| 摘要: |
| 于1984年5-7月在青岛麦岛氮营养盐贫瘠的海区，对人工养殖的龙须菜进行间歇施肥现场实验。结果表明，龙须菜可以在短时间里快速吸收氮盐并累积在藻体内以用于生长；经间歇施肥的藻体生长较快，产量校对照组的高88％；藻体化学组成分析结果显示，龙须菜体内含氮化合物和碳水化合物组成呈现负相关变化，存在氮低糖高、糖低氮高的现象。以上结果提示，对氮盐贫瘠海区人工养殖的龙须菜间歇施肥，可以促进藻体生长，提高产量；在养殖后期适时停止施肥，有利于藻体累积碳水化合物，从而达到提高琼胶产量的目的。 |
| 关键词: 龙须菜 人工养殖 间歇施肥 琼胶 |
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| EFFECT OF INTERMITTENT NITROGEN FERTILIZATION ON GROWTH AND CHENHCAL CONSTITUENTS OF GRACILARIA LEMANEIFORMIS |
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HUANG Xiao-hang,WEN Zong-cun,PENG Zuo-sheng,WU Chao-yuan
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Institute of Oceanology,The Chinese Academy of Sciences,Qingdao,266071
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| Abstract: |
| The effect of ammonium nitrogen fertilization on growth and chemical constituents of cultured Gracilaria lemaneiformis was studied using the data collected from the Maidao area in Qingdao from May to July, 1984. The thalli were tied on floating ropes and kept 0.5 - 1m underneath the sea surface The total nitrogen level (NH4-N + NO3-N) in ambient seawater was 0.93 - 2.44 μmol/L and the seawater temperatures were 14.9 - 20.8°C during the experiments. For the nitrogen fertilized group, the thalli were intermittently immersed in the seawater with a NH4Cl concentration of 10 mmol/L for 1 hour at 3-day intervals. The samples for chemical analysis were collected before fertilization. For every 6 - 9 days, the weight and length of the thalli were measured and growth rates calculated. The results show that the fertilized thalli had an average growth rate of 8.6% per day, 1.2% higher than the unfertilized group. This growth rate was close to that cultivated in the nitrogen rich Pier area (Tab. 1). At the end of the experiment, the average biomass of fertilized thalli was 687 g/rope. It was 88% increase over that of the control group. Chemical analysis shows that there were slightly higher levels of total nitrogen (Tab. 2) and protein content (Tab. 3) in fertilized thalli, indicating that the absorbed nitrogen was mostly utilized for growth. The total carbohydrate and low molecular weight carbohydrate contents were slightly higher in the control group (Tab. 3). An inverse relationship of total nitrogen with total carbohydrates and proteins with low molecular weight carbohydrates was observed (Fig.1). The accumulation of nitrogen in fertilized thalli at later periods of cultivation suggests that to halt nitrogen fertilization at this time may help the accumulation of polysaccharide and increase the output of the agar. For efficient nitrogen fertilization, different methods for evaluating critical nitrogen point are discussed; the simplest way is observing the thalli pigments variation in order to determine the proper time and strength of nitrogen application. |
| Key words: Gracilaria lemaneiformis, Aquaculture, Intermittent fertilization, Agar |
