EFFECTS OF SIMULATED ACID RAIN ON PHYSIOLOGICAL CHARACTERISTICS AND ACTIVE INGREDIENT CONTENT OF ASPARAGUS COCHINCHINENSIS (LOUR.). MERR

The effects of simulated acid rain at pH 2.0, 3.0, 4.0, 5.6 and 6.8(control) on the morphological characteristics, chlorophyll content, resistance physiology and active ingredient content of A. cochinchinensis cultured in pots were studied so as to explore the sensitivity and tolerability of A. cochinchinensis to acid rain with the hope to provide the theoretical basis for the cultivation of A. cochinchinensis. The results showed that 1) compared to the control, acid rain with pH 5.6 did not significantly affect the shape and color of the leaves as well as the contents of amino acids and soluble sugar in tuber roots of A. cochinchinensis, but significantly enhanced the activities of superoxide dismutase (SOD) and peroxidase (POD), and 2) with the increase of acid rain stress (pH <= 3), the damage degree of leaves and the content of malondialdehyde (MDA) in leaves gradually increased, but the photosynthetic pigment content, stem length, root weight increment, POD and SOD activities, as well as contents of amino acids, soluble sugar and saponin in tuber roots all decreased. The experiments indicated that 1) acid rain significantly affected the physiological characteristics and active ingredients accumulation of A. cochinchinensis, 2) A. cochinchinensis showed a certain resistance to acid rain, 3) pH <= 3 is the critical point (threshold) for acid rain to damage A. cochinchinensis, and 4) artificial cultivation of A. cochinchinensis should avoid medium and strong acid rain pollution.