[Monthly dynamics and distribution of major cations in Iris lactea].

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.

4,6-Dinitro-benzene-1,3-diamine.

The mol-ecule of the title compound, C(6)H(6)N(4)O(4), is almost planar, being stabilized by two intra-molecular N-H⋯O hydrogen bonds. Further N-H⋯O links lead to a sheet in the crystal structure.