Forage potentials of interspecific hybrids between elephant grass selections and cultivated pearl millet genotypes of Nigerian origin

Abstract

This study was conducted to highlight the forage potentials of related Pennisetumspecies through interspecific hybridization. Non-reciprocal crosses were made involving two selections of elephant grass (Pennisetum purpureum Schumach) (♂), S.13 and S.15, and five cultivated pearl millet (Pennisetum glaucum (L.) R. Br.) (♀) genotypes in Nigeria viz., Dauro, Gero A, Maiwa 25-2, Maiwa 28-1 and Maiwa 94-2, in September 2009. In May 2010, germination test and preliminary screening for successful crosses were conducted. Successful hybrids with Dauro and Maiwa genotypes were transplanted to the field at 90 × 90 cm spacing for forage evaluation from June to December 2010. Three harvests, at six-weekly interval, were obtained from the plants cut at 30 cm above ground level. ANOVA showed significant differences (p = 0.05) between harvest intervals, plant height (cm) and dry matter content (%) of the hybrids, except dry matter yields (g/m2). Dry matter content of the hybrids negatively correlated with plant height (r = -0.434). Dry matter yield had significant positive correlation with plant height (r = 0.780). Maiwa 94-2 x S.13 and Maiwa 28-1 x S.13 were not significantly different (p = 0.05) as they out-yielded other hybrids in dry matter yields and were associated with satisfactory forage potentials.

Full text

Journal of Plant Breeding and Crop Science Vol. 4(9), pp. 136-143, June 2012
Available online at http://www.academicjournals.org/JPBCS
DOI: 10.5897/JPBCS12.019
ISSN 2006-9758 ©2012 Academic Journals
Full Length Research Paper
Forage potentials of interspecific hybrids between
elephant grass selections and cultivated pearl millet
genotypes of Nigerian origin
Ekemini E. Obok1*, Micheal E. Aken’Ova2 and Godfrey A. Iwo1
1Department of Crop Science, Faculty of Agriculture, Forestry and Wildlife Resources Management,
University of Calabar, Calabar, Cross Rivers State, Nigeria.
2Department of Agronomy, Faculty of Agriculture and Forestry, University of Ibadan, Ibadan, Oyo State, Nigeria.
Accepted 4 May, 2012
This study was conducted to highlight the forage potentials of related Pennisetum species through
interspecific hybridization. Non-reciprocal crosses were made involving two selections of elephant
grass (Pennisetum purpureum Schumach) (♂), S.13 and S.15, and five cultivated pearl millet
(Pennisetum glaucum (L.) R. Br.) (♀) genotypes in Nigeria viz., Dauro, Gero A, Maiwa 25-2, Maiwa 28-1
and Maiwa 94-2, in September 2009. In May 2010, germination test and preliminary screening for
successful crosses were conducted. Successful hybrids with Dauro and Maiwa genotypes were
transplanted to the field at 90 × 90 cm spacing for forage evaluation from June to December 2010. Three
harvests, at six-weekly interval, were obtained from the plants cut at 30 cm above ground level. ANOVA
showed significant differences (p = 0.05) between harvest intervals, plant height (cm) and dry matter
content (%) of the hybrids, except dry matter yields (g/m2). Dry matter content of the hybrids negatively
correlated with plant height (r = -0.434). Dry matter yield had significant positive correlation with plant
height (r = 0.780). Maiwa 94-2 x S.13 and Maiwa 28-1 x S.13 were not significantly different (p = 0.05) as
they out-yielded other hybrids in dry matter yields and were associated with satisfactory forage
potentials.
Key words: Breeding genetics, dry matter yields, dry matter content, harvest intervals, Pennisetum purpureum,
Pennisetum glaucum, plant height.
INTRODUCTION
There are about 140 species of the genus Pennisetum L.
(Rich) in the family Poaceae (Haroun, 2010). Comprising
such important species are elephant grass (Pennisetum
purpureum Schumach) and pearl millet (Pennisetum
glaucum (L.) R. Br.) (Brunken, 1977; Kativu and Mithen,
1987; Kellogg, 2000). Pearl millet, a diploid (2n = 14)
dual-purpose annual species of this genus, is used for
food (grain) by humans and as feed (forage or fodder) for
livestock. The association of pearl millet with high quality
forage earns it greater palatability and acceptability by
livestock. Elephant grass, on the other hand, is a tetra
*Corresponding author. E-mail: ekeminiobok@gmail.com. Tel:
+234-806-365-6516.
-ploid (2n = 28) and a perennial tropical grass species
primarily used as forage or fodder owing to its high forage
yields. Elephant grass has been highlighted as one of the
most important tropical forages for dairy grazing system
improvement in the tropics (Pereira, 1994). Its productive
potential, associated with other desirable forage traits,
such as vigour, persistence, carrying capacity and
nutritional quality have stimulated the cultivation and the
genetic improvement of the species (Souza et al., 2005).
In Africa, the cut-and-carry ruminant livestock feeding
system involving P. purpureum has been widely adopted
by small-holder farmers for feeding dairy cattle (Valk,
1990). Elephant grass was originally introduced to
commercial farming systems early in the 20th century as
mulch for coffee, but has subsequently been widely
adopted as cattle fodder in small-holder farming systems

(Boonman, 1993). Predominantly, elephant grass is
vegetatively propagated. It is perennial, can withstand
repeated cutting and rapidly regenerates producing
forage which is palatable to cattle at the leafy stage.
However, as the plant grows, the dry matter production
increases with decreasing nutritional value (Maria et al.,
2010). According to Patel et al. (1967) and Lavezzo
(1985), these occur when elephant grass is harvested
after 50 to 60 days of re-growth.
It has also been reported that elephant grass is useful
for phyto-remediation of petroleum-hydrocarbon-
contaminated agricultural soils (Ayotamuno et al., 2006).
However, apart from these two species of Pennisetum
with excellent forage qualities, there are other species
which have also been identified to have medicinal values
viz., Pennisetum setaceous, Pennisetum villoseum and
Pennisetum divisum (Sujatha et al., 1989). In crop
breeding programmes, genetic resources have been
highlighted as the needed basic materials. On improving
allogamous crop species via hybridization, the
importance in the exploitation of wide crosses can no
longer be overemphasized as it is expected that the
existing genetic compatibilities between the genera or
species of interest will likely result in heterosis (that is,
hybrid vigour) in the hybrids. When genomes of different
species combine, either as interspecific or intergeneric
hybrids, they present various stages of intergenomic
conflicts. The theoretical basis of these genomic conflicts
in the hybrids anticipates antagonisms in nucleo-
cytoplasmic incompatibilities and compromises
chromosome pairing at meiosis (Jones and
Pasakinskiene, 2005). Successful crosses involving
different species with different ploidy lead to hybrid
vigour. This genetic gain also confers useful
morphological characteristics, agronomic attributes and
chemical composition to the resulting interspecific hybrids
in spite of the anticipated genetic bottlenecks (Ortiz,
2004).
Interspecific hybridization of elephant grass with pearl
millet represents one approach to the genetic
improvement of elephant grass with the aim of producing
perennial sterile hybrids, with high forage yields,
improved palatability and high nutritional value, which can
be vegetatively propagated. The success in the use of
pearl millet in interspecific hybridization with elephant
grass is greatly influenced by the level of genetic
compatibility (Techio et al., 2002). Elephant grass (2n =
28) with A'A'BB genome and pearl millet (2n = 14) with
AA genome are closely related species of Pennisetum
presenting good genetic combining ability, producing low
fertility or sterile interspecific hybrids that are of great
forage interest because they are better accepted by
livestock than elephant grass itself (Jauhar, 1981; Shank
and Chynoweth, 1993; Diz, 1994). Normally, the resulting
hybrid (2n = 21) with AA'B genome usually has greater
similarity to the elephant grass type due to the larger
genetic contribution (66.7% chromosomes) and
dominance of the elephant grass B genome over the
Obok et al. 137
pearl millet A genome (Gonzalez and Hanna, 1984).
The need for the genetic improvement of forage
grasses to sustain the extensive and cut-and-carry
systems of ruminant livestock production in Nigeria is a
continuous quest. To increase livestock production in
Nigeria, forage availability and the use of highly
productive good quality pasture grasses are important
nutritional factors that have been identified to increase
productivity (Agishi, 1971; de Leeuw and Agishi, 1978). In
Nigeria, there are three types of cultivated pearl millets
viz., Gero which is an early-maturing genotype, Dauro
which is a late-maturing genotype and Maiwa, the late-
maturing short-day photoperiod-sensitive genotype
(Aken’Ova et al., 1982). Research into both indigenous
and exotic forage species has been going on in Nigeria,
particularly in the savannah zones, since the 1950s.
Studies at Ibadan, the derived savannah of the low-
altitude humid tropics of Nigeria, showed that hybrids that
had Maiwa outperformed hybrids which had Tifton, an
early maturing pearl millet variety from Georgia, United
States (Chheda et al., 1973; Aken’Ova et al., 1982). The
study revealed that the pearl millet genotypes used as
parents in crosses with elephant grass were likely to
influence the performance, in terms of forage potentials,
of the resulting interspecific hybrids. Until now, no study
has been conducted involving other widely grown pearl
millet genotypes of Nigerian origin such as Dauro and
Gero.
This type of genetic combination tries to gather in the
hybrid, some of the desirable characteristics of pearl
millet such as vigour, drought resistance, disease
tolerance, forage quality and seeds size, whereas
rusticity, aggressiveness, perennity, palatability and high
dry matter yield are provided by napier grass (that is,
elephant grass) (Schank et al., 1996; Jauhar and Hanna,
1998; Souza et al., 2005).
However, there is much variability for maximising
forage yields among elephant grass clones used as male
parents (Hanna and Monson, 1980). Consequently, the
aims of this study were to assess the combining ability of
the representative pearl millet parents of Nigeria origin,
Dauro, Gero and Maiwa with the two local high forage
yielding selections of elephant grass, S.13 and S.15, and
highlight satisfactory forage potentials among the
successful interspecific hybrids which can be adapted to
contribute to livestock production in Nigeria.
MATERIALS AND METHODS
Production of hybrid seeds
On 1st June 2009, two rows each of five pearl millet genotypes of
Nigerian origin, Gero A, Dauro, Maiwa 28-1, Maiwa 25-2 and Maiwa
94-2, were sown at 90 × 90 cm spacing on a separate plot
measuring 8.1 × 3.6 m to ensure coincidence of flowering between
the pearl millet types and the two elephant grass selections, S.13
and S.15, which are maintained in the Department of Agronomy
crop garden, University of Ibadan, Nigeria. Non-reciprocal diallel
crosses (Griffing, 1956) were made for the production of inter-

138 J. Plant Breed. Crop Sci.
Table 1. Chemical and physical characteristics of the
experimental site soil.
Soil characteristic*
Value
pH (H2O)
6.6
Organic carbon (g/kg)
14.9
Total nitrogen (g/kg)
0.75
Available phosphorus (mg/kg)
41.2
Trace elements
Iron (mg/kg)
14.8
Copper (mg/kg)
2.58
Manganese (mg/kg)
129.00
Zinc (mg/kg)
14.08
Exchangeable bases
Potassium (cmol(+)/kg)
0.59
Calcium (cmol(+)/kg)
3.53
Magnesium (cmol(+)/kg)
5.36
Sodium (cmol(+)/kg)
0.37
Particle size
Clay (g/kg)
48
Silt (g/kg)
98
Sand (g/kg)
858
Textural class (USDA†)
Loamy sand
*Depth = 15 cm. †USDA = United States Department of
Agriculture.
specific hybrid seeds. In the month of September when flowering
had occurred in the pearl millet, the panicles were protected with
shoot bags to prevent pollination from adjourning plots. The
elephant grass panicles were also bagged at the onset of anther
emergence with shoot bags with the open end clipped for pollen
collection. The collected pollen from the bagged elephant grass
selections were dusted on previously protected pearl millet panicles
with fully emerged stigmas just before anther emergence. This took
place between 9 and 11 am daily, a time when pollen viability is
high (Rai, 1997). The pollinated pearl millet plants were re-bagged
and the open end of the bags clipped. On the outside, the bags
were appropriately marked according to the parent plants crossed
and the date of pollination. Harvesting of the panicles followed four
weeks later and they were threshed manually to extract the seeds.
The seeds were then cleaned of glumes in a tray (sieve) and
transferred to seed packets that were appropriately labelled.
Germination test and preliminary screening
Germination tests of all the seeds obtained from the crosses were
conducted on 26th May 2010. This was carried out in the Plant
Breeding Laboratory of the Department of Agronomy, University of
Ibadan, Ibadan, Nigeria, for seven days. Fifty seeds per cross were
placed on a moist filter paper laid inside Petri dishes. Proper
germination was indicated by full radicle and plumule extensions.
Two millilitres of distilled water was applied daily to maintain moist
condition within the Petri dishes. Observations of seedlings with
purple coleoptiles from each of the crosses were made. The purple
colour served as a marker for the identification of hybrid seedlings,
as distinct from seedlings with light green plumules as a result of
possible selfing that occurred on the pearl millet panicles. The
identified purple seedlings were subsequently moved into seed
boxes in the nursery on the eighth day.
Preliminary screening was conducted in the screenhouse of the
Department of Agronomy, University of Ibadan, Ibadan, Nigeria.
Wooden boxes with inside measurements of 50 × 40 × 15 cm with
perforations at the base were filled with sieved topsoil and placed
on a supporting metal stand at 100 cm above ground level for
proper aeration and drainage. The soil in the boxes was manually
irrigated till saturation before the seedlings were places at 10 × 5
cm distance. Wetting of the soil was carried out twice daily, in the
morning and evening, using 2000 ml of water. This lasted for 21
days. The observed vigorous seedlings were earmarked for
transplanting.
Field evaluation and data collection
The experimental site was the Teaching and Research Farm of the
Department of Agronomy, University of Ibadan, Ibadan, Nigeria
(7°27’N; 3°54’E) at 218 m above sea level. Soil samples at 15 cm
depth were taken with soil auger for analysis (Ryan et al., 2001).
The field was manually cleared and lightly tilled. Vigorous seedlings
from all the crosses were then transplanted to the field at a spacing
of 90 × 90 cm on 25th June 2010. At four weeks after transplanting,
compound fertilizer (NPK 15:15:15) was applied to supply 50, 21.8
and 41.5 kg/ha, of N, P and K respectively. The first harvest was
taken at 12 weeks after transplanting (17th September, 2010). The
plants were cut manually with machetes. Six weeks later, the
second harvest was taken on 29th October, 2010. This was followed
by the third harvest on 10th December, 2010, following another six
weeks interval. After the first and second harvests, fertilizer (NPK
15:15:15) was applied three days after at the rate of 100, 43.6, and
82.9 kg/ha N, P, K and 50, 21.8, and 41.5 kg/ha, N, P, K
respectively. At each harvest, the plant height was measured and
the plants cut at 30 cm above ground to achieve good quick
regrowth (Andrews and Kumar, 1992; Tudsri et al., 2002; Teutsch,
2009). The experimental plot was manually weeded by slashing
within and between rows before each fertilizer application. Six
representative plant samples from each cross were bulked from the
second harvest and oven-dried at 80°C, for three to five days, to
constant weight to determine the dry matter content according to
Association of Official Analytical Chemists (AOAC) (1990) methods.
The plants were not sampled at first harvest because there were
not yet established, that is, acclimatized on the field following
transplanting. This is allowed to ensure uniformity of growth of the
pasture. The mortality rate (%) were determined on the field as the
number of surviving plants (stands) at each harvest divided by the
total number of plants at previous harvest × 100. Dry matter content
(%) and dry matter yield (g/m2) were also determined. Harvested
plants were dried at 80°C for three to four days to determine dry
matter weight. Dry matter yield was the product of dry matter weight
of each harvested plant with plant density. Percentage dry matter
was calculated as dry matter weight divided by fresh matter weight
× 100.
Soil analysis
The physical and chemical properties of the experimental soil prior
to planting as presented in Table 1 show that the soil was slightly
acidic. The soil was characterized by low nitrogen, relatively high
level of organic matter and high level of available phosphorus.
However, high level of available phosphorus is often attributed to
slightly acidic soils and this also has implication for phosphorus
release. Phosphorus as well as nitrogen has a strong influence on

Obok et al. 139
Table 2. Climatological variables of the study area.
Month
Rainfall (mm)
Avg. temp. (°C)
Avg. RH (%)
Evapotranspiration (MJ/m2/day)
May
0.226
26.8
85.4
9.232
June
0.120
26.1
87.1
8.221
July
0.103
24.6
88.7
7.328
August
0.077
19.7
72.2
5.280
September
0.027
24.9
88.8
9.104
October
Traces
23.7
88.5
9.347
November
Traces
14.3
90.0
7.823
December
Scarce
26.7
73.5
12.817
Source: Department of Geography, University of Ibadan, Ibadan.
the growth and yield of forage grasses (Rao et al., 1999). However,
moisture availability often affects the dry matter yield of forage
grass more than fertilization (Volesky and Berger, 2010). The
exchangeable bases ranged from 0.37 to 5.36 cmol/kg. These low
values could partly be attributed to soil erosion and nutrient
leaching from the topsoil, which is a characteristic feature of the
humid lowland tropics soil. The soil texture was loamy sand.
Climatological conditions
Table 2 shows the prevailing weather conditions of the
experimental site. Rainfall peaked in May (0.226 mm) and it
scarcely rained in the month of December though there were traces
of rainfall in October and November. The mean temperature ranged
from 14.3 (November) to 26.8°C (May). Overall, the highest relative
humidity (90.0%) was also observed in November with the least
mean daily temperature. However, evapotranspiration (solar
radiation) ranged from 12.817 (December) to 5.280 MJ/m2/day
(August).
Statistics analyses
Analysis of variance (ANOVA) was carried out in a randomized
complete block design (RCBD) using GenStat Discovery Edition 4
software package. Each of the harvest intervals was considered as
a source of variation and taken as a block (replicate). Post-ANOVA
statistical analysis was conducted using least significant difference
(LSD) (p = 0.05) to declare significant differences among the
harvest intervals. Duncan’s multiple range test (DMRT) (p = 0.05)
was, however, used to determine significant differences among the
genotypes since there were more than five treatment means
(Gomez and Gomez, 1984). Pearson’s bivariate correlation
coefficients (p = 0.05) between plant height, dry matter content and
dry matter yield were also calculated using Predictive Analytics
Software (PASW) version 18.
RESULTS AND DISCUSSION
At first and second harvests, mortality (%) and dry matter
content (%) were not significantly different (p = 0.05)
though these observations increased over each harvest.
The second harvest was characterized by an increase in
dry matter yield (Table 3). This boost in forage yield was
partly attributed to an increase in the fertilizer rate to
100 kg/ha of N (that is, double the initial dose of 50 kg/ha
of N) after first harvest and the availability of moderately
low soil moisture, high relative humidity and solar
radiation evidenced in late September to early November,
2010 (Table 2). This result highlighted the need for
adequate fertilization alongside moderate moisture avai-
lability for high forage yields in the tropics. Observations
made on plant height (cm), and dry matter yield (g/m2) at
third harvest were not significantly different (p = 0.05)
from the first harvest though the highest values of these
observations were recorded at second harvest (Table 4).
The decrease in characteristics, morphologic and
productive, with age is a phenomenon observed
throughout tropical grasses (Ademosun, 1973) and young
pasture leads to higher organic matter digestibility and
intake (Onifade and Agishi, 1990). On the other hand,
this study also showed that dry matter content of forage
grasses increases with low amount of available soil
moisture as the rains receded, resulting in reduced water
uptake and accumulation in the plants. Apart from Gero A
hybrids which had 100% mortality, Dauro x S.13 (42.9%)
and Maiwa 25-2 x S.13 (21.2%) also had the least
number of surviving individuals and were not significantly
different (p = 0.05). Other hybrids viz., Maiwa 28-1 x S.13
(12.8%), Maiwa 94-2 x S.13 (6.7%), Dauro x S.15 (6.2%),
Maiwa 28-1 x S.15 (5.1%) and Maiwa 94-2 x S.15 (1.7%)
were also not significantly different (p = 0.05) from Maiwa
25-2 x S.15 (1.3%) with the highest number of surviving
individuals (Table 4).
Overall, hybrids which had S.13 parent recorded the
highest mortality, ranging from 6.7 to 42.9%, whereas
hybrids with S.15 parent had a range of 1.3 to 6.2%
mortality. The mortality rate of the interspecific hybrids on
the field was viewed as an aid to selection for crosses
with the genetic ability to overcome hybrid inviability
which has been earlier reported by Stebbins (1958) as an
important post-zygotic barrier to interspecific
hybridization. This study also highlighted mortality rate as
a measure of the ability of the successful interspecific
hybrids to withstand transplanting shock and
acclimatization challenges on the field. Consequently, the
moderate to high mortality rates observed among
interspecific hybrids between pearl millet and elephant

140 J. Plant Breed. Crop Sci.
Table 3. Mean squares relevant to the harvest intervals and genotypes.
Source
df
Mortality (%)
Plant height (cm)
Dry matter content (%)
Dry matter yield (g/m2)
Harvest
2
1157.28**
3204.82***
21.138*
70552.0***
Genotype
7
586.49**
290.62*
14.299*
9193.0NS
Residual
14
99.17
96.37
3.543
4394.0
*, ** and ***significant at the 0.05, 0.01 and ≤0.001 probability levels, respectively. NS Non-significant difference, df = degree of freedom.
Table 4. Mean effects of harvest interval on survival, morphology and forage yield components of interspecific hybrids between pearl
millet and elephant grass.
Harvest
Mortality (%)
Plant height (cm)
Dry matter content (%)
Dry matter yield (g/m2)
H1 (12WAT)
2.2
112.0
14.36
174.0
H2 (6WAH1)
9.0
149.3
14.52
348.0
H3 (6WAH2)
25.5
117.9
17.25
199.0
±SEM
3.52
3.47
0.665
23.4
F pr.
0.001
<0.001
0.013
<0.001
LSD(p = 0.05)
10.7
10.5
2.02
71.1
H1, H2 and H3 = first, second and third harvests respectively. WAT and WAH = weeks after transplanting and weeks after harvest,
respectively.
grass is linked to the fact that pearl millet is an annual
crop species and this trait was conferred on the hybrids
at varying degrees by the different pearl millet genotypes.
The results practically showed that cytogenetic barriers to
interspecific hybridization involving Nigerian pearl millet
type parents, Dauro, Gero A and Maiwa, with S.13 and
S.15 elephant grass selections were at their strongest in
crosses involving Gero A.
Interspecific hybrids have a mosaic of both parental
and intermediate morphological characters rather than
just intermediate ones. Plant height ranged from 113.1
(Dauro x S.13) to 141.2 cm (Maiwa 94-2 x S.13). Maiwa
94-2 x S.13 which was also not significantly different (p =
0.05) from other hybrids except Dauro x S.13. Only
Maiwa 25-2 x S.15 (116.0 cm) was not significantly
different (p = 0.05) from the shortest hybrid, Dauro x S.13
(Table 5). Hybrids of all Maiwa parents with S.13
elephant grass selection were generally taller than those
hybrids with S.15 elephant grass selection except with
Dauro parent which had its hybrids with S.15 being taller
than its counterpart hybrids with S.13. These variations
are often expected from interspecific hybrid plants from
parents with contrasting agronomic and morphological
features. The observations corroborate the reports of
Hanna and Monson (1980) and van de Wouw et al.
(1999) who reported variations between and within
accessions of elephant grass × pearl millet hybrids in
terms of plant height, ranging from 120 to 340 cm at ten
weeks after cutting. However, distinguishing
morphological parental characters expressed by hybrids
of closely related species have been reported to show
dominant inheritance pattern (Gottlieb, 1984; Hilu, 1993).
In any case, the expression of parental or intermediate
character in hybrids is significantly attributed to the
genetic control of the character, as well as interactions
with the environment.
One major forage quality that complements higher yield
is digestibility, and it is directly related to succulence of
forage which invariably depends on the moisture contents
in plant tissues. The drop in water content or decrease in
percentage dry matter, caused by stem-hardening, have
been reported to decrease digestibility and palatability of
forage (stem and leaves) at maturity in pearl millet and
pearl millet × elephant grass hybrids (Schank et al.,
1993). Mature leaves of plant tissues generally contain
water from 75 to 85% of the fresh weight. Succulence of
forage depends on the value of moisture contents (%).
The least dry matter content was observed for Maiwa 94-
2 x S.13 (11.74%) and was significantly different (p =
0.05) from Maiwa 28-1 x S.15 (17.93%) and Dauro x S.15
(17.06%). Maiwa 28-1 x S.13 (12.49%) was significantly
different (p = 0.05) from Maiwa 28-1 x S.15 but similar to
hybrids of Maiwa 25-2 x S.13 (16.08%), Maiwa 94-2 x
S.13 (11.74%) and Dauro x S.13 (15.27%). Hybrids with
Maiwa 25-2 parent were not significantly different (p =
0.05) from Maiwa 94-2 x S.15 (15.72%) and Dauro x S.13
(15.27%). Overall, hybrids with S.15 parent had higher
dry matter content than hybrids with S.13 parent (Table
5). This was a trend similar to mortality because hybrids
with S.15 had greater number of surviving plant stands
after each harvest. McCullough (1977) reported a dry
matter content range of 28 to 34% in elephant grass and
19.4% was reported in pearl millet (Aguiar et al., 2006;
Fulkerson et al., 2008). Overall, the results of this study

Obok et al. 141
Table 5. Mean genotype effect on plant height and forage yield components of interspecific hybrids between pearl millet and
elephant grass.
Genotype
Mortality (%)
Plant height (cm)
Dry matter content (%)
Dry matter yield (g/m2)
25-2 x S.13
21.2ab
133.4a
16.08abc
171.0NS
25-2 x S.15
1.3b
116.0ab
16.73abc
171.0
28-1 x S.13
12.8b
135.3a
12.49bc
324.0
28-1 x S.15
5.1b
120.9a
17.93a
227.0
94-2 x S.13
6.7b
141.2a
11.74c
308.0
94-2 x S.15
1.7b
123.1a
15.72abc
249.0
Dauro x S.13
42.9a
113.1b
15.27abc
232.0
Dauro x S.15
6.2b
128.2a
17.06ab
239.0
±SEM
5.75
5.67
1.087
38.3
F pr.
0.002
0.037
0.013
0.114
Figures with diff erent letters denote significant genotype differences at 0.05 and 0.01 probability levels using Duncan’s mul tiple range
test (DMRT). NS Non-significant difference.
Table 6. Correlation between plant height and forage yield components of interspecific hybrids between pearl millet and
elephant grass.
Variable
Dry matter content (%)
Dry matter yield (g/m2)
Plant height (cm)
-0.434*
0.780**
Dry matter content (%)
-0.430*
* and ** = significant correlation at 0.05 and 0.01 probability levels, respectively.
showed that none of the hybrids had over 18% dry matter
content because the pasture was still at its early stage of
establishment. Increase in dry matter content of forage
increases with age (maturity) of forage (Maria et al.,
2010). Thus, low dry matter content will impart on the
succulence and palatability of the hybrids as forage
(fodder) (Schank et al., 1993; Wadi et al., 2004).
However, the digestibility of forage dry matter by
ruminants is the summation of the digestibility of the
component tissues as affected by morphology, anatomy
and chemical composition (Murphy and Colucci, 1999).
Where silage is to be made, forages with low dry matter
content are selected against but this should not exceed
30% dry matter content (Aganga and Tshwenyane, 2003;
Snijders and Wouters, 2003). Moreover, wet forages are
difficult to ensile because high moisture content has
implications for the development of clostridial
fermentation, dilution of plant sugar concentration and
slowing the decline in silage pH (Henderson, 1993). On
the other hand, mature forage grass with high dry matter
content supports good silage quality, though it may also
have high fibre content and consequently low digestibility
(Aganga and Tshwenyane, 2003).
Nonetheless, dry matter yield is a more meaningful way
of comparing fodder yield (Faridullah et al., 2010). From
the study, there was no significant difference (p = 0.05) in
all the hybrids in terms of dry matter yield (g/m2) (Table
5). The highest dry matter yield was obtained from Maiwa
28-1 x S.13 (324.0 g/m2) and the least yield was obtained
from hybrids with Maiwa 25-2 parent. Generally, hybrids
of Maiwa parents with S.13 elephant grass selection were
higher in dry matter yield than hybrids of Maiwa parents
with S.15 elephant grass selection. Hybrids of Dauro
parent with S.13 elephant grass selection, however, had
lower dry matter content over those with S.15 elephant
grass selection. According to Arshadullah et al. (2011),
higher production of fodder is appreciable only if its
quality is acceptable as well and the production of milk,
meat and associated products of livestock depends upon
hereditary factors by approximately 25%, while 75% is
dependent on the feed (forage) quality and quantity. The
results showed that the genotypes producing higher dry
matter yield (biomass) also had lower dry matter content
(that is, greater moisture contents). Consequently, this
highlighted that all the genotypes had similar moderate
moisture content presenting them with more succulence
and digestibility as forage.
Pearson’s bivariate correlation coefficients between
plant height, dry matter content and dry matter yield were
calculated and these showed significant relationships
between these parameters (Table 6). Dry matter content
was negatively and significantly correlated with dry matter
yield (r = -0.430) of the hybrids, implying that these two
attributes cannot be significantly improved. Though plant
height was also negatively correlated with dry matter
content (r = -0.434), there was a significantly strong

142 J. Plant Breed. Crop Sci.
positive correlation between plant height and dry matter
yield (r = 0.780), indicating that plant height had the
highest effect on dry matter yield. These results were at
par with the report of Vidyadhar et al. (2007) where there
was a significant positive correlation (r = 0.65) between
plant height and fodder yield of pearl millet. This report
agreed with those of Faridullah et al. (2010) on pearl
millet and Zhang et al. (2010) on elephant grass. Wadi et
al. (2004) reported that there exit a positive high
significant correlation, r = 0.917 and r = 0.938, between
dry matter yield and plant height in hybrids of both
reciprocal crosses between elephant grass and pearl
millet (hybrid napier grass) and pearl millet with elephant
grass hybrids (king grass), respectively. The positive
significant (p = 0.05) correlation recorded for plant height
suggests that this morphological attribute is of value for
selecting interspecific hybrids of pearl millet × elephant
grass with high forage yield.
Conclusion
The significant genetic incompatibility status of Gero A
presents it as an unsuitable pearl millet type for
interspecific hybridization between elephant grass and
further cytogenetic and genomic analyses that would help
explain the differences among the pearl millet types as
suitable parents are suggested. Overall, hybrids between
Maiwa and S.13 (Maiwa 94-2 x S.13 and Maiwa 28-1 x
S.13) were the most promising in terms of dry matter
yields and should be subjected to further studies such as
forage yield evaluation over a number of seasons as well
as animal trials. The significantly strong correlation
between these forage attributes viz., plant height and dry
matter yield, showed that these could be used as
selection and adaptability indices.
ACKNOWLEDGEMENTS
The authors acknowledge the financial support provided
through the University of Calabar Study Fellowship to
conduct this study at the Plant Breeding Unit of the
Department of Agronomy, University of Ibadan, Ibadan.
The field assistance provided by Mr. Shaba, Mr. Christian
and Mr. Eragbe and the laboratory assistance provided
by Mr. Paulinus and Mr. Omosuli is appreciated.
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