Using the methods introduced by Bier, X.H., Buchinock, Wang Jing-wen, Shi Rihe et al., different varieties of poplar (poplar-Mei譗ing, Poplar-A100, Poplar-Xiaohe14 et al.) were inoculated with poplar ice nucleation active (INA) bacteria respec-tively in 1997-1999. The water content, relative turgidity, lignin content, phenylalanine ammonialyase (PAL) activity, electrolyte effusion rate, and inorganic element content of poplar bark were measured before and after inoculating. The results showed that after the poplar trees were inoculated with INA bacteria, the moisture content of bark decreased but relative turgidity increased, electrolyte effusion rate increased and had a peak at temperatures of 4 and 5 C, lignin content increased and positively cor-related with poplars disease-resistance, and the plenylalanine ammonialyase activity increased and also showed a significant positive correlation with poplars disease-resistance. For the contents of inorganic element, Cu and Fe decreased but K and Zn increased obviously, while Mn, Ca and Mg changed little.
