Physiological and Morphological Responses of Grain Sorghum to Varying Temperature, Irrigation and Carbon Dioxide Levels

ABSTRACT The increasing frequency and unpredictability of adverse growing conditions pose significant challenges to crop productivity and ecosystem sustainability. Early‐stage vigour strongly influences crop establishment and yield potential, making it essential to understand sorghum responses for developing resilient cultivars. This study examined physiological, morphological and biomass responses of 12 grain sorghum hybrids/inbreds to high temperature (HT), low temperature (LT), drought (DS), salinity (SS), low nitrogen (LN) and elevated CO 2 (eCO 2 ) comapred to control (CNT). Stomatal and non‐stomatal traits were assessed to determine their contribution to early growth performance. LT emerged as the most detrimental stress, causing the largest reductions in above‐ground biomass (76%) and canopy temperature regulation, while HT, SS, DS and LN also negatively affected shoot growth to varying degrees (> 20%). DS increased root biomass, whereas LT suppressed both shoot and root biomass. In contrast, eCO 2 had a minimal impact, with traits remaining largely comparable to those in CNT. Genotypes responses varied with stress: inbred SC35 maintained tolerance across multiple stresses, while RTx430 and LGS06B19 were highly susceptible. These results demonstrate that abiotic stresses significantly constrain early sorghum growth and development, with LT (chilling) being the most limiting factor. Identifying and using genotypes with broad early‐stage stress tolerance, such as SC35, will accelerate development of stress‐resilient cultivars under increasingly unpredictable growing conditions. Future work on combined stress effects is essential for developing multi‐stress resilient sorghum.