Cynodon dactylon (L.) Pers. Origin and diffusion Origin: Africa Distribution: tropical and subtropical regions Invasive potential: high Source: msuturfweeds.net Source: aphotoflora.com Source: montshiredev.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- Reference Contaminants of concern Mechanism involved in phytoremediation: Phytostabilisation/rhizodegradation/phyt oaccumulation/phytodegradation/phytov olatilization/ hydraulic control/ tolerant Types of microorganisms associated with the plant Requirements for phytoremediation (specific nutrients, addition of oxygen) Substrate characteristics Laboratory/field experiment Age of plant at 1st exposure (seed, post-germination, mature) Length of experiment L. J. Krutz, C. A. Beyrouty, T. J. Gentry, D. C.Wolf, 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 Pyrene Rhizodegradation Pyrene degraders No requirements Fine sandy loam (coarsesilty, mixed, nonacid, thermic Typic Udifluvents), with no known prior exposure to PAHs. 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 experiment (growth chamber) Seed 63 days after planting. Samples were collected 14 through 63 days after planting on a 7-day interval.
Phytotechnologies applications Initial contaminant concentration of the substrate Post-experiment plant condition Contaminant storage sites in the plant and contaminant concentrations in tissues (root, shoot, leaves, no storage) Soils were amended with pyrene at 0 and 500 mg /Kg Pyrene reduced root length at 28 days, root dry weight at 42 days, and shoot dry weight at 63 days Root growth was more sensitive to pyrene contamination than shoot growth since pyrene translocation is minimal. Not reported in the publication -Experiment 2- Reference Contaminants of concern Mechanism involved in phytoremediation: Phytostabilisation/rhizodegradation/phyt oaccumulation/phytodegradation/phytov olatilization/ hydraulic control/ tolerant Types of microorganisms associated with the plant Requirements for phytoremediation (specific nutrients, addition of oxygen) White Jr, P. M., Wolf, D. C., Thoma, G. J., & 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, dibenzothiophene, fluoranthene, pyrene, and chrysenes. Rhizodegradation PAH degraders Inorganic fertilizer (13-13-13) and dolomitic lime at rates of 1,600 and 1,450 kg/ha, respectively, were applied to the vegetated fertilized treatments at the beginning of the experiment. Vegetated fertilized plots received additional applications of 320 kg 33-0-0/ha after each sampling at 6, 17, and 21 mo.
Phytotechnologies application Substrate characteristics Laboratory/field experiment Age of plant at 1st exposure (seed, post-germination, mature) Length of experiment Initial contaminant concentration of the substrate Post-experiment contaminant concentration of the substrate Post-experiment plant condition Contaminant storage sites in the plant and contaminant concentrations in tissues (root, shoot, leaves, no storage) 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 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. Field experiment Mature sprig 21 months; soil samples were collected at the beginning of the study and after 6, 17, and 21 months. The main initial concentrations of naphthalene, phenanthrene, anthracene, dibenzothiophene, fluoranthene, pyrene, and chrysenes were 7, 0, 0, 7, 0, 9, 35 µg/kg, respectively. While there was not a significant treatment effect for the alkylated two-ringed naphthalenes (C1-phenanthreneanthracenes or C1-dibenzothiophenes) there was enhanced degradation of the more complex alkylated phenanthrenesanthracenes and dibenzothiophenes attributable to 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. Root length was negatively correlated to the concentration of C2-, C3-, and C4-phenanthrene/anthracene compounds and C2- and C3-dibenzothiophenes. No storage