Yield of maize ( Zea mays L.) logistically declined with increasing length of the consecutive visible wilting days during flowering

Under future climate conditions, the frequency and severity of drought are expected to increase. Maize ( Zea mays L.) is susceptible to drought, especially at flowering. The objective of this study was to investigate the effect of consecutive days of visible wilting (DAW) during tassel emergence using two types of Korean maize hybrids, Gwangpyeongok (Gwp; normal) and Ilmichal (Ilmi; waxy). Traits related to plant growth and yield were measured at harvest. Drought stress during tassel emergence significantly reduced the number of green leaves per plant. Silking was delayed due to drought stress during the stage of tassel emergence, although anthesis was only slightly affected, which resulted in an increase in the anthesis-silking interval (ASI). For each DAW, ASI increased by 1.6 days and 0.8 days for Gwp and Ilmi, respectively. The number of green leaves and ASI showed strong correlation with DAW length and grain yield, which suggested that those factors may be selective traits for drought tolerance at flowering. The filled grain number per plant declined logistically with increasing DAW due to reductions in kernels per row and percentage of filled grains. The filled grain number per plant significantly declined starting at 5 and 10 DAW in Gwp and Ilmi, respectively, which indicated that drought stress effects are dependent on drought severity and the genetic characteristics of specific hybrids. Probit analysis revealed that DAW causing 50% reduction in maize grain yield was about 4.7 and 6.3 days in Gwp and Ilmi, respectively, which resulted in about 13.6% and 9.2% reduction in grain yield per day of DAW, respectively. These results indicate that Gwangpyeongok is more sensitive to drought stress during flowering than Ilmichal.