• The Korean Journal of Ecology
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• 제9권1호
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• pp.33-40
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• 1986

The distribution of giant duckweed (Spirodela polyrrhiza) and small duckweed (Lemna aequinoctialis) was investigated at lead-zinc mine area and the limiting factors for their distribution were studied by laboratory experiments. The metal investigated of water affected on the growth of giant duckweed and small duckweed. Under filed conditions, both giant duckweed and small duckweed did not persist at more acidic conditions than pH 4.8 or at conditions more than 0.30 ppm of Cd concentration. Giant duckweeds were intolerable, under conditiions with less than 0.30 ppm of Cd and above than 0.07ppm of Zn, but small duckweeds were tolerable under conditions of more than 0.07 ppm of Zn concentration. However, neither can live above 7.50ppm of Zn concentration. These field observations corresponded with the results of the laboratory experiments.

• Asian-Australasian Journal of Animal Sciences
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• 제14권4호
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• pp.507-514
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• 2001

Two experiments were carried out to investigate whether duckweed is useful as a dietary protein source for fine-wool Merino sheep and to evaluate its effects on wool yield and characteristics. In Experiment 1, the sheep were given one of three maintenance diets consisting of oaten chaff (520-700 g/d) supplemented with 16-32 g crude protein/d in the form of fresh (1 kg/d) or sun-dried (50-100 g/d) duckweed. Each ration was estimated to provide 5.4 MJ (1.3 Mcal)/d of metabolisable energy (ME). The sheep readily ingested the fresh or dried duckweed. None of the wool measures (yield, rate of fibre elongation, fibre diameter) differed (p>0.05) between dietary treatments. In Experiment 2, oaten-chaff-based diets (800 g/d) supplying 6.5-7.2 MJ (1.6-1.7 Mcal)/d of ME were supplemented with iso-nitrogenous amounts (4-5 g N) either of urea (8 g), cottonseed meal (60 g) or dried duckweed (100 g). In this experiment, the rate of wool fibre elongation, thought to be related to intestinal amino acid absorption, was lower (p<0.05) for sheep given the oaten chaff/urea diet than for those given either oaten chaff/cottonseed meal or oaten chaff/duckweed for which the rates did not differ (p>0.05). Fibre diameter, which ranged from 16.0-16.7 mm, did not differ (p>0.05) between diets, but tended to be lower on the oaten chaff/urea diet so that volume of wool produced was also significantly lower (p<0.05) on this diet than on the diets containing duckweed or cottonseed meal. Rumen ammonia concentrations at 4.5 and 7.5 h after feeding were higher (p<0.05) for sheep given the oaten chaff/urea diet than for those given the other two diets. A comparison of the rumen ammonia concentrations, wool growth rate and predicted flows of amino acids from the rumen of sheep supplemented with duckweed rather than cottonseed meal suggested that duckweed is a valuable source of 'escape protein' for ruminants.

• Asian-Australasian Journal of Animal Sciences
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• 제14권12호
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• pp.1741-1746
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• 2001

An experiment was conducted at the experimental duck farm of Cantho University to determine the effects of feeding duckweed (Lemna minor) that completely replaced commercial protein supplements in diets for crossbred meat ducks. The experiment included five treatments, with four replicates and ten crossbred ducks per replicate (pen). The five diets were based on broken rice offered ad libitum, supplemented with either 27 (control, SB100), 19 (SB70), 15 (SB55), 12 (SB40) or zero (SB0) g/day of ground, roasted soya beans, with fresh duckweed supplied ad libitum, except for the control (SB0) treatment. A vitamin / mineral premix and salt were included in the control (SB100) diet, but not in the diets with duckweed. These diets were fed to growing crossbred meat ducks (Czechoslovak Cherry Valley hybrids) from 28 to 63 days of age, when two birds (one male and one female) per pen were slaughtered for carcass evaluation. Total daily intakes were 95, 108, 108, 105 and 107 g of dry matter (DM) (p<0.001) and daily live weight gains 26.1, 29.1, 28.3, 27.1 and 27.6 g (p<0.001) for the SB100, SB70, SB55, SB40 and SB0 diets, respectively. Corresponding feed conversion ratios (FCR, dry matter basis) were 3.63, 3.71, 3.82, 3.89 and 3.88 kg feed/kg gain, respectively. There were no significant differences in carcass yields, chest and thigh muscle weights, and internal organ weights between the ducks fed the control diet and those fed duckweed diets. Fresh duckweed can completely replace roasted soya beans and a vitamin-mineral premix in broken rice based diets for growing crossbred ducks without reduction in growth performance or carcass traits. If the duckweed is grown on farm, and managed and harvested by household labour, the saving over purchased protein supplements is up to 48%.

• Asian-Australasian Journal of Animal Sciences
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• 제17권8호
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• pp.1168-1176
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• 2004

Intensive animal industries create large volumes of nutrient rich effluent, which, if untreated, has the potential for substantial environmental degradation. Aquatic plants in aerobic lagoon systems have the potential to achieve inexpensive and efficient remediation of effluent, and to recover valuable nutrients that would otherwise be lost. Members of the family Lemnaceae (duckweeds) are widely used in lagoon systems, but despite their widespread use in the cleansing of sewage, only limited research has been conducted into their growth in highly eutrophic media, and little has been done to systematically distinguish between different types of media. This study examined the growth characteristics of duckweed in abattoir effluent, and explored possible ways of ameliorating the inhibitory factors to growth on this medium. A series of pot trials was conducted to test the tolerance of duckweed to abattoir effluent partially remediated by a sojourn in anaerobic fermentation ponds, both in its unmodified form, and after the addition of acid to manipulate pH, and the addition of bentonite. Unmodified abattoir effluent was highly toxic to duckweed, although duckweed remained viable and grew sub optimally in media with total ammonia nitrogen (TAN) concentrations of up to 100 mg/l. Duckweed also grew vigorously in effluent diluted 1:4 v/v, containing 56 mg TAN/L and also modified by addition of acid to decrease pH to 7 and by adding bentonite (0.5%).

• Asian-Australasian Journal of Animal Sciences
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• 제17권1호
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• pp.137-145
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• 2004

Intensive animal industries create large volumes of nutrient rich effluent which, if untreated, has the potential for substantial environmental degradationand to recover valuable nutrients that would otherwise be lost. Members of the family Lemnaceae are widely used in lagoon systems, to achieve inexpensive and efficient remediation of effluent. Only limited research has been conducted into their growth in highly eutrophic media and there has been little done to systematically distinguish between different types of media. This study examined the growth characteristics of duckweed in abattoir effluent and explored possible ways of ameliorating the inhibitory factors to growth on this medium. A series of pot trials was conducted to test the tolerance of duckweed to abattoir effluent partially remediated by a sojourn in anaerobic fermentation ponds, both in its unmodified form and after the addition of acid to manipulate pH, and the addition of bentonite. Unmodified abattoir effluent was highly toxic to duckweed, even at dilutions of 3:1. Duckweed remained viable and grew sub-optimally in simplified media with total ammonia nitrogen (TAN) concentrations of up to 100 mg/L. Duckweed grew vigorously in effluent diluted 1:4 v/v, containing 56 mg TAN/L when modified by addition of acid (to decrease pH to 7) and bentonite at 0.5%. The results of this study suggest that bentonite plays an important role in modifying the toxicity of abattoir effluent to duckweed.

• Nuclear Engineering and Technology
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• 제53권6호
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• pp.1991-1999
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• 2021

The response changes of the specific growth rate of Lemna minor duckweed was modeled using the logarithms of frond numbers on tritium activity concentration and gamma radiation dose from cobalt 60. The concept of average specific growth rate depends on the general exponential growth pattern, where toxicity is estimated based on the effect on the growth rate. One of the main questions of the effect of the radiation dose on duckweed is how to correlate the effect of beta radiation with the effect of any other radiation for modeling radiation on Lemna minor. Experimental data were extrapolated by utilizing the OECD guidelines. A linear relationship of absorbed dose and activity concentration was obtained for the average dependency growth rate of Lemna minor as D = (0.1257)·A^0.585. The dose rate of gamma irradiation from ⁶⁰Co increases with tritium activity dependence, on the specific growth rate of the Lemna minor duckweed. An increase in the tritium activity causes a decrease in the specific growth rate of the Lemna minor duckweed. It indicates that as the quantity of the beta radiation dose increase in Lemna minor duckweed, a higher quantity of gamma radiation will be required to cause the same effect in the specific growth rate of Lemna minor duckweed. The relation between the inhibition of the Lemna minor seedling growth and gamma and beta radiation dosage agrees roughly with that between the decrease of survival rate or fertility and dosage.

• Asian-Australasian Journal of Animal Sciences
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• 제13권5호
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• pp.686-693
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• 2000

Biomass yield, nutritive value and nutrient utilization efficiency of different genera of duckweed (DW, Lemnaceae) under the same nutritional and management conditions were studied. Three genera of DW namely: Lemna perpusilla, Spirodela polyrhiza and Woljfia arrhiza, were cultivated in 18 plastic sinks each of $59{\times}54{\times}35cm^3$ size. Each sink contained approximately 80 L of water and was charged once with 6.648 kg of anaerobically fermented cow dung effluent. The seed rate for Spirodela, Lemna and Wolffia were 600, 400 and $600g/m^2$ respectively. Duckweed were harvested at 48 hours intervals. Media total N concentration for Lemna and Wolffia gradually increased with time. Growth of duckweed was measured by subtracting the inoculum from the total biomass production. Growth of Spirodela ceased within 4 days but Lemna and Wolffia continue to grow up to 34 days. Bio-mass yield was significantly (p<0.05) higher in Wolffia (906 kg/ha/d) than Lemna (631 kg/ha/d). Dry matter (DM) yield was very similar in Lemna (14.80 kg/ha/d) and Wolffia (14.57 kg/ha/d). The N content was non-significant higher in Lemna (5.45%) than Wolffia (5.00%) and Spirodela (4.6%). The crude protein (CP, $N{\times}6.25$) yield was non-significantly higher in Lemna (4.83 kg/ha/d) than Wolffia (4.32 kg/ha/d). The acid detergent fibre (ADF) content was the highest in Wolffia (28.59%), followed by Spirodela (19.47%) and Lemna (12.39%). Utilization efficiency of CP was 273 and 314% respectively for Wolffia and Lemna. However, similar efficiency values for Spirodela was only 1.5%. Considering the bio-mass yield, nutritive value and nutrient utilization efficiency, production performance of DW were in the order of Lemna>Wolffia>Spirodela under the present experimental conditions.

• Asian-Australasian Journal of Animal Sciences
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• 제16권2호
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• pp.297-305
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• 2003

The family of lemnacae colloquially known as duckweed contains the world' smallest species of flowering plants (macrophytes). Aquatic and free-floating, their most striking qualities are a capacity for explosive reproduction and an almost complete lack of fibrous material. They are widely used for reducing chemical loading in facultative sewage lagoons, but their greatest potential lies in their ability to produce large quantities of protein rich biomass, suitable for feeding to a wide range of animals, including fish, poultry and cattle. Despite these qualities there are numerous impediments to these plants being incorporated into western farming systems. Large genetically determined variations in growth in response to nutrients and climate, apparent anti-nutritional factors, concerns about sequestration of heavy metals and possible transference of pathogens raise questions about the safety and usefulness of these plants. A clear understanding of how to address and overcome these impediments needs to be developed before duckweed is widely accepted for nutrient reclamation and as a source of animal feed.

• 한국환경생태학회지
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• 제32권4호
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• pp.425-439
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• 2018

본 연구는 제주도 지역에서 처음 발견된 점개구리밥의 분포와 서식생물상에 대한 점개구리밥의 위해성을 평가하기 위해, 제주도 내 43개 습지 및 하천에서 환경요인과 서식생물상을 조사하였다. 점개구리밥은 43개 중 총 18개 조사지역에서 출현이 확인되었으며, 이들 지역에서는 점개구리밥 외 수생식물의 생물량은 낮은 편이었다. 점개구리밥 등 수생식물과 환경요인에 대한 서식생물상의 영향을 분석하기 위해 SOM(Self-Organizing Map)을 활용한 패턴분석을 실시하였다. 분석 결과, 동물플랑크톤 등 서식생물상은 환경요인보다는 수생식물의 생물량에 대한 영향이 큰 것으로 나타났다. 특히 점개구리밥의 생물량은 부착성 종과 밀접하게 관련되는 것으로 분석되었다. 제주도 내 하천 및 습지는 수원이 일정하지 않고 수위변화가 급격하여 수생식물의 현존량이 적은 점을 감안하면, 제주도 지역의 교란 특성에 비교적 강한 점개구리밥은 서식생물상(동물플랑크톤 등)에게 서식처로서 중요하게 적용될 것으로 판단된다. 더욱이, 점개구리밥의 점유 공간 내 유기물이 서식동물상의 먹이원으로 활용되는 점 등을 볼 때 점개구리밥은 서식처인 동시에 먹이터로의 역할을 수행하고 있는 것으로 보인다. 비록 점개구리밥의 밀생이 그늘 효과 등으로 일부 수생식물의 성장과 발달에 영향을 미치지만, 이것은 부유식물이 수표면에 우점하는 특성 때문이며, 점개구리밥의 위해성이라 판단하기는 어렵다. 결론적으로 점개구리밥은 제주도 지역 내 대부분의 수계에서 확산 및 정착된 것으로 조사되었으며, 서식생물상 및 수중 환경 내 미치는 영향은 적은 것으로 사료된다. 추후 제주도 지역 외 내륙에서의 점개구리밥 분포 및 확산에 대한 모니터링을 수행할 필요가 있다고 보여진다.

• Asian-Australasian Journal of Animal Sciences
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• 제15권4호
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• pp.537-542
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• 2002

A study was conducted to evaluate the nutritive potential value of different aquatic plants: duckweed (Lemna trisulaca), duckweed (Lemna perpusila), azolla (Azolla pinnata) and water-hyacinth (Eichhornia crassipes) from Bangladesh. A wide variability in protein, mineral composition, gas production, microbial protein synthesis, rumen degradable nitrogen and in situ dry matter and crude protein degradability were recorded among species. Crude protein content ranged from 139 to 330 g/kg dry matter (DM). All species were relatively high in Ca, P, Na, content and very rich in K, Fe, Mg, Mn, Cu and Zn concentration. The rate of gas production was highest in azolla and lowest in water-hyacinth. A similar trend was observed with in situ DM degradability. Crude protein degradability was highest in duckweed. Microbial protein formation at 24 h incubation ranged from 38.6-47.2 mg and in vitro rumen degradable nitrogen between 31.5 and 48.4%. Based on the present findings it is concluded that aquatic species have potential as supplementary diet to livestock.