Assessing chilling and drought tolerance in different plant genera for extensive green roofs in an arid climatic region in Mashhad (Iran)

Document Type : علمی - پژوهشی


Department of Horticulture and landscape, Ferdowsi University of Mashhad, Iran


Introduction: The harsh and stressful growing environment of extensive green roofs means that only a limited range of plant species is routinely used.Materials and methods: This paper describes an experiment for investigating suitable plants for extensive green roofs in Mashhad during the natural cold of autumn and winter in the form of a complete block design and, after that, during the warm season (drought stress) with three irrigation interval treatments (48, 72 and 96 hours) in the form of a factorial experiment based on a complete block design with four replicates.Results and discussion: The results of both experiments showed a significant effect in the different seasons. Agropyron cristatum, Frankenia thymifolia and Carpobrotus edulis showed the best visual quality among the plants examined. From the survival point of view, Carpobrotus edulis showed the best performance for both cold and warm seasons and Frankenia thymifolia and Potentilla sp. follow the same manner. Vinca minor was good under cold conditions and Sedum spurium was observed to be an excellent choice for the warm season. Grass plants and groundcovers need regular irrigation during the warm season and showed significant differences regarding watering treatments. However, a very good response to drought was shown in the Sedum spurium plant.Conclusion: Overall succulent and groundcover plants are, respectively, considered good for the warm and cold seasons while grass plants are not properly suited. According to the results of this study, green roofs can be advised as sustainable green structures for Mashhad’s climate with certain considerations. 


  1. منابع
  2. Barrs, H.D. and Weaterley, P.E., 1962. A re-examination of the relative turgidity techniques for the estimating water deficit in leaves. Australian Journal of Biological Sciences. 15, 413-428.
  3. Bousselot, J.M., Klett, J. and Koski, R., 2009. Extensive green roof species and soilless media evaluations in semi-arid Colorado. Hortscience. 44 (4), 1063-1063.
  4. Dere, S. Gunes and T. Sivaci, R., 1998. Spectrophotometric determination of chlorophyll - a, b and total carotenoid contents of some algae species using different solvents. Journal of Botany. 22: 13-17.
  5. Dunnett, N. and Kingsbury, N. 2008. Planting Green Roofs and Living Walls, 2nd edition. Timber Press, Portland Oregon.
  6. Gurevitch, J., Teeri, J.A. and Wood, A.M. 1986. Differentiation among populations of Sedum wrightii (Crassulaceae) in response to limited water availability: water relations, CO2 assimilation, growth and survivorship. Oecologia, 70, 198–204.
  7. MacDonagh, L.P., Hallyn, N.M. and Rolph, S. 2006. Midwestern USA plant communities + design = bedrock bluff prairie greenroofs. Paper presented at the Annual Greening Rooftops for Sustainable Communities Conference, Boston, MA.
  8. Nagasea, A. and Dunnett, N. 2010. Drought tolerance in different vegetation types for extensive green roofs: Effects of watering and diversity. Landscape and Urban Planning. 97: 318-327.
  9. Peter A.Y. Ampim, John J. Sloan, Raul I. Cabrera, Derald A. Harp, and Fouad H. J., 2010. Green Roof Growing Substrates: Types, Ingredients, Composition and Properties. Journal of Environment and Horticulture. 28(4): 244–252.
  10. Snodgrass, E.C. and Snodgrass, L.L., 2006. Green Roof Plants: A Resource and Planting Guide. Timber Press, Portland Oregon.
  11. Singleton, U. L. and Rossi, J., 1965. Colorimetry of total phenolics with phosphomolybdic-posphotungustic acid reagent. Am. J. Enol. Vit. 16,144-158.
  12. Snodgrass, E. and Snodgrass, L., 2006. Green Roof Plants. Timber Press, Portland, Oregon.
  13. Stephenson, R.S., 1994. Cultivated Stonecrops. Timber Press, Portland Oregon.
  14. Terri, J.A., Turner, M. and Gurevitch, J., 1986. The response of leaf water potential and Crassulacean acid metabolism to prolonged drought in Sedum rubrotinctum. Plant Physiology. 81, 678–680.
  15. Van Woert, N.D., Rowe, D.B., Andresen, J.A., Rugh, C.L. and Xiao, L., 2005. Watering regime and green roof substrate design affect Sedum plant growth. HortScience. 40 (3), 659–664.
  16. White, J.W. and Snodgrass, E., 2003. Extensive green roof plant selection and characteristics. In: Proc. of 1st North American Green Roof Conference: Greening Rooftops for Sustainable Communities, Chicago, IL, The Cardinal Group, Toronto.