Introducing Several Ornamental Mallee Into Guangxi And Fundamental Research On The Xerophytism

Mallee is an Aboriginal name for a group of eucalypts which grow to a height of 2-9metres and have many stems raising from a swollen woody base known as a lignotuber. They have an umbrella-like leaf canopy and the trees shade 30-70% of the ground. There are over 100 mallee species. They are drought resistent and adapt arid soil, and play a key role in these sensitive fragile ecosystems. Aim on virescence of deserted hills in south of China, and supply raw material of high quality dry flower. 18 ornamental malle species were introduced into Xindou district,Guangxi province. E.cinerea, E.pulverulenta, E.orbifolia, E.cordata, E.gillii and E.crucis grew sturdily and started to make profit. E.forrestiana,E.tetragona,E.tetraptera,E.albida and E.erythrocorys grew ordinarily, they were still on the way of adaption. E.stoatei, E.youngiana, E.macrocarpa, E.rhodantha, E.macrandra, E.kruseana and E.foecunda could not bear the hot humid summer in Guangxi and died out. The biggest obstacle growing mallee in Guangxi was disease.Morphological differentia research was done between mallee growing Dubbo area, New South Wals, Australia and same species growing Xindou,Guangxi province,China. They had faster growing speed, larger and thinner leaves, longer internode, higher ratio of dry matter of ground above and underground and lower area of hydraulic architecture in unit foliar area the mallee growing Xindou district than the same species growing Dubbo area. It means their xerophilous structure degraded. Leaf anatomy showed that different mallee spicies have defferent leaf structure, the defference shows on leaf types, thickness of cuticles, density of stomat, layer of palisade mesophylla, density of cell arrangement, amount of oil gland. Malle have more dry-resistent structure than local fast growing Eucalytua grandis×uraphylla which is grown widespreaadly in local area, especially the species from low rainfall area. Some primary research on their water retention and pv experiment were done, The dry-tolerant ability of the mallee could be ascertained through the trials and experiments.The pot experiment shows their transpiration and the efficiency of water application. Water is very important to mallee. Especially to some not very dry-resistent species. Higher transpiration rate happened on higher water content groups. The transipiration rate was decreased along seedlings grew, but transpiration was increased. The minimum of efficiency of water application did not happen on very wet or very dry occasion. The possibility to introduce the malle into drier place--the xerothermic velly in...