The sensitivity of germinatingTriticum durumL. kernels to saline environment

Abstract

AbstractOsmotic and ionic effects of NaCl were investigated in germinating wheat. Approximately isotonic solutions of NaCl and sorbitol inhibited germination and seedling growth to similar degrees. When dry kernels were pre-imbibed in salt for 24 h and then transferred to water, germination was equivalent to that of kernels imbibed continuously in water and the development of embryos was delayed to about the same extent as kernels pre-imbibed in sorbitol for 24 h. Measurements of water uptake, respiration, biosynthetic activities and rubidium uptake in embryos dissected from grains imbibed in NaCI or sorbitol for the first 24 h demonstrated that salt supplied to dry kernels closely mimicked sorbitol in counteracting the reactivation of embryo metabolism. No toxic effects of salt were observed when dry kernels were pre-imbibed in very high NaCI concentrations for 24 h and then transferred to water, even though embryo sodium contents increased considerably. Ultrastructural observations of embryo tissue further showed that salt influx into dry grains did not produce ion-specific damage in cell organization. On the other hand, salt specific effects became evident when the 24 h salt exposure was applied to kernels pre-hydrated for 24 h and, even more, for 30 h. We conclude that in wheat the inhibition of germination by salt corresponds to that induced by an osmoticum, provided that the caryopsis has not reached the stage of germination associated with active embryo expansion.