Genetic Variability, Heritability and Genetic Advance in Tef (Eragrostis tef (Zucc.) Trotter) Lines at Sinana and Adaba
Assessing variability is fundamental to identify the most important traits in tef improvement program. The objective of the present study was to estimate variability, heritability and genetic advance on sixteen morphological characters in tef (Eragrostis tef (Zucc.) Trotter). Forty-nine genotypes were evaluated at two locations of Bale in south east of Ethiopia in 2008 cropping season. Simple lattice design of 7x7 with two replication was used to test the treatments. Pooled ANOVA of the two locations showed highly significant (p<0.01) for days to panicle emergence, lodging percentage, thousands kernel weight, grain yield per plant and grain yield per hectare. Significant differences (p<0.05) were noted for panicle length, shoot biomass and number of branch per main panicle. Genotype by location interaction was none significant for all traits which indicated that performance of the genotypes were consistent for these traits across the test locations. High phenotypic coefficient variation were observed for thousand kernel weight (78.82), productive tiller (46.45) and grain yield per plant (34.15) while high genotypic coefficient of variation were noted for traits, thousand kernel weight (40.34), productive tiller (32.46) and grain yield per plant (21.18). Maximum heritability estimate were observed for days to panicle emergence (75.50%) and grain filling period (66.79). High genetic gain was observed for lodging (10.90%) and days to panicle emergence (8.05%). The study showed that there are variation in extent of variability, heritability and genetic advance in traits under study which can facilitate selection for further improvement of important traits in tef.
August 24, 2011; Accepted: October 08, 2011;
Published: October 29, 2011
Tef (Eragrostis tef (Zucc.) Trotter) is an allotetraploid species with
a base chromosome number of 10 (2n = 4x = 40) and belongs to the family Poaceae,
sub-family Eragrostidae and genus Eragrostis, coupled with disomic inheritance
patterns (Berhe et al., 2001). There are a number
of close relatives of tef but the molecular-based studies suggested that Eragrostis
pilosa is an allotetraploid species of tef closest relative and possibly
the immediate wild progenitor of tef (Ingram and Doyle,
Tef is preferred for the production of basic staple food and relatively higher
market price than most of other cereal crops in Ethiopia (Woyessa
and Assefa, 2011). It has better storage keeping qualities under local conditions
than more familiar cereal grains and therefore be stored for longer period than
other cereals with fewer losses, making it a very important cash crop for most
farmers (FAO, 2010).
Tef production that was restricted to Ethiopia and Eritirea, nowadays started
spreading to some countries like USA, Netherlands and Israel. Tef is also gaining
popularity as health food (Spaenij-Dekking et al.,
2005). According to CSA (2008), it is one of the
most important cereal grown in Ethiopia and accounts for about 28% of the total
acreage and 19% of the gross grain production of the major cereals cultivated
in Ethiopia. In Ethiopia, major tef producing areas are found within Oromiya
and Amhara Regional States. It is widely grown in both high-potential and marginal
production areas. These areas include most parts of the vertisols that suffer
from water logging and other non-vertisol parts of the country that suffer from
low-moisture stress (Ketema, 1993). According to Ketema
(1997), tef performs very well at an altitude of 1800-2100 m, annual rainfall
of 750-850 mm, growing season rainfall of 450-550 mm and a temperature range
Breeding information on the nature and the magnitude of variability present
in the genetic material is very essential for a breeder to start any valuable
selection program. Genotypic and phenotypic coefficients of variation along
with heritability plus genetic advance are very essential to improve traits
of interest (Denton and Nwangburuka, 2011).
There are a number of problems in tef production; Low yielding, easily susceptibility
to lodging which is the major bottleneck for tef mechanization and limitation
of variation in landraces are among the existing constraints in tef improvement
programme. Breeding information on the nature and the magnitude of variability
present in the genetic material is very essential for a breeder to start any
effective selection program. Therefore, the present study was, conducted to
know the nature and extent of genetic variability, heritability and genetic
advance in some important traits of tef.
MATERIALS AND METHODS
Forty-nine Tef lines (Table 1) including one local and two
standard checks were brought from Debreziet Agricultural Research Center and
tested in 2008 main season. The field experiment was conducted at locations,
Sinana and Adaba. Sinana station is located at 2400 m.a.s.l and 463 km south
east of Addis Ababa in Bale zone and 33 km east of Robe town. The total annual
rain fall for the year 2008 was 1475.90 mm. The mean minimum and maximum annual
temperature of the same year was 9.56 and 20.19°C, respectively. The soil
type of Sinana is dark-brown (pellic Vertisol) with slightly acidic reaction
(Geremew et al., 1998). Adaba station is located
347 km from Addis Ababa on the way to Bale Robe. Total rain fall of the test
location during growing season was 1172.2 mm with the average temperature maximum
of 20.36°C and minimum of 10.66°C, respectively (source: Herero State
Farm Meteorology Station). The soil type of Adaba station is clay soil (source:
Simple Lattice Design of 7x7 with two replications and spacing of 1 m between plots, 1.5 m between blocks were used. The treatments were sown on 2x2 m plot area in accordance with the recommended seeding rate of 30 kg ha-1 and fertilizer rate of 60 kg ha-1 N and P2O5, respectively.
|| Lists of lines used in an experiment and their origin
Data were collected on plant and plot basis for 16 agronomic traits. Data per plant were collected after thinning to 5 cm between plants on plot size of 0.60 mx2 m from 2x2 m experimental unit so that to record data per plant precisely and all data per plot were taken from a plot size of 1 m2 using a quadrant.
Statistical analysis: Pooled Analysis of variance for locations were
done using the mean values of ten sampled plants for all data taken on plant
basis as well as for those taken on plot base. The data of the two locations
were tested for normal distribution and homogeneous variance and analyzed by
using simple lattice design (Gomez and Gomeze, 1998).
Least Significant Difference (LSD) were used to separate the means both at 1
and 5% probability levels using SAS statistical software. Genotypic (σ2g)
and phenotypic (σ2P) components of variances were estimated
as suggested by Burton and De Vane (1953), Heritability
(h2) for all characters was computed as suggested by Falconer
and Mackay (1996).
and Expected Genetic Advance (GA) for each character at 5% selection intensity
were computed using the methodology described by Johnson
et al. (1955).
GA = Kxσ2xh2
RESULTS AND DISCUSSION
Combined analysis for traits showed that highly significant (p<0.01) differences
for days to panicle emergence, lodging percentage, thousands kernel weight,
grain yield per plant and grain yield per hectare. Similar result was also reported
by Asfaw and Danno (2011) in case of days to panicle
emergence (days to head). Significant differences (p<0.05) were observed
for panicle length, shoot biomass and number of branch per main panicle (Table
2). Non significant (p<0.05) variations in genotypes were observed for
days to maturity, culm length, plant height, number of node, productive tiller
number, grain yield per panicle and grain filling period. Non significant variation
(p<0.05) in location was observed only for traits harvest index, lodging
percentage, grain filling period and thousand kernel weight; but the rest of
the traits were significant (p<0.05). Coefficient of variations ranges from
2.34-23.71%. Highest coefficient of variation (23.71%) was observed for productive
tiller number and the lowest coefficient of variation (2.34%) was observed for
days to maturity.
Genotype by location interaction were non significant for all traits which
indicated performance of the genotypes were consistent for these traits across
locations. Balcha et al. (2003) reported that
the presence of substantial genetic variability for grain yield and component
traits was observed among tef genotypes comprising land races and improved cultivars.
Genotypic coefficients of variation, phenotypic coefficients of variation,
Heritability and Genetic advance: High phenotypic coefficient of variation
was observed for thousand kernel weight (78.82), productive tiller (46.45) and
grain yield per plant (34.15). Greater genotypic coefficient of variation were
also observed for traits, thousand kernel weight (40.34), productive tiller
(32.46) and grain yield per plant (21.18) (Table 3). All phenotypic
coefficient of variation result is greater than genotypic coefficient of variation
in this study which is congruent with the present study of Kotal
et al. (2010), Mohammed et al. (2011),
Yadav et al. (2011) and Jalata
et al. (2011).
|| Combined analysis of variance for 16 traits of 49 Tef genotypes
planted at Sinana and Adaba in 2008
|*: Significant (p<0.05), **: Highly significant (p<0.01),
ns: Not significant, BMS: Block mean square, TrtMS: Treatment mean square,
CV: Coefficient of variation, DPE: Days to panicle emergence, DM: Days to
maturity, PL: Panicle length (cm), CL: Culm length (cm), PH: Plant height
(cm), NN: No. of node, PTLN: Productive tiller number, HI: Harvest index,
GPa: Grain yield per main panicle (g), LOD: Lodging percentage, SBM: Shoot
biomass (kg), GP: Grain filling period, NPB: No. of panicle main branch,
TKW: Thousand kernel weight (g), GYpl: Grain yield per plant (g), GYha:
Grain yield per hectare (kg)
||Components of variances, coefficients of variation, heritability,
genetic advance for sixteen characters in Tef genotypes grown at Sinana
and Adaba in 2008
|DPE: Days to panicle emergence, DM: Days to maturity, PL:
Panicle length (cm), CL: Culm length (cm), PH: Plant height (cm), NN: Number
of node, PTLN: Productive tiller number, HI: Harvest index, GPa: Grain yield
per main panicle (g), LOD: Lodging percentage, SBM: Shoot biomass (kg),
GP: Grain filling period, NPB: No. of panicle main branch, TKW: Thousand
kernel weight (g), GYpl: Grain yield per plant (g), GYha: Grain yield per
Previous study reported that high phenotypic coefficient of variation for productive
tillers (21%) and grain yield per panicle (22%) in tef (Kebebew
et al., 2001). Wide difference of Phenotypic coefficient of variability
(78.82%) and genotypic coefficient of variability in 40.34% in thousand kernel
weight, contradict with the reports of Riaz and Chowdhry
(2003). High genotypic variability facilitates selection for improvement
and widens the chance of heritability of traits from parent to offspring.
Maximum heritability estimate were observed for days to panicle emergence (75.50%)
and grain filling period (66.79) (Table 3). Heritability estimates
along with expected genetic gain is more useful than the heritability value
alone in predicting the resultant effect for selecting the best genotypes (Johnson
et al., 1955). High genetic gain was observed for lodging (10.90%)
and days to panicle emergence (8.05%).
Most of traits under study were showed significant variations, from low to high magnitude of heritability and genetic advance. These can facilitate selecting and utilizing the most preferred traits of interest and also hint the potential of tef for further improvement. High phenotypic and genotypic coefficient of variation especially for traits like thousand kernel weight, productive tiller and grain yield per plant are detrimental which make possible tef improvement breeding program. Broad sense heritability estimates together with genotypic coefficient of variation is important to exploit selection in germplasm improvement, since it bases all genetic effects.
The authors would like to acknowledge Tesfaye Letta, Tilahun Bayisa, Deme Nuguse, Tesfaye Tadess, Habtamu Legese, Gezahegn Tadess for their technical support and Oromia Agricultural Research Institute for financing this study.
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