| The flower beds have significant meanings to improve the quality of urban landscape.Changchun city,the capital of Jilin province,is facing the challenge of water shortage.Meanwhile,its landscape construction cannot separate from the application of flower beds,as well as the selection and researches of drought-resistant plants.In this thesis,we investigated flower beds and their plant application in Changchun,we also studied the flower-bed types,plant species and flower-bed configuration,and other related factors.Moreover,we preliminarily discussed the landscape evaluation of flower beds,raised some existing problems,and proposed solutions in the current situation.In addition,giving different water treatments,we studied the morphological and physiological characteristics of six cultivars of commonly used flower-bed plants in Changchun.By quantitating and comparing the physiological responses of the study plants with different water treatments,we clarified their drought-resistant abilities which provided the theoretical foundations and technical supports for plants screening,allocation and water-saving management of flower-bed plants in Changchun and other cities.The main conclusions are as follows:1.In this study,we conducted field investigations of 74 flower-bed samples from proprietary,public and residential green spaces in Changchun.According to the expressing themes,two types of the flower beds are blooming flowers and horizontal stripes,and the sample numbers of which are 25 and 24 respectively.According to the arrangement forms,two types of flower beds are independent and combinatorial,and the former has 17 samples and the latter has 8.The plant materials of the investigated flower-bed samples belong to the 28 families,39 genera and 47 species.There are 28 species of biennial plants,14 species of perennial plants,5 species of shrubs,among which the crassulaceae,labiatae,and amaranthaceae have higher frequency.The overall appearance of the flower-bed landscape in Changchun is dominated by warm-toned,and complemented by the middle and cold tone.The proportion of three-dimensional flower beds in Changchun is relatively small,and the efforts on water conservation and maintenance is insufficient.2.Based on the findings above,we concluded that six cultivars of plants have long ornamental period and are widely utilized,namely Sedum spectabile,S.hybridum‘Immergriindien’,Sedum lineare cv.‘Jin Ye’,Sedum lineare,Alternanthcra amoena,and Alternanthera bettzickiana,therefore,we choose these plants as materials under CK(100%)、T1(75%)、T2(60%)、T3(45%)、T4(30%)different water treatments.Compared with CK and T1,with the decrease of soil moisture content,the six cultivars of plants under T2 and above conditions all decreased in the plant height,leaf area and dry weight.With the decrease of soil moisture,the leaf morphological damage levels of six materials gradually increase,the damage level of plant leaves from large to small are: Alternanthera bettzickiana> Alternanthcra amoena> S.hybridum ‘Immergriindien’> Sedum lineare cv.‘Jin Ye’= Sedum lineare.3.With the loss of soil moisture content,six materials’ chlorophyll,soluble sugar content,membrane permeability and malondialdehyde content increase in general.The effects of soil moisture decreasing on the chlorophyll content from large to small in turn are: Alternanthcra amoena>Alternanthera bettzickiana>Sedum spectabile >Sedum lineare cv.‘Jin Ye’>S.hybridum‘Immergriindien’>Sedum lineare.Meanwhile,when the content of soil water dropped below T2(60%),there is a inhibitory effect on the synthesis of soluble sugar in plants;moreover,the relative electrical conductivity and malonaldehyde content of the Alternant-hcra amoena leaves aggrandized the largest,and the increase of the Sedum lineare leaves was the smallest.4.With the decrease of soil water,the leaf relative water content of all experimental plants decreased from large to small are: Alternanthcra amoena> Al-ternanthera bettzickiana> S.hybridum‘Immergriindien’> Sedum lineare cv.‘Jin Ye’> Sedum lineare> Sedum spectabile;With the increase of water-loss time,the rate of water-loss of all the selected plants has shown an increasing trending,among which grass has the highest rate,the leaf water retention capability of six cultivars of selected plant from strong to weak are: S.hybridum‘Immergriindien’> Se-dum spectabile> Sedum lineare> Sedum lineare cv.‘Jin Ye’> Alternanthcra amoena> Alternanthera bettzickiana.We applied the subordinate function method,and evaluated the comprehensive evaluation on drought resistance of the six materials,Sedum lineare’s drought-resistant is best,Alternanthcra bettzickiana and Alternanthera amoe-na’s drought-resistant are the weakest,S.hybridum ‘Immergri-indien’ and Sedum spectabile’s drought-resistant is the middle of the scale.the drought-resistant ability from strong to weak are: Sedum lineare cv.‘Jin Ye’> Sedum lineare> S.hybridum ‘Immergriindien’> Sedum spectabile> Alternanthcra amoe-na> Alternanthera bettzickiana,these findings also show that among the experimental materials,the plants from same genera have closer water demand and drought tolerance than those from different genera or families.5.We suggest that Changchun city should increase the proportion of three-dimensional flower beds,select the different color plants from the same species or genera for allocation,in order to facilitate the water-saving management.The best soil water conditions for the six experimental plants are T1(75%).Sedum lineare cv.‘Jin Ye’ and Sedum lineare both can maintain the ornamental characteristics of flower beds under T3(45%)water condition,hence the irrigation frequency can be reduced by half.S.hybridum‘Immergriindien’ Sedum spectabile can remain the ornamental characteristics of flower beds underT2(60%)treatment,the irrigation frequency can be reduced accordingly.Nevertheless,Alternanthcra amoena and Alternanthera bettzickiana need to maintain T1(75%)soil water content to ensure the ornamental characteristics,and the original irrigation frequency should be continued. |
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