Genotype X Environment Interaction of Imiadazolinone Resistant Maize Genotypes For Yield Under Striga Infestation
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Date
2008-04
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Addis Ababa University
Abstract
Twenty-five imidazolinone resistant (IR) maize genotypes were laid down in 5x5 simple lattice design
with 2 replications at six striga infested and five striga free environments during 2006/07 cropping
season. The objectives of the study were to evaluate IR maize genotypes for grain yield and
adaptability under striga infestation and free field conditions, to determine the magnitude of
genotype-by-environment interaction (GEI) of IR maize genotypes for grain yield, to determine
stability of yield performance among the IR maize genotypes and identify the stable genotype(s) and
those with adaptation to specific environments and to study the correlation among various stability
parameters. For trials where successful striga infestation was achieved, yield was reduced on average
from 8.62 to 26.87 Q/ha. The average percent reduction in yield for all the IR maize genotypes was
40.40% whereas for the standard check, WH-403 it was 65.00%. The highest percent reduction due to
striga infestation was observed on WH-403 at Alupe (79.00%) and Kibos (75.54%). Under striga free
condition, WH-403 gave the highest mean yield of 42.28 Q/ha but with only 3.37% yield advantage
over the highest yielding IR genotype, INTA/CML390/373 while under striga infested field the highest
yielding IR genotype, CML445/390/373 had a yield advantage of 86.50% over WH-403 showing the
superiority of IR maize genotypes under striga infestation. Combined ANOVA revealed highly
significant effects of the environments, genotypes and GEI. The presence of significant GEI showed
the inconsistency in performance of maize genotypes across the 11 environments. Six statistical
methods were conducted to determine yield stability. Results of additive main effects and
multiplicative interaction ( AMMI) analysis showed that out of 11 interaction principal component
axis (IPCAs) only the first two IPCAs were found to be highly significant and cumulatively contributed
58% of the total GEI while linear regression explained only 6% of the total GEI. Spearman’s
coefficient of rank correlation between mean yield and regression coefficient ( i
), stability variance
(2i ), ecovalence (Wi) and deviation from regression ( di
2 ) was positive and significant, but there
was non-significant correlation between mean yield and coefficient of variation (CV) and AMMI
stability value (ASV). Since ASV explains interaction effects and provides agronomically meaningful
insights into the data structure, it is better if used as stability measure for reliable selections of stable
genotypes. Based on most of the stability parameters estimated, the three-way cross maize hybrid,
CML78/390/202 and the late maturing maize OPV, ECA-144, were found to be the most stable.
Key Words: AMMI, ASV, GEI, Maize, IR, Stability, Striga
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Keywords
AMMI, ASV, GEI, Maize, IR, Stability, Striga