Article

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

Weed Research (Impact Factor: 1.69). 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-
rius.

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Available from: Seyed Vahid Eslami, Apr 22, 2014
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    • "In line with the studies conducted by Gulzar & Khan (2001), Wei et al. (2008), Ebrahimi & Eslami (2011) and Giménez et al. (2013), who observed that an increase in salinity causes a decrease in germination rate and germination speed, and even complete inhibition when the salt tolerance limit of the species is exceeded, we can confirm that the germination of Limonium insigne is affected by an increase in salinity. "
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    ABSTRACT: Limonium insigne (Plumbaginaceae) is a perennial halophyte endemic to the SE of the Iberian Peninsula. Experiments were conducted to determine the effects of different salinities (0, 100, 200 and 400 mM NaCl) on the seed germination of L. insigne under different temperature regimes (20/10, 25/15, 30/20 and 35/25 °C), both in a 14 h light and 10 h dark photoperiod. Seed germination of L. insigne was affected significantly by salinity levels, temperature and their interaction. Maximum germination was observed in the least saline media (100 mM NaCl) and distilled water (0 mM NaCl) at 20/10 °C temperature. No seeds germinated at concentrations higher than 200 mM NaCl at the highest temperature (35/25 °C). The increase in salinity delayed the beginning and ending of germination, reduced final germination percentage and increased mean time to germination. The rate of germination decreased with an increase in salinity and temperature.
    Full-text · Article · Jun 2015 · Pakistan Journal of Botany
    • "Sorghum treated with 50 mM NaCl in the irrigation water sustained the least Striga infestation, which was reduced by 74 and 55% after 45 and 60 days, respectively. Ceratocarpus arenarius seeds reached germination rates >20% at high levels of salinity (800 mM) and osmotic potential (−1 MPa), indicating that this species is tolerant to saline conditions and drought stress during germination and early seedling growth (Ebrahimi and Eslami, 2012). Therefore, the objectives of the present study were to examine (a) the effects of organic vs. conventional fertilization practices under normal or saline conditions on weed flora in common bean cultivation and (b) the sensitivity of local weed species to salinity stress under different salt concentrations. "
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    ABSTRACT: Two field experiments were conducted to assess the effects of cultural system and irrigation water salinity on weed flora in a common bean crop (Phaseolus vulgaris L. cv. Contender). The experiments were designed as split plot designs with the cropping system as main plot (organic or inorganic fertilization), the level of water salinity as sub-plot (good quality or saline irrigation water with 0.5 or 10mM NaCl, respectively) and four replications per treatment. The lowest weed density was recorded in the saline water treatment. The results of the study showed that the order of weed sensitivity to salinity is redroot bigweed > bermudagrass > common lambsquarters > barnyardgrass >common purslane >purple nutsedge. Moreover, differences in nitrogen availability of the fertilizers had a large effect on weed density and biomass. The highest weed biomass (in 2011: 454 kg ha-1 for saline water treatment and 759 kg ha-1 for control; and in 2012: 331 kg ha-1 for saline water treatment and 578 kg ha-1 for control) was recorded in the plots treated with inorganic fertilizers. These results indicated that organic fertilization and saline water could be used for the suppression of weeds in organic common bean crops.
    No preview · Article · Feb 2014 · Australian Journal of Crop Science
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    • "The authors made a mass collection of seeds (dispersal units), presumably a mixture of our units b – f (Fig. 1). They (Ebrahimi and Eslami, 2012) subsequently removed the pericarp ( probably bracteoles) from the fruits [ probably fruits (utricles) with enclosing bracteoles] and used the seeds ( probably utricles without bracteoles) in the majority of their germination tests. They erroneously concluded that their fruits have physical dormancy, which is not known to occur in Amaranthaceae (including Chenopodiaceae) (Baskin et al., 2000). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background and aims: Several studies have demonstrated trade-offs between depth of seed dormancy and dispersal ability for diaspore-dimorphic species. However, relatively little is known about trade-offs between these two life history traits for a species that produces more than two diaspore morphs. The aim of this study was to investigate the relationship between seed dormancy and dispersal in Ceratocarpus arenarius, an amphi-basicarpic cold desert annual that produces a continuum of dispersal unit morphs. Methods: A comparison was made of dispersal and dormancy breaking/germination responses of dispersal units from ground level (a), the middle of the plant canopy (c) and the top of the plant canopy (f). Various features of the morphology and mass of dispersal units and fruits (utricles) were measured. The role of bracteoles in diaspore dispersal by wind, settlement onto the soil surface and dormancy/germination was determined by comparing responses of intact dispersal units and fruits. Movement of dispersal units by wind and animals, seed after-ripening, germination phenology and the presence of water-soluble germination inhibitors in bracteoles were tested using standard procedures. Key results: Dispersal units a, c and f differed in morphology and mass; in the majority of cases, extremes were exhibited by a and f, with c being intermediate. Overall, relative dispersal ability was f > c > a, whereas relative intensity of dormancy was a > c > f. Bracteoles increased dispersal distance by wind, enhanced settlement of diaspores onto the soil surface and mechanically inhibited germination. Conclusions: The results provide evidence for a model in which there is a continuous inverse-linear relationship between diaspore dispersal ability and depth of dormancy. Thus, dispersal unit heteromorphism of C. arenarius results in a continuum, from no dispersal ability/high dormancy (dispersal unit a) to high dispersal ability/low dormancy (unit f), which may be a bet-hedging strategy in the cold desert environment.
    Full-text · Article · Nov 2013 · Annals of Botany
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