Assessing chilling and drought tolerance of different plant genera on extensive green roofs in an arid climate region in Iran.
The harsh and stressful growing environment of extensive green roofs especially in arid environments allows a limited range of plant species to survive. Therefore, achieving plantings to survive in such conditions is a significant challenge. This paper describes an experiment investigating plant selections for extensive green roofs based on chilling (cold season) and drought (warm season) conditions of Iran. Nine species were selected from the three major taxonomic and functional plant groups that are commonly used on extensive green roofs including grasses, groundcovers and sedums. The species namely Agropyron cristatum, Festuca aurundinacea, Festuca ovina, Potentila sp., Frankinia thymifolia, Vinca minor, Sedum acre, Sedum spurinum, Carpobrotus edulis were imposed to natural chilling in autumn and winter using a randomized complete block design. For spring and summer, irrigation regimes at levels (48, 72 and 96 h intervals) in a factorial experiment based on a randomized complete block design with four replications were applied. The results showed that Agropyron cristatum, Frankinia thymifolia and Carpobrotus edulis were the best plants from each class. Carpobrotus edulis was the best choice for cold and warm seasons and this was followed by Frankinia thymifolia and Potentila sp. Vinca minor performed well in the cold seasons and Sedum spurinum appeared to be excellent in the warm seasons. The plants of the experiment showed significantly different appearances in different watering regimes. Little differences in drought tolerances were observed among the forbs and grasses, which must be watered during warm seasons. However, the succulents responded very well to the drought and low watering regimes. Overall, succulents and groundcovers were considered more appropriate for application in warm and cold seasons, respectively. According to the findings, drought and cold weather conditions cannot be a major obstacle for developing extensive green roofs in Iran if considerations are made on selecting its plant species.
Department of Horticulture Science and Landscape, Ferdowsi University of Mashhad, Iran.
Navid
N
Vahdati
Department of Horticulture Science and Landscape, Ferdowsi University of Mashhad, Iran. Electronic address: tehranifar@um.ac.ir.
Ali
A
Tehranifar
Department of Horticulture Science and Landscape, Ferdowsi University of Mashhad, Iran.
Fatemeh
F
Kazemi
D003247:Conservation of Natural Resources; D003889:Desert Climate; D055864:Droughts; D007492:Iran; D010944:Plants
Chilling; Drought; Environmental stress; Plant selection; Seasonal response; Urban landscaping