Abstract:

To explore the effects of nitrogen and phosphorus inorganic salts in MS medium on the growth of Zostera marina, the young ramets of Z.marina were cultured in natural seawater with different concentrations of KNO₃, NH₄NO₃ and KH₂PO₄ , respectively, and the morphological observation was conducted and leaf chlorophyll content was determined at 7 and 14 days; among them, the addition of KNO₃ was 1/2, 1 and 2 times as much as that of MS medium, and the total concentration of NO₃^- was 39.4 mmol/L, while the addition of KH₂PO₄ and NH₄NO₃ was 1/2, 1 and 2 times as much as that of MS medium respectively. The results showed that: the chlorophyll content in KNO₃ treatment group was the highest (P<0.05), the developing ramets were cultured for 14 days without toxic phenomenon and new leaves sprouted; however, the NH₄NO₃ and KH₂PO₄ treatment groups both had obviously toxic effects on the ramets; the leaves of ramets began to brown after culturing for 48 h in NH₄NO₃ treatment group; subsequently, the tips of root and rhizome softened and began to brown after 7 days of incubation and finally the ramets’ shoots died after 14 days; while the ramets’ leaves of KH₂PO₄ treatment group had the average browning rate up to 56% after culturing 14 days. Thus, neither 1/2 MS medium nor MS medium is suitable for in vitro culture of Z.marina, and the nitrogen source of the culture medium is suggested as addition of NO₃^--N alone or a high concentration NO₃^--N with a low concentration of NH₄⁺-N.

Key words: Zostera marina, Developing Ramets, MS Medium, Nitrogen Inorganic Salt, Phosphorus Inorganic Salt, Indoor Culture