Effect of environmental factors on seed germination and seedling emergence of invasive Ceratocarpus arenarius

Weed Research (Impact Factor: 2.05). 02/2012; 52(1):50-59. DOI: 10.1111/j.1365-3180.2011.00896.x

ABSTRACT Ceratocarpus arenarius is a problematic and noxious
weed of dryland farming in North Khorasan, Iran.
Experiments were conducted to investigate the mecha-
nism of seed dormancy, as well as the effect of
environmental factors on germination and emergence
of this species. Results showed that the pericarp is the
major obstacle to seed germination; seeds without an
intact pericarp had germination rates exceeding 90%.
Ceratocarpus arenarius had identical germination rates
in either light ⁄ dark and continuous dark conditions,
indicating that this weed species is non-photoblastic.
Germination was >35% over a range of alternating
light ⁄ dark temperatures (10 ⁄ 5, 20 ⁄ 10, 25 ⁄ 15, 30 ⁄ 20 and
35 ⁄ 25�C), with maximum germination (96%) at
25 ⁄ 15�C. Ceratocarpus arenarius seeds germinated at
rates >20% in high levels of salinity (800 m M ) and
osmotic potential ()1 MPa), indicating that this species
is tolerant to saline conditions and drought stress during
germination and early seedling growth. Maximum
germination of C. arenarius seeds occurred at a pH
range of 7–9. Seedlings emerged from burial depths
ranging from 0 (without covering with filter paper) to
6 cm, and the maximum emergence (94%) was observed
in seeds placed on the soil surface covered with three
layers of filter paper. This suggests that minimum- and
no-till systems would increase seedling emergence of this
species through maintaining crop residues and seeds on
the soil surface. These attributes, coupled with tolerance
to salinity and drought stress during germination,
should be taken into account when managing C. arena-



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