A review of seed bank and germination characteristics of Agriophyllum squarrosum, a pioneer plant on mobile sand dunes

The pioneer plant Agriophyllum squarrosum has strong adaptability to adverse environments and plays an important role during the early ecological restoration of sand dunes. The seed of A. squarrosum, also known as sand rice, is renowned for its balanced and comprehensive nutritional properties, and has been consumed for more than a millennium. A. squarrosum is therefore recommended as a crop for diversifying future food supply in the arid regions of Northern China. Since the 1980s, great progress has been made with respect to the physiological and ecological characteristics of A. squarrosum. In this study, we present a synthesis of the pioneer plant identity, the ecological function of the crown seed bank and the soil seed bank during the early vegetation succession of sand dunes, the continuous sprouting pattern of A. squarrosum during growing season, and seed dormancy. The optimal germination conditions are dark, 0.5 cm sand burial, and diurnal temperature variation. After releasing from drought stress, salinity stress and/or seed dormancy, A. squarrosum seeds can be restored to a higher germination rate. This study comprehensively summarizes the physiological and ecological mechanisms by which A. squarrosum adapts to mobile sand dune system, and provides a theoretical basis for the genetic domestication and cultivar breeding of A. squarrosum.