Visible and Near‐Infrared Reflectance Assessment of Salinity Effects on Barley

Synopsis We studied the effects of a soil salinity gradient (0.8−1.9 dS m −1 ECa) on spectral reflectance of 10 genotypes of barley ( Hordeum vulgare L.) to determine the efficacy of reflectance as a tool for assessing the responses of barley to salinity. NDVI [normalized difference vegetation index, (R900 nm − R680 nm)/(R900 nm + R680 nm)] and WI (water index, R970 nm/R900 nm) were the reflectance indices used. In response to increasing salinity, near infrared reflectance decreased and visible reflectance increased, thereby lowering NDVI from 0.85 to 0.4, in parallel with decreases in biomass (from 2500–500 g m −2 ) and yield (from 900–50 g m −2 ). NDVI was, thus, a good indicator of biomass and yield. WI increased from 0.73 to 0.96, δT (canopy temperature minus air temperature) increased from −2 to 7°C, and 13 C discrimination (Δ 13 C) in mature kernels decreased from 19 to 14.5 with increasing salinity levels. WI was, thus, related to crop water status response to salinity. NDVI and WI were, therefore, useful for measuring agronomic responses of barley to salinity.