Water scarcity is a major constraint facing vegetable production sustainability in open field farming of arid regions like the Kingdom of Saudi Arabia. This study was carried out in an open field of the Research and Training Station of King Faisal University in the eastern region of the Kingdom. The objective was to assess the influences of the polymer addition (PA), deficit irrigation regime (DIR), and their combination on the production and water use efficiency (WUE) of muskmelons. PA treatments of 0.0, 0.2 and 0.4% and the irrigation treatments of 100, 75 and 50% of reference evapotranspiration (ET<sub>o</sub>), were imposed throughout the growth stages of muskmelons under surface drip irrigation (DI) and subsurface drip irrigation (SDI). The polymer addition of 0.4% enhanced the field water holding capacity of the medium sandy soil within the locality of the emitters by 43.6%. The soil water content of the surface layer within the vicinity of the polymer amended soil layer increased in a range of 72.4 to 99.4% to the combined influences of the 0.4% PA with the DI and SDI, but were marked more under the SDI. The combination of the 100% ET<sub>o</sub> DIR with polymer additions significantly (P < 0.05) enhanced the muskmelon fruit yield (MFY) under the SDI compared to DI. The PA of 0.4% improved WUE and MFY by 67.7, 70.4% under the SDI, and 58.6, 24.2% under the DI, respectively. Without the polymer addition (0.0% PA), the MFY significantly (P < 0.05) decreased with the increase of the DIRs under both DI and SDI.
Effect of Deficit Irrigation, Air injection and Nitrogen Fertilization on Water Productivity of Carrot under Subsurface Drip Irrigation System.
