Effects of saline water irrigation on the soil salinity, yield and quality of field-grown winter jujube (Ziziphus jujuba Mill. “Dongzao”)

Abstract

[Aims] The shortage of freshwater resources and soil salinization have always been considerable challenges for agricultural production in the Yellow River Delta. Safe and efficient use of saline water resources is thus urgently needed. [Methods] To reveal the effects of irrigation with underground saline water on soil salinity, yield and quality of drip-irrigated winter jujube, a field trial was conducted from 2020 to 2022. The experiment was conducted with 5 levels of blending a mix of groundwater and freshwater, namely, 1.7 (T1), 3.3 (T2), 4.9 (T3), 6.5 (T4) and 8.1 (T5) dS·m-1. [Results] The results for three aspects were as follows: (i) Soil surface salinity accumulation occurred when the irrigation water salinity was greater than 4.9 dS·m-1 in 2020, and salinity was maintained in balance in the following two years owing to adequate rainfall during the planting period. (ii) Compared to T1, irrigation with 3.3 dS·m-1 or 4.9 dS·m-1 of saline water had no significant effect on yield, and the winter jujube yield decreased with increasing irrigation water salinity. (iii) Saline water irrigation improved winter jujube quality, as evidenced by the increase in soluble sugar, total soluble solids, titratable acid, vitamin C and flavonoid contents. When the irrigation water salinity ranged from 4.9 dS·m-1 to 8.1 dS·m-1, the comprehensive quality was within the appropriate scope. [Conclusions] Considering the yield, quality and salt accumulation of winter jujube, drip irrigation is conducive to ensuring the sustainability of winter jujube with saline water salinities less than 4.9 dS·m-1.