3种氮源加富对半叶马尾藻幼苗生长和生化组成的影响

Effects of enrichment with three nitrogen sources on growth and biochemical composition of Sargassum hemiphyllum seedlings

中文关键词: 半叶马尾藻  N源  加富  生长  生化组成

英文关键词: Sargassum hemiphyllum  Nitrogen source  Enrichment  Growth  Biochemical composition

中文摘要:

      为了探讨硝氮(NO3-N)、氨氮(NH4+-N)和尿素氮(Urea) 3种氮(N)源对半叶马尾藻(Sargassum hemiphyllum)幼苗生理特性的影响，在实验室条件下，把幼苗分别置于不同N源浓度中培养24 d，而后测定藻体的生长和生化组成含量。结果显示，不同N源和N浓度对幼苗的生长和部分生化组成有显著影响。3种N源加富均能促进幼苗的生长和组织N的增加，相对生长速率随着N浓度的升高而增加，在浓度为25~150 μmol/L组中，幼苗的组织N增加量接近或超过每天以最大速率生长的N需求(0.032 %/d)；在浓度为50 μmol/L时，相对生长速率达到最大值，Urea组的最大相对生长速率显著低于NO3-N和NH4+-N组；在浓度为10、25 μmol/L时，NH4+-N组幼苗的相对生长率显著高于相同浓度下的NO3-N组，而在浓度为50~150 μmol/L时则相反。除了最高浓度组(150 μmol/L)，随着N浓度的升高，幼苗光合色素、可溶性蛋白和组织N含量逐渐增加，而可溶性糖含量逐渐降低；在相同N浓度下，NO3-N加富幼苗的可溶性糖、叶绿素a和叶绿素c含量最高，NH4+-N加富时，可溶性蛋白和组织N含量最高，而Urea加富下墨角藻黄素含量最高。当NH4+-N浓度增加至 150 μmol/L时，幼苗的生长和可溶性蛋白含量下降幅度最大。研究表明，将培养水体中NO3-N加富至50~150 μmol/L或NH4+-N加富至25~100 μmol/L时，可有效促进半叶马尾藻幼苗的生长、光合作用和物质积累，为室内幼苗顺利度夏培育提供保障。

英文摘要:

      To investigate the effect of nitrogen sources (NO3-N, NH4+-N, and Urea) on the physiological characteristics of Sargassum hemiphyllum seedlings, the seedlings were cultured for 24 days in different concentrations of each nitrogen (N) source, and the growth rate and biochemical composition were determined. The results showed that the N source and N concentration had significant effects on the growth rate and biochemical composition of the seedlings. With increasing N concentrations, the relative growth rates and tissue N contents of the seedlings increased, and when tissue N contents approached or reached N requirement (0.032%/d) for the maximum growth rate in 25~150 μmol/L, the relative growth rates reached the maximum at 50 μmol/L. The maximum relative growth rate under Urea enrichment was significantly lower than that under NO3-N and NH4+-N enrichments. The relative growth rate of the seedlings in 10 and 25 μmol/L NH4+-N was significantly higher than that in the same concentration of NO3-N, but the relative growth rate in 50~150 μmol/L showed an opposite change. Except for the highest N concentration (150 μmol/L), the photosynthetic pigments, soluble protein, and tissue nitrogen contents gradually increased, while the soluble sugar content gradually reduced as N concentration increased. At the same N concentration, the contents of soluble sugars, chlorophyll a, and chlorophyll c of seedlings were the highest under NO3-N enrichment, the contents of the soluble protein content and tissue N content were the highest under NH4+-N, and the fucoxanthin content was the highest in Urea-enriched culture medium. When the NH4+-N concentration reached 150 μmol/L, a significant decrease in growth and soluble protein content was observed, indicating the presence of a stressful condition. In conclusion, culture medium enriched in NO3-N (50~150 μmol/L) or NH4+-N (25~100 μmol/L) promoted the growth, photosynthesis, and dry-matter accumulation of S. hemiphyllum seedlings, suggesting that the seedlings may be successfully cultured indoors during summer.