在保证有充足氧气的前提下 ,按正交设计 ,研究水质氨态氮浓度、pH值、盐度和温度四种环境因子 ,对实验感染暴发性流行病病原的中国对虾发病的影响。在感染的不同时期 ,这四种环境因子对带毒对虾死亡率的影响程度不同。感染后 3～ 4天 ,影响程度从大到小的次序为盐度、pH值、温度、氨态氮浓度 ,感染后 5天 ,影响程度从大到小的次序变为氨态氮浓度、pH值、温度、盐度。我们还进行了混合水平的正交实验 ,即在盐度水平不变 ,氨态氮浓度降到适宜的水平 ,再研究温度、pH值、氨态氮三种因子对带毒对虾的影响 ,结果表明 :三种环境因子的影响程度由大到小的次序为温度、氨态氮浓度和pH值 ,这与我国养殖对虾发病时间从南到北推移的现象相符合。还对环境因子与发病率和死亡率的关系进行了探讨 Under the premise of ensuring sufficient oxygen, the orthogonal design was used to study the effects of four environmental factors, ammonia nitrogen concentration, pH value, salinity and temperature, on the pathogenesis of epidemic encephalitis in China. The impact of these four environmental factors on the mortality of poisoned shrimp is different at different times of infection. From 3 days to 4 days after infection, the sequence of descending order of salinity, pH value, temperature, and ammonia nitrogen concentration varied from descending order to ammonia nitrogen concentration at 5 days after infection, and pH Value, temperature, salinity. We also conducted a mixed-level orthogonal experiment, that is, in the same level of salinity, ammonia nitrogen concentration dropped to a suitable level, and then study the temperature, pH, ammonia nitrogen three factors on infected shrimp, the results The results showed that the order of influence of the three environmental factors was temperature, ammonia nitrogen concentration and pH value, which accorded with the phenomenon that the onset time of P. shrimp in our country changed from south to north. The relationship between environmental factors and morbidity and mortality was also explored