Response of Quercus acutissima foliage to different types of simulated acid rain

摘要

Highlights Simulated acid rain changed the morphophysiological traits of Quercus acutissima aboveground. The high acidity was responsible for the plant significant response. NO3- concentration alleviated the adverse effects of low acidity on the plant.The harm of acid rain (AR) to plants foliage is mainly manifested by changing their physiological and biochemical processes, such as chlorosis, nutrient loss, enzyme activity changes, etc., which in turn impacts plant growth. Since the types of AR in China is changing, the response of plants to different types of AR has become a research hotspot. In this research, we investigated the responses of Q. acutissima foliage to simulated AR with different SO42−/NO3−(S/N) ratios and pH through chlorophyll contents, chlorophyll fluorescence characteristics, malondialdehyde content and antioxidant enzyme activities. The results showed that the maximal photochemical efficiency of PSⅡ (Fv/Fm) and superoxide dismutase (SOD) activity of Q. acutissima gradually decreased as the increase of NO3− concentration. With the decrease of AR pH, the inhibitory effect of simulated AR on growth rate and photochemical quenching coefficient (qP) gradually increased, and it also induced the increase of SOD and catalase (CAT) activities. Besides, pure NAR with low acidity (pH = 4.5) significantly increased basal diameter growth rate (DGR), chlorophyll content, peroxidase (POD) activity and qP, while decreased Chla/Chlb, fluorescence efficiency, non-photochemical quenching coefficient (NPQ), malondialdehyde (MDA) content and SOD activity. Correlation analysis indicated that the growth rate, chlorophyll content and fluorescence characteristics of Q. acutissima were highly correlated with foliar antioxidant enzyme activities under simulated AR stress. Our results indicated that different types of simulated AR had discrepant influences on the foliage physiological characteristics and above-ground growth of Q. acutissima, but not always negative, which made the protection of Q. acutissima plantation more complicated.