The temperature of cities continues to increase because of the heat island phenomenon and the undeniable climatic change. The observed high ambient temperatures intensify energy problems in cities, deteriorates comfort conditions, put in danger the vulnerable population and amplify the pollution problems. There are some suggested ways to reduce these issues, among them vegetated roofs are shown to be promising. This study describes energy consumption performance of an extensive modular type green roof with different plant selections using a randomized complete design in Mashhad, Iran. Nine species from three major taxonomic and functional plant groups (grasses, ground covers and sedums) namely (Agropyron cristatum, Festuca aurundinacea, Festuca ovina, Potentilla sp., Frankenia thymifolia, Vinca minor, Sedum acre, Sedum spectabile, Carpoboratus edulis) were selected. Temperature fluctuations during four seasons were recorded with three replicates. Experimental trials with growing beds without plants (bare roofs) were also used as controls. Small hand manual thermometers were placed in each module (box) and air temperature was also recorded. The results showed very significant temperature differences between the green and bare roof modules. Larger plants with higher biomasses kept temperatures more stable. Thermal comfort and energy saving was achieved using green roofs in this research and it could be well used in a large scale for growing cities and population energy requirements. Manuscript profile

Soil salinity is one of the most important problems in dry and semi-dry climate areas of the world. So, we investigated the effects of humic acid on visual quality and quantity parameters of native turfgrasses in compared to commercial one under salinity stress to explore can we reduce salinity effects by humic acid or not? So, an experiment was arranged in factorial experiment based on randomized complete design with three replications. The first factor was three grasses consist of two native accessions of Lolium perenne ҅Chadeganʼ and ҅Yarandʼ and its commercial variety, the second factor was four concentrations of humic acid (HA) (0, 5, 10, 15 g kg-1) and the third factor consisted of three levels of salinity (0, 150, 300 mM). Results of analysis of variance indicated that the interaction effects of cultivar × HA was significant in all traits (P<0.01) except uniformity and height. The treatment of cultivar × salinity significantly affected color, texture, smoothness, uniformity and RWC (P<0.01) and total quality (P<0.05). Treatment of HA × salinity had not significant influence on smoothness and uniformity but other traits were significantly influenced at 5% probability level and RWC at 1% level. Triple interaction effect was significant on texture, quality after clipping, uniformity and RWC (P<0.01) and height (P<0.05). Application of HA could decreased salinity effect on darkness, texture and increased quality after clipping and relative water content of leaves under salinity stress. Also, increasing of severity of salinity had reduction effect on plant height and total quality even with HA application. In conclusion, plants grow on soils which contain adequate humic acids (HA) are less subject to stress condition, are healthier because of having higher relative water content in contrast salinity condition. Manuscript profile