Effects of Irrigation Regimes on Khalas Date Palm Yield Under Surface and Enhanced Subsurface Irrigation Systems with Smart Control Application

The date palm Phoenix dactylifera L. is an essential desert food crop. A study was conducted for two years to determine Khalas palm variety yield response to different irrigation regimes. Bubbler system (BS) and enhanced subsurface stonewool drip system (ESDS) were tested in the Kingdom of Bahrain during the period of 2021–2023. A split-plot design was used with BS and ESDS as main plots. Irrigation regimes of 20, 30, and 50% (D2–D3) as subplots compared with crop water requirements (D1) based on Penman Monteith FAO method (PMFM). A smart volume-based control system was used in the 2nd year. The results revealed no significant differences in date yield, average weight of bunches, and soft fruits (Rutab) percent between the BS and ESDS systems (p > 0.05). No significant yield differences were obtained between the irrigation regimes at p > 0.05. Water productivity was highly significant (p = 0.0003 and 0.0001) regarding irrigation regimes for the two years, respectively. Compared to 1st year, the 2nd year yield has improved by 78.5 and 53.5% under ESDS and BS systems, respectively. Apart from seasonal palm yield variations, smart application has the most impact on yield improvement. It is concluded that published palm KC coefficients may overestimate water requirements by about 50%. More water saving can be attained using smart volume-control application under BS or ESDS systems. It is vital to develop local crop coefficients for date palms under desert and humid climatic conditions similar to Bahrain.