| As a kind of mine wasteland,the vegetation of abandoned quarry has been destroyed,and the site condition is very poor.A large number of gravel slopes with different slopes are the key and difficult points in the ecological restoration of the quarry.The lack of topsoil cover,thin soil layer and drought are the main limiting factors for the settlement of the slope plants in the quarry.Sedums have the characteristics of strong adaptability,barren tolerance and good ornamental,and has high value of landscape application.On this basis,the effects of slope gradient on the growth of eight sedums and on the growth and physiology of sedums under drought stress for 35 days were studied.and the drought tolerance of sedums on the slope of quarry was evaluated comprehensively.The results are as follows:(1)The average transplanting survival rate of eight sedums decreased with the increase of the slope,but there was no significant difference.The increase of slope gradient affects the biomass distribution of aboveground and underground parts of sedums,which leads to the transfer of organic matter from plants to roots.With the increase of slope gradient,the relative growth rate of plant height,crown width and coverage area of each sedums continued to decrease,while the dry weight of root,root length and root crown ratio continued to increase.With the increase of slope gradient,the change trend of leaf area of sedums include continuous decline and first rise and then fall.The change trend of survival rate in winter includes first rise and then fall,continuous decline and basically unchanged.(2)During the period of 35 days drought stress after stopping irrigation,the larger the slope gradient of quarry,the faster the relative water content of soil decreased,and the more serious the degree of soil drought.The response to the plants is that the symptoms of damage of each landscape day increase with the increase of slope gradient.Under the stress of 35 days,some of the sedums appeared chlorosis,scorch and growth stagnation,almost no ornamental value.(3)Under the drought stress of 35 days,the increase of slope gradient of quarry significantly inhibited the plant height,relative growth rate of crown and biomass of eight sedums.With the increase of slope gradient,the ratio of root to crown of each sedum continued to increase.The change trend of root dry weight of eight sedum include three kinds: continuous rise,first rise then fall and basically unchanged.(4)Under drought stress,with the increase of the slope gradient of the quarry,the contents of water,chlorophyll content,Fv / Fm and Yiled of eight sedums showed a continuous downward trend,and the MDA content and relative electrical conductivity of eight sedums rose continuously.The trend of proline content varies with different species / variety?(5)According to the method of membership function value,the order of the comprehensiv e drought tolerance of eight sedums in different slopes of the quarry is: S.selskianum‘Spirit'>S.aizoon>S.hybridum ‘Immergrunchen' >S.reflexum‘Blue Spruce'>S.mexicanum‘Gold Mound'> S.spurium‘Summer Glory'> S.spurium‘Coccineum'> S.sarmentosum,and three main compo nents were extracted from 13 indexes by principal component analysis.The first principal comp onent mainly includes total biomass,leaf water content,malondialdehyde,chlorophyllin,Fv/FM and Yield.The second principal component mainly includes crown growth rate,root crown ratio,and three main components It mainly contains soluble sugar content.The results of this study also show that the drought resistance of medium-sized sedum is generally better than that of sh ort type. |
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