Effect of Landscape Mulches and Drip Irrigation on Transplant Establishment and Growth of Three North American Desert Native Plants

Abstract

A two-year experiment was conducted to determine growth responses of three North American desert native plants, brittle bush ( Encelia farinosa ), four wing salt bush ( Atriplex canescens ), and Santa Rita prickly pear cactus ( Opuntia santa rita ) to four landscape mulch treatments (shredded landscape tree trimmings, composted ponderosa pine residue, decomposing granite, or a no mulch control). In addition, brittle bush and four wing salt bush plants were drip irrigated with either 1275 liters (337 gal) or 2550 liters (674 gal) of water-plant −1 year −1 . Santa Rita prickly pear cacti were not irrigated. Transplant survivability of brittle bush was differentially affected by mulch treatment. In contrast, mulch treatments had no impact on survivability of four wing salt bush or Santa Rita prickly pear. Mulch treatments also had no effect on growth indices of all plants. Compared to the no mulch control treatment, shredded tree trimming mulch increased relative water content of Santa Rita prickly pear padded stems. Shoot dry weights were greatest for non-irrigated four wing salt bush and brittle bush. These findings suggest that supplemental drip irrigation and inorganic mulches might not be needed to grow some North American desert plants in southwest urban landscapes.