Abstract: This paper studied the effects of Colletotrichum higginsianum infection on the ethylene production and the contents of abscisic acid (ABA) and indole3acetic acid (IAA) in leaves of flowering Chinese cabbage (Brassica parachinensis) under six levels of nitrogen (N) nutrition,and their relations to disease-resistance.The results showed that the ethylene production in all N treatments had a mono-peak curve change,and reached the maximum 4～6 days after inoculation.In comparing with high N or non-N treatment,medium or low N treatment could inhibit ethylene production and ABA synthesis,and keep ethylene and ABA stable in Colletotrichum higginsianuminoculated plants.The IAA content in medium or low N treatment increased gradually, while that in high N or non-N treatment had a mono-peak curve change,and reached the maximum 4～6 days after inoculation.The IAA content in medium or low N treatment increased more with inoculation time,indicating that there was a close relationship among N nutrition,endogenous hormones and anthracnose.It is important for plants' diseaseresistance to keep the balance of endogenous hormones.

Key words: Forest soil, Polyphenols, Ecological regulation, Secondary mestabolite