Abstract: The study on the monthly absorption, transportation, and distribution of Na⁺, K⁺, Ca²⁺and Mg²⁺ in Iris lactea under saline-alkali field conditions showed that the contents of test cations in I. lactea varied with months. After June, the cations contents in plant increased with growth. Root Ca²⁺ and Na⁺ contents were the highest in July, being 2.30% and 0.51%, respectively, while root K⁺ and Mg²⁺ contents were the highest in September (0.27%) and October (0.28%), respectively. Leaf Na⁺ content was the highest in July (0.57%), while leaf K⁺, Ca²⁺ and Mg²⁺ contents were the highest in August, being 1.30%, 2.69% and 0.47%, respectively. In July and August, the selective absorption (SA) of K⁺ was higher than that of Na⁺, while the selective transport (ST) was in adverse. The cations contents in I. lacteawere significantly higher than those in soil, suggesting that I. lactea had high accumulation capacity to these cations. The cations were mainly accumulated in the 0-30 cm aboveground part and 0-40 cm underground part ofI. lactea, and the average contents of Na⁺, K⁺, Ca²⁺and Mg²⁺ in aboveground part were 9.11, 4.07, 0.98 and 2.27 times of those in underground part, respectively.

Key words: surface soil moisture, scale, sampling amplitude, sampling density, spatial variability.