| The environmental problems caused by the rapid urbanization in China have become increasingly prominent,roof greening is an effective way to increase green area and improve microclimate in urban areas.In order to solve problems such as high bulk density,poor water retention,unstable properties and low production standardization of roof cultivation substrates in China,this research was prepared by taking perlite as matrix aggregate,aquasorb and biosurfactant as conditioner.Based on the analysis of effects of aquasorb[0（A0）,0.5（A0.5）,1.0（A1.0）g·kg-1]and 2%biosurfactant[0（B0）,100（B100）,200（B200）m L·kg-1]on water-retaining property capacity and physicochemical properties of perlite under the condition of slow-release fertilizer(30 g·kg-1),two groups of high scoring substrates were chosen by matrix methods for cultivation experiment,change of physicochemical properties of different substrate was analyzed and the growth indexes of Caryopteris clandonensis‘Worcester Gold’and Iris lactea were analyzed by membership function to determine the optimal substrate.The results were as follows:（1）The water evaporation resistance and repeated water absorption of perlite substrate increased after the combined application of aquasorb and biosurfactant.The water-retaining property of A1.0B100(aquasorb 1.0 g·kg-1 and 2%biosurfactant 100 m L·kg-1)was the best.Compared with CK(aquasorb 0 g·kg-1 and 2%biosurfactant 0 m L·kg-1),the water evaporation time of A1.0B100(aquasorb1.0 g·kg-1 and 2%biosurfactant 100 m L·kg-1)increased by 20.59%;saturation capacity increased by19.08%after drying 6 times.The water evaporation resistance of perlite substrate to which the aquasorb or biosurfactant was applied respectively respectively increased by 2.94%～20.59%while the repeated water absorption decreased by 3.73%～13.86%after drying for 6 times.（2）The aquasorb and biosurfactant can significantly improve the water-gas ratio and ability of preserving and providing fertilizer of perlite substrate;reduce nutrient leaching and bulk density（P<0.05）.Compared with CK(aquasorb 0 g·kg-1 and 2%biosurfactant 0 m L·kg-1),the bulk density of A1.0B200(aquasorb 1.0 g·kg-1 and 2%biosurfactant 200 m L·kg-1)decreased by 17.11%,capillary porosity and field capacity increased by 10.82%and 55.55%,the mass fraction of total nitrogen,available phosphorus and rapidly available potassium increased by 14.78%,44.36%and 25.28%,respectively.The water holding capacity,fertilizer preserving ability and the contents of total nitrogen,available phosphorus and available potassium of A1.0B200(aquasorb 1.0 g·kg-1 and 2%biosurfactant 200 m L·kg-1)were the highest,the water-gas ratio was close to 3.0 and the p H value was neutral.（3）Through one-year cultivation,compared with CK(aquasorb 0 g·kg-1 and 2%biosurfactant 0m L·kg-1),the particle size at all levels of A1.0B100(aquasorb 1.0 g·kg-1 and 2%biosurfactant 100 m L·kg-1)and A.10B200(aquasorb 1.0 g·kg-1 and 2%biosurfactant 200 m L·kg-1)changed less obvious,physicochemical indexes were still within a reasonable range,the remaining fertility was higher.The plants in A1.0B200(aquasorb 1.0 g·kg-1 and 2%biosurfactant 200 m L·kg-1)grow faster,showing more significant indexes advantages,stronger nutrient absorption capacity and higher nutrient utilization rate than CK(aquasorb 0 g·kg-1 and 2%biosurfactant 0 m L·kg-1)（P<0.05）.The physicochemical properties of A1B200(aquasorb 1.0 g·kg-1 and 2%biosurfactant 200 m L·kg-1)were the best and the plant in A1B200 grew the best.（4）Combined with the comprehensively evaluate of the matrix methods of physicochemical properties of the substrates and the membership function of the growth indexes of Caryopteris clandonensis‘Worcester Gold’and Iris lactea respectively,A1.0B200(aquasorb 1.0 g·kg-1 and 2%biosurfactant 200 m L·kg-1)ranked the first in both screenings.The optimal formula of roof greening in this research was:aquasorb（g）:2%biosurfactant（m L）:perlite（kg）=1:200:1. |
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