Abstract
ABSTRACTMuehlenbeckia astonii Petrie (Polygonaceae) is a nationally endangered shrub undergoing widespread recruitment failure in the wild. Seed germination, dormancy and longevity were investigated to determine factors potentially constraining M. astonii regeneration and population persistence. Muehlenbeckia astonii seeds were collected from restoration plants sourced from Kaitorete Spit, Canterbury. Germination percentage of untreated control seeds in a growth room (20 °C with 16 hours of light daily) was compared with that of seeds in two treatments: (1) chilled at 4 °C for 2 weeks; and (2) chilled for 12 weeks. I also investigated seed longevity by comparing germination of unburied, 6-month old, cold-stratified M. astonii seeds with germination of seeds buried in the field and retrieved after 1–4 years. All seeds were sown in pots outdoors. In the growth room, 24% of untreated M. astonii seeds germinated, while cold-stratification for either 2 or 12 weeks increased germination significantly (to 76%). In the seed longevity experiment, 85.2% of unburied M. astonii seeds sown 6 months after collection germinated. Muehlenbeckia astonii seeds survived burial under the soil in the field for up to 4 years. However, germination declined rapidly to 27.6% after burial for 1 year, and only 2.8% of the seeds germinated after 4 years of burial. The high germination of cold-stratified seeds suggests that low seed viability is not limiting M. astonii regeneration at Kaitorete Spit. Muehlenbeckia astonii has the potential to form a soil seed bank, which may buffer small, isolated populations from local extinction in the short term (< 5 years).
Published Version
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