Correlations Between Physiological Metabolism And Absorption Of Mineral Nutrients Of Poplar Leaf Rust

Poplar are known as one of the typical tree species of Populus F., Salicaceae, which are also referred to as one kind of promising fast-growing forestation species with pines and Eucalyptus. There are large cultivation areas of Poplar in china, and they are widely used in the ecological construction of shelter forests and commercial forests, so as to, not only do they play irreplaceable roles in solving the energy problems, also make great benefits in the economic. Currently, a large area of poplar forest was infected by Melampsora sp, which leads to enormous economic losses, and greatly threatens the production and construction of forestry. Thus, researches on the treatments of this disease are very crucial in both theory and practice area.In this study, we chose the infected Populus cathayana Rehd as the main test materials, of which the incidence rate is high, the Hazard area is wide and the influence is more serious. the main target were to study the correlations between physiological metabolism and absorption of mineral nutrients of poplar’s infected by leaf rust fungus, to reveal the change mechanisms of physiological metabolism and fine root nutrient with different degrees of poplar leaf rust, and to provide a strong theoretical basis for the chemical and biological control of poplar leaf rust, eventually.The results as follows:(1) Significant effects of the extent of poplar leaf rust on physiological metabolismAccording to exterminating the activity changes of PPO and POD, as well as the content changes of MDA and chlorophyll of potting P. cathayana Rehd in its different grades of leaf rust, we found that there were some significant effects on its physiological metabolism in different grades of leaf rust and the activity of POD, the contents of MDA and chlorophyll were all shown to be significantly different from the control. Specifically, in susceptible incipient stage, all of these four variables had a significant change, but the variation was relatively small; in susceptible medium-term, the variation was much larger and the activities of PPO and POD were still on an upward trend with the increasing of disease index. In the final, there were significant differences between activities of PPO, POD and control (P<0.05); the content of MDA presented a downward trend after its peak; besides, the content of chlorophyll decreased gradually, which was significantly with control (P<0.05). In the correlation analysis between diseased level and enzyme activity, the results showed that the activities of PPO and POD were positively correlated with the diseased levels, the content of chlorophyll was negatively correlated with it, and there was no significant correlation between MDA content and the control.(2) The nutrient absorption of poplar root was affected by extent of the leaf rustAccording to exterminating the content changes of N, P and K of potting P. cathayana Rehd in its different grades of leaf rust, the results showed that there were some significant effects on its absorption of root nutrients in different grades of leaf rust. Specifically, in susceptible incipient stage, both the contents of N and K were increased with the increasing of diseased levels; as for P content, it gradually decrease with the increasing of diseased levels after it reached a peak in the medium term; all of these three variables had a significant difference(P<0.05). In conclusion, in the correlation analysis between diseased level and enzyme activity, the results showed that the contents of N and K were positively correlated with the diseased levels, but there was no significant correlation between P content and the control.(3) Correlations between physiological metabolism and absorption of mineral nutrients in different diseased periodBy determining the nutrient contents of roots and Physiological indicators of leaves, and then the correlation analysis about the difference between the susceptible and health of P. cathayana Rehd was established. As for P content, K content, PPO activity and POD activity, they all showed a significant positive correlation; to N content, K content and PPO activity, there was a highly significant positive correlation; besides, there was also a highly significant positive correlation among K content, POD(R= 0.879) and PPO(R= 0.996); In addition, PPO activity and POD activity had a significant positive correlation, but all of both were tested highly significant negative correlation with chlorophyll content. Furthermore, the contents of P and K also had a negative correlation with chlorophyll content. In summary, the correlation analysis showed that there was an intimate relationship between the physiological metabolism (PPO activity, POD activity and chlorophyll content) and the absorption of fine root nutrients(N, P, K), but for MDA, there was no significantly correction with them.(4) The poplar leaf rust can be reduced by fertilizedAccording to the relationship between enzyme activity and root absorption of nutrients, the fertilization control experiment was carried out. The results showed that the relative effect was enhanced by 6.7% and the disease incidence was significantly lower than that in control group after applied with NPK mixed fertilizer.