Ceratocarpus Research Articles

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

Ebrahimi E & Eslami SV (2011). Effect of environmental factors on seed germination and seedling emergence of invasive Ceratocarpus arenarius. Weed Research 52, 50–59.SummaryCeratocarpus 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.

New Combinations in Asian Krascheninnikovia Gueldenstaedt (Chenopodiaceae)

New combinations in the genus Krascheninnikovia are proposed: K. arborescens (Losina-Losinskaja) Mosyakin, K. compacta (LosinaLosinskaja) Grubov var. longipilosa (Tsien Cho-po & Ma Cheng-gung) Mosyakin, and Krascheninnikovia sect. Caudatae (Aellen) Mosyakin. Krascheninnikovia Gueldenstaedt (1772: 551) is the correct name for the genus previously commonly known as Eurotia Adanson and Ceratoides Gagnebin. This nomenclatural problem has been discussed by several authors over the years (LozinaLozinskaya, 1930; Reveal & Holmgren, 1972; Grubov, 1976; Guterman, 1975; Tomsovic, 1990; Tsvelev, 1993). Unfortunately, when establishing the genus Ceratoides, Gagnebin (1755: 59) did not write a diagnosis, but rather only mentioned a pre-Linnaean work by Tournefort (1703). In the latter work the genus Ceratoides included both an annual species (later named by Linnaeus as Ceratocarpus arenarius L.), and a perennial one, which is conspecific with Krascheninnikovia ceratoides (L.) Gueldenstaedt. At the time of its establishment (Gagnebin, 1755) the genus Ceratoides included Ceratocarpus arenarius, the type of Ceratocarpus L. (1753); thus Ceratoides is a synonym of Ceratocarpus. The next available name for the genus is Krascheninnikovia. [More detailed discussion is provided by Guterman (1975) and Tsvelev (1993).] In the Flora Reipublicae Popularis Sinicae (Tsien Cho-po & Ma Chenggung, 1979) the name Ceratoides was accepted for this genus. Thus, the following new nomenclatural combinations are necessary for a forthcoming edition of the Flora of China. Krascheninnikovia arborescens (Losina-Losinskaja) Mosyakin, comb. nov. Basionym: Eurotia arborescens Losina-Losinskaja, Izv. Akad. Nauk SSSR, Ser. 7, Otd. Fiz.-Mat. Nauk 1930, No. 9: 999. 1930. Ceratoides arborescens (Losina-Losinskaja) Tsien Cho-po & Ma Chenggung, Flora Reipublicae Popularis Sinicae 25(2): 27. 1979. Krascheninnikovia compacta (Losina-Losinskaja) Grubov var. longipilosa (Tsien Cho-po & Ma Cheng-gung) Mosyakin, comb. nov. Basionym: Ceratoides compacta (Losina-Losinskaja) Tsien Cho-po & Ma Cheng-gung var. longipilosa Tsien Cho-po & Ma Cheng-gung, Flora Reipublicae Popularis Sinicae 25(2): 28. 1979. When first describing the new variety Ceratoides compacta (Losina-Losinskaja) Tsien Cho-po & Ma Cheng-gung var. longipilosa Tsieng Cho-po & Ma Cheng-gung, the authors did not cite the basionym for their new combination at the species level (see Kung Hsien-wu et al., 1978). Thus, the complete combination (species plus variety) was validated later n the Flora Reipublicae Popularis Sinicae (Tsien Cho-po & Ma Cheng-gung, 1979). Two sections, based mostly on the differences in the structure of trichomes, were established by Aellen (1952) for the genus Eurotia. The correct names for these sections, as well as a new combination for one of them, are given below. Krascheninnikovia sect. Krascheninnikovia. TYPE: Krascheninnikovia ceratoides (L.) Gueldenstaedt (type of the genus). Eurotia sect. Ecaudatae Aellen, Verh. Naturf. Ges. Basel 63: 267. 1952. TYPE: not designated. Because in Aellen's (1952) treatment the section Ecaudatae included the type of the genus, this name should be replaced by the appropriate autonym. Krascheninnikovia sect. Caudatae (Aellen) Mosyakin, comb. nov. Basionym: Eurotia sect. Caudatae Aellen, Verh. Naturf. Ges. Basel 63: 267. 1952. TYPE: Eurotia compacta LosinaLosinskaja = Krascheninnikovia compacta (Losina-Losinskaja) Grubov. The native North American species previously commonly known as Eurotia lanata (Pursh) Moquin-Tandon was transferred to Krascheninnikovia by Meeuse & Smith (1974). If accepted as a distinct NovoN 5: 52-53. 1995. This content downloaded from 157.55.39.34 on Fri, 13 Jan 2017 18:16:50 UTC All use subject to http://about.jstor.org/terms Volume 5, Number 1 Mosyakin 53 1995 Asian Krascheninnikovia entity, another North American taxon described by Rydberg (1912) as Eurotia subspinosa is in need of the same transfer or a new infraspecific combination. However, in view of the current work on the Flora of North America project, I believe this nomenclatural decision should be left to American

INDICATORS OF PASTURE DEGRADATION OF TERSK-KUMA LOWLAND

The regularity of demonstration of the types of vegetation cover indicators of the Kochubei Biosphere Station, the characteristics of the development of indicator communities, and pasture digression processes in connection with unregulated cattle grazing have been studied. Changes in pasture communities are noted with varying degrees of loss of their floristic and phytocenotic potential and changes in the phytocenoses of digressive pastures. Under the conditions of external influence and as they increase, the ordinary components of the community are transformed into its dominant, that is, indicators. Identified plants - indicators, as well as communities - indicators, indicators of changes in the plant species composition of communities in the course of pasture digression. The presence of indicator species in communities is an important indicator for identifying the level of pasture load on vegetation and the most informative parameter for geobotanical monitoring of pasture vegetation. The geobotanical study showed the heterogeneity of pasture vegetation on the phytocenotic composition, which are in a state of severe disruption. The monitoring studies of pastures of the Kochubei Biosphere Station were conducted, where a complex of environmental factors has a significant impact on the change in the species composition and structure of pastures under various loads. The peculiarities of the development of pasture digression on the light chestnut soils of the study area are traced. Changes occurring in the vegetation cover of pastures under the influence of weak grazing are the disappearance of the large-grain cereals of the Stipa series with the predominance of fine-grained cereals like Festuca sulcáta. With intensive grazing with the disappearance of Festuca sulcáta and the emergence of shrubs Artemisia and others, more competitive species appear, this causes a change of plant communities. On the basis of floristic and cenotic analysis, it can be concluded that the types of indicators reducing their abundance under the influence of grazing are Stipa lessingiana, increasing their abundance under the influence of grazing are Artemisia, Ceratocarpus arenarius and other weeds.