Abstract: Populus bollena was very seriously subject to the broken and rotten trunks which urgently needed to be overcomed in forestry operations. Through investigation, it was found that there was a strong disease resistant variant of Populus bollena which was characterized by smooth bark with smaller lenticels on it.Combined with cultivation experiments, analyses were carried out to identify the structure, physiological and biochemical properties of the variant, including water status, permeability of protoplasmic membrance of cells, pH, quntity of phenal, carbohtdrate, cellulose, protein's fat and activity of phenaloxidase, hydrogen peroxide ensyme, and peroxidase.The result of analysis showed that the variant of Populus bollena with smaller lenticelle was more resistant to cold conditions and disease than those with larger lenticelle. It would be a new way select and to use the natural variant to solve the problem of broken and rotten trunks of Populus bollena.

Key words: Populus bollena, Broken and rotten, Lenticel, Physiological and biochemical properties