Flooding temperature affected corn (Zea mays L.) emergence and root growth

Abstract Background and aims Early season weather fluctuations significantly impact corn ( Zea mays L.) seedling establishment and soil nitrogen availability. This study investigated the effect of flooding duration and temperature after planting on corn emergence, seedling biomass and soil inorganic nitrogen content supplemented by polymer-coated urea fertilizer. Methods A controlled environment experiment was conducted using a split-plot randomized complete block design. Corn seeds were planted in soil trays and maintained at temperatures of 5, 12.5, 20, 27.5, or 35 °C in five temperature-controlled chambers during the first four days after planting. Within each chamber, trays were flooded for 0, 1, or 3 days. Trays were relocated to a 25 °C greenhouse for 14 days and assessed for emergence and seedling growth. Soil samples were collected post-flooding and at seedling termination for nitrogen analysis. Results Final emergence remained above 80% when flooded for up to 3 days at temperatures ≤ 12.5 °C. In contrast, flooding reduced final emergence to 35–55% at 20 °C and to 0–8% at temperatures ≥ 27.5 °C. Despite maintaining high emergence rates at cooler temperatures (≤ 12.5 °C), flooding reduced root biomass by 20–60% compared to non-flooded conditions, while shoot growth remained unaffected. At seedling termination, soil NO 3 -N had accumulated significantly under flooding at 27.5 °C, while NH4-N concentration and the NO 3 -N: NH 4 -N ratio remained consistent across all treatments. Conclusion These findings suggest that early season flooding is more detrimental to corn emergence at warmer temperatures. Although emergence remained high under cooler temperatures, impaired root development indicates the substantial risks of stand establishment and nutrient uptake under excessive soil moisture conditions.