Cynodon dactylon (L.) Pers.
Origin and diffusion
Origin: Africa Distribution: tropical and subtropical regions Invasive potential: high
Source: msuturfweeds.net
Source: aphotoflora.com Source: montshire- dev.newenglandwild.org
Introduction
It is a clonal, perennial grass from tropical and warm-temperate areas, where it usually inhabits open locations which are subject to frequent disturbances such as grazing, fire, flooding and drought. The genetic of this species is enormously variable and C. Dactylon populations can evolve tolerance to
several extreme environmental condition as salinity or high concentrations of heavy metals in soil, leading to highly adapted ecotypes. Commonly used as a lawn grass, it is a potential agricultural weed because it spreads by rhizomes and is difficult to control.
Common names: Bermuda grass, devil's grass (English), gramigna comune (Italian)
Description
Life-form and periodicity: perennial grass
Height: it can grow 5 to 45 cm (rarely to 90 or even 130 cm).
Roots habit: Fibrous root system. It forms above-ground stolons and below-ground rhizomes simultaneously; the grass creeps along the ground and roots wherever a node touches the ground, forming a dense mat. In drought situations with penetrable soil, roots can grow to over 2 m deep, though most of the root mass is less than 60 cm under the surface.
Culm/Stem/Trunk: prostate or ascending stems, slightly flattened, often tinged purple in colour.
Fam. Poaceae
Description
Leaf: short, flat, narrow leaf blades occur on upright stem branches that arise from nodes of stolons and rhizomes. The margin is rough.
Rate of transpiration: 4,5 – 14,1 mm/day
Reproductive structure: The inflorescence is composed of 3-7, sometimes purplish, spikes in a fingerlike arrangement (digitately), 3 to 10 cm long. The spikelets are 2 to 3 mm long, in two rows. Propagative structure: The fruit is a caryopsis enclosed within glumes. The seed (grain) is very small, 1,5 mm long, oval, straw-colored to orange-red.
Development
Sexual propagation: by seed. Warm moist conditions promote the production of up to 230 seeds per panicle. Seeds germinate at temperatures above 20°C and germination takes place within the next two weeks. The complete cycle from germination to seed production takes around four months.
Asexual propagation: vegetative propagation by stolons and rhizomes fragmentation. Rapid vegetative spread rate.
Growth rate: rapid
Habitat characteristics
Light and water requirement: the plant has high light requirement and prefers an adequate supply of moisture. Soil requirements: there are varieties adapted for a wide range of soils. It prefers well- drained, fertile soils, especially heavier clay and silt soils not subject to flooding, well supplied with lime and high-nitrogen mixed fertilizers.
Tolerance/sensitivity: it is extremely drought tolerant and it well adapts to anaerobic conditions (flooding), fire and salt. Shade intolerant.
Phytotechnologies applications Bermudagrass, being an highly adaptable species, can evolve heavy metal tolerance; tolerant populations would serve as potential candidates for re-vegetation of wastelands contaminated with
Cr, Pb, Zn and Cu (Shahandeh et al., 2000; Shu et al., 2002).
Due to its fibrous and extended root system, it significantly enhances the microbial numbers and activity in the rhizosphere, that most likely results in increased biodegradation of the more recalcitrant organic compounds in the oil-contaminated soil and petroleum sludges (Hutchinson et al., 2001; White et al, 2006). Experimental studies
-Experiment 1-
L. J. Krutz, C. A. Beyrouty, T. J. Gentry, D. C.Wolf, Reference C. M. Reynolds, 2005. Selective enrichment of a pyrene degrader population and enhanced pyrene degradation in Bermuda grass rhizosphere. Biol Fertil Soils 41: 359–364 Contaminants of concern Pyrene Mechanism involved in phytoremediation: Rhizodegradation Phytostabilisation/rhizodegradation/phyt oaccumulation/phytodegradation/phytov olatilization/ hydraulic control/ tolerant
Types of microorganisms Pyrene degraders associated with the plant Requirements for No requirements phytoremediation (specific nutrients, addition of oxygen)
Fine sandy loam (coarsesilty, mixed, nonacid, thermic Typic Udifluvents), with no known prior exposure to PAHs. Substrate characteristics Particle size: 51% sand, 46% silt, and 3% clay. Nutrient concentrations: P 54 mg kg−1, K 86 mg kg−1, Ca 508 mg/kg and Mg 124 mg/kg. Soil pH (1:1) was 6.1 , and organic matter was 0.5%. Laboratory/field experiment Laboratory experiment (growth chamber)
Age of plant at 1st exposure Seed (seed, post-germination, mature) 63 days after planting. Samples were collected 14
Length of experiment through 63 days after planting on a 7-day interval.
Phytotechnologies applications
Initial contaminant concentration Soils were amended with pyrene at 0 and 500 mg
of the substrate /Kg Pyrene reduced root length at ≥28 days, root dry weight at ≥42 days, and shoot dry weight at 63 days Post-experiment plant condition Root growth was more sensitive to pyrene contamination than shoot growth since pyrene translocation is minimal. Contaminant storage sites in the plant and contaminant Not reported in the publication concentrations in tissues (root, shoot, leaves, no storage)
-Experiment 2-
White Jr, P. M., Wolf, D. C., Thoma, G. J., &
Reference Reynolds, C. M. (2006). Phytoremediation of alkylated polycyclic aromatic hydrocarbons in a crude oil-contaminated soil. Water, air, and soil pollution, 169(1-4), 207-220.
Polycyclic aromatic hydrocarbons (PAH): naphthalene, phenanthrene, anthracene, Contaminants of concern dibenzothiophene, fluoranthene, pyrene, and chrysenes.
Mechanism involved in
phytoremediation: Phytostabilisation/rhizodegradation/phyt Rhizodegradation oaccumulation/phytodegradation/phytov olatilization/ hydraulic control/ tolerant
Types of microorganisms PAH degraders associated with the plant
Inorganic fertilizer (13-13-13) and dolomitic lime at Requirements for rates of 1,600 and 1,450 kg/ha, respectively, were applied to the vegetated fertilized treatments at the phytoremediation beginning of the experiment. Vegetated fertilized (specific nutrients, addition of oxygen) plots received additional applications of 320 kg 33-
0-0/ha after each sampling at 6, 17, and 21 mo.
Phytotechnologies application
The field study was located in an oil storage/separation facility, where a crude oil-spill contaminated the surrounding soil. The soil was a Sacul fine sandy loam. Initial soil nutrient levels Substrate characteristics were not adequate for optimum plant growth with Mehlich 3 extractable P, K, Ca, and Mg levels of 5,
44, 351, and 44 mg/kg, respectively. The pH and %N were 5.5 and 0.05%, respectively. Laboratory/field experiment Field experiment
Age of plant at 1st exposure Mature sprig (seed, post-germination, mature) 21 months; soil samples were collected at the Length of experiment beginning of the study and after 6, 17, and 21 months. The main initial concentrations of naphthalene, Initial contaminant concentration phenanthrene, anthracene, dibenzothiophene, fluoranthene, pyrene, and chrysenes were 7, 0, 0, of the substrate 7, 0, 9, 35 µg/kg, respectively. While there was not a significant treatment effect for the alkylated two-ringed naphthalenes (C1-phenanthrene- anthracenes or C1-dibenzothiophenes) there was enhanced Post-experiment contaminant degradation of the more complex alkylated phenanthrenes- anthracenes and dibenzothiophenes attributable to concentration of the substrate phytoremediation. The degradation pattern was 2-ring > 3-ring > 4-ring and decreased with increased alkylation of larger ringed structures. . While initial vegetation establishment at the field site was successful, early plant growth was reduced due to drought conditions. Post-experiment plant condition Root length was negatively correlated to the concentration
of C2-, C3-, and C4-phenanthrene/anthracene compounds and C2- and C3-dibenzothiophenes. Contaminant storage sites in the
plant and contaminant No storage concentrations in tissues (root, shoot, leaves, no storage)