Evaluation of Salinity Tolerance in Rice : Photosynthesis of Excised Leaves in Relation to Sodium Accumulation

[摘要] Salinity tolerance at the seedling stage of rice(Oryza sativa L.) is related to the ability to maintain photosynthesis under salinity. Sensitivity or photosynthesis to sodium accumulation in leaf blade was evaluated in 13 rice varieties differing in salinity tolerance at the seedling stage. Leaf blades were excised at the leaf base, the cut end immersed in 50 mM sodium chloride solution, and the rates of photosynthesis and transpiration were measured. Photosynthetic rate decreased in parallel to stomatal closure until leaf sodium content reached 3 to 5 mg g-1. However, in the leaves with sodium content of over 3 to 5mg g-1, the transpiration rate was even, while photosynthetic rate decreased further due to another factor related to sodium accumulation in the leaf blade. Vulnerability of photosynthesis to sodium accumulation measured using exeised leaves varied with the variety, similarly to that measured using the leaves of intact plants. These results in dicated that salinity tolerance at the seedling stage in rice could be evaluated by measuring photosynthetic rate in excised leaf blades.

[学科分类] 农业科学（综合）

[关键词] Excised leaf;イネ;Photosynthesis;気孔閉鎖;Rice(Oryza sativa L.);光合成;Salinity tolerance;蒸散;Sodium;切断葉;Stomatale closure;耐塩性;Transpiration;ナトリウム;Varietal difference;品種間差異