replicates. The 3 treatments were calcium at 0, 2 and 4 kg ha–1
from calcium nitrate (analar grade) applied at 3 MAP (months after planting). N in
the experimental site was below the critical determined for optimum yam
production in South West Nigeria, but Ca, Mg and K were above the critical. At 4 MAP,
shoot number (mean, 3.68) was comparable/similar across treatments, but shoot
length (3.43 m) was higher in the 2 kg ha–1 treatment than others. At 5 MAP the
control and 2 kg ha–1 calcium fertilized plants had higher shoot number, a mean of
5, than the 4 kg ha–1 calcium fertilized plants, whereas shoot length had become
similar in the treatments. Tubers were inoculated and incubated for two weeks with
Rhizopus stolonifer, an economic yam storage pathogen in Nigeria, after the 5MAP
and 6MAP harvests. There were no significant differences in weight loss or infection
in the incubated tubers at 5MAP. Weight loss of 11.01% in the 2 kg ha_1 incubated
calcium-fertilized tubers were significantly higher than in the control (3.20%) and
the 4 kg ha_1 treatment (1.90%) at 6MAP. However infection was significantly lower
in the 2 kg ha_1 (0.78%) and 4 kg ha_1 (0.86%) calcium-fertilized tubers than the
control (2.25%) at 6MAP. Calcium nitrate at 2 kg ha_1 and 4 kg ha_1 soil amendment
may be used in smallholder farmers plots to reduce infection in D. alata variety
Atoroku tubers if the six months after planting is desired for income as is the
practice for white guinea yam 6MAP milk harvest in Nigeria. Anthracnose severity
scored at 8MAP was moderately susceptible in the 4 kg ha_1 treatment (3.17),
control (2.83) and the 2 kg ha_1 treatment (2.75) and were not significantly different
from one another. Reduction of anthracnose may be further determined with one
or two foliar sprays in addition to the 3MAP calcium nitrate soil amendment, as well
as leaf calcium analysis to ascertain the optimum concentration commensurate to
anthracnose resistance. Shoot number per plant at 8MAP was in the range 2.07 to
2.54 with no significant differences among the three treatments. Tuber number per
plant was also not significantly different and was 3.55, 4.27 and 3.18 in the 0, 2 and
4 kg ha_1 treatments. Plant weight above the mound of 4.78 kg and tuber weight of
5.35 kg in the 4 kg ha_1 treatment at 8MAP harvest was significantly higher than the
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European Journal of Applied Sciences (EJAS) Vol. 9, Issue 3, June-2021
Services for Science and Education – United Kingdom
control (3.25 kg and 3.55 kg respectively), and the 2 kg ha_1 treatment (3.05 kg and
3.25 kg respectively), whereas both were similar in the control and the 2 kg ha_1
treatment. The 8MAP yield of 3.55 kg, 3.25 kg and 5.35 kg in the 0, 2 and 4 kg ha_1
treatment is the equivalent of 35.5, tons ha_1, 32.5 tons ha_1 and 53.5 tons ha_1 and
are higher than the expected 15 to 25 tons ha_1 with 400 kg (8 bags) NPK 15-15-15
(ICS-Nigeria) and also in the range of the estimated potential of 30 to 75 tons ha_1
(Zinsou, 1997; Diby et al., 2004). Calcium nitrate soil amendment at 4 kg ha_1 is
recommended for increase in yield in Dioscorea alata variety Atoroku after fallow
in South West Nigeria or areas of similar soils.
Introduction
Anthracnose disease caused by Colletotrichum gloeosporioides Penz is still a major constraint
to yam production everywhere yams are grown, as well as storage rots mainly caused by fungi
which reduce all-year-round availability of the staple by 30% to 50% annually, depending on
storage conditions. The latter also depends on the farmers’ wealth and sufficiency. Smallholder
farmers’ who are responsible for higher production across all the agro-ecologies where yams
are grown in Nigeria, the world’s largest producer, wish to make supply exceed demand and
not the reverse (as it is currently), so that greater wealth for their high labour will be cushioned
by export. As at 2014, export was only 0.03% (Verter et al., 2015). This study investigated the
effect of two main nutrient elements namely calcium and nitrogen supplied from calcium
nitrate fertilizer, in the economic field disease anthracnose, tuber rot by Rhizopus stolinifer
which is about the second most important yam tuber rot (storage/market) pathogen (Dania et
al., 2012) and yield in an indigenous water yam variety Atoroku from within Ogun state in South
West Nigeria. The experimental site at the Teaching and Research Farms of DUFARMS
(Directorate of University Farms), Federal University of Agriculture, Abeokuta Ogun State,
South West Nigeria had been left fallow for more than four years before this study. The choice
of calcium is based on its role in improvement of plant cell structural integrity against
pathogenic degradation (Marshner, 1995, Dordas, 2008). Cacium carbonate fertilization had
increased resistance to tuber rot by A. niger and B. theobromae in long-term storage of 2
improved yam varieties D. rotundata TDr 131 and D. alata TDa 92-2 (Otusanya et al., 2016). In
the latter report, NPK was used with CaCO3 to enhance yield, but with no positive significant
effects. Ca (NO3)2 was chosen in this study as it is more readily taken up in the soil than CaCO3
(Lombin, 1990) and there was no need for a separate source of Nitrogen. Nitrogen is one of the
two (the second being potassium, K) major nutrients required for optimum yield in yams (Diby
et al., 2011).
MATERIALS AND METHODS
Sourcing of Tubers
Tubers of D. alata var. Atoroku were sourced from yam farmers’ plots within Ogun State in
South West Nigeria.
Field Plot, Soil Sampling and Analysis
The field plot used is located at the Teaching and Research Farms of DUFARMS (Directorate of
University Farms), Federal University of Agriculture Abeokuta, Nigeria. Clearing of the plot was
done with hoes and machetes with minimal burning of bush. The 31 m by 13 m area, had three
replicates and each replicate was 13 m by 9 m. Soil samples were collected per replicate before
mound making. Fifteen (15) core soil samples were collected per replicate in a zig-zag pattern
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Otusanya, M. O. (2021). Calcium Nitrate Fertilization Effect on Anthracnose Caused by Colletotrichum Gloeosporioides Penz., Tuber Rot By Rhizopus
Stolonifer Ehrenb. and Yield in Dioscorea Alata Variety Atoroku After Fallow. European Journal of Applied Sciences, 9(3). 143-155.
URL: http://dx.doi.org/10.14738/aivp.93.10209
with a slanting soil auger at 20 cm depth to lift surface and lower soil (Page et al., 1982). Air
drying of soil, sieving and bulking according to replicates, as well as soil analysis was according
to standard methods (Page et al., 1982).
Field Plot Design
The field design was RCBD (randomized complete block design), with three replicates and three
treatments. In each replicate there were 6 rows of 5 mounds each. Mounds were 1 m by 1m and
80 cm high. Three rows were treatment rows to which fertilizer treatments of 0, 2 and 4 kg ha- 1calcium from calcium nitrate was applied. Three rows were border plant rows planted to the
same variety but without any fertilizer application. Border plant rows were each 1 metre
distance from the fertilizer treatment rows. Inter-row, intra-row and inter-replicate spacing
were 1 m, 0.5 m and 1 m respectively. Thus there were a total of 30 mounds in each replicate
and a total of 90 mounds in the plot. A clean border of 1 m on all of the four sides of the plot was
maintained.
Planting, Staking and Fertilization
Seed yam tubers of average size 0.5 kg were planted per mound, at the onset of the rains (early
March, 2015). Two metre (2m) length bamboo stakes were established per mound. Soil
amendment of treatment rows with 0 kg ha-1(control), 2 kg ha-1 and 4 kg ha-1calcium from Ca
(NO3)2 (Analar grade) was at 3 MAP (Months After Planting). A 20 cm groove was made at 25
cm radius around the yam plant in each mound. Fertilizer was sprinkled at the early morning
hours (7.00 am) evenly in the groove. The groove was then covered well with soil (Obigbesan
and Agboola, 1978).
Emergence and Shoot Growth Assessment
Number of emerged plants were assessed at 3 MAP and 4 MAP. Number of shoots per plant and
shoot length of a labelled vine per plant were determined at 3 MAP, 4 MAP and 5 MAP.
Tuber Sampling and Infection Experiment at 5 MAP and at 6 MAP
Tubers were sampled per treatment along a diagonal transect (for randomization) of the field
plot at 5 MAP and at 6 MAP. They were transferred to the Crop Protection Laboratory, cleaned
free of soil, surface-sterilized and then inoculated with a 7-day old pure culture of Rhizopus
stolonifer (Otusanya et al., 2016). Incubation period was 2 weeks. Weight loss (Y) in the tubers
was calculated with the formula !
!"#
! " 100. Infection was calculated with the formula !
$
!
" 100,
where A is tuber weight before inoculation, B is tuber weight after incubation period and C is
corrected weight of infected tissue � = (&''()
(&''"*)
where X is weight of infected tissue and Y is %
weight loss(Otusanya, 1994).
Assessment of Anthracnose Severity at 8 MAP
Severity of Anthracnose was determined at 8 MAP using the Anthracnose Seventy Scale in
Figures 1, 2, and 3 (Otusanya et al.,2017).
Plant Weight and Yield at 8 MAP
The above-ground plant weight in treatment and border plants were determined at 8 MAP. This
was done by severing the shoots above each mound and cutting them into smaller portions in
a pre-weighed raffia basket. The above-ground plant weight was measured with a top loading
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field balance. Tubers per plant (in each mound) were counted after soil on the mound was
moved carefully away from the tubers within with a smooth wooden club, to avoid bruising.
Tubers were cleared carefully of soil with a soft cloth and weighed per plant with a top loading
field balance.
Data Analysis
Data were subjected to analysis of variance with SAS 2000 version 9.1.3. Means were separated
using Least Significant Difference.
RESULTS
Soil properties of the experimental plot
Soil properties of the field plot are as shown in Table 1. The values in cmol kg_1 of 31.50 ± 0.04,
2.08 ± 0.01 and 0.70 ± 0.004, for calcium (Ca), magnesium (Mg) and potassium (K) respectively
are above the critical determined for optimum yam production for the 3 elements/minerals in
South West Nigeria (Ibedu et al., 1988). Nitrogen (N) of the value 0.75±o.003% was below the
critical determined for optimum yam production in South West Nigeria (Ibedu et al., 1988).
Emergence and Shoot Growth
There have been two reports only (Otusanya 2018 and Otusanya 2018) of Calcium nitrate soil
amendment fertilization in Dioscorea species, thus it became necessary to assess the fertilizer
effect in some agronomic characters. Emergence was 60%, 50% and 30% in the 0,2 and 4 kg
ha-1 calcium-fertilized plants at 3 MAP respectively (Table 2). At 4 MAP, emergence had
increased by 33.33%, 37.50% and 57.14% respectively in the 0, 2 and 4 kg ha-1 treatments, with
no significant differences between them (Table 2). Shoot number per plant at 3 MAP was 2.25,
2.25 and 2.50 in the 0, 2 and 4 kg ha-1 calcium-fertilized plants respectively (Table 3). At 4 MAP
increase in shoot number was 47.67%, 35.71% and 23.08% in the 0, 2 and 4 kg ha-1calcium- fertilized plants, with no significant differences between them (Table 3). At 5 MAP, shoot
number percent increase in the 0, 2 and 4 kg ha-1 calcium-fertilized plants was 108.89%,
78.87% and 8% respectively (Table 3), indicating significantly higher shoot number in the
control plants and the 2 kg ha-1 treatment plants over the 4 kg ha-1 calcium-fertilized plants.
The control and 2 kg ha-1 treatments were comparable/similar in shoot number (Table 3).
Percent increase in shoot length at 4 MAP of 37.67% in the 2 kg ha-1 calcium-fertilized plants
was significantly higher than the control (15.60%) and the 4 kg ha-1treatment (13.63%) (Table
4). The control and 4 kg ha-1 treatments were not significantly different in shoot length at 4
MAP. At 5 MAP, % increase in shoot length of 76.98%, 129.91% and 63.76% in the 0, 2 and 4 kg
ha-1 treatments were not significantly different from one another (Table 4).
Infection and Weight Loss in Tubers Inoculated with Rhizopus stolonifer for 2 weeks
Weight loss of 27.83%, 23.11% and 35.24% in the 0, 2 and 4 kg ha-1 calcium-fertilized tubers
inoculated with R. stolonifer were not significantly different from one another at 5 MAP (Table
5). Infection of 1.94% (control), 1.52 (2 kg ha-1) and 2.31% (4 kg ha-1) at 5 MAP were also not
significantly different from one another (Table 5). However at 6 MAP, infection of 2.25% in the
inoculated control was significantly higher than in the 2 kg ha-1 treatment (0.78%) and the 4 kg
ha-1treatment (0.86%) (Table 5). The latter two treatments were not significantly different
from one another. Also infection in the 2 kg ha-1 and 4 kg ha-1 treatments at 6 MAP were only
51.32% and 37.23% respectively of that at 5 MAP. Weight loss of 3.20%, 11.10% and 1.90% in
the 0, 2 and 4 kg ha_1 treatments at 6MAP were not significantly different from one another.