Abstract: Salsola nitraria has a strong drought and salt-tolerance capacity in Xinjiang desert. Experiments were conducted to study the seed polymorphism and germination of S. nitraria. It produces three types of fruits that differ markedly in morphological characteristics and germination. Type A fruits are green and spherical and have winged perianth; Type B fruits are red and spherical, the perianth is without wings; Type C fruits are yellow and spherical, the perianth is without wings. Seeds were germinated in incubators at 5 ℃/15 ℃, 10 ℃/20 ℃, 15 ℃/25 ℃, 20 ℃/30℃, and 25 ℃/35℃ (12 h dark/12 h light) for 14 d. Germination percentages of type A seeds under all five temperature regimes were >92%; germination percentages of type B seeds under all five temperature regimes were <60%; germination percentages of type C seeds at all five temperature regimes were <5.3%. Type B seeds have no-deep physiological dormancy and seeds require 2 weeks of cold stratification to germinate. Type C seeds have deep physiological dormancy and scarification was an effective means of breaking the seed dormancy. Germination of type A seeds was not affected by NaCl at concentrations below 0.2 mol·L^-1, but was decreased by NaCl at higher concentrations, and fell to nearly zero at concentrations above 0.8 mol·L^-1. Seeds incubated in NaCl at concentrations of 0.05-4.0 mol·L^-1 recovered after being transferred to distilled water. Bracts of type A seeds formed a mechanical barrier to water uptake, and had a significant influence on the final seed germination percentages. Removal of bracts promoted seed germination. Further research into seed polymorphism in S. nitraria and the associated germination differences may reveal its ecological adaptive mechanism and provide data for ecological construction in the Xinjiang desert.

Key words: seed polymorphism, Salsola nitraria, temperature, NaCl, bracts