Articles
Response of native and non-native landscape shrubs to deficit irrigation in Arizona
Article number
1467_15
Pages
119 – 126
Language
English
Abstract
Nine taxa of shrubs, six native to the Southwestern United States, and three non-natives, were grown in Southern Arizona to determine growth and aesthetic plant quality in response to deficit irrigation.
Weather conditions during the study were characterized by high evapotranspiration, scarce precipitation, and summer temperatures between 38 and 42°C. After one year of establishment, plants received three levels of irrigation based on local reference evapotranspiration (ET0), low (20% ET0), medium (50% ET0), or high (80% ET0). Between April 1 and October 31, 2022, plants were irrigated 3, 10, and 16 times for the low, medium, and high irrigation treatment, respectively.
Irrigation had no effect on canopy size, high irrigation treatment increased the relative growth rate of six taxa, low irrigation treatment increased relative growth rate of one taxon, and relative growth rate of two taxa was unaffected by irrigation treatment.
Monthly visual quality assessment ratings were acceptable or better at the low irrigation treatment for all taxa.
Best performing plants maintained a high overall rating at the low irrigation treatment and included Dodonaea viscosa ‘Emerald Ice’, Eremophila glabra ssp. carnosa ‘Winter Blaze’, Ericameria laricifolia ‘Aguirre’, Hamelia patens ‘Sierra Red’, and Leucophyllum frutescens ‘San Antonio Rose’. High irrigation treatment decreased visual appearance of some plants and stimulated flowering and growth in others.
Air temperatures of -3.3 to -5.5°C in January and February 2022 caused medium to severe freezing damage to two non-native taxa, and one taxon with a broad native range that includes subtropical regions.
Taxa differed in their tolerance to the low irrigation treatment and while all still performed acceptably, some may benefit from additional irrigation during the hottest time of the year for optimum performance.
Weather conditions during the study were characterized by high evapotranspiration, scarce precipitation, and summer temperatures between 38 and 42°C. After one year of establishment, plants received three levels of irrigation based on local reference evapotranspiration (ET0), low (20% ET0), medium (50% ET0), or high (80% ET0). Between April 1 and October 31, 2022, plants were irrigated 3, 10, and 16 times for the low, medium, and high irrigation treatment, respectively.
Irrigation had no effect on canopy size, high irrigation treatment increased the relative growth rate of six taxa, low irrigation treatment increased relative growth rate of one taxon, and relative growth rate of two taxa was unaffected by irrigation treatment.
Monthly visual quality assessment ratings were acceptable or better at the low irrigation treatment for all taxa.
Best performing plants maintained a high overall rating at the low irrigation treatment and included Dodonaea viscosa ‘Emerald Ice’, Eremophila glabra ssp. carnosa ‘Winter Blaze’, Ericameria laricifolia ‘Aguirre’, Hamelia patens ‘Sierra Red’, and Leucophyllum frutescens ‘San Antonio Rose’. High irrigation treatment decreased visual appearance of some plants and stimulated flowering and growth in others.
Air temperatures of -3.3 to -5.5°C in January and February 2022 caused medium to severe freezing damage to two non-native taxa, and one taxon with a broad native range that includes subtropical regions.
Taxa differed in their tolerance to the low irrigation treatment and while all still performed acceptably, some may benefit from additional irrigation during the hottest time of the year for optimum performance.
Authors
U.K. Schuch, J. Gilbert, L.R. Oki, J.A. Sisneroz, K. Reid, Youping Sun, L.L. Nackley, R.N. Contreras, Soo-Hyung Kim, D.L. Haver, N.L. Levy
Keywords
desert landscapes, low water use plants, plant growth, semiarid climate
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