氮素浓度对大白菜小黑点病发生的影响

摘要：研究了大白菜抗小黑点病品系C24、P8-1和感小黑点病品系03B9、P8-2，在氮素浓度为5(N5)、15(N15)、25(N25) mmol/L的水培条件下，对叶柄铵态氮、电导率、丙二醛含量和多酚氧化酶活性的影响及其与小黑点病发生的关系。结果表明，随氮浓度的增大，小黑点病发病加重。抗病品系随时间延长，铵态氮含量逐渐下降，C24在N25浓度下，第14天含量仅是第2天的49.95%。氮浓度对感病品系03B9和P8-2的细胞膜透性和MDA含量的影响比抗病品系C24和P8-1大，感病品系细胞膜结构遭到破坏，可能是小黑点发生的原因。

Effects of Various Nitrogen Levels on Petiole Spot in Chinese Cabbage

The effects of three nitrogen（N） levels （5,15,25 mmol/L）hydroponic culture on cell membrane permeability, activities of polyphenoloxidase（PPO）, content of ammonium nitrogen and malondialdehyde （MDA） in Chinese cabbage disease-susceptible inbred lines 03B9 and P8-2 and disease-resistant inbred lines C24 and PS-1, and the relationship with petiole spot were studied. The experimental results showed that high nitrogen level can increase the number of petiole spots. The content of ammonium nitrogen in disease-resistant varieties continuously decreased and on the 14th day ammonium nitrogen of the treatment N25 is 49.95% of the second day in C24.03B9 and P8-2 are more significant than C24 and PS-1 on the effects of nitrogen on cell membrane permeability and MDA, so petiole spot may caused by the broken membrane.