PERFORMANCE OF LANDSCAPE ORNAMENTALS GIVEN IRRIGATION TREATMENTS BASED ON REFERENCE EVAPOTRANSPIRATION

The use of reference evapotranspiration (ET₀) information for scheduling irrigations and for determining water allotments for landscapes is being adopted by water purveyors, agencies, landscape architects, and maintenance personnel.
There is little research-based information relevant to landscape ornamental plant materials.
The objectives of this project were to determine the response of 30 ornamental species to irrigation treatments with respect to ET₀ and to further refine estimates of ornamental plant water needs for acceptable aesthetic appearance.
Experimental plots were established in Encinitas, California, USA, consisting of nine 180m² blocks allowing three irrigation treatments replicated three times.
Four plants of each of 30 species were planted into 6m² experimental units within the drip-irrigated blocks.
Irrigation treatments were initiated in 1996 and consisted of 0.36, 0.24, and 0.12 ET₀ with irrigation frequency determined by projected soil moisture deficit of 13mm.
During 1997 and 1998, irrigation treatments were adjusted to 0.36, 0.18, and 0.0 ET₀. The aesthetic quality of 16 species was reduced with reduced irrigation amounts.
Many of these species performed well at the 0.36 and 0.18 ET₀ treatments but suffered at the 0.0 ET₀ level.
Aesthetic quality was not affected by irrigation treatment in 11 of the species studied.
The results of the study show that ET₀ treatments affect landscape quality for some species and acceptable appearance can be maintained with reduced irrigation.

IV International Symposium on Irrigation of Horticultural Crops

D.A. Shaw, D.R. Pittenger

Xeriscape, water, drought tolerance

https://doi.org/10.17660/ActaHortic.2004.664.76