Salinity-induced changes in the nutritional status of expanding cells may impact leaf growth inhibition in maize

Salinity-induced excess or deficiency of specific nutrients are often hypothesised to operate as causes of growth inhibition and to trigger primary responses, which directly affect growth. Information concerning salinity effects on microelement nutrition in the growing cells is limited. In this study, salinity-(80 mM NaCl) inflicted alterations in spatial profiles of essential elements (N, P, K, S, Ca, Mg, Fe, Zn, Mn, Cu) and the salinity source (Na and Cl) were studied along the growing zone of leaf 4 of maize (Zea mays L.). Correlations between spatial profiles of growth and nutritional status of the tissue were tested for evaluation of the hypothesis that a disturbance of specific mineral nutritional factors in the growing cells might serve as causes of salt-induced growth inhibition. Examined nutritional elements exhibited unique distribution patterns, all of which were disturbed by salinity. With the exception of Na, Cl and Fe, the deposition rates of all the studied mineral elements were reduced by salinity throughout the elongating tissue. Localised contents of Ca, K and Fe in the growing tissue of the salt-stressed leaf were highly correlated with the intensity of localised tissue volumetric expansion, suggesting reduced levels of Ca and K, and toxic levels of Fe as possible causes of growth inhibition. Na and Cl accumulation were not correlated with growth inhibition under salinity.