Causes and Breaking of Seed Dormancy in Ammodendron bifolium (Pall.) Yakovl. from the Takeermohuer Desert

Ammodendron bifolium is an endangered plant in the Takeermohuer Desert. Its population has gradually decreased due to human activities and the harsh climate, and this decrease was exacerbated by low germination rates in the natural environment. However, the cause and classification of seed dormancy are not entirely clear. We investigated the contributions of seed coats, embryos, and endogenous hormones to seed dormancy and explored methods for breaking dormancy. Studies have shown that A. bifolium seeds exhibit high vitality and impermeability and seed coats and embryos contain germination inhibitors; thus, dormancy of A. bifolium seeds can be classified as exhibiting combinational dormancy based on Baskin’s category system. The authors hypothesized that endogenous abscisic acid (ABA) might be critical for inducing seed dormancy. In addition, this study indicated that ethylene (ETH), 1-aminocyclopropane carboxylic acid (ACC), trans-zeatin-riboside (tZR), fluridone (FL), and thiourea (CH₄N₂S) could be used to break dormancy after scarification treatment. The findings of this study provide a better understanding of the dormancy mechanism of A. bifolium seeds and lay the foundation for the revegetation of desert A. bifolium.