| Impacts of climate change and management parameters on physiology, growth, development, and yield of cotton (Gossypium hirsutum L.), maize (Zea mays L.), and sorghum (Sorghum bicolor (L.) Moench) were assessed at various U.S. locations using GOSSYM and EPIC/ALMANAC crop models. Seasonal, interannual, and geographical variabilities of weather parameters were assessed. Environmental criteria parameters were developed to measure environment's thermal suitability for crop growth and development. Average air temperature (Tavg) decreased northward, increased westward, and correlated positively with, and lagged behind, solar radiation (Irad), which decreased northward and increased westward. Precipitation (PPT) and windspeed were highly variable, but generally increased northward, and decreased westward.; Yield responses to changes in individual weather and management parameters were simulated in sensitivity analyses to identify physical and physiological mechanisms, limiting factors (environmental stresses), and cause-effect relationships within the current climate. Yields generally correlated positively with atmospheric [CO2], irrigation, fertilization, and early planting, and peaked or correlated negatively with optimal temperature. However, maize and sorghum yields decreased at high [CO2]. Irad and Tavg correlations were negative for rainfed (RF) and positive for irrigated (IR) yields; PPT correlations were positive for RF and weak/negative for IR yields. IR-RF yield difference, measuring drought stress severity, correlated positively with Irad and Tavg and negatively with PPT. Maize and sorghum (C4) were more drought tolerant than cotton (C3).; Baseline simulations assessed interannual variability, climatic extremes, irrigation-geography interactions, and climate change impacts on yield. Yields correlated positively with growing season length and negatively with heat/cold/drought stresses. High-temperature stress and growing season length decreased northward. Moving westward, RF yields decreased via increased high-temperature/drought stress; IR yields increased via increased Irad, photosynthesis and growth. Yields correlated positively with photosynthesis, evapotranspiration, vegetative/reproductive growth processes, and hastened maturity. Water use efficiency correlations were negative for RF and positive for IR yields; RF yield correlated negatively with drought-stress days; IR yield correlated positively with irrigation days. Future climate change shifted ideal crop locations northward and altered optimal management practices. Proposed future strategies include increased irrigation/fertilization, earlier planting, and breeding for improved heat/cold tolerance. |
