Irrigation Water Requirement and Crop Coefficient of the Desert Plant Cleome amblyocarpa (Cleomaceae)

Irrigation water management is a necessity in hot and arid regions. The desert Cleome amblyocarpa Barr. and Murb. (Family Cleomaceae) is an annual medicinal herb widespread in countries located in the desert regions, such as the United Arab Emirates (UAE). This herb has been used as a pain killer in traditional therapeutic practices. The study's primary purpose is to determine this herb's irrigation water requirement and its crop coefficient (Kc), both calculated under the UAE's natural climatic conditions. Soil water retention characteristics were obtained from the pF curve. Determination of the irrigation requirement was calculated, for the mature C. amblyocarpa cultivated in sandy soils, by considering the change in soil moisture content (ΔW) irrigated manually to field capacity (At 0.01 MPa, pF: 2). The reference evapotranspiration (ETo) was calculated following the FAO-56 Penman–Monteith equation by utilizing the Food and Agriculture Organization (FAO) software tool (ETo Calculator). The climatic parameters were imported from the closest meteorological station using the FAO climatic database (CLIMWAT 2.0). The lysimeter method was used to calculate crop evapotranspiration (ETc) at the fruiting stage for 30 days. In March, the ETc for C. amblyocarpa at a mid-late stage was found to be 3.651 ± 1.102 mm/day. ETc and ETo were used to determine the Kc, which was 0.652 during this herb's mid to late growth stage in March. Such findings would be provided for the first time in the literature and provide accurate irrigation water requirements.