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

Abstract

Ceratocarpus arenarius is a problematic and noxious weed of dryland farming in North Khorasan, Iran. Experiments were conducted to investigate the mechanism 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 mM) 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. arenarius.

Predicting Seed Germination of Safflower (Carthamus Tinctorius) Cultivars Using Hydrotime Model

“…The interactive effect of water potential on germination rate and percentage of safflower has also been reported in other species (Kebreab and Murdoch, 1999;Ebrahimi and Eslami 2012;Nandula et al, 2006;Bolfrey-Arku et al, 2011).…”

Trade-offs between seed dispersal and dormancy in an amphi-basicarpic cold desert annual

“…A study recently has been published on seed germination of C. arenarius growing as an arable weed in dryland crops (wheat, barley and lentils) in northern Iran (Ebrahimi and Eslami, 2012). 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).…”

“…This species is one of the dominant and important components in desert plant communities of this area, and it is ecologically significant in maintaining plant diversity and stability of the cold desert ecosystem [Xinjiang General Exploration Team of Chinese Academy of Sciences (CAS) and Institute of Botany of CAS, 1978;Wang et al, 2006]. The species recently was reported as a problem weed in dryland farming systems (wheat, barley and lentils) in northern Iran (Ebrahimi and Eslami, 2012).…”

“…The spherical shape of the plant makes it easy for the individual to be dispersed (rolled or tumbled) by wind far away from the site at which it matured. Thus, C. arenarius is a typical 'tumbleweed' (Gao and Wei, 2007;Gao et al, 2008;Zhou, 2009;Ebrahimi and Eslami, 2012). Gao and Wei (2007), Gao et al (2008) and Zhou (2009) reported that C. arenarius produces two distinct fruits (dispersal units), i.e.…”