Reclaimed water and drought effects on growth and physiology of arid-adapted plants

Water demand is increasing in arid regions and the use of reclaimed water for nursery production and landscape irrigation can conserve potable water. The objectives of this study were to assess plant performance of four salt sensitive, arid adapted perennials when irrigated with reclaimed or potable water, and to determine their response under drought stress. Chilopsis lineariz ‘Warren Jones’, Tecoma stans, Salvia greggii ‘Cherry’, and Verbena pulchella gracilior growing in containers were irrigated for 12 weeks with potable or reclaimed water with electrical conductivity (EC) of 0.3 and 1.0 dS m^-1, respectively. Growth index, a measure of canopy size, was at the end of the study not affected by reclaimed water for C. lineariz and T. stans, but was reduced for S. greggii and V. pulchella gracilior. Reclaimed water reduced leaf dry mass of C. lineariz, root dry mass of T. stans, leaf, stem, and root dry mass of S. greggii, and had no effect on biomass of V. pulchella gracilior. Highest concentrations of Na and B were found in leaf tissue of S. greggii irrigated with reclaimed water. Following 12 weeks of irrigation treatments, plants were exposed to drought. C. lineariz and T. stans grown with reclaimed versus potable water maintained a more negative water potential and lower transpiration rates as soil moisture was depleted. These species did not sustain leaf damage following drought. S. greggii and V. pulchella gracilior sustained more tissue damage with plants irrigated with potable than reclaimed water following drought conditions. Salt sensitive plants can be grown with reclaimed water (EC of 1.0 dS m^-1) and show improved drought tolerance. While some components of plant dry mass might be reduced with reclaimed versus potable water, overall aesthetic appeal of ornamental plants is most important and small decreases in biomass are acceptable.