Keanekaragaman Tumbuhan Fitoremediasi Di Ekosistem Riparian DAS Citarum

Riparian ecosystems have a protective function of watersheds from pollution. One important component in riparian ecosystem is the presence of phytoremediation plants, which can degrade contamination content. This research is intended to identify the presence of undergrowth that functions as phytoremediation in Bojongsoang District which is one of the areas around the heavily polluted Citarum watershed zone[1]. The method used in this research is vegetation analysis using the quadrant method with 1x1 m2 plot size. Determination of sampling points used purposive sampling method. The results of the study found that the undergrowth as a potential phytoremediation included rumput teki (Cyperus rotundus), Beluntas (Pluchea indica), Alang-alang (Imperata cylindrica), Jejarongan (Chloris barbata), rumput gajah (Cyperus rotundus), and bayam duri (Amaranthus spinosus). Rumput teki (Cyperus rotundus) is phyto-extractions in mercury-contaminated soils and accumulators of Sn, Zn, As, Cu, and Pb. Alang-alang (Imperata cylindrical) is a cyanide phytoremediator which is able to extract Zn from contaminated soil, and absorb Pb from contaminated soil. Beluntas is able to accumulate Cu, Fe, Al, Pb and Zn in their roots, leaves and stems, and the leaves that can absorb Cr. Rumput gajah (Cyperus rotundus) are a Cd accumulator. Bayam duri (Amaranthus spinosus) hyperaccumulator against mercury. Studies on the presence of phytoremediation plants can provide preliminary information on the condition of riparian ecosystems in the Citarum watershed.

Factors influencing the germination and emergence of tall windmill grass (Chloris polydactyla) and swollen fingergrass (Chloris barbata)

This study characterized the germination of seeds of Chloris polydactyla (synonymy Chloris elata) and Chloris barbata at varying temperature, luminosity, soil texture and cover. The first experiment WAS conducted in laboratory to determine the temperature and light effects on germination of these species. The experimental design was a 2x7 factorial, where 2 represents the absence/presence of light and 7 temperatures 15, 20, 25, 30, 35, 40 and 45°C. The second experiment was conducted in greenhouse to determine effect of edaphic factors on seedling emergence, in a 3x6 factorial arrangement, consisting of 3 soil textures (sandy, medium and clayey) and 6 sowing depths (0, 1, 2, 4, 6 and 8 cm). The third experiment was conducted in greenhouse to determine soil cover effects and to evaluate the percentage reduction of dry matter of weeds, where the treatments were mulching with 0, 5, 10, 15 and 20 t ha-1 sugarcane straw. All experiments were conducted in completely randomized design, analyzed separately for each species. No seed was germinated under absence of light. Both species achieved better germination in medium textured soil. It was observed that the emergence of the species was low even without straw. Chloris showed better germination under higher temperatures of 30ºC and 35ºC, although exhibited a drastic decline in the emergence with the increase in soil depth or mulching with sugarcane straw. Greater germination of these weeds occurs in medium textured soils.

Visual and olfactory floral cues related to ambophilous pollination systems in Poaceae

Usually considered anemophilous, grasses (Poaceae) have been the subject of few studies that recorded insects visiting their flowers. Such visitors, with wind, could act as pollen vectors in a possible ambophilous system. Since colour and scent are floral cues attracting pollinating insects, we aimed to provide the first insights into how these cues could be involved in the attraction of pollinators by grasses. Chloris barbata, Paspalum maritimum (with two morphotypes), P. millegrana and Urochloa plantaginea were studied. We determined the role of each pollen vector (wind and insect) and we registered the frequency of floral visitors. Also, we characterized the colour reflectance of glumes, anthers and stigmas and we determined the colour space in the bee colour hexagon and the chemical composition of floral scents. The floral structures of each species reflect colour differently and are perceived differently by pollinators. Furthermore, the volatile organic compounds detected are similar to those found in entomophilous species. In two of the grass species, we registered eight species of visitors, including bees, wasps and flies. Overall, wind was the most important vector for reproductive success. Insects, however, may induce wind pollination by creating pollen clouds when they visit inflorescences.

Germination of Chloris barbata, Cynodon dactylon, and Cyperus rotundus from Angola at Constant and Alternate Temperatures

The study of weed germination can improve knowledge on their seasonal dynamics in fields and facilitate the design of ecologically sustainable management. An experiment was conducted to evaluate the effect of a range of constant and alternate temperatures on the germination of Chloris barbata, Cynodon dactylon, and Cyperus rotundus collected in Angola. Interesting differences were observed between the germination responses of the three species. No germination was observed for any species at 10 or 15–5 °C. Chloris barbata quickly germinated at most constant and alternate incubation temperatures, showing low primary dormancy and high germinability. Fast and high germination was observed for Cynodon dactylon at most alternate temperatures, while lower germination percentages were achieved at constant temperatures, especially the highest ones. Cyperus rotundus achieved good germination percentage at alternate temperatures, even if with slower and more extended germination dynamics than the other species, while almost no seeds germinated at constant temperatures. This study improves our knowledge of germination ecology for these species and allows some control tools to be identified, such as soil tillage, cover crops, and living or dead mulches, which can contribute to their ecologically sustainable management.

Combining Autoclaving with Mild Alkaline Solution as a Pretreatment Technique to Enhance Glucose Recovery from the Invasive Weed Chloris barbata

Developing an optimum pretreatment condition to enhance glucose recovery assessed the potential of Chloris barbata, which is a common invasive weed in Thailand, as a feedstock for bioethanol production. Chloris barbata was exposed to autoclave-assisted alkaline pretreatment by using different sodium hydroxide (NaOH) concentrations (1% to 4%) and heat intensities (110 °C to 130 °C) that were dissipated from autoclaving. The optimum condition for pretreatment was determined to be 2% NaOH at 110 °C for 60 min. At this condition, maximum hydrolysis efficiency (90.0%) and glucose recovery (30.7%), as compared to those of raw C. barbata (15.15% and 6.20%, respectively), were observed. Evaluation of glucose production from 1000 g of C. barbata based on material balance analysis revealed an estimated yield of 304 g after pretreatment at the optimum condition when compared to that of raw C. barbata (61 g), an increase of five-fold. Structural analysis by the scanning electron microscopy (SEM) and X-ray diffraction (XRD) revealed the disruption of the intact structure of C. barbata and an increase in the cellulose crystallinity index (CrI), respectively. The results from this study demonstrate the efficiency of using C. barbata as a potential feedstock for bioethanol production.