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1.
Solidago canadensis, a perennial Compositae plant originating from North America, was introduced into China as a horticultural plant in 1935.
Under natural conditions, S. canadensis allocates large amounts of energy to sexual reproduction and produces many seeds, which reflects an r-strategy with high seed number and small seed size. In addition, naturalized populations have a great capacity to grow clonally
with underground stems. S. canadensis has become an invasive weed in eastern China, and has caused serious damages to agricultural production and ecosystems in
several provinces in China. In order to understand the reproductive characteristics of S. canadensis and effectively control its spread, we examined soil conditions, seed characteristics, seed germination and the capacity
for asexual reproduction in different plant parts. We investigated the population dispersion of S. canadensis in fixed sites for three years, and analyzed the seasonal dynamics of the morphological parameters of the underground parts
and the caloric values of different organs of S. canadensis. We also compared differences in the root systems of S. canadensis and composite exotic weeds. The following results were obtained:
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Translated from Acta Ecologica Sinica, 2005, 25(11): 1795–2803 [译自: 生态学报] 相似文献
1) | Under natural conditions, the germination season of S. canadensis lasts from March to October, with a peak from April to May. Vegetative growth and asexual reproduction are especially vigorous during summer due to high temperatures and soil drought stress. On the other hand, the rainy season proves suitable for seed germination. Most S. canadensis flower between September and January, and fruit in late October. A mature plant can produce about 20000 seeds. The mean weight of 1000 seeds ranges from 0.045 g to 0.050 g, and the mean seed moisture content ranges from 60% to 80%. The light-winged seeds disperse readily by air, water, vehicles, human activity or through livestock. |
2) | S. canadensis seeds have a wide tolerance for different values of pH, salinity and soil moisture. The mean percent germination of seeds is 30% under suitable conditions. The results of seed germination under various environmental stresses and investigation of soil conditions indicate that well-aerated, slightly acidic soils with low salinity are suitable for the growth of S. canadensis. Additionally, S. canadensis has a high tolerance for contamination by heavy metal elements including Zn, Cu and Pb, but has low accumulation coefficients for these elements. |
3) | S. canadensis reproduces asexually via underground rhizomes and nodes on the stem base to recruit new individuals, and in plants that experience mechanical damage, this reproductive strategy is used to produce clonal shoots. The capacity for asexual reproduction among different plant parts rank as follows: underground parts > stem-base (20 cm) > stem-base (30 cm) > stem-base (45 cm) > stem. Further, with increasing mechanical damage, the quantity of shoots produced by the plant decreases. |
4) | The morphological parameters of the root system of S. canadensis including length, surface area, volume, and average diameter are greater than for composite exotic weeds. These parameters indicate that S. canadensis has the physiological potential to widely invade China. |
5) | The aboveground growth rate and most of the underground morphological parameters vary remarkably among the seasons, with a peak normally occurring in September. In August, a fraction of the energy in leaves and stems is allocated underground to increase fine root growth and water uptake during hot weather. Additionally, the seasonal dynamics of the underground morphological parameters and the caloric values of different organs of S. canadensis enhance its reproductive ability. Based on the results above, we conclude that S. canadensis has great invasive potential in China. We suggest that urgent measures should be taken to control its further spread, and to minimize its impact on local plant diversity. |
2.
Huiyuan Cheng Shu Wang Mei Wei Bingde Wu Daolin Du Congyan Wang 《Population Ecology》2021,63(4):290-301
Reproductive allocation (RA) plays a vital role in the development of ecological strategies during the life cycle of plant species. Invasive alien plants (IAP) may exist at various invasion degrees across a gradient of the colonization process with several grades of relative abundances in the occupied environments. The progressive variation in the invasion degree of IAP has the potential to modify their RA strategy. This study purposes of estimating the RA strategy of the IAP Solidago canadensis L. and the correlations among RA of S. canadensis, the invasion intensity of S. canadensis, the invasiveness of S. canadensis, and the community invasibility across a gradient of invasion degrees by using the field sampling experiment. The height and relative abundance of S. canadensis did not remarkably affect its RA. The RA of S. canadensis was positively related to its reproductive biomass and total biomass. The key reason may be that plant individuals with higher total biomass can allocate more resources into sexual reproduction. The RA of S. canadensis was positively related to its invasiveness. Thus, the RA of S. canadensis may be crucial to its invasiveness. 相似文献
3.
Saman Abeysinghe 《Archives Of Phytopathology And Plant Protection》2013,46(9):835-846
Abstract Sclerotium rolfsii Sacc. the causal agent of collar and root rot of chili (Capsicum annuum L.), is one of the most important soil-borne pathogens in Sri Lanka. Bacillus subtilis CA32r, a stable spontaneous kanamycin resistant isolate, showing antagonism in a Petri plate assay, was selected for greenhouse pot experiments to control S. rolfsii. An ethyl acetate extract of the culture filtrate of B. subtilis CA32r inhibited radial colony growth as well as germination of sclerotia of the pathogen in vitro, indicating the presence of antifungal compound(s) in the culture extract. B. subtilis CA32r was investigated for its effectiveness as a biological control agent against S. rolfsii infecting transplanted chilli seedlings in greenhouse pot experiments. CA32r significantly decreased the disease incidence in terms of lesion development on stem base and roots depending on the mode of the bacterial application. Seed bacterization and soil application alone did not protect chilli plants, but root bacterization prior to the transplanting of seedlings significantly decreased the disease incidence caused by S. rolfsii. However, even in the combined treatment, seed bacterization and soil application, did not protect chilli plants. The best protection was achieved by combination of root bacterization prior to transplant and soil application of CA32r. Root bacterization resulted in maintaining higher numbers of bacteria at the collar region of chilli plants and may have shielded the most vulnerable area from the pathogen, resulting enhanced protection. Since the application of CA32r resulted in a significant reduction of the number of viable S. rolfsii propagules in the soil indicates that B. subtilis CA32r possesses not only protective but also eradicative potential. 相似文献
4.
Summary Members of the genus Solidago are among the most widely studied model systems in plant population biology. A comparative study of Solidago canadensis, S. altissima, and S. gigantea in an experimental garden showed that the three species had different patterns of shoot growth and development, leaf morphology and physiology, and biomass allocation at harvest. These differences were also found in the field. Contrary to some current taxonomic usage, our results show that S. canadensis should ecologically be treated as a separate taxon distinct from S. altissima, and that the latter may be grouped together with S. gigantea. Many of the biological differences between S. canadensis and the other two taxa, such as differential investment into sexual reproduction versus clonal growth, may be explained by differences in genet architecture. These architectures concern high compared to lower within-genet shoot density resulting from differences in rhizome lengths among the taxa (shorter in S. canadensis than in S. altissima and S. gigantea). 相似文献
5.
Paul D. Pratt John C. Herr Raymond I. Carruthers Guillermo Cabrera Walsh 《Biocontrol Science and Technology》2019,29(4):405-409
The leaf-mining fly Hydrellia egeriae Rodrigues-Junior (Diptera: Ephydridae) was evaluated under quarantine conditions as a candidate biological control agent of the invasive aquatic weed Egeria densa Planchon (Hydrocharitaceae) in California, U.S.A. The objective of this study was to test the fly’s feeding preference for E. densa as compared to the North American native Elodea canadensis Michaux (Hydrocharitaceae), an important benchmark species. No choice testing revealed that H. egeriae can complete development on E. canadensis and choice testing indicated the fly presents little oviposition discrimination between E. densa and E. canadensis. It is concluded that the host range of H. egeriae is too broad for use as a biological control agent of E. densa in the U.S.A. 相似文献
6.
Rafik Errakhi Francois Bouteau Ahmed Lebrihi Mustapha Barakate 《World journal of microbiology & biotechnology》2007,23(11):1503-1509
Ten antibiotic-producing Streptomyces spp. isolated from Moroccan soils were evaluated for their ability to inhibit in vitro Sclerotium rolfsii development. Four isolates having the greatest pathogen inhibitory capabilities were subsequently tested for their ability
to inhibit sclerotial germination in sterile soil. This test was carried out by using biomass inoculum, culture filtrate,
and spore suspension of the isolates as treatment. Treatment with biomass inoculum and culture filtrate gave the highest inhibition
of sclerotia. Biological control tests against Sclerotium rolfsii damping-off of sugar beet seeds showed that the selected Streptomyces isolates reduced significantly the disease severity, the J-2 isolate being the more potent. In addition, treatment with the
isolate J-2 resulted in a significant increase (P ≤ 0.05) in seedling development compared to the control. All antagonistic Streptomyces selected here were able to grow in the rhizosphere soil from infected sugar beet culture. 相似文献
7.
The fungus Sclerotium rolfsii is presently under development as a bioherbicide for broadleaf weed species using fungus-infested substrates as application material in this laboratory. The effect of environmental factors and three precursors (citric acid, ascorbic acid, and sodium succinate) on mycelial growth, oxalic acid production, and virulence by SC64 in liquid culture were investigated. The results showed that for mycelia growth the optimum liquid medium was Modified Richard's solution (MRS) among the five tested media, but potato dextrose broth (PDB) produced the maximum oxalic acid production and virulence on detached Solidago canadensis leaves. When PDB was used as the basic medium, the oxalic acid/mycelial dry weight (mg g–1) ratio reached the peak 4 days after inoculation. The optimum temperature for oxalic acid production was at 27°C, but increased mycelial dry weight and virulence were observed at 30°C. The optimum range of initial pH value for oxalic acid accumulation was 4.0–6.0, with the optimal pH 5.0; highest mycelial growth was with an initial pH 3.5–6.0 (optimum pH 5.0) and subsequently pH 3.5–5.5 (maximum at pH 3.5). Both mycelial dry weight and oxalic acid production showed a decreasing trend as a result of the precursor of oxalic acid being added to PDB. Among the three precursors, the greatest decrease in mycelial dry weight, and oxalic acid production was caused by sodium succinate. This clarification of optimal conditions for production of mycelial biomass while insuring high concentrations of oxalic acid and high virulence should be useful for further development of this fungus as biocontrol agent. 相似文献
8.
Parthenium poses serious threat to modern crop production system and
necessitate evaluating control practices for its effective management. Efficacy of
different weed control practices for controlling parthenium was explored in conventional and deep tillage systems in the field conditions. Hand hoeing (20 and
35 days after emergence), S-Metolachlor (pre-emergence herbicide), sorghum
straw mulch @ 5 tons ha-1 and combination of hand hoeing and sorghum straw
mulch (hand hoeing at 20 and straw mulch at 35 days after emergence) were used
as weed control practice. Weedy check where no weed control measure was
applied was also included in this experiment for comparison. Results concluded
that the all weed management treatments significantly reduced parthenium density, its fresh and dry biomass during both the years of study as compared to weedy check. Maximum sunflower achene yield was recorded in hand hoeing (20 and
35 days after emergence) in combination with deep tillage. So, mold bold plough
used for the purpose of deep tillage should be encouraged for better control of
parthenium and higher achene yield of sunflower crop (3293.3 kg ha-1 in 2017
and 3221.3 kg ha-1 in 2018). Moreover, is also inferred that total dose of herbicide
might be reduced by using hoeing and mulching in an integrated way. 相似文献
9.
Karla L. Gage David J. Gibson Bryan G. Young Julie M. Young Joseph L. Matthews Stephen C. Weller Robert G. Wilson 《Ecology and evolution》2015,5(18):4161-4173
Agricultural environments allow study of evolutionary change in plants. An example of evolution within agroecological systems is the selection for resistance to the herbicide glyphosate within the weed, Conyza canadensis. Changes in survivorship and reproduction associated with the development of glyphosate resistance (GR) may impact fitness and influence the frequency of occurrence of the GR trait. We hypothesized that site characteristics and history would affect the occurrence of GR C. canadensis in field margins. We surveyed GR occurrence in field margins and asked whether there were correlations between GR occurrence and location, crop rotation, GR crop trait rotation, crop type, use of tillage, and the diversity of herbicides used. In a field experiment, we hypothesized that there would be no difference in fitness between GR and glyphosate‐susceptible (GS) plants. We asked whether there were differences in survivorship, phenology, reproduction, and herbivory between 2 GR and 2 GS populations of C. canadensis in agrestal and ruderal habitats. We found that geographic location was an important factor in the occurrence of GR C. canadensis in field margins. Although not consistently associated with either glyphosate resistance or glyphosate susceptibility, there were differences in phenology, survivorship, and herbivory among biotypes of C. canadensis. We found equal or greater fitness in GR biotypes, compared to GS biotypes, and GR plants were present in field margins. Field margins or ruderal habitats may provide refugia for GR C. canadensis, allowing reproduction and further selection to occur as seeds recolonize the agrestal habitat. Agricultural practices may select for ecological changes that feed back into the evolution of plants in ruderal habitats. 相似文献
10.
Sabrina Sarrocco Lisbeth Mikkelsen Mariarosaria Vergara Dan Funck Jensen Mette Lübeck Giovanni Vannacci 《Mycological Research》2006,110(2):179-187
The gfp gene from the jellyfish Aequorea victoria, coding for the Green Fluorescent Protein (GFP), was used as a reporter gene to transform a Trichoderma virens strain I10, characterized as having a promising biocontrol activity against a large number of phytopathogenic fungi. On the basis of molecular and biological results, a stable GFP transformant was selected for further experiments. In order to evaluate the effects of GFP transformation on mycoparasitic ability of T. virens I10, sclerotia of Sclerotium rolfsii, Sclerotinia sclerotiorum and S. minor were inoculated with the T. virens strain I10 GFP transformant or the wild type strain. Statistical analysis of percentages of decayed sclerotia showed that the transformation of the antagonistic isolate with the GFP reporter gene did not modify mycoparasitic activity against sclerotia. Sclerotium colonization was followed by fluorescent microscopy revealing intracellular growth of the antagonist in the cortex (S. rolfsii) and inter-cellular growth in the medulla (S. rolfsii, and S. sclerotiorum). The uniformly distributed mycelium of T. virens just beneath the rind of sclerotia of both S. rolfsii and S. sclerotiorum suggests that the sclerotia became infected at numerous randomly distributed locations without any preferential point of entry. 相似文献
11.
P. K. Mukherjee A. N. Mukhopadhyay D. K. Sarmah S. M. Shrestha 《Journal of Phytopathology》1995,143(5):275-279
An isolate of Trichoderma harzianum which is less effective than G. virens in suppressing S. rolfsii and R. solani was compared with G. virens for various mechanisms of antagonism in vitro, viz., antagonism in dual culture/hyphal parasitism, parasitism of sclerotia and antibiosis. G. virens and T. harzianum were equally effective in parasitizing the hyphae of R. solani. Only T. harzianum parasitized the hyphae of S. rolfsii, and the two antagonists were comparable with respect to antibiosis on the test pathogens. However, G. virens readily parasitized the sclerotia of the test pathogens and was found to be more effective than T. harzianum in destroying the sclerotia. Under SEM, G. virens was found to colonize, penetrate, and sporulate inside the sclerotia of the test pathogens.Parasitism of sclerotia is suggested as the principal mechanism of biological control of S. rolfsii and R. solani by G. virens. 相似文献
12.
Sclerotium rolfsii Sacc. causes disease of numerous crop plants worldwide, including groundnuts. Control of this pathogen is difficult as it produces sclerotia which overwinter in the soil to emerge as inoculum and cause disease the following season. Various chemical, biological and cultural control strategies have been suggested and implemented, some of which have reduced disease incidence in the field. No studies have yet been undertaken in South Africa to control this disease on groundnut, either chemically, biologically or by cultural practices. In this study, several strategies were investigated for the control of S. rolfsii on groundnuts. Difenoconazole was identified as a fungicide that could possibly be applied in combination with Trichoderma harzianum, a biological antagonist of S. rolfsii, above carbendazim and flusilazole, and chlorothalonil. Difenoconazole significantly reduced the growth rate of S. rolfsii but not of T. harzianum. The cultivation of infected fields with an inversion plough significantly reduced infection of groundnuts by S. rolfsii and also improved the quality of the produce, while yield was not increased. Lower plant density increased the incidence of disease in an infected field, and is therefore not considered to be a viable form of cultural control. 相似文献
13.
除草剂对黄河三角洲入侵植物互花米草的影响 总被引:1,自引:0,他引:1
互花米草(Spartina alterniflora)作为我国危害最严重的外来入侵植物之一,严重威胁滨海湿地生态系统安全。筛选可高效灭除互花米草的除草剂,为互花米草防治提供技术支持。2017年7月在黄河三角洲潮间带对互花米草茎叶喷施不同除草剂,在施药当年和次年对互花米草生长状况和大型底栖动物密度进行跟踪调查。研究结果表明:1)高效氟吡甲禾灵对互花米草的灭除效果最好,既能杀死互花米草地上部分从而完全抑制有性繁殖,又可完全抑制次年的无性繁殖;2)氰氟草酯对互花米草的灭除效果也比较好,可以完全抑制互花米草的生长和结穗,但抑制根状茎无性繁殖能力的效果稍差,草甘膦可以完全抑制互花米草的有性繁殖,但无法抑制次年互花米草的无性繁殖;3)施用除草剂在短期内会毒害某些底栖动物,但在1年后底栖动物种群数量与对照处理无显著差异。除草剂对环境的影响程度与除草剂用量和施用时间息息相关,未来研究中,应在保证灭草效果的前提下,探索最佳用药时间和最低用量以最大限度地降低环境影响。 相似文献
14.
Exudates from sclerotia of two Sclerotium rolfsii isolates (one causing collar rot in Cicer arietinum, isolate VC971, and the other leaf spots in Rauvolfia serpentina, isolate VL016) were assayed for their antifungal activity against 26 fungi consisting of plant parasites as well as saprophytes. Spore germination of all the test fungi was affected by the exudates reaching 100% in some cases. Foliar spray with exudates of isolate VL016 significantly reduced disease incidence of balsam (Impatiens balsamina) powdery mildew caused by Erysiphe cichoracearum and pea (Pisum sativum) powdery mildew caused by Erysiphe pisi, under field conditions. Characterization of exudates from 25 isolates of S. rolfsii revealed pH ranging from 3.8 to 5.3 and colour from light yellow to deep yellow. Among the phenolic acids found in the exudates were tannic, gallic, caffeic, vanillic, ferulic, chlorogenic and cinnamic acids. Oxalic acid was also found in varied amounts. Among the phenolic acids, ferulic acid was found to be present at high concentration in exudates of most isolates (3.9–153.4 μg/ml). The antioxidant properties of phenolics, which generally inhibit fungal morphogenesis including spore germination along with the antifungal nature of some phenolics are chiefly attributed to the inhibitory effect of sclerotial exudates of S. rolfsii. Additionally, both the isolates VC971 and VL016 showed almost similar antifungal activities despite they are of different origin and thereby demonstrate the antifungal nature of sclerotial exudates. 相似文献
15.
E.A. El-Shazly I.A. Ismail H.A. El Shabrawy R.S. Abdel-Rahman 《Archives Of Phytopathology And Plant Protection》2013,46(19):2304-2313
This study was conducted on Bt and normal maize hybrids during two successive sowing dates, early and late summer plantation. The Sesamia cretica larvae were observed for the first time on first week of April on different commercial maize hybrids. While there was no larva/plant on transgenic maize hybrids, YieldGard and Ageeb-YG, while larvae were found on last week of July by a very little number on maize hybrids for late one. In Early summer planting date showed highly significant differences in reduction percent, between tested compounds and control one, in the pink corn borer population. The bio-residual activity of the NeemAzal-T/S 0.5% on TWC310 was significantly less pronounced, i.e. 75.5%, than other tested ones; the highest percentage of reduction, 86.6%, was achieved by Chlorophan 0.005% on SC2031, followed by NeemAzal-T/S 0.5% on SC2031 83.5% and Chlorophan 0.005% on SC2030 83.4%, respectively. Also the average reduction percentage of S. cretica larvae differed significantly from 69.6%, on NeemAzal-T/S SC2031, to 83.0%, on Chlorophan SC2031, in the late summer planting. The different treatments had positive effects on maize yield in the two planting dates. In the first plantation date, the increased rate of control ranged from 1.04 to 1.24, when NeemAzal-T/S acted on TWC310 and transgenic IYG, respectively. And in the second plantation date, rate of control obtained was 1.06–1.30, when NeemAzal-T/S acted on SC 2031 and transgenic IYG, respectively. The tested compounds played an important role in controlling the pink corn borer insect, S. cretica, and this study suggests that Cry 1Ab-expressing corn hybrids would provide a great value as a component of corn IPM in Egypt. 相似文献
16.
17.
Jin-Hyeuk Kwon Dong-Wan Kang Okhee Choi 《Archives Of Phytopathology And Plant Protection》2016,49(1-4):43-47
Sclerotium rolfsii is one of the most destructive pathogens and thought to affect a broad range of plant hosts. In July 2014, an occurrence of sclerotium rot was observed on bitter melon (Momordica charantia L.) in Jinju, South Korea. The rot symptoms were most developed on stems and fruit near the soil line, and infected bitter melon plants withered and eventually died. White mycelial mats with numerous sclerotia were produced on diseased stems and fruit near the soil surface. Based on the morphological characteristics, pathogenicity tests, and DNA sequencing and phylogenetic analysis of the internal transcribed spacer (ITS) ribosomal RNA (rRNA) gene region, the causal fungus was identified as S. rolfsii Saccardo. This is the first report of sclerotium rot caused by S. rolfsii on bitter melon in Korea. The recent occurrence of sclerotium rot on bitter melon poses a potential threat to its production in Korea. 相似文献
18.
Yan Xiao Junbing Tang Hua Qing Changfang Zhou Weijing Kong Shuqing An 《Hydrobiologia》2011,658(1):353-363
The purpose of this article was to study the trade-offs among vegetative growth, clonal, and sexual reproduction in an aquatic
invasive weed Spartina alterniflora that experienced different inundation depths and clonal integration. Here, the rhizome connections between mother and daughter
ramets were either severed or left intact. Subsequently, these clones were flooded with water levels of 0, 9, and 18 cm above
the soil surface. Severing rhizomes decreased growth and clonal reproduction of daughter ramets, and increased those of mother
ramets grown in shallow and deep water. The daughter ramets disconnected from mother ramets did not flower, while sexual reproduction
of mother ramets was not affected by severing. Clonal integration only benefited the total rhizome length, rhizome biomass,
and number of rhizomes of the whole clones in non-inundation conditions. Furthermore, growth and clonal reproduction of mother,
daughter ramets, and the whole clone decreased with inundation depth, whereas sexual reproduction of mother ramets and the
whole clones increased. We concluded that the trade-offs among growth, clonal, and sexual reproduction of S. alterniflora would be affected by inundation depth, but not by clonal integration. 相似文献
19.
M. Paramasivan S. Mohan N. Muthukrishnan A. Chandrasekaran 《Archives Of Phytopathology And Plant Protection》2013,46(3):357-363
The aim of the study for the importance of oxalic acid produced by Sclerotium rolfsii during the invasion of host tissue during pathogenesis acts synergistically with endopolygalacturonase, lowering the pH of the infected tissues to a level optimal for the activity of this enzyme. Oxalic acid was the principal toxic agent produced in the culture filtrates of S. rolfsii and it was responsible for the death of host cells. The calcium present in structural pectates can be strongly chelated by oxalic acid. As a consequence, plant tissues are rendered more susceptible to invasion by S. rolfsii. Oxalic acid produced by S. rolfsii was very much reduced by Trichoderma viride (TVB1) (0.79 mg/ml culture filtrate), Pseudomonas fluorescens (SBHRPF2) 0.93 mg, neem cake (10%) (0.87 mg/ml), Lippia nodiflora (10%) and Lantana camera (10%) which were recorded as 2.12 and 2.25 mg/ml. The organic biocides that interfered with S. rolfsii led to reduction of oxalic acid production, which specifically reduced the disease incidence, and the oxalic acid degradation was a useful approach as a disease control strategy. 相似文献
20.
Halimeda is a potential carbon sink species and an important player in the global carbonate budget. The objectives of this study were to: (i) examine the CaCO3 and sediment productions of H. macroloba by measuring the density, growth rate, and recruitment; (ii) quantify the numbers of aragonite crystals; (iii) document reproductive events; and (iv) determine the life‐span. This study was carried out at Lidee Lek Island, Satun, Thailand during July 2015 to April 2016. The density was measured using quadrats (0.25 m2) and three 50 m line transects. Alizarin Red‐S marking technique was used for the growth rate and CaCO3 accumulation rate assessments. The recruitment, reproduction and life‐span were measured by tagging 500 individuals. Tagged individuals and new plants were counted. In this study, mean and the highest density of Halimeda were 44.42 ± 13.95 and 138.22 ± 11.68 thalli m?2, respectively, and Halimeda produced 1–2 new segments.thallus?1 day?1 or 0.021 ± 0.001 g dry weight.thallus?1.day?1. The annual biomass production was 1910–5950 g m?2 year.?1. There was a low rate of occurrence of sexual reproduction, observed in late July to September, ranging from 0.17% to 1.92%. For the mortality and recruitment rates, approximately 70–80% of individuals were lost during July to September 2015, probably from sexual reproduction and the recruitment rate varied from 5.36 ± 0.79% to 21.03 ± 2.33%. The highest density of new recruits was found in September 2015 right after the sexual reproductive event occurred. New recruits have been found up to April 2016 without any reproductive events, suggesting that both sexual and asexual reproduction helped maintain the population. The life span of Halimeda was 8–12 months. In addition, Halimeda accumulated CaCO3 at approximately 0.018 g CaCO3 thallus?1 day?1 and produced CaCO3 at approximately 291.94–908.11 g m?2 year?1, indicating that Halimeda contributes to CaCO3 and helps to sink carbon through calcification. The results in terms of the density, growth rate, and CaCO3 accumulation rate can be used to calculate the mass of carbonate sediment contributed by Halimeda. 相似文献