Analysis The Site Condition And Researching On The Selection Of The Drought-resistance Plant In The Median Strip Of The Highway

At present, the low survival rate is the key problem in the vegetation of the Central Isolation Belt in our country; which directly links with the drought environment, In this thesis, the autor put the langzhuo freeway, New Jersey median strip as the study objective, analyze the soil and the Microclimate characteristic, and researches the selection of the plant drought resistance, and though analysis of the physiology and the growth index, to evaluate the capacity of the plant, the research result indicates that:(1) In the Langzhuo freeway, median strip, it is low in soil nutrients and aggregate, the most serious is the P, the low soil aggregate leads to the weak soil stability, and the soil moisture is easily lost. In addition, there still exit cold and dry, and strong wind in winter and spring, high temperature and drought environment in summer, and the situation is especially in Marth and Aprial, the soil moisture was just around 6%, all of these can create greate threate to the growing of the plant.(2) The Pn,Tr,Gs of the five plant are decreased as the drought stress aggravates but in different water content, it behaves different drought resistance features, the Buxus megistophylla are disturbed in the 60%～65% level of the soil moisture, and destroyed at 40%～45%.the Berberis thumbergiithe and the Rosa hybrida are disturbed in the 40%～45% level of the soil moisture, and destroyed at 20%～25%,the Buxus sinica and the Platycladus orientalis are disturbed in the 20%～25% level of the soil moisture, and the moisture threshold of them need further study.(3) the outdoor's test is similar to the indoor's in which the 40%～45% level of the soil moisture at the photosynthetic parameters aspect,the same in Pn, because of the Solar radiation, the Air humidity and the Wind velocity,the Tr and the Gs was lower than the indoor's, maybe the plant Reduce water loss in this way to adapt to the drought environment. Though used the data of the indoor and outdoor's photosynthetic parameters,and the growth index data of the ourdoor, to assess the drought resistance ability of the five plant objectively, it indicate that the Platycladus orientalis (L.)(0.84)>(0.45)> the the Rosa hybrida (0.44)>the Berberis thumbergii (0.28)>the Buxus megistophylla (0.05). so the author choose the the Platycladus orientalis, the Buxus sinica and the the Rosa hybrid are the key plant to the the median strip.