Studies On Freezing Resistance Of Japanese Osmanthus Heterophyllus That Is Excellent Osmanthus Lour Tree

To study the ecophysiological effects of low temperature stress on Osmanthus heterophyllus, trees of Osmanthus 'Goshiki'were selected as experimental material. We researched the changing rules of Pn-PAR responsive curve,MDA,Sugar,POD,Relativity-conductance,Amino acid and Chlorophylla during two processes including the naturally decreasing in temperature in winter and the low cold stress.The results are as follows:(1) There were different Pn-PAR responsive curves in different months of Osmanthus heterophyllus, especially the characteristic parameters. With the temperature decreasing,αhad a increasing trend while LCP and LSP had a decreasing trend, which indicated that Osmanthus heterophyllus improved its ability to use weak light in the process of adapting to the low temperature. It helped to maintain definite photosynthesis under the low temperature stress.(2) With the temperature decreasing, the conductance and MDA have increasing trend in the two low temperature conditions, it reviews the cold stress made the destroy of cell membrane, which lead to the foul up of metabolism. The conductance can be used as a signal index weighting the cold resistance in Osmanthus heterophyllus by means of the cluster procedure and prior communality estimate.(3) Following the REC curve and logistic equation, we calculated the LT₅₀ of Osmanthus heterophyllus that was -14.2℃. In recent years, the lowest temperature in NanJing was no more than -10℃. Therefore, it is not easy to injure by the low temperature if Osmanthus heterophyllus was introduced into NanJing as landscape trees, which had a good applied foreground.(4) In the two low temperature conditions, with the temperature decreasing, the content of SUG had an increasing trend; cha/b had a decreasing trend while POD activity increased before decreasing; the amino acid during the naturally decreasing in temperatures increased while having a large change in the man-made low temperature stress.According to the test results, SUG,MDA,POD and Chlorophylla also can be considered as an important guideline of cold tolerance in Osmanthus heterophyllus.