*4.12. Evaluation of Salt-Stress Tolerance at Reproductive Stage*

"YNU31-2-4", salt-tolerant "Kaijin", and susceptible "Yukinko-mai" plants were evaluated for salt-stress tolerance at the reproductive stage in a semi-controlled greenhouse. Thirty-day-old seedlings were transplanted (1 per bucket) into 2.5-L plastic bucket and each treatment had six replicates. Plants were subjected to 0 or 50 mM NaCl in irrigation water (pH 5) at 60 days after germination (DAG). After 2 weeks, the salt concentration was increased to 75 mM until booting stage (95 DAG), and then plants were recovered by irrigating with fresh water. The net assimilation rate of penultimate leaves was measured with an LI-6400 gas exchange system (LI-COR Inc., Lincoln, NE, USA) 4 weeks after salt was imposed. Gas exchange was determined at 25 ◦C at a photosynthetic photon flux density of 350 µmol m−<sup>2</sup> s −1 . Yield and its attributes, particularly panicle number, spikelet number, and 1000-spikelet weight were determined at harvest.
