Study On The Physiological Response And Quality Variation Characteristics Of Three Seawater Vegetables To Nitrogen-Phosphorus Nutrient Under Salinity

In this study, we took Salicornia bigelovii, Suaeda glauca and Atriplex triangularis as experiment materials. First, we studied that different concentrations of NaCl on growth, photosynthesis, mineral nutrition, ion absorption and distribution of the three plants; Second, we studied that different concentrations of nitrogen (N) and phosphorus (P) applications on growth, mineral nutrition of S. bigelovii and S. glauca under salinity; Finally, we studied that the seawater and marine aquaculture wastewater irrigation on the the plant growth, ion distribution and vegetables’quality. We aimed to comparative study the biological characteristics of three kinds of halophytes, the salt resistance and N, P nutrient regulation effect under salinity, and the practicability of seawater and marine aquaculture wastewater irrigation on three well-known seawater vegetables in Wenzhou beach zone. The main results were as follows:In this study, the growth of S. bigelovii, S. glauca and A. triangularis under different salinity showed different appearance obviously, and the plant biomass achieved to the highest value at400,100and50mmol·L-1NaCl respectively. We also found that the net photosynthetic rate achieved to the highest value at400,100and50mmol·L-1NaCl respectively. Observation by transmission electron microscope (TEM) showed that chloroplast outer membrane was damaged, some grana lamella structure became separated, even became disintegrated in shoot cells of S. bigelovii and S. glauca under the treatment without NaCl, but no damage in those of A. triangularis. S. glauca cells stayed normal in whole under50mmol·L-1NaCl treatment, however, under50mmol·L-1NaCl treatment, the A. triangularis chloroplast became swelling, and part of the lamella structure was damaged, but did not occur plasmolysis.When NaCl concentration is up to200mmol·L-1, chloroplast lamella structure in S. glauca leaf cell was disintegrated, cellular membrane was severely damaged, plasmolysis was happened. Similarly, under200mmol·L-1NaCl treatment, A. triangularis chloroplast obviously became swelling and deformation, and lamella structure was damaged too. But, S. bigelovii cells are basically normal under200mmol·L-1NaCl treatment. And when the concentration of NaCl reaches400mmol·L-1, plasmolysis phenomenon of S. bigelovii was occured, and under600mmol·L-1NaCl treatment, its cells severely damaged. To sum up from TEM observation, among three kinds of seawater vegetables on salt sensitivity, it showed that the A. triangularis>S. glauca>S. bigelovii. In the whole, with the NaCl concentration increased, Na+and Cl-concentrations in three plants were increased with varying degree, and K+and Ca2+concentrations in three plants were decreased. Under high salinity, nitrogen application did not promote S. bigelovii growth, but promote S. glauca growth. Nitrogen application obviously increased N and P contents in S. glauca under salt stress. We found that phosphorus application did not stimulate the growth of S. bigelovii and S. glauca. There were obvious differences among three seawater vegetables under seawater and saline aquaculture water irrigation. Compared with seawater irrigation, saline aquaculture water irrigation increased the total contents of amino acid in shoots of S. bigelovii and S. glauca, but decreased slightly the total content of amino acid in shoots of S. bigelovii. Under saline aquaculture water irrigation, the contents of Ala, Val, Ile, Leu, Phe were all increased in three plants, also, linolenic acid content was increased in in three plants. However, ash content was decreased in each plant, nitrate content was decreased markedly in shoots of S. bigelovii. Overall, S. bigelovii, S. glauca and A. triangularis are suitable for seawater and aquaculture water irrigation in Wenzhou beach.