Salt-affected soils are agricultural and environmental problems on a global scale. Plants suffer from saline stresses in these soils and show nitrogen （N） deficiency symptoms. However, halophytes grow soundly under ...Salt-affected soils are agricultural and environmental problems on a global scale. Plants suffer from saline stresses in these soils and show nitrogen （N） deficiency symptoms. However, halophytes grow soundly under saline conditions. In order to clarify the N nutrition of the halophyte Salicornia bigelovii, it was grown at several N levels （1, 2, 3, and 4 mmol L-1）, supplied in the form of NO3 or ammonium （NH4＋）, under high NaCl conditions （200 mmol L-l）. NH4^＋- fed plants showed better growth than NO3-fed plants at 1-3 mmol L-1N, and plants in both treatments showed the same growth at 4 mmol L-1 N. Nitrogen contents in NO3-fed plants increased with the N concentrations in solution; competitive inhibition of NO3- absorption by Cl- was observed under lower N conditions. In addition, shoot dry weight was significantly correlated only with shoot N content. Therefore, growth of NO3-fed plants was regulated by N absorption. In contrast, N contents of shoots in NH4＋-fed plants did not change with N concentration. Shoot Na content decreased with increasing N concentration, while K content increased. Dry weight was highly correlated only with K content in NH4＋-fed plants. These observations indicated that growth of NH4＋-fed plants was mainly regulated by K absorption.展开更多
基金Supported by the "Global Center of Excellence for Dryland Science",a project of the Ministry of Education,Science,Culture,Sports and Technology of Japan
文摘Salt-affected soils are agricultural and environmental problems on a global scale. Plants suffer from saline stresses in these soils and show nitrogen （N） deficiency symptoms. However, halophytes grow soundly under saline conditions. In order to clarify the N nutrition of the halophyte Salicornia bigelovii, it was grown at several N levels （1, 2, 3, and 4 mmol L-1）, supplied in the form of NO3 or ammonium （NH4＋）, under high NaCl conditions （200 mmol L-l）. NH4^＋- fed plants showed better growth than NO3-fed plants at 1-3 mmol L-1N, and plants in both treatments showed the same growth at 4 mmol L-1 N. Nitrogen contents in NO3-fed plants increased with the N concentrations in solution; competitive inhibition of NO3- absorption by Cl- was observed under lower N conditions. In addition, shoot dry weight was significantly correlated only with shoot N content. Therefore, growth of NO3-fed plants was regulated by N absorption. In contrast, N contents of shoots in NH4＋-fed plants did not change with N concentration. Shoot Na content decreased with increasing N concentration, while K content increased. Dry weight was highly correlated only with K content in NH4＋-fed plants. These observations indicated that growth of NH4＋-fed plants was mainly regulated by K absorption.
