Assessing the effect of solar radiation on plant salt tolerance as definedby the static and dynamic indices

Any interaction between plant salt tolerance and environment is critical to crop breeders, geneticists, molecular biologists, soil-water-crop modelers and all researchers interested in 'global change'. A common criterion used for plant salt tolerance is a threshold value of root zone salinity, a sta tic index that delimits the onset of yield reduction. According to this cri terion, it was discovered that tomato salt tolerance decreases significantl y with reduced solar radiation. In contrast, the threshold values of a new index based on the dynamic processes of salt accumulation relative to growt h, are invariant to solar radiation. The variability and stability of the r espective indices provides new insights for accessing physical and biochemi cal processes governing plant response in saline environments.