Assessment of superabsorbent polymer effect on water use efficiency of plant under water deficit conditions

Deficit irrigation is an optimum technique for producing products under drought stress conditions. The superabsorbent hydrogel is a hydrophilic polymer with cross-linked 3-D hydrophilic nets that can absorb and retain effective amounts of water and aquatic liquids. The objective of this study was to assess the superabsorbent polymer effect on water use efficiency (WUE) and grain yield of Vigna unguiculata L. under drought stress conditions. The experimental treatments included: Treatment I1S0, including 100% ETc demand as irrigation amount and with 0.0 g SAP (I-1:100%; S-0: without SAP); treatment I2S1, including 75% ETc demand as irrigation amount and with 7.0 g Super-AB-A300 polymer for plant (I-2: 75%; S-1: 7 g SAP); treatment I3S2, including 55% ETc demand as irrigation amount and with 14.0 g Super-AB-A300 polymer for plant (I-3: 55%; S-2: 14 g SAP). A drip irrigation system performed irrigation. According to the results, the soil treated with superabsorbent polymer, in mild deficit irrigation treatment (I2S1), made it possible to obtain the same grain yield as the complete irrigation treatment (I1S0) and there was no significant difference between them. Besides, IWUE was conversely depended on the entire water requirement all along the growing cycle, and for higher IWUE, the water would be decreased under the irrigation demand for the maximum grain yield. Thus, the mix of mild deficit irrigation and superabsorbent polymer (I2S1), that leads to increase the plant water productivity (AWP), was an acceptable policy to optimize cowpea grain yield and water utilization.