Abstract: A research was carried out on distribution of Na in Robinia pseudoacacia of various plant-age,and revealed the relationship of Na content in the roots with that in the corresponding soil layers.Under long-term salt stress,the plant accumulated a mass amount of Na, and the accumulation increased drastically with the time going on.The absolute Na content as well as the Na accumulation rate of the roots were evidently higher than that of the aerial parts,and the Na content in the roots observably increased with the roots extending deeper into the soil layer.Combination of all the results reveals that under excessive salt stress,Robinia pseudoacacia avoided physiological harm of Na and enhanced its tolerance towards excessive salt stress.

Key words: Robinia pseudoacacia, salt stress, Na, accumulation, distribution