Stability Analysis for Yield and Yield Related Traits in Fodder Oats (Avena sativa L.)
F.A. Nehvi ,
Shafiq A. Wani ,
Altaf Hussain ,
M.I. Maqhdoomi ,
B.A. Allai ,
Wassem Yousuf ,
Stability analysis was carried in twenty genotypes of fodder oats under four random environmental conditions of Kashmir valley. Observations were recorded on 10 maturity, morphological, quality, yield and yield related traits. Significant variation among genotypes was observed for all the traits indicating presence of high level of variability Significant GXE interaction was observed for all the traits. Partitioning of GXE interaction revealed that both the components were highly significant in all the characters with predominance of the Linear component, thereby, suggesting that the performance of genotypes across environments could be predicted with greater precission. Eleven genotypes showed average stability for green fodder yield of which nine genotypes (EC-3517, EC-35134, EC-13178, EC-1085898, EC-96848, EC-9865, EC-131532, Sabzaar and Kent) were well adopted and two genotypes (EC-54837 and EC-99170) were poorly adopted to all environments. Genotypes EC-35117, EC-35134, EC-13178, EC-1085898, EC-97248, EC-131532, Sabzaar and Kent were found to be stable and well adopted to all environments for most of the yield and yield related traits. These genotypes would be useful for commercial exploitation or can be exploited as elite gene pool in future breeding programme.
The State of Jammu and Kashmir, the Kashmir valley in particular is ideally suited for fodder oat cultivation because of its temperate climate. However, availability of good and sufficient quantity of fodder for stall feeding during the winter months has been a problem in the Kashmir valley. In order to diversify the varietals profile of oats in Kashmir valley it is necessary to identify and evolve more number of genotypes having high potential of fodder yield and quality through application of sound and pragmatic breeding programme. The GXE interactions are of major consequences to the breeders in the process of evolution of new varieties. The breeders aim at evolving strains which may give the maximum mean economic yield over environments and show consistent performance. A variety or genotype is considered to be moreadaptive or stable one if it has a high mean yield but low degree of fluctuations in yielding ability when grown over diverse environments (Arshad et al., 2003) Significant advances have been made in the measurement of contribution of the genotypes over environments by using the regression techniques. Stability model proposed by Eberhart and Russel (1966) is a powerful tool which enables to measure the phenotypic stability related to performance of genotypes. Ebarhart and Russel (1966) recommended growing of varieties in adequate number of environments covering a full range of possible environmental conditions so that useful information is available regarding stability. Mean value, regression slope of the genotype and deviation from the regression is considered while assessing the performance of a genotype in a given environment. Taking into view the above considerations the present investigation was carried out over a set of 4 diverse environments to characterize the nature of GXE interaction and to estimate the stability parameters for identification of stable genotypes across environments.
MATERIALS AND METHODS
Material for the present study comprised of twenty oats genotypes of both indigenous
and exotic origin viz., Oats-16, EC-3230, EC-35117, EC-35134, EC-35151, EC-35189.
EC-35753, EC-13178, EC-1085898, EC-96848, EC-9865, EC-35765, EC-54837, EC-97248,
EC-86444, EC-99170, EC-131532, OS-6, Sabzaar andent. The genotypes were grown
in randomized block design with three replications at 4 random environments
representing the distinct locations of Kashmir valley of India viz., Shalimar
(E1), Malangpora (E2), Khudwani (E3) and Wadoora (E4). Each genotype was planted
in 12 rows of 5 m length spaced 25 cm apart in 2001-02. Observations were recorded
on ten randomly selected and tagged competitive plants from each experimental
plot in each replication for plant height and leaf stem ratio, whereas, for
rest of the traits excepting number of tillers/m2, the data was recorded
on whole plot basis. Observations were recorded on forage characters (days to
50% flowering, plant height, leaf stem ratio, green fodder yield q ha-1,
dry fodder yield q ha-1), seed characters (days to maturity, seed
yield q ha-1, 1000 seed weight) and quality characters (protein content).
The data was subjected to analysis of variance for single as well as pooled
over environments and stability analysis (Eberhart and Russel 1966). Pham and
Kang (1988) indicated that genotype x environment interactions minimize the
usefulness of genotypes by confounding their yield performance. Backer and Leon
(1988) also indicated that assessment of Stability across many locations and
years could increase both repeatability and heritability of important traits.
RESULTS AND DISCUSSION
For a cultivar to be commercially successful, it must perform well across a
range of environments in which the cultivar has to be grown. Since the genotype
environment interaction has masking effect on the phenotype some breeders attempt
to estimate the magnitude of interaction variance attributable to GXE4 4 interaction
so that the precise estimate of genotypic variance could be obtained. Analysis
of variance revealed that all the genotypes possessed highly significant genetic
variability for all the traits). Mean square due to environments were significant
for all the traits revealing influence of environment on their expression. The
mean square due to environment + cultivar x environment were significant for
all the characters revealing variable response of genotypes for all the traits
in the changing environment. The GXE interaction component was also significant
for all the traits revealing that these traits were not stable over the environments.
Pham and Kang (1988) indicated that genotype x environment interactions minimize
the usefulness of genotypes by confounding their yield performance. Backer and
Leon (1988) also indicated that assessment of stability across many locations
and years could increase both repeatability and heritability of important traits.
Further component analysis of environment + genotype environment mean square
revealed that differences between the environments existed and they had considerable
influence on all the traits. The major portion of these variations could be
attributed to linear regression. Significance of linear component implied that
the behavior of the genotypes for all the traits was predictable over environments
and this had resulted from the linear function of the environmental component.
Significance of non linear component for all the traits revealed that the behavior
of deviation from regression existed among genotypes for all the traits (Table
1) When genotype x environment is due to variation in predictable environment
factors, Oat breeders have the alternatives of either developing specific varieties
for different environments (location, soil types, winter type, spring type etc.)
or broadly adapted cultivars that can perform well under variable conditions.
However, when genotype x environment interaction results from variation in unpredictable
environmental factors, such as year to year variation in rainfall distribution,
the breeders needs to develop stable genotypes that can performs reasonably
well under a range of conditions. Similar results have been reported (Akcura
et al., 2005; Wani et al., 2002).
Identification of stable genotypes having adoptability over a wide range of
agro-climatic conditions is of major significance in crop Improvement. Comstock
and Moll (1963) suggested that selection would not be effective due to presence
of significant GXE interaction, therefore breeders should give emphasis on stable
performance of a line over a wide range environments.
|| Analysis of variance for morphological, maturity, quality
and yield related traits in fodder oats
|*, **: Significant at p = 0.05 and 0.01, respectively. ***Very
highly significant at 0.001
According to Ebarhart and Russel (1966) a stable genotype was defined as one
which showed high mean yield, regression coefficient b around unity and deviation
from regression S2di nearer to zero. The non significant linear b
and non Linear S2di components indicated average stability with high
precision across environmental changes. Where as, significant b and non-significant
S2di components suggest above average stability for favorable environments.
The significant/non-significant and S2di component indicates that
behavior of genotypes is highly unpredictable and they are not suitable for
changed environments. Estimates of stability parameters for 20 different genotypes
for ten traits revealed significant mean square deviations from regression S2di
with respect to Days to 50% flowering in 7 genotypes; for plant height in 8
genotypes; for number of tillers/m2 in 10 genotypes; for days to
maturity in 6 genotypes; for green fodder yield q ha-1) in 8 genotypes;
for dry fodder yield (q ha-1) in 6 genotypes; for protein content
in 11 genotypes; for 1000 seed weight in 12 genotypes and for seed yield (q
ha-1) in 7 genotypes. Contrarily the mean square deviation from regression
was non-significant in all the genotypes for leaf stem ratio (Table
2 and 3). The genotypes showing non-significant mean square
deviation from regression (pooled deviation) indicated that non-linear component
(heterogeneity from regression) was equal to zero, hence the performance of
these genotypes for a given environment could be predictable. Accordingly a
genotype whose performance could be predictable (i.e., S2di = 0)
was classified to be stable.
The Linear regression (bi) deviated from unity for days to 50% flowering in 15 genotypes; for plant height in 5 genotypes; for number of tillers/m2 in 6 genotypes; for leaf stem ratio in 2 genotypes; for days to maturity in 3 genotypes; for green fodder yield (q ha-1) in 5 genotypes; for dry fodder yield (q ha-1) in 5 genotypes; for protein content in 3 genotypes; for 1000 seed weight in 3 genotypes and for seed yield (q ha-1) in 6 genotypes. Hence they could be considered as more responsive. However, considering their mean value, deviation from regression (S2di) and desirability of the traits, the genotypes showing above average stability for favorable environment were identified in Oats-16, EC-35134, EC-35151, EC-35189, EC-13178, EC-96848 and EC-35765 for days to flowering; Sabzar for leaf stem ratio; EC-131532 for protein content and EC-13178 and EC-96848 for seed yield (q ha-1). However, for plant height, number of tillers m-2, days to maturity, green fodder yield (q ha-1), dry fodder yield (q ha-1) and 1000 seed weight, no genotype was identified to exhibit above average stability for favorable environments.
The genotypes not deviating significantly from unit regression for a particular
trait revealed that they were average in stability with high prediction across
environments and as such were either poorly or well adopted to all the environments
depending upon the mean performance.
|| Stability parameters for morphological and maturity related
traits in fodder oats
|*Significant, ** Highly significant
|| Stability parameters for quality and yield related traits
in fodder oats
However, the non-significant Linear regression coefficient (bi) was valid
only for genotypes with non-significant deviation from regression (S2di).
Genotypes that showed average stability and were well adopted to all the environments
included EC-3232 for days to 5% flowering; EC-35117 for days to 50% flowering,
green fodder yield, dry fodder yield and protein content; EC-35134 for plant
height, number of tillers m-2, leaf stem ratio, days to maturity,
green fodder yield and dry fodder yield; EC-35189 for leaf stem ratio; EC-35753
for leaf stem ratio, dry fodder yield and protein content; EC-13178 for plant
height, leaf stem ratio, green fodder yield and dry fodder yield; EC-1085898
for days to 50% flowering, plant height, green and fodder yield; EC-9865 for
plant height, leaf stem ratio, green fodder and dry fodder yield; EC-54837 for
number of tillers m-2 and protein content; EC-97248 for plant height,
leaf stem ratio and green fodder yield; EC-99170 for 1000 seed weight; EC-13152
for plant height, number of tillers m-2, green fodder yield and 1000
None of the genotype was well adopted for all the traits to all the environments.
However, EC-35117, EC-35134, EC-13178, EC-10858898, EC-97248, EC-131532, Sabzaarand
Kent exhibited stability and were well adopted to all the environments for most
of the yield and yield related traits. Akcura et al. (2005) also reported
wide adoptability of oat genotypes across locations. Gupta and Singh (1997)
also reported stable performance of several genotypes in respect of various
yield and quality traits. Dubey et al. (1995) identified genotypes that
were best suited to poor environments, normal and high input conditions.
The cultivars EC35117, EC-35134, EC-13178, EC-1085898, EC-97248, EC-131532, Sabzaar and Kent were found to be stable and well adopted to all environments of Kashmir valley of India. These genotypes recorded non-significant mean square deviation from regression for yield. Hence, these cultivar may be recommended for cultivation for all the
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