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African Crop Science Journal
Abstracts
(Volume 8, No 1)
African Crop Science
Journal, Vol. 8. No. 1, pp. 1-10
GENOTYPE X ENVIRONMENT INTERACTION AND OPTIMUM RESOURCE
ALLOCATION FOR YIELD AND YIELD COMPONENTS OF CASSAVA
A.G.O. DIXON and E.N. NUKENINE
ABSTRACT
Dry yield and yield components from 6 multilocational
trials of cassava genotypes conducted for 3 years in
Nigeria were used to study the nature and magnitude of
genotype x environment (G x E) interaction and to
determine the optimum resource allocation for cassava
yield trials. The effects of environment, genotype and G
x E interaction were highly significant for all yield
traits. Variations due to G x E interaction were greater
than those due to genotypic differences for all yield
traits. Genotype x location x year interactions
contributed most to the G x E interaction for all the
yield traits. Therefore, to facilitate selection,
zonation of cassava growing agroecologies into homogenous
ecosystems using multivariate statistical approach should
be done to minimise the influence of the G x E
interaction. Testing at 3-5 locations for 2-3 years with
3-4 replications per location is the optimum combination
that will not jeopardise precision in cassava yield
trials.
Key Words: Manihot esculenta, Nigeria,
yield stability
African Crop Science
Journal, Vol. 8. No. 1, pp. 11-23, 2000
ESTIMATION OF OPTIMUM PLOT DIMENSIONS AND REPLICATION
NUMBER FOR WHEAT EXPERIMENTATION IN ETHIOPIA
GIRMA TAYE, AMSAL TAREKEGNE and D.G. TANNER
ABSTRACT
Bread wheat was row and broadcast sown using uniform crop
management practices on a research station soil
classified as a haplic Nitisol, situated in a major wheat
producing region of Ethiopia, during the 1996 and 1997
crop seasons. The harvested area was divided into basic
units measuring 1 m by 1 m. Resultant basic unit grain
yields were combined to simulate different plot sizes and
shapes, and Smith's empirical model and subsequent
derivations were used to estimate soil heterogeneity. The
broadcast sown trials generally resulted in lower
estimates of soil heterogeneity, higher coefficients of
variation, and higher values for adjacent plot
correlation due to both modified inter-plant competition,
and a more variable distribution of wheat plants and
basal fertiliser within plots. Parameter estimates from
the broadcast sown trials were less consistent over the
two year trial period relative to those from the row sown
trials. The analyses suggested a marginal superiority for
square plot shapes for broadcast sown trials, while for
row sown trials rectangular and square plot shapes were
equally precise in measuring soil heterogeneity. A
comparison of the trial design parameters currently
favoured by wheat researchers in Ethiopia with the
optimal parameters estimated in the current study
suggests that: (a) the design characteristics of
broadcast sown wheat agronomic trials appear close to
optimal, but (b) the net plot areas harvested from row
sown wheat breeding trials are markedly suboptimal.
Key Words: Heterogeneity
African Crop Science
Journal, Vol. 8. No. 1, pp. 25-34, 2000
INFLUENCE OF VARIETY AND MANAGEMENT LEVEL ON PEARL MILLET
PRODUCTION IN NIGER: I. GRAIN YIELD AND DRY MATTER
ACCUMULATION
N. Maman, S. C. Mason and S. Sirifi
ABSTRACT
Pearl millet [Pennisetum glaucum (L.) R. Br.] is
the most important food crop in Niger and most other West
African Sahelian countries. The study was conducted as a
factorial combination of three pearl millet varieties and
two management levels at Kollo, Niger. Low management
consisted of 10,000 hills ha-1 with no
fertiliser application, while high management consisted
of 20,000 plants ha-1 with manure, and N and P
fertiliser application. The three varieties used were the
improved varieties `Zatib' (tall) and `3/4 HK'(short),
and a landrace variety `Heini Kirei' (tall). Two plants
per plot were sampled bi-weekly, partitioned into plant
parts, dried, and weighed. Pearl millet under high
management produced 517 to 551 kg ha-1 greater
yield and 200 to 300 g m-2 more dry matter
than with low management. In 1995, the shorter variety
`3/4 H K' produced 147 to 256 g m-2 less dry
matter and 155 to 485 kg ha-1 less grain yield
than the other varieties. Mean crop growth rates (CGRs)
increased up to a maximum of 18.5 g m-2 day-1
with high management and 2 g m-2 day-1
with low management in 1995, while in 1996 maximum CGRs
were 6.4 g m-2 day-1 with high management
and 1.7 g m-2 day-1 with low management. In
this study, environmental variability due to years had
the greatest effect on crop growth and grain yield;
management had an intermediate effect; and genotypes the
least effect. Pearl millet producers in Niger should
increase plant population and apply fertiliser to
optimize pearl millet grain and stover yield.
Key Words: Crop growth rate, dry matter
partitioning, Pennisetum glaucum, relative growth
rate, sahel
African Crop Science
Journal, Vol. 8. No. 1, pp. 35-47, 2000
INFLUENCE OF VARIETY AND MANAGEMENT LEVEL ON PEARL MILLET
PRODUCTION IN NIGER: II . N AND P CONCENTRATION AND
ACCUMULATION
N. Maman, S.C. Mason and S. Sirifi
ABSTRACT
Pearl millet [Pennisetum glaucum (L.)R. Br.] is
generally grown on nutrient-poor soils and low rainfall
conditions in Niger. Nitrogen and P accumulation and
utilisation are very important factors in pearl millet
growth, and are affected by environment and management.
An understanding of seasonal N and P accumulation is
necessary to improve pearl millet production. A two-year
field study was conducted in 1995 and 1996 at Kollo,
Niger with the objective to determine N and P
concentration and accumulation by pearl millet as
affected by variety and management level. Treatments were
factorial combinations of three pearl millet varieties:
`Heini Kirei', a landrace tall variety; `Zatib', an
improved tall variety; and `3/4HK', a short improved
variety, with low management (10,000 hills ha-1
with no fertiliser) and high management (20,000 hills ha-1
with manure and N and P fertiliser application).
Management level had no influence on N and P
concentration even though N and P fertiliser, and manure
were applied. Variety influence was small and
inconsistent. More N and P were translocated from the
stem and leaves to the panicle in the higher rainfall
year when grain yield was greater. The shorter variety
3/4HK had less N and P accumulation than the tall
varieties likely due to less dry matter production. The
average maximum total plant N accumulation for low
management was 1.42 g N m-2 in 1995 and 0.62 g
N m-2 in 1996, while for high management it
was 4.58 g N m-2 in 1995 and 2.45 g N m-2
in 1996. Biomass N use efficiency was not
influenced by management in either year, while grain
nitrogen use efficiency was 17 g grain g-1 N
higher with high management than with low management in
1995. In 1996, grain N use efficiency was 11 g grain g-1
N higher with low management than with high management.
The short, early maturing variety `3/4HK `tended to have
lower N use efficiencies than the other varieties.
Nitrogen and P accumulation, and grain N use efficiency
was influenced more by management than variety.
Key Words: Nitrogen accumulation, nitrogen use
efficiency, Pennisetum glaucum, phosphorus
accumulation
RÉSUMÉ
African Crop Science
Journal, Vol. 8. No. 1, pp. 49-62, 2000
PERFORMANCE OF PIGEONPEA AND ITS FINGER MILLET AND
SORGHUM INTERCROPS
P.R. Rubaihayo, D.S.O Osiru and P. Okware
ABSTRACT
Field trials were conducted to determine the optimum
plant population and spatial arrangement of finger
millet/pigeonpea and sorghum/pigeonpea intercropping
systems, identify the intercrop compatibility of finger
millet and sorghum with short- and medium-duration
pigeonpea, and evaluate insecticide application
strategies for the control of pod borers, pod sucking
bugs and podfly on pigeonpea. The experiments were
conducted at Makerere University Agricultural Research
Institute Kabanyolo (MUARIK) and Ngetta experimental
station during the second rains season of 1997 and first
rains season of 1998. Theoretical planting densities
(2.1, 2.8, 4.2, 4.8, 5.6, 8.3, 11.1, and 16.7 plants m-2
) for pigeonpea, (8.3, 11.1, 16.7, and 33.3 plants
m-2 ) for finger millet and 5.6 plants m-2
for sorghum intercrops were studied using KAT 60/8,
ICPL 87091 and ICP 6927 pigeonpea varieties, Pese
1 finger millet variety and Seredo sorghum
variety. Spraying against major pigeonpea insect pests
was carried out at vegetative stage, vegetative to pod
maturity, flower bud initiation to pod formation, and pod
formation to pod maturity. In the pigeonpea/finger millet
intercrop system, optimal combinations in terms of higher
land equivalent ratio (LER) values were given by 16.7
plants m-2 of ICPL 87091 and 8.3 plants m-2
of Pese 1, 4.2 plants m-2 of KAT
60/8 and 33.3 plants m-2 of Pese 1.
Planting of pigeonpea and finger millet or pigeonpea and
sorghum in a 2:2 row arrangement gave higher total LER
values than in the other arrangements and thus, was found
to be an optimal row arrangement. Spraying pigeonpea
cultivars ICPL 87091 and KAT 60/8 against major insect
pests at flower bud initiation to pod formation and at
pod formation to pod maturity, respectively, produced
significantly (P<0.05) better yields than unsprayed
and was more cost effective than the other spraying
regimes.
Key Words: Cajanus cajan, insect pest
management, intercropping, plant density, spatial
arrangement, sole cropping, yield advantage
African Crop Science
Journal, Vol. 8. No. 1, pp. 63-76, 2000
CHEMICAL COMPOSITION, PHENOLIC CONTENT AND IN
VITRO GAS PRODUCTION CONSTANTS OF FORAGE OF
PSYLLID-RESISTANT LEUCAENA SPECIES
GROWN IN ZIMBABWE
L. R. Ndlovu, L. Mlambo and B. H. Dzowela
ABSTRACT
Leaves from Leucaena species L. esculenta, L.
diversifolia, L. pallida, L. pulverulenta, L.
salvadorensis, L. shannonii, L. trichodes and the
interspecific hybrid L. Leucocephala x L.
diversifolia that are resistant to the psyllid Heteropsylla
cubana were harvested at the end of the rainy season
(April) and the dry season (November) from two sites. The
leaves were either sun or oven ( 50ºC) dried and
subsequently analysed for concentrations of dry matter
(DM), organic matter (OM), crude protein (CP), neutral
and acid detergent fibres (NDF and ADF), lignin,
extractable proanthocyanidins (PAs), soluble phenolics
(SPs) and protein precipitating potential (PPP). In
vitro gas production was measured over 72 hours.
Season of harvest and method of drying had no significant
(P>0.05) effect on the variables measured. Species
significantly affected concentrations of CP, lignin, PAs,
SPs and PPP. Cluster analysis based on content of
fibre or content of polyphenolics or total gas produced
identified L. shannonii, L. salvadorensis, L.
esculenta and the intraspecific hybrid L.
leucocephala x L. diversifolia as potentially
good quality forages.
Key Words: Gas production, Heteropsylla
cubana, leucaena, nutritive value, phenolic, tannin
African Crop Science
Journal, Vol. 8. No. 1, pp. 77-83, 2000
PEARL MILLET GRAIN SIZE AND HARDNESS IN RELATION TO
RESISTANCE TO SITOPHILUS ORYZEA (L.)
(COLEOPTERA: CURCULIONIDAE)
K. Leuschner, E. S. Monyo, E. Chinhema, E. Tembo and
D. Martin
ABSTRACT
Fifty-seven varieties of pearl millet (Pennisetum
glaucum (L.) R. Br.) were evaluated for resistance to
the rice weevil Sitophilus oryzea (L.) by using
artificial infestation. Kernels of each cultivar were
separated into three grain sizes; small, medium and
large, to remove the effect of grain size from that of
variety. Grain hardness was measured using the sodium
nitrate specific gravity floaters test. In general,
larger and softer grains supported more weevils. However,
there seems to be a good spread of variability for weevil
progeny production within the large grain fraction,
suggesting the possibility of selecting for resistance
among large grains. Most of the soft grain types had
floury endosperm, but no relationship was found between
grain size and endosperm type. This suggests that floury
and/or vitreous endosperm is not influenced by size, and
that it may be possible to develop varieties with a
combination of large grain, vitreous endosperm, and
weevil resistance. Irrespective of grain size, SDMV
90016, Nandi Code 24, TSPM 91018, and SDMV 89001 were
resistant compared to the farmer's local variety.
Key Words: Grain size and hardness,
Pennisetum glaucum, rice weevil
African Crop Science
Journal, Vol. 8. No. 1, pp. 85- 91, 2000
SHORT COMMUNICATION
PROLINE ACCUMULATION IN RESPONSE TO DROUGHT AND HEAT
STRESS IN COTTON
J.A. de Ronde, A. van der Mescht and H.S.F. Steyn
ABSTRACT
Water and heat stress are the most important
environmental variables affecting cotton growth and
development. The main objective of our study was to
evaluate the effect of water stress and a combination of
water and heat stress on proline accumulation in six
cotton cultivars (Gossypium hirsutum) and to
determine the suitability of using this proline
accumulation in a drought index. Drought and a
combination of drought and heat stress were induced in
three-week-old seedlings in the greenhouse. It was
detected that with decreasing water content there was a
progressive increase in free proline in all six
cultivars, as well as differences in the proline level
between the different cultivars. Maximum accumulation of
free proline in drought stressed cotton occurred at 11
days without water. The combination of heat and drought
stress exhibited an increase in proline concentrations in
five cultivars. Different proline profiles were observed
for the different treatments and different mechanisms for
heat and drought are proposed for this phenomenon.
Key Words: Drought stress, Gossypium
hirsutum, proline
African Crop Science
Journal, Vol. 8. No. 1, pp. 93-98, 2000
SHORT COMMUNICATION
PRODUCTION AND EVALUATION OF PRECOOKED DEHYDRATED UNRIPE
BANANA SLICES
J. H. MUYONGA
ABSTRACT
This study was aimed at developing a process for
production of easy to prepare dehydrated banana slices.
Steaming unripe bananas for 7 minutes followed by hand
peel stripping, slicing and dehydration in air dryers
produced slices with better rehydration properties than
slices produced without steaming, even when the latter
were dehydrated by freeze drying. No significant change
in total aerobic counts or yeasts and moulds counts
occurred in dehydrated banana slices packaged in 250
gauge polyethylene bags and stored at ambient temperature
for 3 months. The slices were found to be high in starch
(~68.5%) and minerals. When shallow fried, the dehydrated
banana slices were found to have acceptable flavour,
appearance, taste and texture. Overall, they were
considered acceptable by sensory panelists. The findings
of this study indicate that steaming, in addition to
easing peeling and reducing discolouration, improves
rehydration and reduces cook loss.
Key Words: Musa spp., dehydration,
rehydration, pretreatments
African Crop Science
Journal, Vol. 8. No. 1, pp. 99-108, 2000
- FORUM -
THE USE OF DNA MARKERS FOR RAPID IMPROVEMENT OF CROPS IN
AFRICA
G. Thottappilly, H.D. Mignouna and O.G. Omitogun
ABSTRACT
Genetic engineering and biotechnology are providing new
tools for genetic improvement of food crops. Molecular
DNA markers are some of these tools which can be used in
various fields of plant breeding and germplasm
management. For example, molecular markers have been used
to confirm the identity of hybrids in breeding
programmes. Another application of molecular markers is
in determining phylogenetic relationships in related
species. Information on phylogenetic relationships is
useful in facilitating introgression of desirable traits
from wild relatives to cultivated crop species. Molecular
markers are also being used to construct genetic maps. A
genetic map is a collection of genetic markers that have
been grouped according to their linkage. Breeders can use
DNA maps to carry out marker-assisted selection. This
technique enables plants carrying desirable traits such
as pest and disease resistance to be selected while still
in the seedling stage. Ultimately, this enables the
cloning of the genes to be used for crop improvement. The
polymerase chain reaction (PCR) has become a popular
technique for molecular genome mapping and the diagnosis
of plant pathogens. The technique ensures amplification
of specific DNA sequences by the use of primers and the
enzyme Taq DNA polymerase. Restriction Fragment Length
Polymorphisms (RFLPs), Random Amplified Polymorphic DNAs
(RAPDs), microsatellites and Amplified Fragment Length
Polymorphism (AFLP) are some of the most useful molecular
markers for DNA fingerprinting. For viral, fungal and
bacterial DNA fingerprinting and diagnosis as well as
strain differentiation of rhizobia, PCR-RAPD and cDNA
probes can be applied alongside with monoclonal
antibodies.
Key Words: Crop improvement, DNA polymorphism,
marker-assisted selection
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