The effect of brackish water irrigation on crops cultivated in the Vietnamese Mekong Delta

Brackish water is formed when freshwater mixes with saltwater resulting in differential NaCI concentrations. To identify safe and effective ways of using brackish water in the VMD, we assessed its impact on soil salinity, and on productivity of beetroot, maize and peanut cultivated on loam-clayey soil under greenhouse conditions at Tra Vinh University. No to high salinity stress was induced by crop irrigation with 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5 or 4 ppt NaCI solution, as gradually increasing NaCI concentration (acclimatising saline experiment) or acute NaCI solution applied at different developmental growth stages (shock saline experiment). Continuous irrigation with ≤1.5 ppt NaCI solution does not significantly decrease yield within a single growing season while also leading to substantial enhancement of crop quality-sugar content of beetroot bulbs. Although both beetroot and peanut were negatively impacted under strong saline conditions, beetroot yield was minimally reduced stimulating responses expected of salt tolerant crops or varieties. Thus, beetroot performs better than peanut and maize under saline conditions, and can be cultivated as an alternative crop during dry, salinized seasons in the VMD. However, long term effect of brackish water irrigation on soil salinity and crop yield needs further evaluation.