Water requirements of banana and papaya under different water table depths and soil types in the Lower Indus Basin of Pakistan

The water requirements of banana and papaya, the two most important fruit crops of Pakistan, are not known because farmers continue to apply water even if the crop does not need it. In this study, the evapotranspiration (ET), groundwater contribution (GW) and crop coefficient (K_c) values of banana (1995–1999) and papaya (2013–2016) were determined under different water table depths (WTDs) and soil types using drainage-type lysimeters. The WTDs were maintained at 1.50, 2.00 and 2.50 m from the ground surface by means of Mariotte bottles. The banana ET during the first year was between 1653 and 1992 mm with a GW contribution of 11–20%, whereas during the second to fifth years, it was between 2430 and 3023 mm with a GW contribution of 10–16%. The banana yield was in the range of 58,638–79,780 kg ha⁻¹, and the water use efficiency (WUE) was between 2.65 and 3.31 kg m⁻³. The papaya ET was between 1478 and 1766 mm with a GW contribution of 7–18% at 1.50–2.50 m WTDs. The papaya yield was in the range of 61,184–83,004 kg ha⁻¹ with a WUE of 4.13–4.70 kg m⁻³. Therefore, GW contribution is an important component of the water balance under shallow water table conditions and should be considered when devising irrigation scheduling for banana and papaya crops.