Relationship between seed and clonal growth in the reproduction of Carex rugulosa Kük. in riverside meadows

Abstract

. No seedlings were observed at plots where the ramets from rhizomes grew densely. In contrast, seedlings appeared in plots where all rhizomatous ramets were artificially cut. The number of seedlings corresponded to 17.5-39.5% of that of buried seeds. All these seedlings were submerged and died when it rained heavily. In the genotype analysis using allozyme detection, one of the phosphoglucoisomerase loci (Pgi-2) indicated a pair of alleles. Among eight plots (each plot was 50 or 60-cm square), four showed an excess of heterozygotes and two showed homozygote domination in the Pgi-2 genotype. These results suggest that: (i) seed germination is suppressed in crowded ramets; (ii) seedling survival is severely reduced by inundation; and (iii) the population is usually maintained by clonal growth. As germination is induced in open areas, it is hypothesized that the main role of seed is recovery after vegetation decline caused by environmental stresses or colonization to other areas without dense vegetation.

The role of seedling recruitment from juvenile populations of Carex brevicuspis (Cyperaceae) at the Dongting Lake wetlands, China

“…Other environment factors, such as varied water regimes23, sediment deposition24, or soil heavy metal pollution25, may also influence the seed number and the seed germination ability. The genetic diversity of clonal plant populations is usually increased by seedling recruitment, even if this is rare5. Therefore, we can infer that the genetic diversity in mature C. brevicuspis population may be established in juvenile populations and sustained by vegetative reproduction, which may be a new mechanism in explaining the high genetic diversity in clonal populations where no seedling recruitment were found in mature C. brevicuspis population.…”

“…Nine seedlings per square metre (13% of the total shoots) were found in juvenile populations at the end of first growing season, and no seedlings were found at the end of the second growing season, suggesting that seedling recruitment only occurred in juvenile populations after flooding. Although the shoots of seedlings withered during the cold winter, 62.5% of seedlings could resprout as ramets in the next spring, which may play a critical role in increasing and sustaining the genetic diversity of C. brevicuspis populations5.…”

“…In perennial clonal plant populations, seedling recruitment plays a critical role in maintaining population genetic diversity, even though the number of recruited seedlings is usually low in the field12345. In North American tallgrass prairie, seedlings usually compose less than 1% of total stems in mature clonal populations2.…”

“…In North American tallgrass prairie, seedlings usually compose less than 1% of total stems in mature clonal populations2. Nevertheless, genetic diversity is usually high in mature clonal populations56. Many hypotheses, including self-incompatibility, environmental condition selection, or/and seedling recruitment model variation, have been proposed, but the issue is still controversial789.…”

Conditions for seedling establishment and probable function of seed in the clonal sedge Carex rugulosa Kük. in riverside marshes

“…This suggests that seeds of C. rugulosa germinate in two situations: (i) after a reduction in ramet density caused by disturbances or environmental pressure; or (ii) after dispersal of seed to areas without dense vegetation. However, it has also been observed that young seedlings die when submerged during periods of rain (Araki & Kunii 2008). This suggests that inundation during the seedling stage may have a serious effect on new genet recruitment.…”