*3.1. Crop Response to Soil Salinity Stress*

The electrical conductivity of saturation soil-past extracts from the root zone (ECe) is commonly used as an indicator of the soil salinity stress to determine the total reduction in biomass production, determines the value for soil salinity stress coefficient (Ks, salt).

The coefficient of soil salinity stress (Kssalt) varied between 0 (full effect of stress of soil salinity) and 1 (no effect). The following equation determined the reduction in biomass

$$\mathbf{B}\_{\rm rel} = 100 \ (1 - \mathbf{K} \mathbf{s}\_{\rm salt}) \tag{6}$$

Brel represents the expected biomass production under given salinity stress relative to the biomass produced in the absence of salt stress. The coefficient is adjusted daily to the average ECe in the root zone [35].

Then, the thresholds values are given for the sensitive and tolerant barley genotype and expressed in dS m<sup>−</sup>1. This allows the estimation of the lower limit (ECen) to which the soil salinity stress begins to affect the production of biomass and the upper threshold (ECex), in which soil salinity stress has reached its maximum effect.
