稻萍鱼体系中红萍供氮的特点

THE RELEASING PATTERN OF NITROGEN FROM Azolla IN RICE Azolla-FISH SYSTEM

应用^(15)N示踪技术,研究了稻萍鱼共生体系中红萍氮素的循环利用效率。试验结果表明,红萍作饵针对尼罗罗非鱼生长有良好效率,早、晚季稻田的鱼体增重率分别为47.9％和52.1％。鱼体排泄物对水稻生长有益,其稻谷产量与等量红萍压施作肥料的结果相近。早、晚季稻田罗非鱼对^(15)N-红萍的利用率分别为21.73％和23.76％,早、晚季水稻对鱼体排泄物中^(15)N利用率分别为18.90％和16.59％,其^(15)N总利用率分别达40.63％和40.35％。而红萍直接压施作肥料,早、晚季稻株对萍体氮素的利用率分别为28.84％和24.30％。

The releasing pattern of N from Azolla in Rice-Azolla-Fish system was studied.The results showed that Azolla had a good effect on the growth of rice and the fish weight was increased by 47.8%,52.1% during early and late season rice,respectively.The fish's excreta could be utilized as manure for rice growth after fish eating Azolla and the yield of grain was equal to that when Azolla was used as green manure.15N-Azolla utilization efficiency in Rice-Azolla-Fish system was 21.73%.and 23.8% by fish and 18.90% and 16.59% by rice during early and late season rice,respectively.When Azolla was used as green manure in early and late season rice,the 15N.utilization efficiency by rice was 28.8%,24.3% respectively.