Nano-Calcium Enhances Drought Tolerance by Regulating Photosynthesis and Amino Acid Metabolism In Brassica napus - Ahsan Ayyaz; Iram Batool; Tongjun Qin; Kangni Zhang; Weiqi Chen; Zafar Ullah Zafar; Basharat Ali; Muhammad Ahsan Farooq; Fakhir Hannan; Weijun Zhou (Journal of Plant Growth Regulation, 2026)