Relationship between salt tolerance, and contents of cation and free amino acid in reed canarygrass (Phalaris arundinacea L.) grown on soil perfused with cattle urine

Abstract

The differences in salt tolerance between reed canarygrass (RCG) grown on soil perfused with urine(U-RCG) and on soil not perfused (C-RCG) were discussed in regard to the growth rate and the contents of cation and free amino acid. The seedlings grown on each soil were cultured in standard solution (KIMURA's B solution) for 10 days, then NaCl was applied to the solution to adjust its concentration to 0, 100 and 200 mM. Ten days after NaCl application, the plants were harvested to measure the weights and the contents of cations and free amino acid. The relative value of dry weight increase in plant tops during NaCl treatment to that during standard solution culture was used as an indicator of salt tolerance. 1. When the growth rates of U-RCG and C-RCG in standard solution were expressed as 100, the rate of U-RCG was higher than that of C-RCG at 200 mM NaCl (82 and 68), suggesting the stronger salt tolerance in U-RCG. 2. Sodium content of the plants increased, while K, Mg and Ca contents decreased with increasing NaCl concentrations in solution culture. The cation contents, especially K of plant tops in U-RCG tended to be higher. In U-RCG, the plant top/root ratios in Na, K, Mg and Ca contents were higher, and increased by the application of NaCl. 3. Total free amino acid contents of plant tops were increased by the application of NaCl. Though the contents were higher in U-RCG, the increase rates were higher in C-RCG. Proline content markedly increased in both RCGs and the Pro/total amino acid content ratio attained to 21.4% inU-RCG and 15.5% in C-RCG, being the highest at 200 mM NaCl. In roots, changes in free amino acid contents by the application of NaCl were different between U-RCG and C-RCG. However, no remarkable tendency of changes was shown.