The influence of application hyperaccumulator plant straw on photosynthetic pigment content and photosynthetic parameter of lettuce under cadmium stressLe Liang, Qiaoman Ao, Ying Zhu, Yan Zhao, Ran Zhang and Yi TangE3S Web Conf., 136 (2019) 07007DOI: https://doi.org/10.1051/e3sconf/201913607007