氨氮浓度对金鱼藻生长及生理指标的影响

Effects of Ammonia Concentration on Growth and Physiological Indices of Hornwort Ceratophyllum demersum L.

为了探讨水中氨氮浓度对金鱼藻生长及生理指标的影响,采用静态水培实验方法,在水温(25±1.0)℃、p H7.25±0.37下,分别将35 g金鱼藻(Ceratophyllum demersum)放入10.0 L含0 mg·L^(-1)(对照组PC)、2.00 mg·L^(-1)、4.00 mg·L^(-1)、8.00 mg·L^(-1)、16.00 mg·L^(-1)和20.00 mg·L^(-1)NH_(4)^(+)-N的霍格兰氏培养液玻璃缸中。设置不加植物无NH_(4)^(+)-N的空白组(BC)。然后在不同时间测定金鱼藻生物量、水溶性蛋白、叶绿素、植物可溶性糖和脯氨酸含量,及水体中NH_(4)^(+)-N、NO_(2)^(-)-N和NO_(3)^(-)-N的浓度,比较金鱼藻对NH_(4)^(+)-N的去除效果。结果表明,在较低(2.00~8.00 mg·L^(-1))NH_(4)^(+)-N浓度下,金鱼藻生长良好,生物量提高,但在较高浓度(≥16 mg·L^(-1))下生长受到抑制。五个处理组中的NH_(4)^(+)-N浓度均随培养时间延长而下降,NO_(2)^(-)-N和NO_(3)^(-)-N浓度均呈先升高后降低的趋势。培养21d,金鱼藻对NH_(4)^(+)-N的去除效率随水溶液中NH_(4)^(+)-N浓度的增加而逐渐降低。随着NH_(4)^(+)-N浓度的增加,金鱼藻的可溶性蛋白、叶绿素a、总叶绿素、植物可溶性糖和脯氨酸含量均逐渐降低,最大值均出现在2.00 mg·L^(-1)浓度组。研究表明,低浓度NH_(4)^(+)-N能够促进金鱼藻的生长并被其利用合成细胞物质;适宜pH条件下,金鱼藻能够耐受超富营养水平(20.00 mg·L^(-1))的氮胁迫。

In order to probe for the effects of ammonia concentration on the growth and physiological indices of aquatic plant hornwort Ceratophyllum demersum L.,the hornwort was placed in a 10.0 L glass jar containing 0 mg·L^(-1)(control PC),2.00 mg·L^(-1),4.00 mg·L^(-1),8.00 mg·L^(-1),16.00 mg·L^(-1)and 20.00 mg·L^(-1)NH_(4)^(+)-N Hoagland medium at density of 35 g at water temperature of(25±1.0)℃and pH of 7.25±0.37 by a hydroponic culture.There was a blank group(BC)without addition of plants and without NH_(4)^(+)-N.Then the contents of phytomass,water-soluble protein,chlorophyll,plant soluble sugar and proline,and the changes in ammonia concentration and nitrogen removal efficiency were determined during this hydroponic culture process.The results showed that the hornwort had good growth and the phytomass was increased when the concentrations of ammonia were changed between 2.00~8.00 mg·L^(-1),but it was inhibited in higher ammonia aqueous solution(≥16.00 mg·L^(-1)).The ammonia concentrations in five treatment groups were all decreased with time,whereas the and NO_(3)^(-)-N concentrations were all increased first and then decreased as exposure time increases.With the increase in ammonia concentration,the contents of soluble protein,chlorophyll a,chlorophyll c,plant soluble sugar and proline were found to be decreased gradually,with the maximum values in 2.00 mg·L^(-1)group.This finding indicated that low concentration of ammonia promoted the growth of hornwort and used to synthesize cellular substances.The hornwort appeared to withstand the ultra-eutrophic nitrogen stress(20.00 mg·L^(-1))under suitable p H.