Ammonium tolerance and toxicity of Actinoscirpus grossus--a candidate species for use in tropical constructed wetland systems.

Actinoscirpus grossus, a native species in tropical wetlands of South-East Asia, North Australia and the Pacific islands, has been reported to perform well in experimental scale constructed wetland (CW) systems. However, little is known about how high NH4(+) concentrations prevailing in wastewater affect growth and performance of this species. We examined growth, morphological and physiological responses of A. grossus to NH4(+) concentrations of 0.5, 2.5, 5, 10 and 15mM under hydroponic growth conditions. The relative growth rates (RGR) of the plants were highest at 2.5mM NH4(+) but significantly reduced at 10 and 15mM NH4(+). The roots of the plants were stunted and produced subepidermal lignified-cell layers at exposure to 10 and 15mM NH4(+). The photosynthetic rates did not differ between treatments (average An=21.3±0.4µmolCO2m(-2)s(-1)) but the photosynthetic nitrogen and carbon use efficiency (PNUE and PCUE) were significantly depressed at 10 and 15mM NH4(+) treatments. The concentration of NH4(+) in the roots, but not in the leaves, reflected the NH4(+) concentration in the growth medium suggesting that the species is unable to regulate the NH4(+) uptake. The high root respiration rates in concert with high tissue NH4(+) and declined C/N ratio at 10 and 15mM NH4(+) suggest that the NH4(+) assimilation occurs primarily in the roots and the plant has inadequate C-skeletons for NH4(+) assimilation and exudation at high NH4(+) concentration in the external solution. The concentrations of mineral cations were generally reduced and the root membrane permeability increased at high external NH4(+) concentrations. Our study shows that A. grossus tolerates NH4(+) concentrations up to 5mM which is characteristic of most types of wastewater. Hence, A. grossus is a good native candidate species for use in CW systems in tropical and subtropical climates in South-East Asia, North Australia and the Pacific islands.

Response of Salvinia cucullata to high NH4(+) concentrations at laboratory scales.

Growth, morphology, NH(4)(+) uptake and mineral allocation in Salvinia cucullata Roxb. ex Bory grown with different amounts of NH(4)(+) were investigated. Plants of uniform size were grown on full strength Smart and Barko medium with different NH(4)(+) concentrations (0.5, 1, 5, 10 and 15 mM) and incubated in a greenhouse for four weeks. Salvinia cucullata grew well in the medium with 0.5-1 mM NH(4)(+) with a relative growth rate of 0.11-0.12 d(-1) without exhibiting NH(4)(+) toxicity symptoms. With an NH(4)(+) concentration above 5 mM, plant growth was suppressed and signs of NH(4)(+) toxicity were observed. NH(4)(+) toxicity symptoms were obvious in plants supplied with 10 mM and 15 mM NH(4)(+). These plants had low growth rates, short roots, low numbers of roots and showed chlorosis. Rotted roots and stems were also found in plants fed with 15 mM NH(4)(+). This species had a high uptake rate even though the NH(4)(+) concentrations increased, making it an ideal candidate for growth in eutrophic environments. The high NH(4)(+) concentration had a negative effect on K uptake resulting in low K concentration in the plant tissue, but the plants increased N content in plant tissue. Thus, harvested plants can be used as soil fertilizer or for animal feed. Furthermore, maintaining plant biomass can improve the efficiency of water treatment.

Growth, morphology, ammonium uptake and nutrient allocation of Myriophyllum brasiliense Cambess. under high NH4⁺ concentrations.

The effects of high NH(4)(+) concentration on growth, morphology, NH(4) (+) uptake and nutrient allocation of Myriophyllum brasiliense were investigated in hydroponic culture. The plants were grown under greenhouse conditions for 4 weeks using four levels of NH(4)(+) concentration: 1, 5, 10 and 15 mM. M. brasiliense grew well with a relative growth rate of c.0.03 day(-1) at NH(4)(+) concentration up to 5 mM. At the higher NH(4)(+) concentrations the growth of the plants was stunted and the plants had short roots and few new buds, especially when grown in 15 mM NH(4)(+) where the submerged leaves were lost and there were rotten roots and submerged stems. To avoid NH(4)(+) toxicity, the plants may have a mechanism to prevent cytoplasmic NH(4)(+) accumulation in plant cells. The net uptake of NH(4)(+) significantly decreased and the total N significantly increased in the plants treated with 10 and 15 mM NH(4)(+), respectively. The plant may employ NH(4)(+) assimilation and extrusion as a mechanism to compensate for the high NH(4)(+) concentrations. However, the plants may show nutrient deficiency symptoms, especially K deficiency symptoms, after they were exposed to NH(4)(+) concentration higher than 10 mM. The present study provides a basic ecophysiology of M. brasiliense that it can grow in NH(4)(+) enriched water up to concentrations as high as 5 mM.

Interactive Effects of N Form and P Concentration on Growth and Tissue Composition of Hybrid Napier Grass (Pennisetum purpureum × Pennisetum americanum).

This study aimed to assess effect of nitrogen (N) form and phosphorus (P) level on the growth and mineral composition of hybrid Napier grass. Experimental plants were grown with different N forms (NO3-, NH4NO3, and NH4+; 500 µM) and P concentrations (100 and 500 µM) under greenhouse conditions for 42 days. Growth rate, morphology, pigments, and mineral nutrients in the plant tissue were analysed. At the low P concentration, the better growth was found in the plants supplied with NH4+ (relative growth rate (RGR) = 0.05 g·g-1·d-1), but at the high P concentration, the NH4+-fed plants had 37% lower growth rates and shorter roots and stems. At the high P level, the NH4NO3--fed plants had the highest RGR (0.04 g·g-1·d-1). The mineral nutrient concentrations in the plant tissues were only slightly affected by N form and P concentration, although the P concentrations in the plant tissue of the NO3--fed plants supplied with the high P concentration was 26% higher compared to the low P concentration plants. The N concentrations in the plant tissues did not vary between treatments. The results showed that the optimum N form for the plant growth and biomass productivity of hybrid Napier grass depends on P level. Hybrid Napier grass may be irrigated by treated wastewater containing high concentrations of N and P, but future studies are needed to evaluate biomass production and composition when irrigating with real wastewater from animal farms.

Treatment of Anaerobic Digester Effluent Using Acorus calamus: Effects on Plant Growth and Tissue Composition.

The responses of Acorus calamus under greenhouse conditions for 56 days when exposed to three dilutions (25%, 50%, and undiluted) of anaerobic digester effluent from a swine farm were determined. Plant growth, morphology, pigments, and minerals in plant tissues as well as water quality were investigated. The plants grew well in all concentrations of anaerobic digester effluent with no statistically significant effects on plant growth and morphology, and without any toxicity symptoms. The NH4⁺ concentrations in leaves and roots and the NO3− concentrations in leaves as well as the nitrogen, phosphorus, and potassium concentrations in the plant tissues increased with increasing effluent concentration. The nutrients in the anaerobic digester effluent were removed effectively (NH4-N > 99% removal; PO4-P > 80% removal), with highest removal rates in the undiluted digester effluent. The removal of total suspended solids (>80% in 42 days) and chemical oxygen demand (37⁻53%) were lower. The dissolved oxygen concentration in the anaerobic digester effluent increased overtime, probably because of root oxygen release. It is concluded that Acorus calamus could be a promising species for treating high-strength wastewater with high nutrient concentrations, such as effluents from anaerobic digesters as well as other types of agricultural wastewaters.

Karen and Lawa medicinal plant use: uniformity or ethnic divergence?

ETHNOPHARMACOLOGICAL RELEVANCE: We here tease apart the ethnopharmacological knowledge of plants in two Thai villages to determine to which degree the uses are particular to individual ethnic groups and to which degree they are part of a generalized and uniform set of widespread medicinal plants used over a large geographic range. We compared Karen and Lawa knowledge of medicinal plants in the Mae Cheam watershed of northern Thailand, where both ethnic groups have settled and share ecological conditions for resource extraction. We were interested in documenting the degree to which these two ethnic groups use the same or different medicinal plant species. The use of the same plant species by the two groups was considered a sign of uniform and cross-cultural local knowledge, whereas the use of different medicinal plants by each group was considered a sign of culturally specific local knowledge that developed within each ethnic group. MATERIALS AND METHODS: We inventoried the plant species in different habitats around one Karen village and one Lawa village using stratified vegetation plots and using semi-structured questionnaires we interviewed 67 key informants regarding their use of plants for medicine. We then calculated the Fidelity level FL (FL values near 100% for a species indicate that almost all use reports refer to the same way of using the species, whereas low FL values indicate that a species is used for many different purposes) and cultural importance index CI (the sum of the proportion of informants that mention each of the use categories for a given species) to estimate the variation in medicinal plant use. We used Jaccard's Index JI (This index relates the number of shared species to the total number of species) to analyze the similarity of medicinal plant use between the two villages. RESULTS: A total of 103 species of medicinal plant species in 87 genera and 41 families were identified and they were used to cure 35 ailments. The FL of the medicinal plant species varied from 10% to 100%, was different for each ailment, and differed between the two ethnic groups. The most important medicinal plant species, those with the highest CI value, were not the same in the two villages. Costus speciosus, which is used to treat urinary infections and wounds in animals, had the highest CI value in the Karen village, whereas Sambucus javanica, which is used to treat wounds, fractures, bloat, and edema in humans, had the highest CI value in the Lawa village. Only 17 medicinal species (16.5%) were shared between the two villages. Methods of preparation and application were significantly different between the two villages, whereas the plant parts used, habit, and route of administration were similar. CONCLUSION: Our study demonstrates that ethnic groups that live in the same geographic area can have significantly different traditional knowledge systems for medicinal plants, at least when it comes to the species used and their preparation and medicinal application. We assume that differences in cultural history and background in the two villages led to differences in medicinal plant use, preparation, and application.

Ethnobotanical study of medicinal plants used by Tai Yai in Northern Thailand.

ETHNOPHARMACOLOGICAL RELEVANCE: We studied traditional knowledge of medicinal plants used by Tai Yai people in Northern Thailand. We documented traditional medical practices and determined importance among the Tai Yai. This paper reports on knowledge in usage of medicinal plants of the Tai Yai people in Northern Thailand. MATERIALS AND METHODS: Interviews were conducted in 4 Tai Yai villages in Mae Hong Son and Chiang Mai provinces whose inhabitants immigrated from Myanmar at different times. Discussions and interviews were held with 126 key-informants (56 males and 70 females) ranging in age from 16 to 80 years in three age groups (age 16-40, 41-60, and 61-80). We calculated the informant consensus factor (ICF) for use category, use value index (UV) for use report of plant. We tested differences between the knowledge of different age groups and locations using principal component analysis (PCA). RESULTS: These Tai Yai people used of 141 medicinal plants belonging to 59 families. Of the medicinal plant species, the highest percentage was in the family Euphorbiaceae: Croton acutifolius and Croton roxburghii. The highest number of Informant consensus factor was for metabolic system disorders. Overall, Tai Yai people use medicinal plants to cure many sicknesses such as hypertension, lumbago, wounds, puerperium, kidney disorders, kidney stones, coughs, fevers, hemorrhoids, flatulence and malaria. There were no significant differences in knowledge of plants usage among villages of different ages. In addition, the knowledge of the plants was not significantly different between men and women. However, we found that the younger had less experience with and knowledge of medicinal plants than older people. CONCLUSIONS: The result indicates loss of accumulated knowledge of medicinal plants and traditional use. Although, the medicinal plant knowledge was passed from one generation to the next by word of mouth, the detailed documentation of medicinal plants and their use may effectively prevent the knowledge-loss through time.

Medicinal plants from swidden fallows and sacred forest of the Karen and the Lawa in Thailand.

BACKGROUND: Many ecosystem services provided by forests are important for the livelihoods of indigenous people. Sacred forests are used for traditional practices by the ethnic minorities in northern Thailand and they protect these forests that are important for their culture and daily life. Swidden fallow fields are a dominant feature of the agricultural farming landscapes in the region. In this study we evaluate and compare the importance of swidden fallow fields and sacred forests as providers of medicinal plants among the Karen and Lawa ethnic minorities in northern Thailand. METHODS: We made plant inventories in swidden fallow fields of three different ages (1-2, 3-4, 5-6 years old) and in sacred forests around two villages using a replicated stratified design of vegetation plots. Subsequently we interviewed the villagers, using semi-structured questionnaires, to assess the medicinal use of the species encountered in the vegetation survey. RESULTS: We registered a total of 365 species in 244 genera and 82 families. Of these 72(19%) species in 60(24%) genera and 32(39%) families had medicinal uses. Although the sacred forest overall housed more species than the swidden fallow fields, about equal numbers of medicinal plants were derived from the forest and the fallows. This in turn means that a higher proportion (48% and 34%) of the species in the relatively species poor fallows were used for medicinal purposes than the proportion of medicinal plants from the sacred forest which accounted for 17-22%. Of the 32 medicinal plant families Euphorbiaceae and Lauraceae had most used species in the Karen and Lawa villages respectively. CONCLUSION: Sacred forest are important for providing medicinal plant species to the Karen and Lawa communities in northern Thailand, but the swidden fallows around the villages are equally important in terms of absolute numbers of medicinal plant species, and more important if counted as proportion of the total number of species in a habitat. This points to the importance of secondary vegetation as provider of medicinal plants around rural villages as seen elsewhere in the tropics.