Research On The Cold-resistant Ability Of Five Kind Of Eucalyptus Species In Seedling In Zhengzhou City

Based on the research of growth index, physiological index, external observation of plant character and cold-resistant index of five kinds of Eucalyptus species. Their inclusion's imitative rules were discussed. The Eucalyptus species of having better cold-resistant ability in Zhengzhou city and the better judgment indexes of cold-resistant ability were find out at the same time. Those are the theoretic gist to introducing south species, optimizing forestry structure and reserving abundant germplasm resource.The research to the growth index of five kinds of Eucalyptus species showed that E. camaldulensis> E. saligna> Eucalyptus globules> E. sideroxylon> E. dalrympleana. E. dalrympleana are crawl while others are very straight in seedling.The daily variation of net photosynthenic rate (Pn) of E. sideroxylon and E. dalrympleana is double-peak carve, May 18th ,2005. while the daily variation of Pn of five kind of Eucalyptus species is single-peak carve, Nov 10th,2005. E. dalrympleana have the higher Pn, that is necessary condition to reserve matter and energy and to insure plant normal growth.According to the freezing harm investigation in winter and the divisiory standard of freezing harm and cold-resistant ability of Eucalyptus species, E. dalrympleana have the first-rate cold-resistant ability, E. sideroxylon have the secondary ability, E. camaldulensis have the low ability while Eucalyptus globules and E. saligna lack the cold-resistant ability.With the temperature declining, the soluble protein content in five kinds of Eucalyptus species increased eventually while they haven't obvious difference. The Chlorophyll content declined. SOD increased mostly except E. salign, POD have the similar rule to SOD.MDA and the electrical permeation rate are sensitive to temperature, they are the best indexes of judging Eucalyptus species' cold-resistant ability according to the investigation in winter.Under the condition of 2℃ for 24,48 hours, the soluble protein content in five kind of Eucalyptus species haven't obvious change on Sep 28th, 2005.The Chlorophyll content of E. dalrympleana and E. sideroxylon increase obviously, E. camaldulensis and Eucalyptus globules haven't visible change, and E. saligna decrease slightly. Enzyme of E. dalrympleana and E.