Seed dynamics of Aeschynomene denticulata and Aeschynomene indica

Abstract

AbstractJointvetch (Aeschynomene spp., Fabaceae) is considered a problematic broadleaf weed for rice production in Brazil, the United States, and Asia. Seed dormancy is particularly important for the perpetuation of annual weeds, representing the only link between different generations and thus the source of all future weed infestations. Seed dynamics in annual species are complex and related to many biotic and abiotic factors. The objectives of this study were to determine whether dormancy occurs in Aeschynomene denticulata and Aeschynomene indica seeds, and, if so, what is the most efficient method to break it. In addition, the persistence of seeds in soil also was investigated for both species. Three experiments were conducted, two in lab conditions and one in field conditions. The first experiment consisted of germination tests conducted in controlled conditions to determine whether seeds have dormancy. The second experiment tested the effectiveness of preheating, precooling, potassium nitrate, gibberellic acid, water soaking, chemical scarification, and mechanical scarification as dormancy breaking methods. Finally, the third experiment evaluated seedbank longevity for 1‐year period in the rice‐cultivated soil during which seeds were buried and recovered every 3 months. Variations in physical dormancy are present at different levels in both species due to seed‐coat impermeability to water absorption. Meanwhile, A. denticulata can persist over a year in soil seed bank but A. indica seeds only persisted for half a year.