Impact of a Novel Water-Saving Subsurface Irrigation System on Water Productivity, Photosynthetic Characteristics, Yield, and Fruit Quality of Date Palm under Arid Conditions

Abstract

Water scarcity is a major constraint in arid and semi-arid regions. Crops that require less irrigation water and those, which are considered drought-tolerant such as date palm (Phoenix dactylifera L.), are dominant in these regions. Despite the tolerance of these crops, the development of technologies that ensure efficient use of irrigation water is imperative. Taking these issues into consideration, the study was conducted to investigate the impact of limited irrigation water using a new subsurface irrigation system (SSI) on gas exchange, chlorophyll content, water use efficiency, water productivity, fruit physicochemical characteristics, and yield of date palm (cv. Sheshi). The impact of the SSI system was compared with two surface irrigation systems, namely, surface drip irrigation (SDI) and surface bubbler irrigation (SBI). The field experiment was carried out during 2018 and 2019 at the Date Palm Research Center of Excellence, King Faisal University, Kingdom of Saudi Arabia. The annual crop evapotranspiration (ETc) was 2544 mm. The applied irrigation water was set at 50%, 75%, and 125% of ETc for SSI, SDI, and SBI, respectively, which were based on the higher crop water productivity recorded in an initial field study. The total annual volume of water applied for SSI, SDI, and SBI was 22.89, 34.34, and 57.24 m3 palm−1, respectively. The crop water productivity (CWP) at the SSI system was significantly higher, with a value of 1.15 kg m−3, compared to the SDI (0.51 kg m−3) and SBI systems (0.37 kg m−3). The photosynthetic water use efficiency (WUE) was 10.09, 9.96, and 9.56 μmol CO2 mmol−1 H2O for SSI, SBI, and SDI, respectively. The maximum chlorophyll content (62.4 SPAD) was observed in SBI, followed by SSI (58.9 SPAD) and SDI (56.9 SPAD). Similarly, net photosynthesis and the transpiration rate were significantly higher in SBI and lowest in SSI. However, the SSI system substantially increased palm yield and enhanced fruit quality. The new SSI system, through its positive impact on the efficiency of irrigation water use and enhancement on fruit yield and fruit quality of date palm, seems quite suitable for the irrigation of palm trees in arid and semi-arid regions.

Efficient IoT-Based Control for a Smart Subsurface Irrigation System to Enhance Irrigation Management of Date Palm

“…The annual cumulative value of ETc was 2137 mm, as shown in Figure 14. The obtained data of ETo was similar to the resulted data presented by the authors in [1,11,32].…”

“…The irrigation amount was determined in the T-BIS method based on calculated crop evapotranspiration (ETc) and target soil area for the irrigated date palm trees. We applied 50 % of ETc according to the recommendation of Mohammed et al [1]. The following equation was used for calculating the irrigation water requirement:…”

“…The applied shaded area in the experiment was 22 m 2 . The calendar set the irrigation timing under the T-BIS method was conducted according to Mohammed et al [1] every three days from 1-January to 31 March, every two days from 1 April to 30 September, and every three days from 1-October to 31 December using a programmable timer (model: TM919, Shenzhen HHT Electronics Technology Co., Ltd., Shenzhen, China). The designed IoT system mounted the actual amount of irrigation water and the cumulative irrigation water throughout the year for the two methods of time-based scheduling (T-BIS) and sensor-based scheduling (S-BIS).…”

“…Water scarcity in arid and semi-arid regions is a primary constraint to sustainable cultivation [1]. However, ongoing population growth requires sustained growth of food production in the future, which in turn requires irrigation water inputs that can support irrigated cultivation.…”

“…The irrigation water does not evaporate from the soil surface using subsurface irrigation systems compared to traditional surface irrigation methods. The subsurface irrigation systems are characterized by water application at low intensity directly in the functional root zone of the date palm [1,16,[27][28][29]. The automatic irrigation system, including wireless soil moisture sensors, obtains more yield with less irrigation water requirement, and the water productivity is improved [5,17,25].…”