Abstract:

Chinese Wingnut (Pterocarya stenoptera) is one of the typical native species in the riparian zone of the Three Gorges Reservoir region. Its habitat has apparently been influenced by the abnormal water fluctuations annually. Four different kinds of water treatment simulating the dynamic change of soil water gradients in the riparian zone were applied to study the physiological and biochemical responses of Chinese Wingnut seedlings. The water treatments were normal growth water treatment (C), mild drought water stress (MD), wet soil (WS) and belowground submergence (BS). The results showed that water treatment, time, and the interaction of water treatment and time, had significant impact on growth, biomass, and contents of oxalate and tartarate in the roots (Pa < 0.001 or 0.01). Compared to C, height growth and biomass accumulation in MD, WS and BS were significantly decreased. However, content of oxalate in taproot, lateral roots, and total roots was significantly increased in MD, WS and BS, respectively. Likewise, content of tartarate in taproot, lateral roots, and total roots was also significantly increased in BS. Furthermore, the content of tartarate in lateral roots enhanced significantly in WS in contrast to a significant reduction of that in MD. As treatment continued to progress, contents of oxalate and tartarate in the roots displayed a decline trend. According to our results studied, although the Chinese Wingnut seedlings less than one-year-old are to some extent susceptible to submergence, wet, and/or drought, all of the seedlings could survive relatively well.

Key words: Three Gorges Reservoir Region, riparian zone, water stresses, Pterocarya stenoptera seedlings, oxalate, tartarate, physio-biochemistry