Mineral Nutrient Acquisition and Response by Plants Grown in Saline Environments

Abstract

Plants acquire mineral nutrients from their native soil environments. Most crop plants are glycophytes and have evolved under conditions of low soil salinity. Consequently, they have developed mechanisms for absorbing, transporting, and utilizing mineral nutrients in nonsaline soils. Under saline conditions, which are characterized by low nutrient-ion activities and extreme ratios of Na / Ca , Na /K , Mg /Ca , and Cl /NO3 , nutritional disorders can develop and crop growth and quality may be reduced. This is not surprising, since under saline conditions, Na and/or Cl often exceed macronutrient concentrations by one or two orders of magnitude and even more in the case of micronutrients. Halophytes, native to saline environments, may also develop nutrient disorders despite their remarkable ability to absorb nutrients selectively from soil solutions dominated by Na and Cl . Nutrient imbalance can develop in salt-stressed plants in different ways. It may result from the effect of salinity on nutrient availability, uptake, transport, or partitioning within the plant or may be caused by physiological inactivation of a given nutrient resulting in an increase in the plant’s internal requirement for that essential element. It is likely that salinity may affect one or more of these processes at the same time, but whether or not this imbalance results in loss of crop yield or quality depends on its severity, which is influenced by a number of environmental factors. Nutrient availability and uptake by plants grown in saline environments is related to (a) the activity of the nutrient ion in the soil solution which depends on pH, pE (the negative log of