Genetic Variability in Sweet Corn for Yield and Ear Traits

Genetic Variability for Grain Yield, Flowering and Ear Traits in Early and Late Sown Full – Sib Families of Sweet Corn in Makurdi (Southern Guinea Savanna), Nigeria
Genetic Variability for Grain Yield, Flowering and Ear
Traits in Early and Late Sown Full – Sib Families of Sweet
Corn in Makurdi (Southern Guinea Savanna), Nigeria
G.O.S. Ojo1*, T. Vange2 and M. O. Adeyemo3
1,3Department of Crop Production, Federal University of Agriculture, P. M. B. 2373, Makurdi, Nigeria
2Department of Plant Breeding and Seed Science, Federal University of Agriculture, P. M. B. 2373, Makurdi, Nigeria
Field experiments were carried out to estimate genetic variation in full – sib families of a sweet
corn population during the early and late sowing dates of 2012 at the Federal University of
Agriculture, Makurdi, Nigeria. Experiments were laid out as lattice but analysed using
Randomised Complete Block Design (RCBD) with three replications. Families differed
significantly (P < 0.01) for all the traits (days to anthesis, days to silking, anthesis – silking interval
(ASI), ear traits of ears/plant, cob length, kernel rows/cob and kernels/row on cob and grain yield),
indicating genetic variability for these traits. The Genotypic Coeffient of Variation (GCV),
Phenotypic Coefficient of Variation (PCV) and Genetic Advance (GA) were higher for ASI
compared to days to anthesis and silking, but with similar range for the ear traits. Heritability was
however moderate for ASI and high for days to anthesis and silking. The higher heritability and
GA observed for most of the traits in the late sowing date is an indication that progress in
selection will be faster during this date. Full-sib recurrent selection for grain yield via ear traits
should therefore be used to improve the local sh2 sweet corn population in the Southern Guinea
Savanna of Nigeria.
Keywords: GA, GCV, heritability, PCV, sh2 sweet corn
INTRODUCTION
Maize is a very important and dynamic crop (Entringer et
al., 2016) in the world and the most important staple cereal
in Africa (Ajiboye et al., 2018) that is produced, marketed
and consumed in both the forest and savanna ecologies of
Nigeria. It is the most widely grown cereal in the country,
and has replaced sorghum and millet in the savanna due
to its optimum performance in the ecology and availability
of improved high yielding varieties (Fajemisin, 1984).
Between 1980 and 1990, Nigeria was responsible for
producing over 50% of the total grain output in West and
Central Africa (Badu – Apraku et al., 2012). However, per
capita consumption within the same period was only
16kg/year which was almost the lowest for the region, even
with a net import of 3,000 metric tonnes between 1990 and
1992. Therefore, there is the need for Nigeria to increase
its output and become a net exporter.
Out of the total land area cultivated to maize (corn) in
Nigeria, more than 90% is devoted to the production of
field corn (dent, flint and flour maize) alone. Hence, field
corn is used to not only produce dry grain for flour and
other products, but also to substitute two other types of
corn (pop and sweet corn) as green maize (Ojo and
Odoba, 2016; Abe et al., 2019), in view of their low yield,
poor adaptation and narrow genetic base (Tracy, 2001;
Agele et al., 2008; Olaoye et al., 2009; Teixeira et al.,
2013; Mahato et al., 2018). Therefore, there is the need to
obviate this trend, by intensifying the production of pop and
sweet corn towards releasing the field corn for other uses.
Concerted research effort towards the development of
improved high yielding pop and sweet corn varieties
precedes the release of such varieties to farmers for
*Corresponding Author: G.O.S. Ojo; Department of Crop
Production, Federal University of Agriculture, P. M. B.
2373, Makurdi, Nigeria. Email: gosojo2016@gmail.com
Co-Author 2
Email: tervange@gmail.com
3
Email: mo_adeyemo@yahoo.com
International Journal of Plant Breeding and Crop Science
Vol. 7(1), pp. 661-666, May, 2020. © www.premierpublishers.org, ISSN: 2167-0449
Research Article

Ojo et al. 662
production. Much research effort had been intensified in
the development of improved varieties of popcorn with
dearth of information on sweet corn research in Nigeria.
Previous effort at introducing and breeding of sweet corn
had led to the development of tropically adapted sh2 corn
populations by four cycles of mass selection from broad-
base temperate super-sweet sh2 corn population
(Adetimirin, 2008). These tropically adapted sh2 corn
populations have served as base populations for sweet
corn improvement in Nigeria and have been further
improved by crossing to field corn to generate sh2 super-
sweet corn populations (Abe and Adelegan, 2019; Abe et
al., 2019). Unfortunately, these research efforts are
concentrated in the rain forest ecology where the
environmental conditions are completely different from the
savanna ecology of the country. Hence, there is the need
for the improvement of these populations for the savanna
ecology of Nigeria.
Elsewhere, the current research effort in sweet corn is
concentrated on quality traits. However, the neglect in
sweet corn research in Nigeria necessitates that research
effort should first be focused on quantitative traits towards
the selection of high yielding genotypes prior to addressing
research in qualitative traits.
Full-sib recurrent selection has been extensively used in
preference to other Population improvement in maize in
previous studies (Bänziger et al., 2000; Ajala et al., 2010).
Rainfall amount and distribution during the rainy season
affect the expression of the quantitative traits of grain yield
and yield components, and research results on maize
sown at different dates in both the forest and savanna
ecologies of Nigeria (Kim and Ajala, 1996; Ojo et al., 2007,
Oluwaranti et al., 2008; Ojo and Odoba, 2016) attest to
this.
The current research was therefore initiated to determine
genetic variability for grain yield, flowering and ear traits in
early and late sown full – sib families of sweet corn in
Makurdi (Southern Guinea Savanna), Nigeria.
MATERIALS AND METHODS
Location
The experiment was conducted during the early and late
rain fed cropping seasons of 2012 at the Teaching and
Research Farm of the Federal University of Agriculture
Makurdi, Nigeria. Makurdi is located on latitude 07o 41’N
and longitude 08o 37’E, in the southern Guinea Savanna
agro – ecological zone of Nigeria. Meteorological
information for Makurdi is presented in Table 1 while the
soil physical and chemical characteristics for the
experimental sites are summarized in Table 2. There was
no rain in the months of January, February, March and
December. Soil samples were taken for analysis prior to
planting for each sowing date.
Table 1: Meteorological data of Makurdi in 2012
Month
Number of rainy
days
Total rainfall
(mm)
Average
(0C)
Temperature Average
Humidity
Relative
(%)
Minimum Maximum Minimum Maximum
January - - 18.3 34.6 26 47
February - - 22.7 35.9 38 66
March - - 23.5 38.2 38 71
April 6 143.2 22.8 35.2 53 80
May 11 145.2 21.4 31.9 64 83
June 8 160.6 21.1 30.6 70 85
July 13 351.9 20.6 29.8 73 85
August 13 174.3 20.6 29.4 74 85
September 13 190.7 20.5 30.2 73 84
October 16 199.1 20.4 31.1 68 83
November 1 27.3 20.7 33.4 55 79
December - - 15.5 34.5 30 53
Planting Materials
A local shrunken-2 (sh2) sweet corn population was
obtained from the International Institute for Tropical
Agriculture (IITA), Ibadan, Nigeria to generate full-sib
families in 2011. Paired plants were identified and crossed
(including reciprocal crosses) to generate full-sib (FS)
families in 2011. At harvest, seeds from cobs of each pair
were shelled and bulked to form a particular full-sib family
giving a total of one hundred and eight (108) full – sib
families. The 108 FS families were evaluated during the
early and late planting dates of the 2012 cropping season.
Experimental Layout and Cultural Practices
The experiments were laid out in a lattice with three
replications during the early (16th June) and late (1st
August) plantings of 2012 cropping season, but analysed
using Randomised Complete Design (RCBD) for each
planting date. Three seeds of each of the 108 full – sib
families were sown to designated plots on June 16th (early
planting) and August 1st (late planting), 2012, at an intra –
row spacing of 0.50m on ridges spaced 75cm apart.
Emerged seedlings were later thinned down to two stands
per hill two weeks later.

Int. J. Plant Breed. Crop Sci. 663
Table 2: Physical and chemical properties of the
experimental sites during the early and late cropping
seasons of 2012
Soil characteristics Early 2012 Late 2012
Sand (%) 76.72 73.40
Silt (%) 12.08 14.10
Clay (%) 11.20 12.50
Textural Class Sandy Loam Sandy Loam
PH (H2O) 6.42 6.48
PH (KCl) 5.01 5.66
Organic Matter (%) 1.66 1.54
Organic Carbon (%) 0.96 0.89
Total Nitrogen (%) 0.75 0.09
Available P (mgkg-1) 4.6 3.80
Exchangeable Ca
(cmolkg-1)
3.30 3.99
Exchangeable K
(cmolkg-1)
0.31 0.30
Exchangeable Mg
(cmolkg-1)
1.41 1.81
Exchangeable Na
(cmolkg-1)
0.56 0.87
CEC (cmolkg-1) 5.30 7.60
Base Saturation (%) 85.1 89.4
CEC: Cation Exchange Capacity
Compound fertilizer (NPK 20:10:10) was applied 2 weeks
after planting, and top dressed with urea (46% N) at 5½
weeks after planting to supply 120kg N/ha, 45kg P2O5/ha
and 45kg k2O/ha. Hoe weeding was carried out at 2½
weeks after planting and just before top dressing.
Data Collection and analysis
Data collected in the course of the experiments include
days to anthesis, days to silking, anthesis – silking interval
(ASI), ears/plant, cob length, kernel rows/cob, kernels/row
on cob and grain yield. Two families were deleted from the
entries prior to analysis due to incompleteness of data on
them. Hence, the evaluation was based on 106 families.
Data generated from each of the two experiments (early
and late) were separately subjected to analysis of variance
by the General Linear Model (GLM) and the Analysis of
variance (ANOVA) procedures of SAS (2007).
Components of genetic variation for each experiment were
estimated according to Allard (1960) as presented below:
δ2
g = MS variety – MS error/r
δ2
e = MS error
δ2
ph = δ2
g + δ2
e
Where: MS error = mean squares for error, r = number of
replications, δ2
g = genetic variance, δ2
ph = phenotypic
variance and δ2
e = error variance.
Broad sense heritability (HBS) was calculated as the ratio
of the genetic variance to phenotypic variance using the
formula of Allard (1960)
δ2
g/ δ2
ph x 100
Where HBS = broad sense heritability (%).
PCV (phenotypic coefficient of variation) and GCV
(genotypic coefficient of variation) were calculated from
the formula:
PCV (%) = (phenotypic standard deviation/mean) X
(100/1);
GCV (%) = (genotypic standard deviation/mean) X (100/1)
Genetic advance (GA) as percentage of the mean was
calculated at 10% selection intensity (I=1.76).
RESULTS
Highly significant difference in full sib families was
observed for the flowering traits (days to anthesis, days to
silking and anthesis-silking interval), ear traits (ears/plant,
cob length, kernel rows/cob and kernels/row on cob) and
grain yield, during the early and late planting dates (Table
3). Families were consistent in flowering across the early
and late seasons, with similar range in days to anthesis
and silking. Mean anthesis-silking interval (ASI) was
almost 3 days with a very wide range of 0 to 6 days in both
seasons (Table 4). Genetic variance was higher than error
variance for all the traits in both seasons except for ASI
and kernels/row on cob in the early season. Genotypic and
Phenotypic Coefficients of Variation (GCV and PCV) and
Genetic advance as a percentage of the mean (%) (GA)
were low (< 10%) for days to anthesis and silking, but high
for ASI in both seasons. The GCV and PCV were higher
than 30% for the ASI in both seasons, higher than 50% for
ears/plant and grain yield in the late season and very high
(> 100%) for grain yield in the early season.
Broad sense heritability was high for days to anthesis and
silking and moderate for ASI in both seasons. The trend in
heritability for the ear traits and grain yield differed
between seasons. Heritability was very high for the ear
traits of cob length (99.31%), kernel rows/cob (99.26%),
kernels/row on cob (98.58%) in the late season compared
to the moderate to high heritability (46.27 – 81.05%)
observed for the same traits in the early season. Similarly,
grain yield recorded a higher heritability of 98.32% in the
late season compared to a lower value of 88.38%
observed for the early season.

Ojo et al. 664
Table 3: Mean squares for grain yield and yield components of full-sib families derived from a local sweet corn
population evaluated during the early and late planting dates of 2012 cropping season in Makurdi
Source of
variation
Df Days to
anthesis
Days
to
silking
Anthesis-
silking
interval
Ears/
plant
Cob
length
Kernel
rows
/cob
Kernels/row
on cob
Grain yield
Early
Reps 2 5.14 5.91 2.08 0.15 2.79 1.91 37.33 1531158.00*
Families 105 21.27** 21.15** 6.84** 0.22** 12.99** 4.69** 119.63** 9203612.00**
Error 210 2.84 2.08 2.33 0.05 0.94 0.72 33.39 386568.00
Late
Reps 2 3.23 2.98 1.16 1.28 0.11 0.11 0.06 925.00
Families 105 19.28** 22.12** 4.96** 3.46** 8.64** 4.07** 75.23** 57076.00**
Error 210 3.11 3.04 1.09 0.81 0.02 0.01 0.36 323.50
*= significant at P<0.05; **= significant at P<0.01
Table 4: Means, range, variance components, coefficients of variation, heritability and genetic advance for grain
yield and yield components of full-sib families derived from a local sweet corn population evaluated during the
early and late planting dates of 2012 cropping season in Makurdi
Traits Mean Range δ2
g δ2
e δ2
ph GCV
(%)
PCV
(%)
HBS
(%)
GA
(%)
Early
Days to anthesis 59.16±1.38 53.00 – 65.50 6.14 2.84 8.98 4.19 5.07 68.37 6.10
Days to silking 62.12±1.18 54.50 – 67.00 6.36 2.08 8.44 4.06 4.68 75.36 6.20
Anthesis-silking
interval
2.93±1.25 0.00 – 6.83 1.50 2.33 3.83 41.80 66.79 39.16 46.03
Ears/plant 1.37±0.19 1.00 – 2.50 0.06 0.05 0.11 17.88 24.21 54.55 23.24
Cob length 14.06±0.87 7.81 – 23.61 4.02 0.94 4.96 14.26 15.84 81.05 22.60
Kernel rows/cob 12.05±0.69 8.67 – 15.00 1.32 0.72 2.04 9.53 11.85 64.71 13.50
Kernels/row on cob 30.65±4.72 11.00 – 48.10 28.75 33.39 62.14 17.49 25.72 46.27 20.94
Grain yield 1413±507.70 147 – 4021 2.94x106 3.87x105 3.33x106 121.33 129.06 88.38 188.72
Late
Days to anthesis 58.51±0.91 54.11 – 64.56 5.39 3.11 8.43 3.97 4.96 63.94 5.58
Days to Silking 61.01±1.11 54.91 – 65.98 6.36 3.04 9.40 4.13 5.03 67.66 5.98
Anthesis-silking
interval
2.91±1.10 0.00 – 6.12 1.29 1.09 2.38 39.03 53.01 54.20 50.57
Ears/plant 1.36±0.17 1.00 – 2.50 0.88 0.81 1.69 68.98 95.59 52.07 87.60
Cob length 11.69±0.05 7.89 – 17.47 2.87 0.02 2.89 14.49 14.54 99.31 25.42
Kernel rows/cob 11.43±0.09 7.00 – 14.00 1.35 0.01 1.36 10.17 10.20 99.26 17.82
Kernels/row on cob 30.33±0.49 14.00 – 42.00 24.96 0.36 25.32 16.47 16.59 98.58 28.78
Grain yield 245.80±14.69 151.30 –
589.30
1.89x104 323.50 1.92x104 55.96 56.43 98.32 97.65
DISCUSSION
Genotypes were generally earlier in the late season
compared the early season. This observation is in
agreement with the previous findings of Oluwaranti et al.
(2015) who observed that genotypes were earlier in the
late season compared to the early season for the rain
forest ecology of Nigeria. The minimal variation of only one
day observed for days to anthesis and silking between the
early and late season in the current work could be
attributed to consistent diurnal and nocturnal temperatures
during the growing stage of the crop. The inconsistency in
the days to flowering (tasselling, anthesis and silking)
between seasons observed in the previous studies
(Oluwaranti et al., 2015) was attributed to a positive
correlation between these traits and temperature. The
consistent values of the components of genetic variation
and the high heritability observed for the flowering traits of
days to anthesis and silking in the current work, is an
indication that these flowering traits are least affected by
the environment and could be selected for, at any time of
the year. Mean values for flowering (days to anthesis,
silking and ASI) and ear (cob length and number kernel
rows/cob) traits in the current study are very close to
previously observed values in the evaluation of a sweet
corn derived populations (Abe et al., 2019). However, the
very wide range in the values of these flowering and ear
traits observed in the current study compared to the
previous (Abe et al., 2019), is a favourable development
and makes the current full-sib families amenable to
selection for these traits.

Int. J. Plant Breed. Crop Sci. 665
The high GCV estimate that resulted in high PCV and GA
observed for the anthesis – silking interval and grain yield
in the current study had been previously observed (Urrea
– Gomez et al., 1996) in maize evaluated on acid soils and
attributed to spatial variability. The very high coefficients of
variation observed in the early season could be attributed
to the wide range in the grain yield. For example, the
highest grain yield of 4021kg/ha recorded for the best
family, is 27 times the value of 147.00kg/ha recorded for
the poorest family during the early season. The grain yield
of 589.00kg observed for the best family in the late season
was only 3.89 times the value of 151.30kg/ha recorded for
the poorest family in the same season.
The higher grain yield of 1413.00 kg/ha observed for the
early season compared to the very poor yield of 245.80
kg/ha recorded for the late season, despite similar range
in the flowering and ear traits in both seasons, could be
attributed to the uneven distribution of rainfall during the
late season. Rainfall distribution in the month of October
was uneven, while it rained only once in November. This
led to the dearth of moisture required for dry matter
accumulation for the grains and drastically reduced grain
yield in the late season. The implication of this result is that
only extra early maturing genotypes of sweet corn that
would be physiologically mature before the middle of
October should be planted late (late July – first week of
August). Also, medium to late maturing genotypes should
be planted between late June and early July to allow for
the harvest of properly filled dried seeds/grains.
The implication of the higher heritability observed for ear
traits and grain yield in the late compared to the early
season, is that a faster progress in selection for the
improvement of ear traits and grain yield would be better
achieved when sweet corn is planted late compared to
early planting.
CONCLUSION
The current study has established that there is sufficient
and reliable variability for flowering (days to anthesis and
silking) and ear traits given the values of GCV, heritability
and GA for these traits in the full-sib families. Full-sib
recurrent selection for different maturity groups and grain
yield via the yield components of cob length, kernel
rows/cob and kernels/row on cob should therefore be used
to improve the local sh2 sweet corn population in the
Southern Guinea Savanna of Nigeria.
REFERENCES
Abe A and Adelegan CA (2019). Genetic variability,
heritability and genetic advance in shrunken-2 super-
sweet corn (Zea mays L. saccharata) populations. J.
Plant Breed. Crop Sci. 11(4): 100-105
Abe A, Lasisi OA and Akinrinbola OJ (2019). Field
performance of shrunken-2 super-sweet corn
populations derived from tropical field maize ×
shrunken-2 super-sweet corn crosses in Ibadan,
Nigeria. J. Plant Breed. Crop Sci. 11(5): 158 – 163.
Adetimirin VO (2008). Stand establishment and early field
vigour variation in a tropicalised shrunken-2 maize
population. Field Crops Res. 108:143-149.
Agele SO, Ayanwole JA and Olakojo SA (2008).
Evaluation of some newly developed popcorn varieties
for tolerance to diseases and pest and popping quality
in south-western Nigerian Agro-Ecologies. Adv. Envi.
Biol. 2(3): 89-95.
Ajala SO, Kling JG, Menkir A, Alabi SO, (2010). Full-Sib
Vs S1 Selection Scheme for the Improvement of a
Maize Population for Tolerance to Low Soil Nitrogen
Maydica 55: 239-248.
Ajiboye TO, Paul I, Anjorin B, Aladele SE, Olosunde AA,
Odutem S, (2018). Deduction of Striga-Sand Ratio in
Resistance Screening of Cereal. Nigerian J. Gen. 32:
107 – 113.
Allard RW. Principles of Plant Breeding. 1st Edition. John
Willey and sons Inc., New York. 1960; 485Pp
Badu-Apraku B, Menkir A, Fakorede MAB, Ajala S, and
Ellis-Jones J, (2012). Building partnerships and
encouraging innovation for sustainable maize
production: the West and Central Africa Collaborative
Maize Research Network, achievements and impact.
IITA, Ibadan, Nigeria. 82 pp.
Bänziger M, Edmeades GO, Beck D, Bellon M, (2000)
Breeding for drought and nitrogen stress tolerance in
maize: From theory to practice, Mexico, D.F. CIMMYT
68p.
Entringer GC, Vettorazzi JCF, Santos EA, Pereira MG and
Viana AP, (2016). Genetic gain estimates and selection
of S1 progenies based on selection indices and REML/
BLUP in super sweet corn. Australian J. of Crop Sci.
10(3):411-417
Fajemisin JM (2014). The Revolutionary Trend of Maize in
Nigeria: My Memoirs. 1st Edition. Phaloray Book
Works, Nigeria. 176 Pp.
Kim SK and Ajala SO, (1996). Combining ability of tropical
maize germplasm in West Africa II. Tropical Vs
Temperate X Tropical origins. Maydica 41:135 – 141.
Mahato A, Shahi JP, Singh PK, Kumar M, (2018). Genetic
diversity of sweet corn inbreds using agro-
morphological traits and microsatellite markers. 3
Biotech 8:332
Ojo GOS, Adedzwa DK, and Bello LL, (2007). Combining
Ability Estimates and Heterosis for Grain Yield and
Yield Components in Maize (Zea mays L.). J. Sust.
Dev. Agric. & Envi. 3:49-57
Ojo GOS and Odoba A, (2016). Genetic variation and
relationship among grain yield and yield component
traits for simultaneous selection in dry and green maize.
Inter. J. Sci. 5 (7): 66 – 73.
Olaoye G, Bello OB, Ajani AK and Ademuwagun TK,
(2009). Breeding for improved organoleptic and
nutritionally acceptable green maize varieties by

Ojo et al. 666
crossing sweet corn (Zea mays saccharata): Changes
in quantitative and qualitative characteristics in F1
hybrids and F2 populations. J. Plant Breed. Crop Sci.
1(9): 298-305.
Oluwaranti A, Fakorede MAB, and Badu-Apraku B, (2008).
Grain Yield of Maize Varieties of different Maturity
Groups under Marginal Rainfall Conditions. J. Agric.
Sci. 53(3): 183 – 191.
Oluwaranti A, Fakorede MAB, Menkir A, and Badu-Apraku
B, (2015). Climatic conditions requirements of maize
germplasm for flowering in the rainforest Agro-ecology
of Nigeria. J. Plant Breed. Crop Sci. 7(6): 170 - 176
Teixeira FF, Miranda RA, Paes MCD, Souza SM, Gama
EEG (2013). Melhoramento do milho doce. Sete
Lagoas: Embrapa Milho e Sorgo. 32 p
Tracy WF (2001). Sweet corn. Speciality corns. Hallauer,
A.R. Ed. 2nd ed. CRC Press, Boca Raton, Florida. pp.
155-197.
Urrea-Gomez R, Ceballos H, Pandey S, Bahia-Filho AFC,
Leon LA, (1996). A greenhouse screening technique for
acid soil tolerance in maize. Agron. J. 88: 806 – 812.
Accepted 20 May 2020
Citation: Ojo GOS, Vange T, Adeyemo MO (2020).
Genetic Variability for Grain Yield, Flowering and Ear
Traits in Early and Late Sown Full – Sib Families of Sweet
Corn in Makurdi (Southern Guinea Savanna), Nigeria.
International Journal of Plant Breeding and Crop Science,
7(1): 661-666.
Copyright: © 2020: Ojo et al. This is an open-access
article distributed under the terms of the Creative
Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium,
provided the original author and source are cited.

Genetic Variability in Sweet Corn for Yield and Ear Traits

Recommended

Recommended

More Related Content

What's hot

What's hot (19)

Similar to Genetic Variability in Sweet Corn for Yield and Ear Traits

Similar to Genetic Variability in Sweet Corn for Yield and Ear Traits (20)

More from Premier Publishers

More from Premier Publishers (20)

Recently uploaded

Recently uploaded (20)

Genetic Variability in Sweet Corn for Yield and Ear Traits