Effect of salinity on salt accumulation and reproductive development in the apical meristem of wheat and barley

Abstract

Two cultivars of wheat and two of barley differing in salt tolerance were grown at 0, 100 and 175 mМ NaCl, and the development of the apex was followed as it turned from vegetative to reproductive. Apices were taken for ion analysis when most of the spikelet primordia had been produced and the process of differentiation into floral organs was starting. K ⁺ concentrations in apices were unaffected by the salinity treatment, Na ⁺ concentrations were generally low in all treatments, below 50 mМ, while Cl ⁻ levels were very low, below 30 mМ. These levels of Na ⁺ and Cl ⁻ are too low to affect metabolism. In spite of these negligible effects on ion levels in the apex, salinity affected reproductive development: fewer spikelet primordia formed, and final spikelet numbers at ear emergence were reduced. Salinity greatly advanced the time of floral initiation in the wheat cultivars. This indicates that modification of apical development by salinity was not determined by salt in the apex itself, but mediated by signals or substrates derived from elsewhere in the plant.