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Otusanya, M. O. (2022). Tuber Minerals and Phenolic Compounds in Calcium Nitrate Foliar-Sprayed Dioscorea Alata Var. Agbodo and D. rotundata

Var. Amula. European Journal of Applied Sciences, 10(1). 176-184.

URL: http://dx.doi.org/10.14738/aivp.101.11606

Mg in white Yam Amula was overall mean of 20.19mg/100gdm, similar across

treatments. A numerical comparison may be made of the two species (two varieties)

because statistical analysis was carried out separately in the two experimental

plots. Thus numerically (not statistically) overall means were higher in Agbodo in

yield (TNPP and TWPP), TPC, Ca, Mg, N, P and K, than Amula. Amula was numerically

higher in Sulphur only than Agbodo. Phenolic compounds reports of association

with defence mechanisms in crop plants because they exhibit anti-fungal, anti- bacterial and anti-viral properties is discussed. Phenolic compounds reports of

exhibition of antioxidant or free radical scavenging properties that boost immunity

against diseases caused by free radical reactions such as cancer, diabetes, aging and

cardio vascular diseases, as well as analgesic and anti-inflammatory properties is

also discussed. This is to draw attention to inputs during Crop Protection Research

such as this study which will effect synthesis of, or increase phenolic compounds in

the edible food yams for disease resistance as well as for health benefits. Increase

in calcium in this study would enhance disease resistance due to calcium role in the

enhancement of the integrity of intracellular cementing materials. Magnesium and

phosphorus requirement in yams is reported to be low, thus the increase in this

study will ensure yams receive the optimum of the two elements. Lastly, Nitrogen

and Potassium increase is to be emphasized for recommendation of 5mgl-1 and

10mgl-1 calcium nitrate foliar spray in Dioscorea species as the two are the most

important for optimum yield in yams.

INTRODUCTION

Calcium Nitrate Foliar Spray for control of Anthracnose disease in two improved and one local

variety of Dioscorea species was reported, with five concentrations between 0mgl-1 and

12000mgl-1 (Otusanya et al., 2017). Yield obtained in the first year was similar across

treatments. Yield in the second year however, was significantly higher than the control, after a

change in rate and time of the foliar spray. In a second study, relatively lower concentrations of

5 and 10 milligram per litre of calcium nitrate foliar spray without surfactant were evaluated

for anthracnose control in two Nigerian local varieties of Dioscorea alata and D. rotundata

namely Agbodo and Amula respectively. The results of Yield, Tuber Total Phenolic Compounds

and six tuber minerals (Calcium, Magnesium, Nitrogen, Phosphorus, Potassium and Sulphur) in

the study are presented in this paper.

MATERIALS AND METHOD

Planting Material

Tubers of Dioscorea alata variety Agbodo and D. rotundata variety Amula were sourced from

the Osiele Yam market in Abeokuta, Ogun State, Nigeria. Agbodo is a Yoruba (South West

Nigeria) local name and the variety is widely grown in the South West region of Nigeria. Amula

is widely grown in Benue State in the middle belt region of Nigeria (Shiriki et al., 2015). But

Amula has also been adopted in South West Nigeria and other parts of the country as farmers

refer to it as a good yielding variety.

Field Experiment

Two experiments were carried out in two separate plots in COLPLANT (College of Plant Science

and Crop Production Fatms), Federal University of Agriculture, Abeokuta FUNAAB, Ogun State,

Nigeria. Each was RCBD (Randomized Complete Block) with three replications. Mounds in each

replicate were 1metre (m) by 1m, and about 80cm high, with inter-replicate, inter-row, and

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

Services for Science and Education – United Kingdom

intra-row spacing of 1m, 1m and 0.5m respectively. A clean border of 1m space was maintained

on each of the four sides of each plot. Each replicate had eighteen mounds. The two experiments

were of calcium nitrate foliar spray at the rates 0mgl-1 (control) 5mgl-1 and 10mgl-1 applied

without surfactant at 12WAP (Weeks after planting), to evaluate calcium nitrate effect on

anthracnose incidence and severity, and the results have been presented elsewhere.

However tubers from the plots were analysed for effect of the spray solution on tuber quality

in terms of mineral content and total phenolic compounds. The tuber analysis results as well as

tuber yield at 24 WAP are presented in this paper.

Tuber Sampling and Processing for Analysis at 24 WAP

Tuber sampling was along the diagonal transect of each plot replicate. Wooden spoons were

used to move soil away from tubers within the mound and the shoots attached cut away with a

sharp stainless steel knife. Mounds were then closed up with soil for the final harvest the

following day. Tubers were removed in triplicate per treatment per replicate. Sampled plants

were tagged so as to have a correct record of total number of tubers produced by the plant and

tuber weight per plant in the final harvest. The tubers were cleared of soil, washed in tap water

and left to dry on top of laboratory benches under low-speed ceiling fans. After drying, they

were sliced into thin chips with stainless steel knives and left to dry in labelled plastic trays on

the bench tops for about four days. They were milled after drying with a Hammer and Bull Mill.

The milled samples were transferred to the Biological Tetfund Laboratory in FUNAAB and the

Biotechnology centre in FUNAAB for tissue analysis. Total phenolic compounds and mineral

analysis of Calcium (Ca) Magnesium (Mg) Nitrogen (N) Phosphorus (P) Potassium (K) and

Sulphur (S) in the samples was according to standard methods of the A.O.A.C (1990/2000).

Havest at 24 WAP

The final harvest was done one day after the tuber sampling for analysis. Dislodging tubers from

within the mounds was in the same way as for the tubers harvested for analysis, to avoid

bruising or wounding. Total number of tubers per plant was recorded as well as weight of

tubers per plant using a field top loading mettler balance (field scale).

Statistical Analysis

Data obtained were analysed with SAS 2000 version 9.1.1 and means separated with Tukey’s

Honest Studentized Range (HSD) test.

RESULTS AND DISCUSSION

Dioscorea alata variety Agbodo and D. rotundata variety Amula were sprayed in two separate

experimental plots in COLPLANT (College of Plant Science & Crop Production, Federal

University of Agriculture, Abeokuta, Nigeria) FARMS with Calcium Nitrate rates 0mgl-1

(control) 5mgl-1 and 10mgl-1 for the management of Anthracnose disease. Tubers were sampled

in the two plots at 24 WAP, to assess the effect of the spray solution on tuber minerals and tuber

total phenolic compounds. In the first report of Calcium nitrate foliar spray to control

Anthracnose in two improved varieties and one local variety of Dioscorea species in Nigeria,

there were four differences in methodology namely variety as well as rate and time of spray

solution application and addition of surfactant (Otusanya et al., 2017). In the cited report, rate

and time of calcium nitrate foliar spray were 0mgl-1 to 12000mgl-1 (5 treatments) at emergence

and thereafter bi-weekly until 12 weeks after planting (12 WAP) in the first year. And 0mgl-1to