Crop Water Stress Index of Ornamental Plants

Abstract

Water requirements were determined for eighteen species of ornamental plants produced under non-limiting water conditions at Las Cruces, New Mexico. Baseline equations were determined from regression analysis of canopy-air temperature differential versus air vapor pressure deficit. Canopy temperature was measured using an infrared thermometer. Air temperature and air vapor pressure deficit were measured using an Assmann psychrometer. Regressions for Salt Cedar, Sycamore, Ash, and Aleppo Pine had statistically equivalent slopes and intercepts (P < 0.05); all others were unique in their responses. Canopy and aerodynamic resistance were calculated from the baseline equations and the noontime and daily transpiration rates were calculated. Daily transpiration ranged from 12.5 mm d–l (0.49 in. d–l) (alfalfa) to 3 mm d–l (0.12 in. d–l) (Barberry). Relative transpiration was calculated using alfalfa as a standard. Redbud exhibited a relative transpiration of 0.78 and Mulberry showed a relative transpiration of 0.42.