Salt tolerance of wheat according to soil and drainage water salinity.

To determine salt tolerance of spring wheat genotype (On_Farm 9) to soil salinity (ECe) and drainage water salinity (ECd), a pot experiment containing three irrigation water salinities of 4, 9 and 12 dS m(-1) and four leaching levels of 3, 20, 29 and 37% was conducted in a completely randomized design arranged as factorial with 7 replications on a silty clay loam soil during 2005. The results showed that decrease of leaching water quality and quantity significantly increased soil and drainage water salinity and decreased crop yield and evapotranspiration. Application of leaching water fraction in the range of 20-29% were highly significant in decreasing soil salinity, drainage water salinity and increasing grain yield, while the most increase in crop evapotranspiration occurred in the range of 29-37%. This study shows that the effects of increase of soil salinity on grain relative yield are more significant than effects of increase of salinity of drainage water and wheat has greater threshold value in drainage water salinity than soil salinity method. The correlation of relative grain yield (Ry) with ECe and ECd indicated that ECd could estimate Ry as well as ECe.