Interactive Effects on CO2, Drought, and Ultraviolet-B Radiation on Corn (Zea mays) Growth and Development.

Crop growth and development are highly vulnerable to global climate change components such as elevated carbon dioxide (CO₂), drought, and ultraviolet-B (UV-B) radiation. Interactive effects of these factors are clearly unknown to date. The objectives of this study were to test the hypothesis that corn hybrids differ in their response to multiple environmental factors of (CO₂) [400 and 750 µmol mol⁻¹ (+(CO₂)], irrigation treatments based evapotranspiration (ET) [100 and 50% (-ET)], and UV-B radiation [0 and 10 kJ m⁻² d⁻¹ (+UV-B)]. Six corn hybrids (P1498, DKC 65-81, N75H-GTA, P1319, DKC 66-97, and N77P-3111) with known drought tolerance variability were grown in seven sunlit, controlled environment chambers in which control treatment consisted of 400 µmol mol⁻¹ [CO₂], 100% ET-based irrigation, and 0 kJ UV-B. Plants grown at +UV-B alone or combination with -50% ET produced shorter plants and smaller leaf area while elevated CO₂ treatments ameliorated the damaging effects of drought and higher UV-B levels on corn hybrids. Total stress response index (TSRI) for each hybrid, developed from the cumulative sum of response indices of vegetative and physiological parameters varied among the corn hybrids. The hybrids were classified as tolerant (P1498 and DKC 65-81), intermediate (N75H-GTA) and sensitive (P1319, DKC 66-97, and N77P-3111) to multiple environmental stresses. The differences in sensitivity identified among the corn hybrids imply the options for selecting hybrids with tolerance to multiple environmental stresses projected to occur in future climates.