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.