Effect of mulches on some characteristics of a drought tolerant flowering plant for urban landscaping

Mulches are relatively new landscape components and are becoming recognized for their environmental and aesthetic outcomes on urban landscapes especially in arid environments. However, the effects of mulches on landscape plants have not been extensively discussed. This study examined the effects of organic and inorganic mulches on the performance of a widely used herbaceous drought tolerant flowering plant, Zinnia elegans, toward low maintenance landscaping. This study was designed as a randomized complete block design with three replications. Four widely commercially available and utilized mulches, including wood chips, pine needles, scoria (volcanic stone) and black polyethylene were used as the treatment mulches. The study contained plots with only bare soil as the control. The results showed that utilizing the selected mulches demonstrated positive effects on the plant growth, and increased the fresh and dry weight of shoots (p<0.05) compared to the control. In the Zinnia, the highest fresh and dry weights were recorded for the wood chip treatment. The decreased the percentage of weeds (p<0.01) compared to the bare soil. The highest water use efficiencies were recorded when polyethylene, wood chips (M=16 kg/m3) and pine needles were used as mulches, respectively. Mulches increased the flowering period up to 6 days and decreased the number of days to flowering up to 19 days with polyethylene mulch compared to the control treatment. Therefore, utilizing organic and inorganic mulches for improving landscape quality, performance and aesthetics especially in arid environments is to be recommended.