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

Weed Research (Impact Factor: 2.02). 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-

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The effects of environmental factors on germination and emergence of Campsis radicans seeds were examined in laboratory and greenhouse experiments. Campsis radicans pods produced numerous, papery, and small seeds (696 seeds/pod; 4 mg/seed). Seeds exhibited dormancy that was relieved (74% germination) after 2 wk of prechilling. Fluctuating temperatures and a 12-h photoperiod were required for maximum germination. Optimum conditions for C. radicans seed germination (74%) were 35/25 C (day/night, 12/12 h) with a 12-h photoperiod. Temperatures below 25/15 C or above 40/30 C were unfavorable for germination. Germination in constant temperatures or in continuous darkness was less than 15%. More than 59% of C. radicans seeds germinated at pH 5 to 9, but at pH 4 or 10 seed germination was totally inhibited. Germination was totally inhibited at osmotic stress higher than −0.2 MPa. Germination was 60% at 40 mM NaCl and 20% at 160 mM NaCl. Emergence was maximum (68%) for seeds that were placed on the soil surface, but no seedlings emerged from a soil depth at 4 cm. About 10% of seeds were still viable even after 20 wk of prechilling. Each pod contained about 700 seeds and each plant produced 20 to 40 pods. These results suggest that the spread potential of C. radicans by seeds would be at least 1,400 to 2,800 seeds plant−1. However, only seeds near the soil surface would be able to germinate. Nomenclature: Trumpetcreeper; Campsis radicans (L.) Seem. ex Bureau CMIRA.
    Weed Science 01/2009; · 1.68 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Germination of African mustard seeds collected from southern Australia was not influenced by light conditions at the optimum temperature of 20/12 C. However, seed germination was inhibited by light at the lower temperature (15/9 C). Presence of light increased the sensitivity of seeds to low temperature, as well as salt and osmotic stress. In dark conditions, seed germination was relatively unaffected at a low level of salinity (80 mM NaCl) but decreased even at 10 mM NaCl in light/dark conditions. In the dark, seed germination was unaffected up to an osmotic potential of −0.6 MPa but declined thereafter. Seeds of African mustard germinated over a broad range of pH from 4 to 10. Seed germination was stimulated by potassium nitrate (from 0.005 to 0.04 M) and gibberellic acid (0.001 M). Seedling emergence of African mustard was the greatest (51%) for seeds buried at 1 cm but no seedlings emerged from seeds placed at a depth of 5 cm. At the end of the growing season, seed decay (77 to 87%) and dormant (12 to 18%) components were similar among different seed burial depths. Information gained in this study will be important in developing a better understanding of the requirements for African mustard germination and emergence. Nomenclature: African mustard, Brassica tournefortii Gouan BRATO.
    Weed Science 01/2009; · 1.68 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Annual sowthistle has become more abundant under no-till systems in southern Australia. Increased knowledge of germination biology of annual sowthistle would facilitate development of effective weed control programs. The effects of environmental factors on germination and emergence of annual sowthistle seeds were examined in laboratory and field experiments. Seeds of annual sowthistle were able to germinate over a broad range of temperatures (25/15, 20/12, and 15/9 C day/night temperatures). Seed germination was favored by light; however, some germination occurred in the dark as well. Greater than 90% of seeds germinated at a low level of salinity (40 mM NaCl), and some seeds germinated even at 160 mM NaCl (7.5%). Germination decreased from 95% to 11% as osmotic potential increased from 0 to −0.6 MPa and was completely inhibited at osmotic potential greater than −0.6 MPa. Seed germination was greater than 90% over a pH range of 5 to 8, but declined to 77% at pH 10. Seedling emergence was the greatest (77%) for seeds present on the soil surface but declined with depth, and no seedlings emerged from a soil depth of 5 cm. In another experiment in which seeds were after-ripened at different depths in a field, seed decay was greater on the soil surface than at 2 or 5 cm depth. At the end of the growing season, there was a much greater persistence of buried seed (32 to 42%) than seeds present on the soil surface (8%). Greater persistence of buried seed could be due to dormancy enforced by dark in this species. Nomenclature: Annual sowthistle, Sonchus oleraceus L. SONOL.
    Weed Science 01/2009; · 1.68 Impact Factor


Available from
May 29, 2014