Abstract:

Ion distribution in the root of Cyclocarya paliurus seedlings of three provenances from Huangshan in Anhui, Jiujiang in Jiangxi and Kunming in Yunnan under 0, 1, 3 and 5 g·L^-1NaCl stress was measured with the method of X-ray microanalysis. The results showed that under the NaCl stress of 3 and 5 g·L^-1, the relative content of Na+ and Cl- in the root tissues increased, while the relative content of K⁺, Ca ²⁺ and Mg ²⁺ in the root tissues decreased. With the increasing of salinity, the increase of the relative content of Na⁺ occurred in epidermis and cortex of the root, while the remarkable increase of the relative content of Cl- occurred in stele and cortex of root. Therefore, the two kinds of ions in root tissues were imbalance. The ratios of K⁺ Na⁺ and Ca²⁺Na⁺ decreased, and hence Na⁺(K⁺ +Na⁺+Ca ²⁺+Mg ²⁺ ) increased; The decrease in K⁺ Na⁺ ratio and the substantial increase in Cl-in root tissues would be the factors that reduced the seedling survival and growth in leaf area, height, basal diameter as well as biomass. In preliminary conclusion, the level of salt tolerance of the tested provenances was in an order of Huangshan > Kunming > Jiujiang, and around 1 g·L^-1 was the threshold concentration of salt to which the seedlings were able to tolerate. 

Key words: NaCl stress, Cyclocarya paliurus, ion distribution, root tissue, X-ray microanalysis