[Adaptation of Suaeda salsa to water/sediment conditions and nitrogen input in tidal flat wetlands in the Yellow River Delta, China]

The application of Water-Sediment Regulation Project provides abundant freshwater for the Yellow River Delta, changes water and sediment condition, as well as brings lots of exogenous substances. Using orthogonal test with three factors and four levels, we examined the effects of water condition, sediment burial depth and exogenous nitrogen input on the growth of wetland plant, Suaeda salsa. The results showed that sediment burial had great effect on protein content and SOD activity. Nitrogen input had great effect on POD activity. CAT activity was not affected by sediment burial, nitrogen input and water depth. The water depth manipulation had significant effect on leaf, stem and total dry weight. With the increases of water depth, leaf, stem and total dry weight showed a decreasing trend, with the maximum values (25.70, 40.86, 69.73 g) at the 2 cm water depth. There was no effect of nitrogen input and sediment burial on dry weight. The results of range analysis showed that the effect of water depth on leaf, stem, root and total dry weight was great, and followed by nitrogen input and sediment burial, with an optimal combination of 2 cm water depth +12 cm sediment burial + 9 g·m^-2 nitrogen input. These findings suggested that water condition played a decisive role in affecting the growth of S. salsa. Consequently, more attention should be paid to the control of water depth in the process of water and sediment regulation.