Effects of Nitrogen and Phosphorus Addition on Photosynthetic Characteristics and Antioxidant System of Suaeda salsa in the Yellow River Delta

PurposeTo study the effect of nitrogen (N) and phosphorus (P) addition on photosynthetic characteristics and antioxidant system of Suaeda salsa in the Yellow River Delta.

MethodsA field experiment with N addition (0, 5, 15, 45 g/m², respectively) as the main plot, and P addition (0 and 1 g/m², respectively) as the subplot, was carried out with a split-plot design to investigate the effects on the growth, photosynthetic characteristics, and antioxidant system of S. salsa.

ResultsN addition significantly increased the biomass and plant height of S. salsa, and had a significant interaction with P addition. The highest biomass and plant height were found in the treatment with 45 g/m² of N application combined with P. When the P was added, the content of chlorophyll a, chlorophyll b, and carotenoids in the treatment with 45 g/m² of N addition were significantly increased by 84.0%-408.4%, 99.0%-499.6%, and 71.9%-269.9%, respectively, compared to other N treatments. N addition significantly increased the net photosynthetic rate of S. salsa leaves, and there was a significant interaction between N and P in chlorophyll content, transpiration rate and leaf water use efficiency. The treatment with or without P addition at the 45 g/m² of N addition significantly increased the peroxidase activity of leaves, and there was a significant interaction between the N and P addition on superoxide dismutase and peroxidase activities.

ConclusionN and P addition can effectively increase the chlorophyll content, photosynthesis and antioxidant enzyme activities of S. salsa, to adapt to the saline habitat and promote its growth.