The impact of treated and untreated municipal sewage water on growth and physiology of the desert plant Calotropis procera

The present study investigated the effect of irrigation with Al-Madinah Al-Munawwarah domestic sewage water on the desert shrub Calotropis procera. Five treatments including distilled, well water, untreated (T0), primary (T1), secondary (T2) and tertiary (T3) treated sewage waters were used to irrigate the plants. The chemical and physical properties of different sewage waters were determined. A number of growth parameters including % germination, plant height, leaf number, fresh and dry weights of leaves, stems, roots and whole plant. Root:Shoot ratio was also determined. Some physiological parameters such as photosynthetic rate, initial fluorescence Fo, maximum fluorescence Fm and quantum yield Fv/Fm, and chlorophyll content index were measured. Most growth and physiological parameters were increased in response to irrigation with treated and untreated sewage waters. Carbohydrate content was increased under treatment with T0 but decreased under T2 and T3; while protein content was increased under most of sewage water treatments. In contrast, proline levels showed no change. The levels of heavy metals in sewage water were in trace amounts. The possibility of using sewage water as a potential and sustainable alternative water resource for irrigating non-crop plants for multiple uses is discussed.