Relationship between kernel drydown rate and resistance to gibberella ear rot in maize

Development of gibberella ear rot (GER) resistant genotypes in maize is important to reduce yield loss and most importantly to avoid mycotoxin contamination of food and feed. The objective of the current study was to investigate the effect of kernel drydown rate (KDD) on GER disease development and to test whether using KDD as an indirect selection trait could warrant selection gains for GER resistance. Six inbred lines with various levels of disease resistance were evaluated for GER silk and kernel resistance and KDD as line per se and testcrosses in one location over three consecutive years. From our results, the genotypes showed significant differences (P < 0.05) to GER and KDD. Heritability estimates were high for GER and were consistently higher than estimates for KDD. Genotypic correlation estimates between GER and KDD, which were averaged over the 3 years were significant (P < 0.01, 0.05) only for kernel inoculated plots and the strength of correlations increased when kernels progress towards maturity. The indirect selection efficiency of KDD as compared to direct selection for GER was less than one but was substantially higher for kernel inoculated plots. Our overall result demonstrated that fast KDD was among the factors that contribute to kernel resistance to GER however its use as an indirect selection trait was less promising. Thus, screening for GER resistance using disease inoculated nurseries still remain to be the most effective method for GER breeding.