Cell and Plant Responses to Nacl in Zea Mays L. Cultivars Differing in Salt Tolerance

Two Zea mays cultivars, salt sensitive Trihybrid 321 and salt tolerant Giza 2, were studied, namely their adaptation to NaCl imposition at cell and whole plant level. Changes in growth and mineral content of roots and shoots, glycinebetaine (GB) and free proline (Pro) levels of shoots, plasma membrane permeability and solute potential (ø s) of leaf sheath subepider-mal cells were measured. NaCl decreased fresh mass (FM), dry mass (DM), relative growth rate (RGR) of shoots and roots, and leaf area ratio (LAR) in both cultivars. Greater decrease (except LAR) was obtained in Giza 2 than in Trihybrid 321. NaCl stress resulted in accumulation of GB and free Pro in shoots of both cultivars. The magnitude of increase in both omsolytes was higher in Giza 2 than in Trihybrid 321. Salt stress induced Na + and Cl-accumulation while it decreased K + and Ca 2+ levels in shoots and roots of both cultivars. The increase in Na + and the decrease in K + and Ca 2+ was greater in Giza 2 than in Trihybrid 321. Cl-was increased more in Trihybrid 321 compared to Giza 2. NaCl increased plasma membrane permeability in both cul-tivars. Salt stress decreased cell ø s in both cultivars, especially in Giza 2. It was concluded that Na + exclusion from the shoot was not correlated with salt tolerance and that Pro and GB accumulation in the shoot was a possible indicator for salt tolerance in the maize genotypes studied.