Differences in physiological characteristics of Populus×euramericana varieties ‘Purui’ and ‘107’ under simulated acid rain stresses

We analyzed changes in the physiological indexes of Populus×euramericana varieties ‘Purui’ and ‘107’ under different degrees of acid rain stresses. The experiment established three different acid rain gradients (CK, moderate stresses, severe stresses). Under severe stresses, the leaf surface of ‘Purui’ showed sporadic dry spots, whereas ‘107’ already showed symptoms under moderate stresses. Under an acid environment, ‘Purui’ exhibited a certain resistance to acid rain and maintained normal growth and photosynthetic capacity after moderate and severe stresses. However, for ‘107’, acid rain caused a significant decrease in photosynthesis, with non-stomatal factors found to be the main reason leading to its decline. Furthermore, acid rain impacted the water balance, especially for ‘107’, but stomatal closure was not the main reason for the decline in photosynthesis intensity. Thus, ‘Purui’ expressed significantly stronger resistance to acid rain than ‘107’.