Seed polymorphism, dormancy and germination of Salsola affinis (Chenopodiaceae), a dominant desert annual inhabiting the Junggar Basin of Xinjiang, China

Salsola affinis C.A. Meyer, a dominant annual that primarily occurs in deserts of the Junggar Basin, China, produces three types of utricles that differ in shape, size, colour and size of wings on the fruits. Type A fruits have lignified perianths with long wings and green utricles, and they can easily be dispersed long distances from the mother plant by wind. Type B fruits have lignified perianths with short wings, or no wings, and green utricles, and they are tightly attached to the mother plant. Type C fruits have tepals without wings and yellow utricles, and are also attached tightly to the mother plant. Freshly harvested Type A and Type B seeds (utricles) can germinate at 5–30°C in light or in darkness. Rate and final percentage of germination of Type B seeds are higher than those of Type A seeds. Type C seeds have non-deep physiological dormancy; they germinate slowly and to a low percentage. Four weeks of cold stratification, scarification of covering layers (pericarp and seed coat) and treatment with KNO3 can increase the percentage and rate of seed germination. Utricle polymorphism may allow Salsola affinis to respond to spatial and temporal variations in environmental conditions, thus increasing the chances for survival of this annual species in its harsh desert habitats.