Physiological response to salinity in rice [Oryza sativa] plant, 2: Relationship of sodium exclusion to transpiration and root-respiration rates in NaCl-treated rice plant
1994
Naito, H. (Okayama Univ. (Japan). Faculty of Agriculture) | Tsuchiya, M. | Kumano, S.
In order to clarify the relationships of sodium exclusion to transpiration and root-respiration rates in 100 mmol l(-1) NaCl-treated rice plant, transpiration stream concentration factor of Na+ (TSCFNa+) was measured at different oxygen concentrations, pH and temperatures of root medium under different humidity conditions. It was confirmed that TSCFNa+ decreased hyperbolically with the increase of the transpiration rate, namely, sodium-exclusion efficiency increased with transpiration rate. However, TSCFNa+ and top-Na content were not clearly related to root-respiration. Neither was a difference found in the relationship between TSCFNa+ and transpiration rate measured at 20 and 32 degrees C, and at pH 4.0 and 7.0 of culture solution. These results imply that root respirations not directly related to the sodium exclusion mechanism. It was shown that the sodium-exclusion mechanism also works for chlorine because of a positive correlation between TSCFNa+ and TSCFCl-. These results suggest that ion exclusion in rice plants may be based on a non-metabolic process and it is important to maintain a high transpiration rate for exclusion and growth under saline conditions
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