Achene germination of the spring ephemeroid species Carex physodes in the Gurbantunggut Desert

Much of the seed germination research on Carex has focused on wetland species, and little is known about the species of arid habitats. Here, we investigated seed dormancy and germination of Carex physodes, which is an important component of the plant community of the Gurbantunggut Desert of the Junggar Basin in Xinjiang, China. Our studies included the effects of mechanical and chemical scarification, dry storage, treatment with GA(3), wet-cold stratification, and burial in the field. No freshly matured achenes germinated over a range of temperature regimes after treatment with GA(3), 6 months of dry storage or removal of part of the endosperm. The mechanical scarification resulted in < 5% achene germination, however, higher percentage of achene germination occurred after removal of the pericarp (60%), H2SO4 scarification (30%) or scarification in 10% NaOH (85%). Six and nine months of wet-cold stratification promoted < 40% achene germination. The optimal germination temperatures ranged from 25/10 degrees C to 35/20 degrees C. Maximum germination after 9 months of burial at a depth of 3 cm in the field was 36%. These results indicate that the seeds have non-deep physiological dormancy (PD) and that the pericarp contains germination inhibitors and has strong mechanical resistance to germination.