The Coordination Design Of Landscape And Fire Fighting System In High-rise Residential Areas

Taking Melaleuca bracteata cv.’Revolution Gold’as test material, using potted approach simulating soil drought conditions, we set 6 levels on the water stress, W1、W2、 W3、W4、W5、W6 represent 10%(extreme drought),20%(severe drought),40%(moderate drought),60%(light drought),80%(normal watering)and 100%saturation soil moisture respectively, the W5 was the CK, this paper studied its morphological and physiological and biochemical characteristics under water stress, explored the drought-resistant mechanism and provided the basic data for the future introduction and cultivation and using and spreading in the garden. The main results of this paper were as follows:Melaleuca bracteata cv.’Revolution Gold’ grow well under 100% saturation soil moisture conditions but had no significant difference compared with the control. Only their crown width slightly declined in 60% saturation soil moisture.40% saturation soil moisture was drought stress intensity threshold that limited its growth. Less than 20% saturation soil moisture, the plant height, crown width, leaf length、width、thickness and leaf area were severely retarded, The dry weight and dry weight/fresh weight were firstly increased and then decreased with stress intensifying, but decreased the ratio of specific leaf weight and leaf modal traits.Under normal water and saturated water treatment, the leaves of the shrubs had higher relative water content. With the increasing extent and duration of drought stress, the leaf relative water content decreased, under severe and extreme drought conditions, the shrubs lost water seriously, have a significant difference compared with the control.With water stress intensifying, soluble sugar and proline content in the leaves all showed a tendency to increasing; they were firstly increased and then decreased with time went by. Under drought stress the soluble sugar and proline content were higher than control and remained a high Ss content in the latter part of the experiment. Under severe and extreme drought stress, the soluble sugar and proline of Melaleuca bracteata cv.’Revolution Gold’ accumulated early and kept for a long time, the shrubs had a positive adjustment mechanism for a short period of extreme drought.The MDA content in the leaves were firstly increased and then decreased with time went by. The experiment in the early treatment showed no significant difference compared with the control, with the increasing extent and duration of water stress, the MDA content in the leaves gradually increased and they were significantly higher than under drought control, in the late drought stress, the MDA content decreased, but still significantly higher than control even under moderate and extreme drought, under light drought stress and saturated water treatment showed no difference to the control. This indicated that Melaleuca bracteata cv.’Revolution Gold’ can withstand a certain degree of drought stress, the appropriate drought stress, help to improve the drought resistance.With the extension of stress time, the activity of SOD、 POD and CAT in the leaves increased first and then decreased, this indicated that the shrubs improved the ability to adapt to drought stress by increasing the protective enzyme activity, but when stress beyond its endurance limit. Under drought stress, the shrubs primarily through increased activity of SOD and CAT to effectively clear H2O2 and protect the internal organization from the damage.Drought stress significantly increased the content of Chla, Chlb, Chla+b and significantly higher than the control, but decreased the ratio of Cha/b.During the experimental period, there were no significant difference between light drought and normal watering; saturated water treatment plants did not reflect all aspects of the advantages, so in actual production, light drought (The actual moisture content (27.03± 0.84)%) was more meaningful. Moderate drought stress (the actual moisture content (17.92±0.73)%) was plant growth threshold. However, there was no mortality even under extreme drought stress (the actual moisture content (4.42±0.82)%), this indicates that this shrubs have a strong ability to tolerate drought.