Performance of Quality Protein Maize Genotypes in the Warm Rainfed Hill Environments in Nepal
G. Ortiz- Ferrara
This study was conducted in the hills of Nepal in four years to determine
performance stability of open pollinated QPM genotypes in comparison to
open pollinated cultivars of normal maize. Replicated field experiments
were conducted in 29 environments using 20 QPM and seven normal maize
genotypes. The normal maize genotypes included released cultivars, advanced
breeding lines, one improved (Manakamana-3) and one local check (farmers`
variety). Grain yield, days to flowering, plant and ear height, prolificacy,
husk cover tightness and plant and ear aspect were analyzed. Stability
and genotype superiority for grain yield was determined using genotype
and genotypexenvironment (GGE) biplot analysis that compares among a set
of genotypes with a reference ideal genotype, which will have the highest
average value of all genotypes and be absolutely stable. The highest yielding
QPM genotype in each year had significantly higher grain yield than the
local check and higher or comparable yield to the improved check. Across
years, many QPM genotypes produced significantly higher grain yield than
the local check. Two genotypes (S03TLWQ-AB-01 and Obatampa) produced significantly
higher grain yield than the improved check. GGE-biplot analysis showed
that five of the seven most superior genotypes for grain yield were QPM
(S03TLWQ-AB-01, Obatampa, S01SIYQ S99TLWQ-HG-AB and S99TLWQ-HG-A). Deuti
and Manakamana-3 were the most superior among the normal maize cultivars.
These genotypes also had acceptable to superior agronomic traits. Grain
yield showed significant positive correlation with plant and ear height
and prolificacy. The results show that superior open pollinated QPM genotypes
were comparable to the outstanding cultivars of normal maize in performance
stability and agronomic traits. The findings of this study provide new
information on stability of the open pollinated QPM genotypes tested across
warm rainfed hill environments. These cultivars are also adapted to other
developing countries and this information could be useful for international
and national QPM improvement programs.
to cite this article:
S.R. Upadhyay, K.B. Koirala, D.C. Paudel, S.N. Sah, D. Sharma, D.B. Gurung, R.C. Prasad, R.B. Katuwal, B.B. Pokhrel, R.K. Mahato, R. Dhakal, N.B. Dhami, T.P. Tiwari, G. Ortiz- Ferrara and R.C. Sharma, 2008. Performance of Quality Protein Maize Genotypes in the Warm Rainfed Hill Environments in Nepal
. Asian Journal of Plant Sciences, 7: 375-381.
Maize (Zea mays L.) is an important food and a strategic
crop in many parts of the developing world where livelihoods of millions
of resource poor farmers depend on maize cultivation. Besides, several
hundred million people in the developing world rely on maize as their
principal daily food. In many countries in Latin America, Africa and Asia,
maize is the staple food and at times, the only source of protein
in human diet, which is deficient in amino acids lysine and tryptophan
that are essential for human and monogastric animals (Bressani,
1992). Hence, nutritional quality of maize is a concern where it is consumed
as human food. Quality Protein Maize (QPM) has superior nutritional and
biological value (Prasanna et al., 2001). The importance of QPM
in improving nutrition and livelihoods of the poor is well documented
(Cordova, 2001). The superior nutritional value of QPM, compared to normal
(non-QPM) maize and other cereals, has been reported by previous researchers
(Prasanna et al., 2001; Vasal, 2001). The importance of QPM is
also reflected through the release of QPM cultivars in many developing
countries (Prasanna et al., 2001; Vasal, 2001; Krivanek et al.,
Performance and stability of commercial QPM hybrids are well documented
in the literature (Pixley and Bjarnason, 2002; Bhatnagar et al.,
2003; Hossain et al., 2006). However, only limited information
is available on the performance of open pollinated varieties (OPVs) of
QPM (Pixley and Bjarnason, 2002; Akande and Lamidi, 2006). In early years
of QPM development, agronomic traits of high yielding genotypes were a
concern. However, in recent years many improved QPM cultivars have been
developed by CIMMYT and partners in developing countries (Prasanna et
al., 2001; Vasal, 2001; Akande and Lamidi, 2006; Badu-Apraku et
al., 2006; Yasin et al., 2007), which are being promoted for
commercial cultivation (CIMMYT, 1999; Krivanek et al., 2007). Studies
have also shown that QPM hybrids are becoming more competitive with normal
maize cultivars for performance, particularly in the tropical environments
(Pixley and Bjarnason, 2002). However, information is needed on performance
stability of OPVs of QPM for warm rainfed environments in particular.
Further, information is also needed on comparative analysis of performance
stability of OPVs of QPM and normal maize evaluated together. For their
adoption, the OPVs of QPM cultivars must show grain yield and agronomic
traits comparable to or better than the commercial OPVs of normal maize.
This study was conducted to determine performance stability and suitability
of agronomic traits of QPM genotypes in the hill environments in Nepal.
One specific objective was to compare the performance of QPM with the
commercial cultivars of normal maize.
MATERIALS AND METHODS
This study included 27 maize genotypes comprised of 20 OPVs of QPM
and seven of normal type (Table 1). The normal type
maize included advanced breeding lines and improved open pollinated cultivars.
One improved (Manakamana-3) and one local check (farmers` variety) were
also used in the study. Manakamana-3 is a high yielding medium maturing
open-pollinated variety with tall height, one to two ears per plant, tolerance
to lodging and turcicum leaf blight (Exserohilum turcicum). (CIMMYT,
Field trials were conducted in the 2004, 2005, 2006 and 2007 main maize
seasons (April to September) in different mid-hill sites, spread from
east to west Nepal. There were 29 different environments (year-site combinations)
in the four years. Each trial was conducted in a randomized complete block
with three replicates. Each experimental plot of 9 m2 was seeded
at the standard seeding rate of 20 kg ha-1. Fertilizers were
applied prior to seeding at the rate of 90, 30 and 30 kg ha-1
respectively of N, P2O5 and
||Mean values for various traits of 27 maize genotypes evaluated across
29 environments in the mid-hills of Nepal
|†a = Better than local check (LC), b = Equal to
LC, c = Worse than LC, A = Better than improved check (IC), B = Equal
to IC and C = Worse than IC for a given trait based on LSD0.05
K2O in addition to 15 t farm yard manure ha-1.
The plots were kept free of weeds by hand weeding. The trials were managed
under summer and monsoon rainfed conditions. Other trial management practices
were as per recommended maize crop husbandry in the country.
All traits in each plot were recorded according to the procedures described
by CIMMYT for conducting standard maize trials. Days to flowering was
recorded as the number of days from planting until the date on which 50%
of the plants in a plot had 2-3 cm long silk. Plant and ear height were
measured on the same five randomly selected plants in each plot between
two and three weeks after flowering. Plant height was recorded as the
distance from the plant base to the point where the tassel started to
branch. Ear height was measured as the distance from plant base to the
node bearing the uppermost ear. All plants and ears in each plot were
counted. Prolificacy for each plot was determined as the number of ears
divided by the number of plants times 100. Extremely small secondary ears
were not recorded. Data on plant aspect (plant and ear height, uniformity
of plants, disease and insect damage and lodging) in each plot was recorded
at the brown husk stage on a scale of 1 to 5, where 1 and 5 represent
excellent and poor, respectively. At maturity, husk cover was rated on
a scale of 1 to 5, where 1 represents husk tightly covering the ear tip
and extending beyond it and 5 signifies clearly exposed tips. After harvest,
all ears from a plot were placed in a pile and ear aspect (size, disease
and insect damage, grain-filling and uniformity) was recorded on a scale
of 1 to 5, where 1 and 5 signify the best and the poorest, respectively.
The plots were harvested individually, the cobs were threshed and grains
weighed to record grain yield. Grain moisture content for each plot was
recorded and grain yield was adjusted to 15% moisture basis.
Statistical analyses were conducted on various parameters recorded in
the study. Since the values for plant and ear aspect and husk cover were
between 1 and 5, data transformation was accomplished for these traits
using (X + 0.5)½ as outlined by Gomez and Gomez (1984).
The transformed data were used for analysis, but means have been reported
after reverting the values to the original scale. The statistical analysis
included an analysis of variance for each environment and a combined analysis
across environments using SAS (SAS, 2003) software. After confirming the
homogeneity of variance (Gomez and Gomez, 1984), a combined analysis of
variance was also conducted. Each year-site combination was considered
a unique and random environment, while genotypic effect was analyzed as
fixed. The test of significance using F-ratios was conducted according
to the procedure outlined by McIntosh (1983) for analysis of combined
experiments. Since several experimental genotypes changed across years,
environment was considered a bigger blocking factor, with replications
of genotypes in each environment as replications nested within environments.
Hence, analysis was conducted using Proc GLM. Significance of superiority
of experimental genotypes to the checks was tested in pair wise comparisons
performed using statistical LSD option in MEANS statement (Joshi et
To determine stability and identify superior lines across environments,
genotype and genotype x environment (GGE) biplot analyses was conducted
using GGE biplot software (Yan and Kang, 2002). GGE biplot is a method
of graphical analysis of multi-environment data (Yan et al., 2000).
The method differs from regular biplot analysis in that it simultaneously
displays both genotypes and environments (Gabriel, 1971). The GGE biplot
is a statistical tool that displays the main genotype effect (G) and the
genotype x environment interaction of multi-environment tests. It is
constructed by plotting the first two principal components (PC1
and PC2, also referred to as primary and secondary effects,
respectively) derived from singular value decomposition of the environment-centered
data. In this model, only the main effects of the genotypes plus G x E
are absorbed into the bilinear terms. A specific option in GGE biplot
analysis allows comparison among a set of genotypes with a reference genotype.
This method defines the position of an ideal genotype, which will have
the highest average value of all genotypes and be absolutely stable; that
is, it expresses no genotype by environment interaction. A set of concentric
circles are generated using the ideal genotype as the concentric center.
The ideal genotype is used as a reference to rank the other genotypes.
A performance line passing through the origin of the biplot is used to
determine mean performance of a genotype. The arrow on the performance
line represents increasing mean performance. A stability line perpendicular
to the performance line also passes through the origin of the biplot;
the two arrows in opposite directions represent decrease in stability.
A genotype farther from the biplot origin on either side on the stability
line represents relatively lower stability. A genotype closer to the performance
line is considered more stable than the one placed farther. Average simple
correlation coefficients (r) over environments were calculated using Fisher`s
z-transformation (Sharma et al., 2006).
The analysis of variance revealed significant effect of environment
on grain yield, days to flowering, plant and
||ANOVA for various traits for the 27 maize genotypes
tested across 29 hill environments in Nepal
**Significant at p = 0.01, xMS = Mean square
||Performance of the highest yielding QPM genotypes tested
across 29 hill environments across four years in Nepal
|† Means within a column followed by different
letter(s) are significantly different based on LSD0.05,
¶Highest yielding genotype in a given year
ear height, prolificacy, husk cover tightness and plant and ear aspect
(Table 2). The 27 maize genotypes differed significantly
for all traits. Genotype x environment interaction was significant for
grain yield, days to flowering, plant and ear height and prolificacy.
In each of the four years, the highest yielder QPM genotype produced
significantly higher grain yield than the local check (Table
3). The highest yielder QPM genotype produced significantly higher
grain yield than the local and improved checks in 29 and 18 trials, respectively
(data not shown). In 23 of the 29 trials, the highest yielder QPM genotype
had grain yield not significantly different from the highest yielding
normal maize cultivars. In 6 of the 29 trials, the highest yielder QPM
genotype produced significantly lower (11 to 16%) grain yield than the
highest yielder normal maize cultivar.
The 27 maize genotypes produced arrays of variation for grain yield (Table
1). The improved check (Manakamana-3) showed significantly higher
grain yield, later flowering, shorter plant and ear height and superior
plant and ear aspect than the local check. Fifteen QPM genotypes showed
significantly higher grain yield than the local check. Two QPM genotypes
[S03TLWQ-AB-1 (No. 21) and Obatampa (No. 23)] also produced significantly
higher grain yield than the improved check, which was equal to the highest
yielding normal maize (Deuti). Seven other QPM genotypes produced grain
yield not significantly different from the improved check. The local check
flowered significantly earlier than the improved check. Four QPM genotypes
(7, 17, 20 and No. 24) flowered significantly earlier than the local check.
Seventeen QPM genotypes flowered earlier than the improved check. Improved
check had significantly shorter plant and ear height than the local check.
There were four QPM genotypes (2, 6, 7 and No. 11) with significantly
shorter plant height than both checks. Further, there were 13 other QPM
genotypes with plant height not significantly different from the improved
check. There were six QPM genotypes with significantly lower ear height
than both checks. There were seven QPM genotypes with significantly higher
prolificacy than the local check. None of the QPM genotypes showed significantly
higher prolificacy than the improved check. However, there were 15 QPM
genotypes with prolificacy comparable to the improved check. The two checks
did not differ in husk cover tightness. None of the QPM genotypes showed
tighter husk cover than the two checks. However, there were 11 QPM genotypes
with husk cover tightness comparable to the two checks. There were 11
QPM genotypes with more superior plant aspect than the local check. None
of the QPM genotypes showed plant aspect superior to the improved check.
However, there were 16 QPM genotypes with plant aspect similar to the
improved check. There were only two QPM genotypes with ear aspect better
than the local check. None of the QPM genotypes showed better ear aspect
than the improved check. However, there were two QPM genotypes with ear
aspect equal to the improved check.
The GGE biplot analysis for grain yield revealed that three QPM (No.
4 = S01SYIQ, No. 21 = S03TLWQ-AB-1 and No. 23 = Obatampa) and one normal
(No. 19 = Deuti) genotypes were close to the point of an ideal genotype
(Fig. 1). Their performance and stability for grain yield were very close
to that for an ideal genotype making them the highest yielding and most
stable genotype across environments. Two other QPM (No. 13 = S99TLWQ-HG-A
and No. 5 = S99TLWQ-HG-AB) and the improved check (No. 26 = Manakamana-3)
also were relatively stable by being closer to the point of the ideal
Grain yield was significantly positively correlated with plant and ear
height and prolificacy and significantly negatively correlated with husk
cover tightness and plant and ear aspect (Table 4).
There was a significant negative correlation of days to flowering with
plant height and plant and ear aspect. Prolificacy showed a significant
||Average simple correlation coefficient of among various
traits recorded on 27 maize genotypes tested across 29 warm rainfed
environments in Nepal
*, **Correlation coefficient significantly different
from zero at 0.05 and 0.01 probability levels, respectively. N =
||GGE biplot showing a comparison of 27 maize genotypes
with an ideal genotype for grain yield tested on-station across 29
hill environments, Nepal. The environments are represented by the
letter E and treated as random samples of the target environments
(Refer to Table 1 for name of the genotypes)
positive correlation with days to flowering. Husk cover tightness was
significantly positively correlated with plant and ear aspect.
Mean grain yield of the maize genotypes differed across years and
sites, which may be due to differing environmental conditions over time
and sites. The sites themselves differed greatly in key attributes, such
as geographic location, temperature and rainfall that affected performance
(data not shown). The 27 genotypes represented a range of variability
for grain yield and other agronomic characters (Table 1),
with opportunities for selecting maize genotypes for high yield and acceptable
agronomic characters. This was also reflected through a significant positive
correlation of grain yield with days to flowering, plant and ear height
This study identified several high yielding QPM genotypes such as S01SYIQ
(No. 4), S99TLWQ-HG-AB (No. 5), S99TLYQ-HG-AB (No. 10), S99TLWQ-HG-A (No.
13), S03TLWQ-AB-1 ( No. 21), S03TLWQ-AB-01 (No. 22) and Obatampa (No.
23). The above QPM genotypes were also relatively stable (Fig. 1). Obatampa
is a white dent and flint endosperm QPM with elevated levels of lysine
and tryptophan and was released in several countries (Prasanna et al.,
2001; Akande and Lamidi, 2006; Badu-Apraku et al., 2006). S99TLYQ-HG-AB
(No. 10) was reported to be a high yielding QPM in Indonesia (Yasin et
There were three QPM (No. 4 = S01SYIQ, No. 21 = S03TLWQ-AB-1 and No.
23 = Obatampa) and one normal (Deuti)) genotypes that could be considered
highly stable for grain yield across environments (Fig.
1). Besides, two other QPM (No. 5 = S99TLWQ-HG-AB and No. 13 = S99TLWQ-HG-A)
genotypes and the improved check (No. 26 = Manakamana-3) could also be
considered superior. All these genotypes could be of value for maize breeding
programs in Nepal and in the region attempting to develop high yielding
maize cultivars for warm rainfed environments.
In general, the high yielding QPM genotypes had satisfactory to superior
maturity, plant and ear height and plant aspect compared to the local
check. However, they were inferior to the checks in terms of husk cover
and ear aspect. This suggests that husk cover tightness and ear characteristics
of the high yielding QPM genotypes need to be improved for their adoption.
Tight husk cover protects the ears on standing plants from rain water
during monsoon which is common in Nepal. It also helps in storing the
cobs during off season. Tight husk cover has also been reported important
in other countries for resistance to earworm (Helicoverpa zea)
(Archer et al., 1994; Butron et al., 2002) and Fusarium
ear rot (Fusarium moniliforme) (Farrar and Davis, 1991).
The highest yielding QPM genotype showed significantly higher grain yield
than the local check in four years. The highest yielder QPM genotype always
produced higher grain yield the local check in all 29 environments. These
findings demonstrate consistent genetic superiority of the QPM genotypes.
This also suggests that, if properly chosen, farmers would never lose
money for growing an appropriate QPM in place of the local check of the
normal maize. On the contrary, the farmers growing a local cultivar of
normal maize would frequently earn additional income by choosing an appropriate
QPM. Several QPM genotypes also compared well with the best commercial
cultivars and improved check of normal maize suggesting that QPM bears
potential for the warm rainfed environments in the hills of Nepal. The
finding that QPM cultivars are competitive and at times could be more
productive than normal maize is in agreement with a previous report (Yasin
et al., 2007). Pixley and Bjarnason (2002) reported that QPM OPVs
were more stable than hybrids for grain yield with the latter producing
13% higher grain yield. Akande and Lamidi (2006) also reported that QPM
hybrids outyielded OPVs and suggested that the later should be tested
across diverse target environments before making their recommendation
for commercial cultivation.
The adoption of QPM in Nepal and other developing countries would depend
not only on its nutritional value, but also on its yield performance.
The results of this study highlights the opportunities of this type of
maize in increasing food sustainability, livelihoods and the nutritional
aspects of millions of resource-poor farmers in the hills of Nepal. It
is expected that these results would also be of value in other national,
regional and/or international breeding programs aiming at improving and
Exotic QPM genotypes tested under the diverse hill environments
in Nepal showed significant variation for grain yield, days to flowering,
plant and ear height, prolificacy, husk cover tightness and plant and
ear aspect. There were QPM genotypes that outyielded the checks, were
also highly stable, indicating that superior QPM germplasm is becoming
available in the region through the international collaborative work.
Three QPM genotypes, Obatampa (No. 23), S03TLWQ-AB-01 (No. 21) S01SIYQ
(No. 4), were comparable to the improved check (Manakamana-3) and the
highest yielder (Deuti) normal maize cultivars in terms of grain yield
and its stability, days to flowering, plant height (No. 21 only), ear
height (4 and No. 21 only), prolificacy (No. 4 only), husk cover tightness
(21 and No. 23), plant aspect and ear aspect (No. 4 only). With improvement
in ear characteristics and husk cover tightness; these genotypes could
be well adopted in the region. These high yielding QPM genotypes could
also serve as improved parents for QPM improvement. Superiority of these
exotic QPM genotypes underscores continuous development and dissemination
of superior maize germplasm across continents in terms of saving resources.
A regular stability analysis often does not provide relative ranking
of superior entries in reference to an ideal genotype that results in
making a subjective judgment in selecting a cultivar. The GGE biplot approach
used in this study could help breeders to better decide what genotypes
should be promoted or released: the visual combined assessment of performance
and its stability is a big advantage and adds confidence in the decision
to promote a superior genotype.
The authors appreciate the assistance of Mr. Surath Pradhan in preparing
the tables and figures. This study was conducted as a part of the Hill
Maize Research Project under financial support by Swiss Agency for Development
and Cooperation (SDC) to the Government of Nepal and CIMMYT (Grant No.
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