VISIBLE AND NEAR-INFRARED REFLECTANCE ASSESSMENT OF SALINITY EFFECTS ON BARLEY

We studied the effects of a soil salinity gradient (0.8-1.9 dS m(-1) E Ca) 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 veget ation index, (R900 mn - R680 nn)/(R900 mn + R680 nm)] and WI (water in dex, R970 nm/ R900 nm) were the reflectance indices used. In response to increasing salinity, near infrared reflectance decreased and visibl e reflectance increased, thereby lowering NDVI from 0.85 to 0.4, in pa rallel with decreases in biomass (from 2500-500 g m(-2)) and yield (fr om 900-50 g m(-2)). NDVI was, thus, a good indicator of biomass and yi eld. WI increased from 0.73 to 0.96, delta T (canopy temperature minus air temperature) increased from -2 to 7 degrees C, and C-13 discrimin ation (Delta(13)C) in mature kernels decreased from 19 to 14.5 with in creasing salinity levels. WI was, thus, related to crop water status r esponse to salinity. NDVI and WI were, therefore, useful for measuring agronomic responses of barley to salinity.