Growth and yield of lemongrass (Cymbopogon citratus) in fly ash with nutrient amendments and Mycorrhiza for three-ratoon period

Ethnobotanical uses, phytochemistry and bioactivities of Cymbopogon plants: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Cymbopogon (Poaceae) plants have been used for various purposes by many indigenous peoples in all continents. In particular, almost all species in the genus have traditionally been used as folk medicine to treat ailments. Traditional application records indicated that Cymbopogon might be used extensively to treat cold, dizziness, headache, loss of appetite, abdominal pain, rheumatism, diarrhea, whole grass for cold, sore throat, tracheitis and others.

AIMS OF THE REVIEW

Despite several research confirmed that Cymbopogon includes a range of active components, no review has been undertaken to consolidate information on its traditional uses, phytochemistry, pharmacology, and/or quality control. Thus this article aims to update a comprehensive review about the traditional uses, phytochemistry, pharmacology, cultivation techniques, economic benefits, trade, threats, and future conservation implications of Cymbopogon species. It may provide informative data for future development and further investigation of this important plant group.

MATERIALS AND METHODS

Traditional medicinal books and ethnomedicinal publications related to Cymbopogon from 1992 to 2023 were collated to investigate its ethnobotanical, phytochemical and pharmacological information. The online databases including Google Scholar, SciFinder, Web of Science, Scopus, Springer Link, PubMed, Wiley, China National Knowledge Infrastructure (CNKI), Baidu Scholar, and WanFang Database were screened.

RESULTS

Cymbopogon (Gramineae or Poaceae) plants have been grown worldwide. Traditional Chinese medicine and other medicinal systems believes that Cymbopogon has the effect of relieve a cough, analgesia, treating dizziness, traumatic injury and can relieve abdominal pain. A total of 153 compounds, including flavonoids, terpenoids, fatty acid and other compounds were isolated or identified from Cymbopogon species by phytochemical studies. The extracts or compounds from Cymbopogon have exhibited numerous biological activities such as antibacterial, antiinflammatory, antiviral, antineoplastic, antiarrhythmic, antidiabetic and other activities. The rich contents of citronellal, citronellol and geraniol found in Cymbopogon also provide significant nutritional benefits.

CONCLUSION

Based on their traditional uses, phytochemicals, and pharmacological activities, Cymbopogon plants are potential medicinal and edible resources with diverse pharmacological effects. Due to various advantages of this group, they possess huge application potential in food and pharmaceutical industries, and animal husbandry. Among them, citronella is very important in terms of economic development. Further comprehensive research to evaluate the medicinal properties of Cymbopogon species will be necessary for future development.

Lemongrass (Cymbopogon flexuosus) growth rate, essential oil yield and composition as influenced by different soil conditioners under two watering regimes

The vast cultivation of lemongrass (Cymbopogon flexuosus) as an essential oil-bearing plant worldwide relies heavily on its compound citral that holds immense industrial potential. Soil fertility practices greatly affect the growth and quality of these plants, with a majority of the agricultural land globally grappling with water scarcity. In this respect, field experiments were conducted at the University of Embu research farm during the November 2021-September 2022 growing period and aimed to investigate the influence of two different factors, namely; (i) two watering regimes (rainfed and irrigated) and (ii) four soil conditioner levels (control (T1), cow manure (T2), cow manure plus NPK fertilizer (T3), and NPK fertilizer alone (T4)) on the growth and essential oil parameters of C. flexuosus. The field trials were arranged in a split-plot design with three replicates for each treatment. The essential oil from C. flexuosus was obtained using steam distillation method and analyzed for quality using gas chromatography with mass spectrometry (GC-MS) technique. Results revealed that treatments T4 and T3 improved the growth of C. flexuosus under rain-fed conditions, implying the plant's sensitivity to soil fertility practices and watering regimes. Herbage from rain-fed plants harvested after 120 days had high oil content, ranging from 0.17 to 0.23 %, while herbage from irrigated plants harvested after 180 days had the lowest oil content, ranging from 0.11 to 0.17 %. Using GC-MS, the main components of C. flexuosus oil were citral (75.97-87.70 %), geranyl acetate (0.80-4.91 %), geraniol (0.80-4.26 %), isogeranial (1.83-3.45 %), and isoneral (1.29-2.78 %). Notably, citral, a racemic mixture of geranial and neral, was found in a high concentration (87.70 %), meeting the acceptable international market standards for its use. Altogether, the major oil compounds, oil yield and growth properties of C. flexuosus in this experiment differed as a function of different soil conditioners under the two watering regimes, and so with the time scale. The outcomes of this research highlight implications for enhancing and bolstering the production of high-value lemongrass oil in Kenya, where it holds potential significance as a vital economic and export-oriented crop.

Heavy metals in soil, plants, and associated risk on grazing ruminants in the vicinity of Cu-Ni mine in Selebi-Phikwe, Botswana

The impact of BCL Cu-Ni mines on the surrounding environment has indicated high levels of heavy metal contamination in soil and some plant species. A comprehensive assessment of heavy metal concentration in plants, heavy metal concentration and availability in soils, and the estimates of risk associated with grazing animals in the area are presented. Exhaustive quantification of heavy metal contents in 82 plant samples revealed that some plants such as Boscia albitrunca and Boscia foetida are suitable for multi-metal phytoextraction, and others can accumulate one or two of the metals in soils or tolerate high levels of contamination. Current levels of soil contamination were manifested by acidification and high electrical conductivity, high contamination factor, and a pollution index between 8.31 and 10.79. The amount of exchangeable fractions of metals was higher than ordinary soils which is attributed to the high solubility of deposited materials on the soil surfaces. Daily intake estimates showed a possible risk associated with Pb and Cu contamination among grazing animals in the study area. Overall, the information has identified potential plants or combination of plants that could be utilized for the rehabilitation of the study area through phytoremediation. In addition, the estimates of the daily intake of the minerals due to consumption of plants in the vicinity of the BCL mines warrant for evaluation of the actual levels of heavy metals in grazing animals near the study area and in other mining areas in Botswana.

Phytostabilization of coal mine overburden waste, exploiting the phytoremedial efficacy of lemongrass under varying level of cow dung manure

A pot study was performed to assess the phytoremedial potential of Cymbopogon citratus (D.C.) Staf. for reclamation of coal mine overburden dump wastes, emphasizing the outcome of amendment practices using cow dung manure (CM) and garden soil mixtures on the revegetation of over-burden wastes (OB). Wastes amendment with cow dung manure and garden soil resulted in a significant increase in soil health and nutrient status along with an increment in the phytoavailability of Zn and Cu which are usually considered as micronutrients, essential for plant growth. A significant increment in the total biomass of lemongrass by 38.6% under CM20 (OB: CM 80:20) was observed along with improved growth parameters under amended treatments as compared to OB (100% waste). Furthermore, the proportionate increases in the assimilative rate, water use efficiency, and chlorophyll fluorescence have been observed with the manure application rates. Lemongrass emerged out to be an efficient metal-tolerant herb species owing to its high metal-tolerance index (>100%). Additionally, lemongrass efficiently phytostablized Pb and Ni in the roots. Based on the strong plant performances, the present study highly encourages the cultivation of lemongrass in coal mining dumpsites for phytostabilization coupled with cow-dung manure application (20% w/w).