Preliminary Study On Insect Resistance Of Populus Szechuanica Schneid

There are more species of poplar in our province and some of them have a long history of cultivation, but most are exist obvious shortcoming on insect resistance. In order to improve the structure and insect resistance of poplar, a new species named Populus szechuanica schneid was introducted from Tibet.The planting character was determined through the research of photosynthesis on Populus szechuanica schneid, which layed a foundation for insect resistance study,the ability against plagiodera versicolora and Anoplophora glabripennis was studied by observation their harm state on Populus szechuanica schneid. In order to study the relationship between the change of some indexes of Populus szechuanica schneid and the harming level of the twe pests, the moisture content, the wood volume, and the protective enzymes of plagiodera versicolora and Anoplophora glabripennis feeding Populus szechuanica was detected in laboratory test, the main conclusions were as fallows:1 By observation the physical properties and anatomy of Populus szechuanica schneid and the control tree, Populus szechuanic schneid had obvious advantage on insect resistance which could make full use of insect characteristic to prevent insect invasion in the course of planting.2 The photosynthesis characteristics of Populus szechuanica schneid and Fast Growing Poplar (Zhonglin-46) were both a bimodal curve, the first peak appeared at 9:00 and 10:00 with 17.45μmol/(m2·s)and 18.27μmol/(m2·s) respectively.The second peak was lower than the first one. Diurnal changes of transpiration rates appeared a single peak and the peak value appeared at 11:00 at the same time, Populus szechuanica schneid was 9.77mmol/(m2·s) and Fast Growing Poplar (Zhonglin-46) was 4.67mmol/(m2·s). There was a great correlation between Zhonglin-46 and environmental and Physiological factors compared with Populus szechuanica schneid.3 3 Fecundity of Populus szechuanica schneid was lower than that on Fast Growing Poplar (Zhonglin-46)indoor, there were some differences on survival of plagiodera versicolora that feeding on Populus szechuanica schneid and Fast Growing Poplar (Zhonglin-46). There were clearly differences on fecundity and food consumption of Anoplophora glabripennis that feeding with Populus szechuanica schneid and poplar tomentosa . 4 After eating Populus szechuanica schneid, the enzyme of SOD and CAT rised at first and lowered later and decreased at last, but POD was increased at first stage and then maintained in a lower level. Except POD of third instar larvae was higher than feeding by Fast Growing Poplar (Zhonglin-46), others were all lower. Three enzymes in third and second instar larvae of plagiodera versicolora were higher than that in the second generation adults.5 Althought the three enzymes changes of Anoplophora glabripennis after feeding Populus szechuanica schneid were to be in conformity with that feeding by Populus tomentosa, the change level was stronger than that feed with Populus tomentosa. In the course of observation, there was no death which showed that Anoplophora glabripennis has some adaptability in forced feeding. The SOD decreased with larvae growing, the CAT increased rapidly first but decreased rapidly later. The decreasing degree was bigger than increasin degree which demonstrated the total capacity of remove H2O2 was along with the growth of larvae.