Roselle Plants Research Articles

Antioxidant Compounds and Activities of Roselle (Hibiscus sabdariffa L.) Decoction Residues from Cordial and Juice Production

Roselle is a popular plant in Malaysia, especially for its use in food and beverage production. The calyces of the roselle plant are commonly decocted to make roselle juice and cordial, resulting in a significant amount of waste in the form of decocted calyces. Surprisingly, these decocted calyces retain their dark red colour and are still intact although soften. However, to date, there is no research on the antioxidant compounds and activities of roselle decoction residues from cordial and juice production have been reported. Therefore, the aim of this study is to determine the phenolic compounds and antioxidant activities of the roselle decoction residues. The roselle decoction residues were evaluated for colour, Delta E (∆E), pH, total anthocyanin content (TAC), total phenolic content (TPC), total flavonoid content (TFC), DPPH radical scavenging assay, ferric reducing ability assay (FRAP), and ferrous ion chelating (FIC). All assays were also correlated and show positive effect among themselves. The decocted residues reported were still in acidic conditions ranged of pH 2 to 4. The decocted cordial residue (DCR) showed similar colour with control or fresh roselle calyx (FRC), and a bit duller in decocted juice residue (DJR). The DCR showed similar and slightly lower antioxidant content and activity of TAC, TPC, TFC, DPPH, FRAP and FIC to FRC but much better than DJR. Therefore, the DCR were still rich in anthocyanin contents and had good antioxidant activity without having colour changes. These residues have the capacity to be converted to wealth and could be an alternative source for natural antioxidants. Further research is needed to explore their potential applications in functional foods, dietary supplements, and pharmaceuticals. By harnessing the potential of roselle decoction residues, we can contribute to a more sustainable and environmentally friendly approach to food and beverage production.

Influence of Colored Shade Nets and Salinity on the Development of Roselle Plants

Adequate fertilizer concentration and use of shade nets can favor the development and yield of agricultural crops. The objective of this investigation was to evaluate the growth of roselle plants with nutrient solutions of different electrical conductivities (ECns) (1.0, 2.0, 3.0, 4.0 and 5.0 dS m−1) and under different colored shade nets (red, blue, black) compared with full sun. The experiments were conducted in a controlled greenhouse environment and in full sun in the Plant Production Department of ESALQ-USP, Piracicaba, SP, Brazil. The experiments were organized using a 4 × 5 randomized block design. The results of analysis of variance and regression showed a significant impact of EC and colored shade nets on plant height, stem diameter, number of leaves, number of flowers, fresh and dry mass of shoots and fresh and dry calyxes. The data were subjected to analysis of variance and regression, which showed a quadratic effect for the variables studied, with increasing values up to 3.0 dS m−1; after this value, there was a decrease. Increasing ECns up to approximately 3.0 dS m−1 promoted increments of 2.34% in plant height, 7.21% in number of leaves, 19.76% in shoot fresh mass and 12.38% in shoot dry mass.

Impact of marine algae extract and balanced fertilizer(NPK) on Hibicsus sabdariffa.L growth, quotient, and vitamin C content.

A field experiment was conducted in one of the experimental fields affiliated to Ibn Al-Bitar Vocational Preparatory School located in Al-Hussainiyah District - Karbala Governorate during the 2023 agricultural season with the aim of studying the impact of adding different concentrations of marine algae extract, balanced fertilizer in the growth qualities, yield and vitamin C in the roselle plant. The experiment was carried out according to a randomized complete block design (RCBD) with factorial arrangment and three replications. The experiment included two factors. The first factor included spraying with marine algae extract in concentrations ( 0, 0.25, 0.5 and 0.75 ml L-1) . The second factor included spraying with balanced fertilizer (NPK) in concentrations (0, 2.5 and 5 ml L-1). The results showed that spraying with marine algae extract (0.75 ml L-1) has a significant superiority in the vegetative growth qualities and vitamin C content of the roselle plant compared to other agile agreements, and the spraying with balanced fertilizer at a concentration of (5 ml L-1) It significantly excelled in all study indicators. The interaction between the two study factors, The spray treatment superiority (0.75 ml L-1) of algae extract with the of balanced fertilizer (5 ml L-1), and gave the highest averages for all the studied qualities., giving the highest Means for all the studied qualities.

Enhancing Roselle Growth and Yield through Planting Density and Fertilization Strategies: A Study on BRIS Soil Area

Optimizing planting density and fertilization practices are crucial factors influencing the micro-environment of agricultural fields, thereby profoundly impacting the growth, development, and yield formation of Roselle plants. This study investigates the combined effects of planting density and Sesbania grandiflora integration on nitrogen dynamics within the BRIS soil area, aiming to enhance Roselle growth and yield. Employing a randomized complete block design (RCBD), three fertilizer treatments—control, green manure, and organic fertilizer—were implemented. Nitrogen content was analyzed using the Kjeldahl method, while phosphorus and potassium contents were determined via UV spectrometry and atomic absorption spectrophotometry, respectively. Within an agroforestry model employing a spacing of 20 cm between plants, results revealed that Roselle plants treated with organic fertilizer exhibited higher nitrogen (N: 3.54 %), phosphorus (P: 0.54 %), and potassium (K: 1.61 %) content in their leaves, and similarly in their roots (N: 1.93%, P: 0.45%, K: 2.11%). However, soil analysis indicated that green manure fertilizer treatment led to higher nitrogen (0.11 %), phosphorus (44.67 %), and potassium (0.17 %) content within the BRIS soil. In conclusion, the green manure fertilizer treatment demonstrated a propensity to enhance nitrogen dynamics within the poorly structured BRIS soil, thereby promoting growth and development. Conversely, the integration of Sesbania grandiflora along with suitable plant spacing appeared instrumental in sustaining Roselle yield productivity. This research sheds light on the interplay between planting density, fertilizer strategies, and soil dynamics, providing valuable insights for optimizing Roselle cultivation practices in similar agroecological contexts.

Implementasi Pembelajaran Tematik Melalui Media Pembuatan Teh Bunga Rosela (Teburos) untuk Meningkatkan Keterampilan Wirausaha Siswa

This research aims to implement thematic learning through the medium of making roselle flower tea (teburos) to improve the entrepreneurial skills of class VI students at SD Negeri Rojopolo 06. The research method used was classroom action research involving 20 students as research subjects. The research steps involve planning, pre-test, implementation, observation, post-test and reflection. The implementation of this learning is a pre-test, providing thematic material, planting roselle plants, active involvement of students in making and packaging Teburos products, developing students' analytical skills in marketing Teburos products, as well as post-tests and reflections. The data collection method used was giving tests to students. From the research results, it is known that the implementation of thematic learning through the teburos media can show improvement. This increase can be seen from the comparison of the average pre-test and post-test scores of students, which experienced a significant increase of 65% from the pre-test score of 55.75, increasing to the post-test of 75.25. The application of thematic learning using Teburos media can improve students' entrepreneurial skills and have a positive impact on students' learning motivation.

Effect of NPK combinations on some growth and yield indicators of two varieties of roselle plant (Hibiscus sabdariffa L.)

A field experiment was carried out during the 2022 agricultural season in one of the experimental fields affiliated with Ibn Al-Bitar Vocational Preparatory School, located in Karbala Governorate, to study the effect of NPK combinations on the growth and yield traits of two varieties of Roselle plant. The experiment was carried out in with three replicates, according to a randomized complete block design (RCBD) with two factors. The first factor included combinations of NPK fertilizers and according to the as follows: C0= 0 NPK kg ha-1, C1= 50,25,25 NPK kg ha-1, C2 = 75,50,50 NPK kg ha-1, C3 =100,75,75 NPK kg ha-1, C4 = 125,100,100 NPK kg ha-1, C5 = 150,125,125 NPK kg ha-1, C6 = 175,150,150 NPK kg ha-1. The second factor was two varieties of Roselle plants: white (W) and red (R). The results showed that the red variety excelled in most of the studied traits, such as growth traits, plant height 173.27 cm, leaves number 295.65 leaf plant-1, leaf area 3.48 m2,total chlorophyll content in leaves 6.61 mg g-1, fresh weight 2188.57 g plant-1, yield characteristics, number of nuts 137.65 nut plant-1, total nut yield 6298. 44 kg ha-1 and total yield of calyx leaves 1558.01 kg ha-1. C5 and C6 combinations were superior in plant height (189.05 and 195.05 cm), leaves number (331.0 and 348.0 leaf plant-1), chlorophyll a ( 6.10 and 6.45 mg g-1), chlorophyll b( 4.23, and 4.72 mg g-1 , Total chlorophyll(10.36 and 10.96 mg g-1), number of nuts (141.90 and 143.30 nut plant-1), total nut yield (6815.82 and 7090.42 kg ha-1), total yield of calyx leaves(1769.68 and 1967.81 kg ha-1 and fresh weight (2845and 2969 g plant-1) respectively. The C6 treatment was significantly superior to the C5 treatment in the characteristics of chlorophyll b, total chlorophyll, fresh weight, total nut yield, and total yield of calyx leaves.

First Report of Rhizoctonia solani AG-4 HG-I Causing Root and Basal Stem Rot on Roselle (Hibiscus sabdariffa) in Mexico.

Roselle (Hibiscus sabdariffa L.) is a crop of economic importance, refreshing drinks are prepared from its calyces, it is also attributed to antioxidant, antibacterial, and antihypertensive properties (Da-Costa-Rocha et al. 2014). In November 2022, in municipality of Iguala (18.355592N, 99.548546W, 749 m above sea level), Guerrero, México, roselle plants of approximately 1.5 months of age with basal rot were detected under greenhouse conditions. The symptoms consisted of wilting, yellowing, and root and stem rot with constriction in the base of the stem. The symptoms were detected in approximately 15% of plants at the operation. From symptomatic tissue, cuts were made into approximately 0.5 cm pieces, sterilized with 2% NaClO, washed with sterile distilled water, transferred to PDA medium amended with 50 mg/liter of Chloramphenicol, and incubated in the dark for four days at 28 °C. Rhizoctonia-like colonies were consistently obtained, and nine isolates were selected and purified by the hyphal-tip method. After four days, isolates developed a mycelium was light-white that became brown with age. Right-angled hyphal branching was also observed, in addition to a slight constriction at the base of the branches. In some older cultures, numerous dark brown sclerotia were observed. They were multinucleate cell with three to eight nuclei and measured from 1 to 2 mm in diameter. Together these characteristics were consistent with the description of Rhizoctonia solani Kühn (Parmeter 1970). The anastomosis group (AG) was confirmed by amplifying the ITS region with the primers ITS1 and ITS4 (White et al. 1990) of the RIJAM3 and RIJAM5 strains. The sequences were deposited in GenBank (Nos. OR364496 and OR364497 for RIJAM3 and RIJAM5, respectively). BLAST analysis, both isolates indicated 99.7 identity to R. solani AG-4 HG-I (GenBank: KM013470) strain ICMP 20043 (Ireland et al. 2015). The phylogenetic analysis of AGs sequences allowed assignment of isolates RIJAM3 and RIJAM5 to the AG-4 HG-1 clade. A pathogenicity test was performed on 20 one-month-old roselle plants. Mycelium of RIJAM3 isolate was inserted into the base of the stem with a sterile toothpick. As a control, a sterile toothpick with no mycelium was inserted in ten healthy plants. Additionally, 50 eight-day-old seedlings were inoculated by placing a 5-mm diameter agar plug colonized with mycelium of RIJAM3 at the base of the stem 10 mm below the soil surface. As control treatments, uncolonized PDA plugs were deposited at the base of 25 seedlings. The inoculated plants were incubated in a greenhouse with an average temperature and relative humidity of 28°C and 85%, respectively. Following inoculation, symptoms similar to those observed in the original outbreak were observed in plants after six days and only after four days in seedlings. In both experiments, the control plants and seedlings remained asymptomatic. R. solani was re-isolated from plants and seedlings, complying with Koch's postulates. The pathogenicity testing was repeated twice, with concordant results. In Nigeria and Malaysia R. solani was reported to seedling death to cause seedling dieback in roselle (Adeniji 1970; Eslaminejad and Zakaria 2011). In México R. solani AG-4 has been previously reported in crops of potato, chili and tomato (Montero-Tavera et al. 2013; Ortega-Acosta et al. 2022; Virgen-Calleros et al. 2000). To the best of our knowledge, this is the first report of R. solani AG-4 HG-I as a causing of root and basal stem rot on roselle in Mexico. This research provides information essential for informing the management of this disease, and may help design measures to prevent the spread of the pathogen to other regions.

Optimization of Ultrasound Assisted Extraction (UAE) Conditions on Vitamin C from Roselle Flower

Roselle plant (Hibiscus sabdariffa L.) has many benefits. Vitamin C is an antioxidant in which the human body required. It contains a high amount of vitamin C. However, vitamin C is susceptible to high temperatures. Proper extraction treatment conditions produce optimum vitamin C. This study aims to determine the optimization of vitamin C in rosella flowers. This research uses UAE with Qsonica type – Q500 (500 W, 20 kHz). Extraction treatment conditions control amplitude, time and amount of solvent. The research method used is a laboratory experiment with the RSM (Response Surface Methodology) type CCD (Central Composite Design) approach. The research method was an experimental laboratory using a CCD (Central Composite Design) via RSM (Response Surface Methodology) with an amplitude level from 20% to 50%, a time level from 10 minutes to 20 minutes, and a ratio of the amount of solvent from 140 mL to 260 mL by weight. The results showed that the length of time and the amount of solvent had a significant effect, while the amplitude had no significant effect. The significant quadratic model at p value 0.05 and R2 0.9221 with optimum UAE conditions in the treatment combination of 50 percent amplitude, 20 minutes of time, and 140 ml of solvent resulted in an optimum vitamin C content of 38.76 mg/100g. This research can be used as a reference to determine the value of vitamin C with different amplitude, time, and amount of solvent from the research data.

A Review on Medicinal and Pharmacological Importance of Roselle Hibiscus sabdariffa L

Abstract: Roselle, Hibiscus sabdariffa L. (family Malvaceae) is one of the most important and popular medicinal plants. Roselle is native from India to Malaysia, where it is commonly cultivated, and must have been carried at an early date to Africa. It is known as karkadeh in Asia, Pundi palle in South Asia, isapa in Africa Florida Cranberry in America. Recent researches & studies shown that the use of Roselle plant in medical, food & industrial fields also. It is used in cold &warm drinks, jams & jellies. Its use as emollient, laxative, antioxidant, nutritive, antihypertensive, antifungal agent. Rosella helps in digestion, refreshing, moisturizing & used in treatment of cancer

Improving the BRIS Soil management and practices for growing roselle (Hibiscus sabradiffa L.)

Beach ridges with interspersed swales (BRIS), commonly referred to as BRIS soil or sandy soil, are extensively distributed along the eastern coast of Peninsular Malaysia. Despite the challenging nature of the lowland agricultural soil, characterised by its sandy texture and sterility, agricultural activities on BRIS soils have experienced an upward trend in recent times. The objective of this study was to conduct a literature review on the challenges and possibilities of roselle (Hibiscus sabdariffa L.) growth in the BRIS soil environment. Soil concerns can be classified into three categories: physical, chemical, and biological. The soil in BRIS is characterised by its acidic nature and low CEC values, with sand content occasionally reaching as high as 95 percent. Significant challenges associated with sandy soil conditions encompass soil water repellency (SWR), soil compaction, surface crust formation, soil erosion, low fertility, and Cation Exchange Capacity (CEC) value, as well as nutrient leaching into the groundwater, leading to pollution. The roselle plant is currently being commercially cultivated in the state of Terengganu as a substitute for tobacco in BRIS soil. This is due to the plant's exceptional aeration and deep root zone. However, owing to its diminished fertility, its output is restricted. This book concentrates on the challenges related to BRIS soil and environmental concerns, including issues such as inadequate nutrient levels, weak soil structure, and excessive drainage. This review comprehensively elucidates the management strategies for sandy soil in the context of agricultural operations and evolving climatic conditions, thereby contributing to the advancement of research on the prospective cultivation of roselle.

Integrated Action of Rhizobacteria with Aloe vera and Moringa Leaf Extracts Improves Defense Mechanisms in Hibiscus sabdariffa L. Cultivated in Saline Soil.

Osmotic stress is a serious physiological disorder that affects water movement within the cell membranes. Osmotic stress adversely affects agricultural production and sustainability and is largely caused by soil salinity and water stress. An integrated nitrogen-fixing bacteria (NFB) soil amendment and an exogenous foliar application of Aloe vera leaf extract (ALE), and moringa leaf extract (MLE) were evaluated on roselle (Hibiscus sabdariffa L.) growth, calyx yield, secondary metabolites, and tolerance to osmotic stress in salt-affected soil. The osmotic stress markedly decreased above- and below-ground development of the roselle plant, but integrated NFB soil amendment with ALE or MLE foliar application significantly alleviated its negative impacts. Broadly, an improvement was observed in chlorophyll, carbohydrates, and protein levels following NFB and extracts foliar application, as well as a significant enhancement in antioxidant production (total phenols, ascorbic acid, and FRAP), which decreased peroxide production and increased stress tolerance in plants. Under osmotic stress, the roselle calyx revealed the highest anthocyanin levels, which declined following NFB soil amendment and foliar extract application. Additionally, an enhancement in nitrogen (N), phosphorus (P), and potassium (K) contents and the K/Na ratio, along with a depression in sodium (Na) content, was noticed. The integrated application of Azospirillum lipoferum × ALE exhibited the best results in terms of enhancing above- and below-ground growth, calyx yield, secondary metabolites, and tolerance to osmotic stress of the roselle plants cultivated in the salt-affected soil.

Comparative Analysis of Water Extracts from Roselle (Hibiscus sabdariffa L.) Plants and Callus Cells: Constituents, Effects on Human Skin Cells, and Transcriptome Profiles

Roselle (Hibiscus sabdariffa L.) is a plant that has traditionally been used in various food and beverage products. Here, we investigated the potential of water extracts derived from Roselle leaves and callus cells for cosmetic and pharmaceutical purposes. We generated calluses from Roselle leaves and produced two different water extracts through heat extraction, which we named Hibiscus sabdariffa plant extract (HSPE) and Hibiscus sabdariffa callus extract (HSCE). HPLC analysis showed that the two extracts have different components, with nucleic acids and metabolites such as phenylalanine and tryptophan being the most common components in both extracts. In vitro assays demonstrated that HSCE has strong anti-melanogenic effects and functions for skin barrier and antioxidant activity. Transcriptome profiling of human skin cells treated with HSPE and HSCE showed significant differences, with HSPE having more effects on human skin cells. Up-regulated genes by HSPE function in angiogenesis, the oxidation-reduction process, and glycolysis, while up-regulated genes by HSCE encode ribosome proteins and IFI6, functioning in the healing of radiation-injured skin cells. Therefore, we suggest that the two extracts from Roselle should be applied differently for cosmetics and pharmaceutical purposes. Our findings demonstrate the potential of Roselle extracts as a natural source for skincare products.

Ultrasound application for the decontamination of roselle (Hibiscus sabdariffa L.) seeds: Influence on fungal inhibition and seed quality

Seed decay is a major problem caused by pathogens that adversely affect seed yield and quality in agricultural production. Herein, the effect of 28 KHz ultrasound treatment for 20, 40 and 60 min and 1.5% sodium hypochlorite solution for 20 min was assessed for the decontamination of roselle (Hibiscus sabdariffa L.) seeds. In addition, seed germination indices, seedling growth traits, total phenolic content and the activity of defense-related enzymes, viz. peroxidase, superoxide dismutase, catalase and malondialdehyde were measured in the treated seeds. An isolate of Fusarium solani was obtained from roselle seeds and identified as the causal agent of roselle seed rot based on morphological and molecular characteristics. After six days of seed storage, the microbial infection caused the highest seed rot in the control seeds on the average of 56.67%, whereas ultrasound treatment for 60 min could remarkably reduce the seed decay by 3.33%. At the end of seed storage, the fungal load showed the highest (7.72 Log CFU ml−1) and lowest (6.99 Log CFU ml−1) rates in the control and ultrasound treatment for 60 min, respectively. Total phenolic content was significantly increased in ultrasound treatment for 60 min compared to control and sodium hypochlorite treatments. Moreover, the activity of peroxidase, superoxide dismutase and catalase was noticeably improved in ultrasound treatment for 60 min. Furthermore, ultrasound treatment did not show any adverse effects on seed germination indices and seedling growth traits of the roselle plants. Overall, ultrasound treatment for 60 min could effectively decrease roselle seed decay and the fungal load without changing seed and seedling quality.

First report of root rot caused by Fusarium solani on roselle in Nanning, Guangxi, China.

Roselle (Hibiscus sabdariffa L.) is an annual herbaceous plant in the Malvaceae family with high anthocyanin and is widely cultivated in Nanning, Guangxi of China due to its economic and nutritional importance. In August 2021, a severe root rot disease with incidence of 42.4% (860 plants in the field) was observed in roselle plants in an open-field crop in Nanning (108°33"E, 22°84"N), Guangxi, China. The roots of the diseased plants were discolored and rotten, and the xylem became black, extending along the main root to the junction of the rhizomes. The above-ground symptoms were leaf yellowing, vascular tissue browning, wilting and death. Three diseased samples were rinsed thoroughly with sterile distilled water, cut with a sterile scalpel into approximately 0.5-cm pieces, surface disinfested with 75% ethanol for one minute, rinsed 3-4 times with sterile water, and finally incubated on potato dextrose agar (PDA) at 28 °C in the dark for 3 days. Emerging colonies were transferred to new PDA two-three times until a single colony was obtained. The aerial mycelium was initially white, turning pale yellow after 5 days of growth on PDA. Microscopic observations revealed that microconidia were hyaline and ovoid with sizes of 5.13 to 15.12 and 2.50 to 4.20 μm (average 9.02, 3.32 μm, n=30). Macroconidia were falciform with 3- to 4-septate, with sizes of 19.08 to 24.35 and 4.5 to 8.00 μm (average 24.35 and 5.23 μm, n=30). The morphological characteristics of the microscopic images were identical to those described for Fusarium solani (Leslie and Summerell 2006). A representative isolate (GXRST29) was selected for DNA extraction for further characterization. The internal transcribed spacer rRNA regions (ITSs), beta tubulin gene sequence and a fragment of the translation elongation factor 1-alpha (EF 1-α) gene sequence were amplified using the primer pairs ITS1/ITS4 (Chehri 2014), Bt-1/Bt-2 (Wang et al. 2014) and EF1-F/EF2-R (O'Donnell et al. 2010), respectively. PCR products were sequenced and deposited in GenBank (accession Nos. OL314654, ON157430 and ON157431, respectively). BLASTn analysis showed that the ITS sequence had 96.99% homology with sequence of F. solani (NR 163531), and 99.26% for Fusarium cf. solani (MG775565) obtained from Homo sapiens. The beta tubulin sequence had 97.96% similarity with BLAST sequence of F. solani (MN295052.1) and EF 1-α gene had 100% identity to published F. solani (MN977912.1). The fungus was identified as F. solani. Five roselle plants at the 5-leaf stage were artificially inoculated by root dipping into a 106-107-mL-1 spore suspension of the isolated GXRST29 for pathogenicity testing. The experiment was conducted three times, and the negative controls were replaced with sterile water. Compared to the control, the growth of plants was significantly inhibited, leaves turned yellow, plants dwarfed and wilted, and roots decayed three days post-inoculation. One week post-inoculation, all plants exhibited symptoms similar to those observed in the field, and F. solani was steadily reisolated from those diseased plants, while no positive isolations were obtained in the controls. F. solani has been reported to cause root rot on roselle in Upper Egypt (Hassan et al. 2014) and lisianthus in China (Xiao et al. 2018). To our knowledge, however, this is the first report of Fusarium wilt caused by F. solani in roselle plants in Nanning, Guangxi, China, and could result in severe crop losses.

Insight into Green Extraction for Roselle as a Source of Natural Red Pigments: A Review.

Roselle (Hibiscus sabdariffa L.) is a source of anthocyanins as red pigments that is extensively farmed in tropical and subtropical regions, including Indonesia, Malaysia, China, Thailand, Egypt, Mexico, and West India. The roselle plant contains a variety of nutrients, including anthocyanins, organic acids, pectin, etc. Due to the toxicity and combustibility of the solvents, traditional extraction methods for these compounds are restricted. Obtaining pure extracts is typically a lengthy procedure requiring many processes. Supercritical carbon dioxide (ScCO2) extraction as a green technology is rapidly improving and extending its application domains. The advantages of this method are zero waste production, quicker extraction times, and reduced solvent consumption. The ScCO2 extraction of natural pigments has great promise in food, pharmaceuticals, cosmetics, and textiles, among other uses. The ScCO2 technique for natural pigments may also be advantageous in a variety of other contexts. Due to their minimal environmental risk, the high-quality red pigments of roselle rich in anthocyanins extracted using ScCO2 extraction have a high sustainability potential. Therefore, the objective of this review is to increase knowledge related to the natural colorant of roselle as a substitute for chemically manufactured colorants using ScCO2 as a green method. This article covers ScCO2 extraction, particularly as it relates to the optimization of pigments that promote health. This article focuses on the high extraction efficiency of ScCO2 extraction. Natural colorants extracted via ScCO2 are regarded as safe compounds, especially for human consumption, such as novel functional food additives and textile and pharmaceutical colors.

Effects of compost and biofertilizer on carbon dioxide emission, yield, and quality of roselle (Hibiscus sabdariffa L.) plants grown on clay loam

Use of compost and biofertilizer provides nutrients to crops and improves the chemical and physical properties of soils. A pot and incubation experiment was conducted to evaluate the effects of compost and Azotobacter chroococcum and Azospirillum brasiliense as biofertilizer on the carbon dioxide emission, nutrient availability under various incubation periods (0-time, 3, 7, 14, 30, 45, and 60 days) and growth, quality, and yield of roselle plants in pots. The treatments were control (C), compost 14 ton ha−1 (T1) and compost + biofertilizer (T2). Results showed that the soil CO2 flux was increased by 24.38, 33.16, 68.46, 70.17, 62.62, 50.34, and 47.49% over the control for 0-time, 3, 7, 14, 30, 45, and 60-days incubation periods, respectively, at compost + biofertilizer treatments. Available N was increased by increasing incubation period to two months 71.07, 63.67, 63.17, 57.77, 62.57, 57.89, and 58.01%, respectively, under treatment of compost + biofertilizer. The heaviest sepals of fresh and dry weights of sepals were gained by compost + biofertilizer treatment. Total anthocyanin and total flavonol increased by 29.68 and 32.45%, respectively, above the untreated plants. Also, the available N, P, and K content in the soil after the harvesting stage of roselle plants increased by 174.85, 178.24, and 50.96%, respectively, using compost with bio fertilizer treatment. Compost application with biofertilizer may, therefore, be a good strategy for increased to nutrient availability, growth parameter, and yield.

Alleviating the adverse effects of salinity on Roselle plants by green synthesized nanoparticles

In the present study, an eco-friendly process was made for the rapid synthesis of silver nanoparticles using aqueous leaf extract of Hibiscus sabdariffa. The process was characterized by Fourier Transform Infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–visible and X-ray diffraction (XRD). These green silver nanoparticles (NPs) were used for mitigating the adverse effects of salinity on seed germination and growth parameters in plants. Accordingly, two experiments were conducted. In the first experiment, seven concentrations of green silver NPs and nine levels of NaCl:CaCl were apptoed on seeds for germination, and their effects were evaluated. In the second experiment, three concentrations of green silver NPs and NaCl were hypothesized to affect plant growth parameters. Seed germination, plant height, leaf, and root fresh and dry weights, as well as relative water content (RWC), decreased significantly under salt stress. However, green silver NPs intervened by alleviating the adverse effects of stress. Accordingly, green silver NPs were beneficial due to (1) activation of the antioxidant system by enhancing antioxidant enzymes such as catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), and superoxide dismutase (SOD); (2) increase in the amounts of proline, soluble sugars and carbohydrates for osmoprotection; (3) improvements in flavonoid and anthocyanin contents. Real-time PCR showed that flavonoid and anthocyanin contents increased because of higher expressions in chalcone synthase (CHS), flavanone 3‐hydroxylase (F3H), and anthocyanidin synthase (ANS) genes. In conclusion, green silver NPs offered an eco-friendly application for further research on agricultural development.

Compost and Non-Symbiotic Nitrogen Fixers to Reduce Inorganic-N Rates for Roselle (Hibiscus sabdariffa L.)

ABSTRACT Organic and biofertilizers can be good tools in increasing plant growth and yield without negative impacts in environmental ecosystem. Compost and non-symbiotic nitrogen fixers were used in a pot experiment to reduce inorganic nitrogen (N) rates for roselle. The experiment consisted of five treatments i.e. C = without any N fertilization, T1 = 100% of recommended N does from urea, T2 = 100% of N from compost (2.5% N) at a rate of 12 ton ha −1, T3 = 75% of inorganic N + 3 ton ha −1 of compost, and T4 = 50% of inorganic N + 6 ton ha −1 compost. The compost and biofertilization increased the soil quality and enhanced the synthesis of chlorophyll and nutrients uptake by roselle plants compared to the full inorganic N fertilization. Nitrogen use efficiency (NUE) affected significantly (p < 0.05) by the compost and biofertilization. The maximum NUE (58%) was recoded in the treatments received 75% of inorganic N + 3 ton ha −1 of compost. The mixtures of compost and inorganic N fertilization under the biofertilization gave the highest values of the total anthocyanin and total flavonol in the sepals of roselle plants. The maximum dry weight of sepals was obtained from the T4. T4 improved growth, yield, and quality of sepals in comparison with the full inorganic N fertilization. The inorganic N rates for roselle can be reduced by 50% by the application of 6 ton ha −1 of compost and the inoculation with bio-fertilizer containing a mixture of Azotobacter and Azospirillum.

The Effects of Various Drying Techniques on Physicochemical and Nutritional Qualities of (Hibiscus sabdariffa L.) Roselle Calyx

The calyx of the roselle plant (Hibiscus sabdariffa L.) has been extensively studied for its anthocyanins. Roselle calyces are exceedingly perishable, making the process of drying and extracting them without sacrificing quality quite difficult. Similarly, there are several commercial drying procedures available, each with its own set of benefits and drawbacks on nutritional and physicochemical qualities in the final product. The goal of this study was to examine the effects of sun, oven and freeze drying on the physicochemical and nutritional properties of roselle calyx. The antioxidant (%RSA), total anthocyanin content (TAC) and their HPLC identification, physicochemical as well as proximate composition were determined. The results showed that freeze drying increased the drying rate significantly and retained the antioxidant activity (32 mg/100 g QE) then fresh calyx, sun and oven drying, freeze-dried calyx also have higher TAC (176.9 mg/l) than sun and oven dried calyx, the HPLC analysis revealed two anthocyanidin cyanidine glucoside and cyanidin glucoside. phytochemicals and proximate of roselle calyces were higher in freeze-dried than oven and sun drying techniques employed. The findings demonstrated that freeze drying the roselle calyces preserve their quality characteristics.

Preliminary Survey of Parasitism of Leaf Roller, Sylepta derogata (Fabricius) (Lepidoptera: Pyralidae) in Roselle (Hibiscus sabdariffa L. (Malvales: Malvaceae) in Maiduguri, Nigeria

This study was carried out in Maiduguri in north eastern Nigeria during the cropping seasons of 2018 and 2019 to determine the seasonal infestation rate, larval abundance and parasitism of Syleptaderogata (Fabricius) (Lepidoptera: Pyralidae) in roselle, Hibiscus sabdariffaL. Data collection was from 30 farmer fields planted with roselle plants. Data on plant infestation, pest abundance and parasitism were analyzed using Kruskal-Wallis test. Mean percent plant infestation by S. derogataper farmers’ field ranged from 84% in 2019 to 88% in 2018, and was not significantly different between years. Mean number of S. derogata larvae per farmers’ field was significantly higher in 2018 (83) than in 2019 (69). In both years, parasitization by microgastrinae was high (97%-98%), whilst that by Bracon sp. was low (2%-3%). Mean total larval parasitism per farmers’ field significantly varied between years, and was particularly higher (18%) in 2018 than in 2019 (5%). In conclusion, results indicate that S. derogata is seasonally responsible for heavy infestation of roselle plants in parts of north eastern Nigeria. Microgastrinae accounts for a high proportion of host parasitization, whilst that by Bracon sp. is negligible. Total larval parasitism is seasonally low, and insufficient to control this pest in roselle grown in this locality.