0023-6152

AA00697606

4581

査読無

0023-6152

AA00697606

The effect of nitrate (4mM NO3[-]) and enhanced ammonium (3.5 mM NH4[+] + 0.5mM NO3[-]) nutrion on the growth soybean and cucumber plants grown hydroponically at 2 level (25 and 50Mm Cl[-]) of NaCl and CaCl2 salinity stress was investigated. The growth of both plants was better in nitrate nutrion than in enhanced ammonium nutrion. The pH values for enhanced ammonium solution decreased si,ilarly for both plants regardless of salinity stress In nitrate nutrion, lower sarinity did not affect soybean growth, whereas higher salinity clearly suppressed its growth. In the case of nitrate-fed cucumber plants, dry matter production was not decreased by the addition of CaCl2 but was by the addition of NaCl. In enhanced ammonium nutrion, the extent of growth suppression due to salinity was only small in soybean and cucumber plants. In both plants, trends in increases in the concentrations of Na, Ca and Cl in leaf parts caused by NaCl and CaCl2 salinity were similar in both nitrate nutrion and enhanced ammonium nutrion. Leaf Na concentrations did not increase in soybean plants but did in cucumber plants. Leaf N concentrationos that were higher in enhanced ammonium nutrion than in nitrate nutrion were not affected by salinity treatments. These results suggest that the acidity of the solution rather than the high levels of added salts affects plant growth in enhanced ammonium nutrion, and therefore, the effect of salinity on plant growth is less discentable in enhanced ammonium nutrion.