Salinity Threshold of Tall Wheatgrass for Cultivation in Coastal Saline and Alkaline Land

Tall wheatgrass (Elytrigia elongata) has the potential to be utilized on marginal land, such as coastal saline-alkaline soils, to meet rising ruminant feed demand. However, the salinity threshold for cultivation of tall wheatgrass remains unclear, which restricts its extensive application. Here, a tall wheatgrass line, Zhongyan 1, was grown in saline-alkaline soils in the Yellow River Delta region to determine its salinity threshold. The results showed that the soil salinity of AM = 1.23, measured with a PNT3000 activity meter, led to only 5% dead plants of tall wheatgrass. Four grades of seedling plants were classified according to the morphological response of Zhongyan 1 to saline soils. The soil salinity declined while the survival rate and forage yield increased from grade 1 to grade 4 plants. Plant height and dry matter yield were negatively related to soil salinity. When the salinity in the soil depth of 0–10 cm was over 1%, the survival rate of tall wheatgrass declined dramatically with the increase in soil salinity. Under saline-alkaline stress, the plant height during 12–31 May was positively related to forage yield, which can be used as an indicator of productivity. The tall type (70–120 cm) produced 5627.2 kg ha−1 of dry matter, which was 3.32 times that of the dwarf type (20–69 cm). The forage yield of tall wheatgrass in saline-alkaline land was largely affected by the proportion of highly saline soil. Collectively, the soil salinity of 1% at a depth of 0–10 cm and the AM values of 1.23 measured with a PNT3000 activity meter can be used as the salinity threshold for cultivation of tall wheatgrass in coastal saline-alkaline land.