Contribution of Stem Borer Damage Parameters and Agronomic Traits to Grain Yield Reduction in Maize (Zea mays L.)

Abstract

A study was conducted at IITA Ibadan in 2009 and 2010 to determine the contributions of agronomic and
damage parameters to grain yield reduction due to infestation by two stem borer species (Sesamia calamistis
and Eldana saccharina) in a yellow maize population, DMR ESR-Y. This aims at identifying the most
important damage parameter(s) contributing to grain yield reduction in maize.
The result of analysis of variance revealed significant difference among the maize entries for days to 50%
silking, plant height, grain yield, stalk breakage and stem tunneling. Mean square of entry by environment was
significant for cob damage. Damage parameters had negative correlations with most agronomic traits. Grain
yield was also negatively correlated with damage parameters with the highest being between grain yield and
stem tunneling (rp = -0.25*, rg = -0.52**), followed by cob damage (rp = -0.20*). Correlations among damage
parameters were however positive.
Path coefficient analysis revealed that plant height and ears per plant had relatively high negative direct effect
on grain yield reduction. Stem tunneling had the highest positive direct effect on grain yield loss (0.106) among
damage parameters, followed by cob damage (0.028). This indicates that the direct contribution of stem
tunneling and cob damage accounted for about 85% and 68% of the total correlation between stem tunneling
and grain yield reduction, and cob damage and grain yield reduction respectively. When the effects of only the
damage parameters were considered, stem tunneling also had the highest direct effect (0.094) accounting for
over 90% of the total correlation, followed by cob damage (0.033) which accounts for 80.5% of the total
correlation. The results of this study indicated that both stem tunneling and cob damage due to stem borer
infestation are the most important damage parameters contributing to grain yield reduction in maize and could
therefore be used as selection criteria in breeding for stem borer resistance.