###### Abstract
Common agronomic practices to reduce the deleterious effects of salinity stress on crop growth and productivity include the addition of mineral gypsum and organic amendments into the soil, use of effective leaching and drainage schemes, and treatment of plants and seeds with hormones, growth regulators, and nutrient nanoparticles [9; 10; 11]. However, these approaches require particular skills in their application. Therefore, improving the salt tolerance of genotypes through different breeding techniques is generally seen as an integrated approach with agronomic practices to sustain crop production and harvest reasonable yields under salinity conditions, as well as reducing reliance on the costlier agronomic practices [5; 12; 13; 14]. Although many efforts have been made during the past five decades to develop the genotypes salinity tolerance of field crops, especially wheat, limited salinity-tolerant genotypes have been released through breeding programs. The lack of easy screening methodologies necessary for the in-depth multidimensional assessment of phenotypic traits associated with salinity tolerance and the lack of assessment methods for the salt tolerance of a large number of genotypes at different growth stages, locations, and years remain a major challenge for plant breeders to accelerate wheat breeding for salinity tolerance [15; 16; 17; 18; 19; 20]. The potential yield of a crop through different growth stages and under normal or stress conditions is controlled by three main integrative processes: (1) the interception of incident sunlight radiation by the canopy, (2) the conversion of this intercepted light into biomass, and (3) the biomass allocation patterns between plant organs or harvest index (HI) [21; 22]. Generally, overall crop biomass is closely associated with the first two processes, which depend on the photosynthetic area and overall photosynthetic efficiency of the canopy [21]. Furthermore, because it may be difficult to achieve further genetic improvement in grain yield based on HI, further improvement in grain yield may rely more on increasing plant biomass rather than on HI [23; 24]. Therefore, when monitoring dynamic changes in the salt tolerance trait at different growth stages, the total biomass of a crop could be used to practically evaluate and elucidate the mechanisms of salt tolerance of various wheat genotypes. Unfortunately, conventional phenotyping of plant biomass based on laborious field work and destructive plant sampling makes the evaluation of salt tolerance of a large number of wheat genotypes at different growth stages cumbersome, expensive, and time consuming. Therefore, the availability of effective phenotyping tools to assess several key plant traits for a large number of genotypes in a time- and cost-efficient, nondestructive manner is necessary to shorten the evaluation process and improve salt tolerance genetics in wheat-breeding programs [19; 25]. Generally, salinity stress causes noticeable changes in several biophysical and biochemical characteristics of plants: photosynthetic efficiency, pigment content, chlorophyll fluorescence, ion concentrations, biomass accumulation, vegetative vigor, internal leaf structures, leaf area index, and plant water status [5; 26; 27; 28; 29]. Fortunately, these changes eventually result in unique changes in the characteristics of the spectral signatures that are reflected from the canopy at certain wavelengths from the three different regions of the spectrum. For example, [PERSON] et al. [30] reported that the canopy spectral reflectance of Chinese castor bean shifts to a shorter wavelength at indigo blue (420-470 nm) and red-edge (700-750 nm) regions in response to salt stress. Previous studies related to the response of spectral signatures to salinity stress showed a decrease in the visible region (VIS, 350-700 nm) and at a peak of 550 nm with increasing salinity levels [23; 31; 32].