IS THE SALT TOLERANCE OF MAIZE RELATED TO SODIUM EXCLUSION .1. PRELIMINARY SCREENING OF 7 CULTIVARS

Maize (Zea maysL.) plants in the early stage of development were treat ed with 80 mM sodium chloride (NaCl) with or without supplemental calc ium (Ca2+) (8.75 mM) for a seven day period. The effects of salinity o n dry matter production and shoot and root concentrations of sodium (N a+), Ca2+, and potassium (K+) were measured for seven Pioneer maize cu ltivars. Salinity significantly reduced total dry weight, leaf area, a nd shoot and root dry weight below control levels. For all seven culti vars, Naf concentrations were reduced and leaf area was significantly increased by supplementing salinized nutrient solutions with 8.75 mM c alcium chloride (CaCl2). The two cultivars with the lowest shoot and r oot Na+ concentrations under NaCl-salinity showed the greatest increas es in total, shoot and root dry weights with the addition of supplemen tal Ca. Shoot fresh weight/dry weight ratios for all cultivars were de creased significantly by both salinity treatments, but supplemental Ca 2+ increased the ratio relative to salinity treatments without supplem ental Ca. Root fresh weight/dry weight ratios were decreased only by s alinity treatments with supplemental Ca. With NaCl-salinity, cultivars which had lower shoot and root Na+ concentrations were found to be mo re salt sensitive and had significantly lower amounts of dry matter pr oduction than those cultivars which had higher shoot and root Na+ conc entrations. It was concluded that Na+ exclusion from the shoot was not correlated with and was an unreliable indicator of salt tolerance for maize.