Research Of Drought And Cold Resistance Of Introducted Woody Ornamental Plants In Inner Mongolia Bayan Obo Mining District

Bayan Obo mining area located in the northwest of China belongs to the inland dry climate zone which is cold in winter and dry. Serious exploitation of the mine leads to ecological destruction and and bare ground. Consequently, an urgent need in the local growth and improve the ecology of landscape plants. For this reason, it has great significance for introduction to Bayan Obo mining area. Drought and cold are the restriction factor for the introduction by the way of analysis of site conditions, climate and cultivation conditions. Therefore the purpose of this study is introduction of certain drought and cold tolerance plants and electing suitable plant species.In this paper, Acer truncatum, Hibiscus syriacus, Cercis chinensis, Wisteria sinensis and Ulmus pumila are used for the introduction and experimental materials whose reproduction method, drought and cold tolerance differences are researched. The main conclusions are as follows:(1) Physiological and ecological responses, and the changes of physiological and biochemical indexes of four seedlings, Acer truncatum, Hibiscus syriacus, Cercis chinensis and Wisteria sinensis are investigated under4different treatment of water stress (relative water content of well-water control, mild water stress, moderate water stress and severe water stress followed by80%-90%,60%-70%,40%-50%and20%-30%). On the basis of different responses of four seedlings under drought stress, the drought resistance of Acer truncatum was the highest, followed by Cercis chinensis, Hibiscus syriacus and Wisteria sinensis.(2) When selecting drought tolerance indicators in the process of plant breeding, except for dry mass ratio, other indices such as death rate, plant height and leaves increment, fresh weight, plant water content, leaf water content, leaf saturated water deficit, SLW, leaf waxes value, stomatal density, stomatal length, photosynthetic and chlorophyll fluorescent, MDA content, leaf electric conductivity, osmotic substance conten and antioxidative enzyme activities could be used as drought resistance evaluation indices.(3) After investigating of leaf electric conductivity, MDA content and free proline content of5woody plants seedlings, research shows that leaf electric conductivity can be used effectively investigating plant cell membrane injury degree and cold resistance ability. Through the comparative analysis, it is cold intolerance for Hibiscus syriacus and Wisteria sinensis. MDA content of different species response to low temperature changes is different. The variation of free proline content is insensitivity for Hibiscus syriacus and Ulmus pumila, but in contrast of Cercis chinensis. The accumulation of free proline increased. Nevertheless, there is no obvious correlation between the accumulation of free proline and cold resistance ability, which has its limits for comparing cold resistance of5plants.(4) Acer truncatum, Hibiscus syriacus, Cercis chinensis and Wisteria sinensis can be cultivated and prouducted through seed breeding, the survival rate of which is more than90%. Hibiscus syriacus can be propagated by cottage with vermiculite and no auxin treatment, the survival rate of which is84.0%. With the study of introduction and cultivation observation, drought and cold resistance, Acer truncatum is the most suitable species for introduction in Bayan Obo mining area, the drought resistance of which is the highest. Phenology performance of other3species Cercis chinensis, Hibiscus syriacusand Wisteria sinensis in Bayan Obo mining area are to be further observation and discussed.Combine with the above results of the analysis and natural distribution of4woody plants species, the author suggests that with the followed characteristic of ornamental plants can be planted in Bayan Obo mining area.(1) High ability of drought resistance and higher water use efficiency in drought conditions. Higher plant water content, LRWC, SLW, R/S. Lower ratio of free water and bound water content. The stomatal density is higher, and stomatal length is smaller. The value of AQY, Fv/Fm, the content of leaf waxes, and the content of osmoregulation substance (soluble sugar, soluble protein, free proline) are higher. Enzyme system (SOD, POD, CAT, APX) activity is higher.(2) Strong ability to low temperature resistance and natural live through the winter. Or in simple protection cultivation measures conditions after the winter can survive.