Drought-Tolerance Screening of Date Palm Cultivars under Water Stress Conditions in Arid Regions

Drought stress poses a considerable challenge to agriculture sustainability in arid regions. Water scarcity severely affects date palm growth and productivity in these regions. However, as water resources become increasingly scarce in arid regions, understanding the drought tolerance of date palm cultivars becomes imperative for developing drought-resistant cultivars and optimizing irrigation water usage for sustainable agriculture. This research examines the impact of different drought stress levels based on evapotranspiration (ET_c), i.e., 40%, 60%, 80%, and 100% ET_c, and time intervals (0, 6, 12, 18, and 24 months) on leaf growth, net photosynthesis, chlorophyll <i>a</i> and <i>b</i> content, and leaf relative water content (LRWC) of four prominent date palm cultivars, Khalas, Barhee, Hilali, and Ashrasee. In addition, the study also examines the effects of drought stress on dry weight, potassium and calcium content of leaf, stem, and root, and proline content in fresh leaves of these four cultivars. A solar-powered drip irrigation system with automated time-based irrigation scheduling was used to accurately control the irrigation water amount. To real-time estimate ET_c in the study area, meteorological data were collected using a cloud-based IoT system. The findings of this study revealed that severe drought conditions (40 and 60 % ET_c) significantly reduced leaf growth, plant dry biomass, and physiological and biochemical attributes; however, date palm cultivars can be grown under moderate drought conditions (80% ET_c) with minimal effect on phenotypic, physiological, and biochemical traits to conserve water. The study also revealed that the drought-related characteristics decreased gradually with an increase in water stress time over 24 months. Comparing the date palm cultivars revealed that the Khalas and Barhee cultivars are more drought-tolerant, followed by Hilali, while Ashrasee is susceptible. The study elucidated a water conservation strategy employed in response to drought-induced stress based on the physiological and morphological parameters of date palm cultivars. It provides valuable insights into irrigation practices in arid regions. However, future studies can be focused on other nondestructive innovative techniques such as pulse-amplitude-modulation (PAM) fluorimetry, infrared radiation (IR), and video imaging system (VIS) methods to identify drought stress in date palms.