Effect of fruit bristles on fruit dispersal and germination of Calligonum roborowskii (Polygonaceae) in south Xinjiang, China

Calligonum roborowskii A. Los. is an endemic species distributed only in the desert environments of northwest (Gansu and Xinjiang provinces) China. The achene fruit of this species is covered in oval bristles, with dispersal and seed germination occurring from intact achene fruit. In this paper, we investigated the effects of these bristles on dispersal, water absorption and dehydration, and fruit germination both in the field and laboratory. Results showed that there were significant differences in fruit color, size, weight, and length of bristle hairs at different storage time. The amount of time the bristled fruit floated on the surface of water and the water diffusion capacity associated with the amount of water absorption were greater than that for the non-bristled fruit. The diffusion distances of intact fruit at 1 m/s and 4 m/s wind speed were longer than that of non-bristled fruit. In addition, significant differences were found in the germination rates of bristled and non-bristled fruits under 20℃/30℃ and light-dark conditions, 10 mmol/L of AG₃, and different dry storage time; specifically, the germination rate of fruits without bristles was higher than that of intact fruits in each treatment. Outdoor potted experiments show that the fruit bristles of this species have an inhibitory effect on seed germination. However, the fruit bristles have an important effect on the dispersal and germination characteristics of this species and on population renewal in the environments on the edge of the Taklamakan Desert.