浮萍放养体系中氮的平衡与浮萍体内氮的亚细胞分布研究

采用15N示踪技术研究了浮萍放养体系中氮的平衡与浮萍体内氮的亚细胞分布.结果表明,两个不同氮浓度处理浮萍的含氮量分别为3592.0和3366.0 mg/kg FW、标记氮的吸收量分别为每瓶0.2919和0.3031 mg,差异不大,可能与处理浓度较高,已能满足浮萍对氮的需求有关.两个处理未能回收的15 N量也比较接近,分别为每瓶0.8921和0.8206 mg,由于溶液pH控制在5.5左右,氨挥发作用十分有限,可以认为是由硝化-反硝化作用所致.研究还发现,浮萍吸收的外源15N标记铵态氮主要分布在可溶性组分中,即细胞质液和液泡溶液中,以可溶性蛋白质(包括酶)、多肽和游离氨基酸等形态存在,这有利于浮萍的资源化利用.

Studies on nitrogen balance in duckweed-nitrogenous solution system and the subcellular distribution of absorbed nitrogen in duckweed (Spirodela oligorrhiza ) plants

With the15N tracer technique,nitrogen balance in duckweed-nitrogenous solution system and the subcellular distribution of absorbed nitrogen in duckweed(Spirodela oligorrhiza) plants were investigated.The results indicated that N content and15N absorbed in duckweed plants at two treatments(where the concentrations of N were 28 and 56 mg/L) did not differe significantly,as N concentrations were high enough to meet the N need of duckweed plants.The uncovered15N in two treatments were also similar,which seemed to result from the denitrogenation through nitrification-denitrification processes that occurred in the system since the ammonium volatilization was limited under condition of solution pH 5.5.Approximately,98% of NH4+-15N absorbed by duckweed plants existed in the soluble fraction of the plant body(e.g.plasmic and vacuole saps),being associated with soluble proteins(including enzymes),peptides,and free amino acids,which is favorable to utilization of duckweed plants as one of feed resources.