USE OF NORMALIZED DIFFERENCE VEGETATION INDEX (NDVI) FOR ESTIMATING GENOTYPIC DIFFERENCES IN WHEAT SEEDLINGS RESPONSE TO WATER STRESS INDUCED BY GRADUAL DRYING OF THE SUBSTRATE

Drought and osmotic stresses, that can both affect the plant in any vegetation stage, including seedling stage, may be characterized through water status measurements. Non-destructive remote sensing offers a viable alternative for screening many genotypes in a short time. Significant genotypic differences were previously demonstrated in seedlings growth response to water stress, but characterizing growth necessitated frequent measurements, which limited the usefullness of this method in routine screening of breeding material. In an attempt to avoid this limitation, we searched for genetic differences between wheat cultivars in normalized difference vegetation index (NDVI) in seedlings exposed to water stress through gradual drying. 17 wheat genotypes, contrasting in drought resistance, were subjected to water stress by gradual drying of the substrate, during 27 days, using 1000 cm(3) of soil, initially soaked with 300 ml of water. The cultivars were tested under controlled conditions in a growth chamber. We found significant differences between wheat genotypes for NDVI, as well as significant correlation between NDVI measured in water stress seedlings and osmotic adjustment estimated by pollen test, as well as between NDVI and an estimation of yield response to drought in the field. NDVI measured in seedlings exposed to gradual drying of the substrate can allow exploring and test a large number of genotypes and can be used for off-season direct comparison between cultivars.