Effect of Acid Stress on Physiological Characteristics of Hedera nepalensis var. Sinensis

Using the Hedera nepalensis var. sinensis cuttings as the hydroponic materials, setting three treatments with different degree of acid stress (pH 6.0 (CK), pH 5.0 and pH 4.0) for 15 days, to study the effects of different degree acid stress on the physiological characteristics of Hedera nepalensis var. sinensis. Exploring its physiological mechanism under acid stress, and promote its application in acidic environments. The results showed that: Compared with CK, the contents of photosynthetic pigments were decreased significantly under acid stress. The non-photochemical quenching coefficient, electron transfer rate, net photosynthetic rate, transpiration rate, and stomatal conductance were all significantly reduced. The contents of malondi-aldehyde and the soluble substances increased markedly. In addition, the activities of Peroxidase, Ascorbate Peroxidase, Catalase, and Superoxide Dismutase were also increased markedly under each acid treatment. In this experiment, the intensification of acid stress leads to damage in the photosynthetic system, which weakens both the photochemical efficiency and electron transfer rate. Additionally, it reduces the content of photosynthetic pigments. Concurrently, the lipid peroxidation reaction becomes more intense, increasing the accumulation of MDA. Hedera nepalensis var. sinensis plants can adapts to acidic environments by elevating the activities of antioxidant enzymes and the content of osmoregulatory substances.