Response of Spring Wheat to Sulfate-Based Salinity Stress under Greenhouse and Field Conditions

Spring wheat (Triticum aestivum L.), a moderately salt-tolerant crop, is often grown in saline areas worldwide. This study was conducted to assess spring wheat response to sulfate-based salts under greenhouse and field conditions. In a greenhouse experiment, salinity treatments (control and 3.0, 5.0, 9.0, and 15.0 dS m(-1)) were established by adding Na2SO4 and MgSO4 center dot 7H(2)O salts in soil-silica mixes. Similarly, field studies were conducted in naturally saline farmers' fields in eastern North Dakota for a total of four site-years. In the fields, the soil was sampled to the 120 cm depth, and the depth-weighted mean root-zone salinity was calculated. Results indicated a variable response of spring wheat to salinity under greenhouse and field conditions. Under greenhouse conditions, plant height and number of tillers per plant decreased significantly at a soil saturated paste extract electrical conductivity (ECe) of 5 dS m(-1) and above. Similarly, root growth decreased significantly at a ECe of 9.0 dS m(-1) and above. Relative kernel and straw yields were unaffected by sulfate salts up to 8.2 and 2.9 dS m(-1), respectively. Above the threshold value, the kernel and straw yields declined by 12.0 and 4.9% per unit increase in ECe, respectively. In naturally saline fields, soil salinity decreased with soil depth, and the spring wheat responded by decreasing plant height by 1.2 cm per unit increase in ECe. However, root growth and relative crop yields were maintained. Our results suggest that the majority of the crop roots were exposed to low salinity levels in the surface soil layers in naturally saline fields, providing greater salinity tolerance in the crops.