The Effect of Medium Cultures on Water Use and Charactristic of Gazania Flowers (Gazania hybrida) in Green Roof

Green roof is one of the newest phenomenons in architecture and urbanism that refers to the sustainable development concepts and it will be usable for increasing landscape design, improving quality of the environment and reduction in energy consumption. Ensure of existing adequate green landscape in urban areas and improving access to natural areas surrounding the cities can help to offset negative effects of urban life. The use of green roof technology in cities is one of advanced techniques of green landscape. A green or living roof is a roof of a building that is partially or completely covered with vegetation and a growing medium on top view of buildings. Green roof layers that considered for roof side consist of protection layer, drainage layer, growing medium and plant layer. Medium layer is the medium culture of green roof that plants are begins to grow in it. This space should enable to save enough minerals and water for conserve of green-roof plants. All kinds of plants can growth on the green roof, but there are some constraints in creative of design because of roots dimension, plant canopy, necessary volume of soil, suitable direction to light, good weather, weight of designed structures, budget of repairing and keeping.
To evaluate the effect of some culture medium on water consumption, vegetative and reproductive traits of Gazania (Gazania hybrida) in condition of green roof a factorial experiment was conducted based on a completely randomized design with nine treatments and three replications in 2014. Treatments were three levels of vermicompost (zero, 5%, and 10%) and rice hull (zero, 7, and 14%). Seedlings of plants cultivated in the media mixture of coco peat 15%, perlite 15%, leaf 10%, manure 10%, and filed soil 50%. The container had 60 × 60 ×25 cm dimensions that placed on the roof of greenhouse building with four meters height. The measured traits was number, average, and diameter of flower, stem diameter, plant height and diameter, crown diameter, the number of produced seedlings, root volume and chlorophyll. The weight of different mediums measured for medium of green roof suitable texture. In addition, in the certain period (three months), water consumption calculated with considering of daily evaporate and transpiration for each of medium. Data analyzed using SAS and MSTAT-C statistical program and means compared using a Duncan test (p The results showed that vermicompost treatments had significant effects on the number and diameter of flowers and stem height of the plant, but had no effect on plant's stem diameter. Based on the results, different amounts of vermicompost increased the flower number and average per day and also the plant length. The largest flower number (88.33) and average (6.3) per day and the plant length (14.52) were observed in 10% vermicompost treatment and the lowest observed in control treatment. In addition, rice hull treatments had significant effect on flower number and diameter. However, rich hull had not any significant effect on stem number and diameter. Mean comparisons showed the highest and lowest flower number (82.4 and 82.1), mean flower number per day (5.88 and 5.86) in 14% and 7% rice hull treatments, respectively. Also, the highest flower diameter was related to 14% rice hull treatments. Result of analysis variance table showed significant effect on flower crown weight, length and diameter and root volume. Rice hull treatments also had significant effect on flower crown number and diameter and root volume. In this study, combination of 10% vermicompost with %7 rice hull treatment, have the greatest impact on the latedmost traits and reducing water consumption on green roof. As results showed water consumption in the certain period (three months), the lowest consumption belonged to 14% rice hull without vermicompost that had lowest water consumption in comparison with reference. In addition, the heaviest weight of different mediums was related to control and the lightest medium was belonged to 5%, vermicompost in combination with 14% rice hull.
The vermicompost and rice hull as bio-fertilizers not only increased structure, physical and chemical condition of medium but also increased nutrition and reduced water consumption. Vermicompost and rice hull both improved the most flower traits on green roof and reduced water consumption and weight of different mediums. Therefore, the vermicompost and rice hull (14% and 7%) combined with soil mixture can be used as a culture medium in green roofs.