Effects of exogenous indole-3-acetic acid on the photosynthesis characteristics of lettuce under cadmium stressGuochao Sun, Yan Wang, Xiaohan Wei, Yunying Xiao, Xiangting Xu and Yi TangE3S Web Conf., 136 (2019) 07003DOI: https://doi.org/10.1051/e3sconf/201913607003