Roselle Plants Research Articles

Combined Effect of Prickly Pear Waste Biochar and Azolla on Soil Fertility, Growth, and Yield of Roselle (Hibiscus sabdariffa L.) Plants

Although the use of biochar to promote plant growth has been reported by many researchers, the combined effect of prickly pear waste biochar (BC) and Azolla (AZ) in a field experiment on the roselle plants did yet receive attention. Therefore, the study aims to evaluate the effect of biochar and Azolla extract on the growth, production, and quality of roselle plants. The experiment treatments were in a completely randomized block design with three replicates. Biochar was added at rates of 0, 10, and 20 ton ha−1 and AZ was applied at rates of 0, 3, and 6% in addition to a control treatment. Biochar added at high rate (20 ton ha−1) significantly increased the fresh and dry weights of sepals by 27.98 and 35.73%, respectively, compared to the control. The corresponding values were significantly increased by 11.89 and 11.85% over the control when Azolla was added at rate of 6%. The interaction effect of both BC and AZ treatments at high rate significantly increased the fresh and dry weight of sepals by 47.16 and 60.59%, respectively, compared to the control. The interaction effect of BC and AZ realized significant effect on soil properties, growth and yield, as well as pigments of roselle plants. This is a good evident means that BC and AZ applications separately or combined are considered promising materials for sustainable organic agriculture and safety food.

Determining the production function and optimal irrigation depth of Roselle in deficit irrigation conditions and using potassium fertilizer

The limitations of water resources in supplying the demands of consumer sectors including drinking, hygiene and healthcare, agriculture, industry, as well as environment well reflect the importance of proper use of water. Thus, it is essential to choose an optimal and superior strategy to use water under water deficit conditions. This experiment was implemented as split plot in a fully randomized block design in a research farm in the southeast of Iran on Roselle plant. The experimental treatments included three levels of potassium fertilizer 75 t ha−1 (K1), 112.5 t ha−1 (K2), and 150 t/ha (K3) (equivalent to 50%, 75%, and 100% of potassium fertilizer requierment) and four levels of irrigation water including 40%, 60%, 80%, and 100% of the plant water requierment (l1, l2, l3, and l4). The main aim of the research was to estimate the production function as well as to calculate the index and optimal depths of consumed water. Regression analyses were done by linear, Cobb-Douglas, Quadratic and Transcendental functional forms of Roselle production. The final production indicators in relation to the water depth and potassium fertilizer, the final rate of technical substitution for potassium fertilizer and water depth, and the final production value in relation to water depth and potassium fertilizer were calculated. The results indicated that the Quadratic function was chosen as the superior function. The final production index in relation to the minimum water depth was 1.4 and for maximum water depth was − 0.86 kg cm−1 of water depth. The final production index in relation to the minimum and maximum potassium fertilizer was calculated as 3.92 and 1.77 kg respectively. The results also showed that by applying deficit irrigation under water constraint conditions, the optimal depths of consumed water in relation to the maximum depth at 75, 112.5 and 150 kg levels of potassium fertilizer per hectare had 13.29, 14.34, and 13.1 cm reduction of water consumption respectively. As can be seen, elevation of potassium fertilizer up to 75% resulted in more saving of water consumption. Use of potassium fertilizer can modify the damages resulting from drought stress in Roselle.

Microwave Assisted Synthesis of Antimicrobial Nano-Films from Water Hyacinth <i>(Eichhornia crassipes)</i> and Roselle <i>(Hibiscus sabdariffa</i>) Plant Extract

Cellulose based nanofilms have large applications in biomedical and related fields due to their antimicrobial properties. Their applicability depends upon purity of cellulose, composition, and structural properties of films. The nanofilms of cellulose extracted from Water Hyacinth (Eichhornia crassipes) and Roselle (Hibiscus Sabdariffa) plant possesses excellent properties for biomedical applications due to their biological origin and ZnO or other metal loading properties. Microwave assisted physical separation of cellulose provided excellent films formation properties and ZnO loading compared without any chemical traces. The presence of chemical impurities to affects structural, morphological properties and contact angle. It affects the biomedical applicability of cellulose based films. The microwave-based extraction was further assisted by use of polyethylene glycol with molecular weight 600, which increases the solubility and extractability of cellulose to 90 %. Formed films showed higher contact angle and hydrophobicity. This increased hydrophobicity of cellulosic nanofilms showed enhanced antimicrobial activities towards gram-negative and gram-positive bacteria by water hyacinth nanofilms. Thus, microwave-based synthesis of cellulose nanofilms resulted into enhanced microbial activities.

Using of blue green algae extract and salicylic acid to mitigate heat stress on roselle (Hibiscus sabdariffa L.) plant under Siwa Oasis conditions

Increasing temperature is a global issue due to the existing climate change problem that reduces agricultural productivity and increases prices. It badly affects the yield, and active constituents of medicinal and aromatic plants, especially in newly reclaimed lands in desert areas. The Hibiscus sabdariffa L. is a remarkable crop known for its calyces to make a refreshing drink. It is in other food industries and has many healing effects. A split-plot field experiment was conducted on Hibiscus sabdariffa L. at Siwa Oasis, Egypt, during the 2018 and 2019 seasons for studying to reduce the harmful effect of heat stress on plants and yield improvement. Spraying with three salicylic acid concentrations was put to main plots as 0, 500, and 1000 mg/l and the number of sprays with Spirulina platensis algae extract was allotted to sub-plots and used as 0, 1 and 2 times in the season. Some quantity and quality parameters were under investigation. The significant highest increases in dry weight per plant, number of fruits per plant, dry yield of sepals per hectare and sepal's anthocyanin content were from the combination among spraying with salicylic acid at the concentration of 500 mg/l and spraying with blue green algae extract twice through the season. This treatment was helpful to decrease the high-temperature injury on growth through the summer months.

Effect of fulvic acid and chitosan in the growth of Roselle plants, Hibiscus sabdarrifa L and their nutrient content

Effect of fulvic acid and chitosan in the growth of Roselle plants, Hibiscus sabdarrifa L and their nutrient content

Improvement of Selected Morphological, Physiological, and Biochemical Parameters of Roselle (Hibiscus sabdariffa L.) Grown under Different Salinity Levels Using Potassium Silicate and Aloe saponaria Extract.

Two successive field trials were carried out at the experimental farm of the Agriculture Department of Fayoum University, Fayoum, Egypt, to investigate the sole or dual interaction effect of applying a foliar spray of Aloe saponaria extract (Ae) or potassium silicate (KSi) on reducing the stressful salinity impacts on the development, yield, and features of roselle (Hibiscus sabdariffa L.) plants. Both Ae or KSi were used at three rates: 0% (0 cm3 L−1), 0.5% (5 cm3 L−1), and 1% (10 cm3 L−1) and 0, 30, and 60 g L−1, respectively. Three rates of salinity, measured by the electrical conductivity of a saturated soil extract (ECe), were also used: normal soil (ECe < 4 dS/m) (S1); moderately-saline soil (ECe: 4–8 dS/m) (S2); and highly-saline soil (ECe: 8–16 dS/m) (S3). The lowest level of salinity yielded the highest levels of all traits except for pH, chloride, and sodium. Ae at 0.5% increased the values of total soluble sugars, total free amino acids, potassium, anthocyanin, a single-photon avalanche diode, stem diameter, fruit number, and fresh weight, whereas 1% of Ae resulted in the highest plant height, chlorophyll fluorescence (Fv/Fm), performance index, relative water content, membrane stability index, proline, total soluble sugars, and acidity. KSi either at 30 or 60 g L−1 greatly increased these abovementioned attributes. Fruit number and fruit fresh weight per plant also increased significantly with the combination of Ae at 1% and KSi at 30 g L−1 under normal soil conditions.

Foliar spray of potassium silicate, aloe extract composite and their effect on growth and yielding capacity of roselle (Hibiscus sabdariffa L.) under water deficit stress conditions

Plants face various abiotic stresses such as drought and salinity during growing stages adversely affect their physiological and biological processes. The use of bioactive compounds could mitigate the detrimental effects of abiotic stresses. The experimental layout was a split split-plot system based on a randomized complete block design with three replications. The treatments included three levels of potassium silicate (0, 3, and 6 cm L-1 or 0, 12, and 24 l-1 of K2SiO3 ha−1) combined with three levels of Aloe saponaria L. extract (Ae) 0, 0.5, and 1% under two levels of irrigation regimes (IR70 and IR100; representing irrigation at 70 and 100% of crop evapotranspiration). The obtained results revealed that control roselle plants were adversely affected by drought, which recorded the lowest growth and yield parameters. Meanwhile, the exogenous addition of Ae and KSi significantly improved the growth and yield of deficit and full irrigated roselle plants. The foliar application of Ae (1%) and KSi (3 or 6 cm L-1) under full irrigation led to a significant increase in growth and yield parameters of roselle. In addition, considerable enhancements in yield quality of roselle plants under deficit irrigation were recorded.

First report of Agrobacterium tumefaciens causing crown gall disease of roselle (Hibiscus sabdariffa L.) in Taiwan.

Roselle (Hibiscus sabdariffa L.) plants, whose calyces are used for production of beverages or jams, are mainly cultivated in Taitung County of eastern Taiwan. Since 2016, large crown galls were observed on the roselle plants in the commercial plantations at Taimali and Jinfong Townships of Taitung County. A follow-up survey in July and August of 2017 revealed spreading of this disease to the neighboring areas including Beinan and Dawu Townships. Disease incidence was estimated to be 0.6-10%. Galls of varying sizes (2-15 cm in diameter) were usually found on the roots and crowns of the roselle plants, starting with small swellings at the infection sites. Galls were light-colored, and smooth and tender in texture at the early stage, but later turned dark-colored, and appeared rough and woody. In some cases, adventitious roots extruding from the larger crown galls could be seen. Isolation of the causal agent was performed by quadrantally streaking bacterial suspension made from surface-sterilized, macerated galls on trypticase soy agar (TSA). After incubating at 28°C for 5 days, single colonies were transferred onto new TSA plates for further cultivation at 28°C. Finally, circular, convex, viscous and milky white colonies with smooth surface similar to colony morphology of Agrobacterium tumefaciens C58 were obtained for further identification. First, all six candidate isolates (TZ-1, TL1-2, TL2-1, TD1-1, TD1-24 and TD2-1) were identified as Agrobacterium spp. using the partial sequences of the 16S rRNA gene (accession numbers MW205820 to MW205825 in the GenBank database). The selected isolates also showed some biochemical and physiological characteristics similar to A. tumefaciens, including oxidase positive, growth at 35°C and in 2% NaCl, and alkalinity from litmus milk. Moreover, they were tested negative for utilization of citrate and acid production on potato dextrose agar (PDA) supplemented with calcium carbonate. Under a transmission electron microscope, the bacterium was rod-shaped and possessed peritrichous flagella. By means of multiplex PCR using primers designed for differentiation of Agrobacterium rubi, Agrobacterium vitis and Agrobacterium biovars 1 and 2, a 184 bp product was detected in all six isolates, indicating that they all belong to Agrobacterium biovar 1. Furthermore, the recA allele of each isolate was PCR amplified using primers F2898/F2899, and recA sequence analysis assigned all six isolates to A. tumefaciens genomospecies G7 (GenBank accession numbers MZ570905-MZ570910). Pathogenicity assay was carried out by inoculating the stems of 2-week-old roselle seedlings through wounds made with a sterile needle with bacteria on it. The inoculated seedlings were kept in plastic bags to maintain high humidity. Symptoms similar to those observed in the field developed at the inoculation sites after 7 days, and Koch's postulates were fulfilled when the bacteria re-isolated from the galls were also identified as A. tumefaciens genomospecies G7 using recA gene sequence analysis. To our knowledge, this is the first report of crown gall disease caused by A. tumefaciens on Hibiscus sabdariffa in Taiwan. This disease may potentially damage the roselle industry if no action is taken to stop its spreading. Identification of the causal agent of roselle crown gall disease could help us further investigate its ecology and develop integrated pest management strategies for prevention of this disease in the future.

Influence of sulphur,potassium humate and their interactions on growth, flowering and chemical constituents of roselle plant (Hibiscus sabdariffa)

Influence of sulphur,potassium humate and their interactions on growth, flowering and chemical constituents of roselle plant (Hibiscus sabdariffa)

Roselle Plant Pigments As Natural Photosensitizers For Dye Sensitized Solar Cells: the Effect of Tin Oxide Blocking Layer on the Photoelectric Properties.

Dye sensitized solar cells (DSSCs) assembled on titanium dioxide (TiO2) synthesized with plant dye extracted from dried Roselle plant pigments were fabricated. The dye extract and active layers were characterized using a (UV 752) ultraviolet-visible-Near Infra-Red (UV-VIS-NI) spectrophotometer, at the wavelength interval of 250 nm to 1100 nm, while the Tauc model was used to obtain the optical band gap. The absorption coefficient and behaviour of the extinction coefficient was investigated. The current and voltage features of the dye sensitized solar cell fabricated with the synthesized TiO2 Photoanode were analysed. The optical band gap of the dye sensitized solar cells fabricated were 2.6eV, 2.8eV and 3.0 eV respectively, while the conversion efficiency of the dye sensitized solar cells was 1.34%, 1.32% and 2.9%.

Phytochemical Properties of Roselle (&lt;i&gt;Hibiscus sabdariffa,&lt;/i&gt; L.) Plants Grown under Bio and Mineral Fertilizers in Different Types of Soil

The aim of this study was to clarify the phytochemical property evaluation of Roselle plants grown under bio Azotobacterine (Azotobacterchroococcum) and phosphorein (Bacillus polymyxa) and mineral (N, P and K fertilizers at the rates of 25, 50 and 100% from the doses recommended by Ministry of Agriculture) fertilizers applied in different types of soil. Samples of Roselle plants were obtained from different soils (clay soil at Dar El-Ramad farm, sandy loam and saline loamy sand soil at Demo farm, Faculty of Agriculture) at El-Fayoum governorate conditions. Moreover, some of the phytochemical properties (N, P and K percentage in roselle herb and its uptake, photosynthetic pigments (chlorophyll A, chlorophyll B and carotenoids), anthocyanin pigment and pH value) of roselle plants (Hibiscus sabdariffa, L.) under different soils were determined. The data obtained showed that, bio and mineral (NPK) fertilizers increased the above compositions of roselle plants under different soils of experiment. The maximum increase of these compositions was obtained by the treatment clay soil × 100% NPK + bio fertilizers, followed by clay soil × 50% NPK + bio fertilizers as compared to saline loamy sand soil × non fertilizer treatment, although, the differences between these treatments and mineral fertilizer at the rate of 100% NPK alone were insignificantly. Therefore, it is economically and environmentally recommended to inoculate roselle seeds with mixture of Azotobacter + Bacillus and fertilize these inoculated plants with 50% NPK for improve chemical compositions (N, P and K percentage in roselle herb and its uptake, photosynthetic pigments (chlorophyll A, chlorophyll B and carotenoids), anthocyanin pigment and pH value) of roselle plants under clay soil. Key words: Roselle, Hibiscus sabdariffa L., nitrogen, phosphorus, potassium, biofertilization, soil type, salinity, chemical composition.

Phytochemical Properties of Roselle (&lt;i&gt;Hibiscus sabdariffa,&lt;/i&gt; L.) Plants Grown under Bio and Mineral Fertilizers in Different Types of Soil

The aim of this study was to clarify the phytochemical property evaluation of Roselle plants grown under bio Azotobacterine (Azotobacterchroococcum) and phosphorein (Bacillus polymyxa) and mineral (N, P and K fertilizers at the rates of 25, 50 and 100% from the doses recommended by Ministry of Agriculture) fertilizers applied in different types of soil. Samples of Roselle plants were obtained from different soils (clay soil at Dar El-Ramad farm, sandy loam and saline loamy sand soil at Demo farm, Faculty of Agriculture) at El-Fayoum governorate conditions. Moreover, some of the phytochemical properties (N, P and K percentage in roselle herb and its uptake, photosynthetic pigments (chlorophyll A, chlorophyll B and carotenoids), anthocyanin pigment and pH value) of roselle plants (Hibiscus sabdariffa, L.) under different soils were determined. The data obtained showed that, bio and mineral (NPK) fertilizers increased the above compositions of roselle plants under different soils of experiment. The maximum increase of these compositions was obtained by the treatment clay soil × 100% NPK + bio fertilizers, followed by clay soil × 50% NPK + bio fertilizers as compared to saline loamy sand soil × non fertilizer treatment, although, the differences between these treatments and mineral fertilizer at the rate of 100% NPK alone were insignificantly. Therefore, it is economically and environmentally recommended to inoculate roselle seeds with mixture of Azotobacter + Bacillus and fertilize these inoculated plants with 50% NPK for improve chemical compositions (N, P and K percentage in roselle herb and its uptake, photosynthetic pigments (chlorophyll A, chlorophyll B and carotenoids), anthocyanin pigment and pH value) of roselle plants under clay soil. Key words: Roselle, Hibiscus sabdariffa L., nitrogen, phosphorus, potassium, biofertilization, soil type, salinity, chemical composition.

Effect of different concentrations of IAA, GA3 and chitosan nano-fiber on physio-morphological characteristics and metabolite contents in roselle (Hibiscus sabdariffa L.)

The roselle (Hibiscus sabdariffa L., Malvaceae) is one of the most widely used medicinal plants due to its economic importance and high bioactive compounds. In the present study, the effects of two exogenous plant growth regulators (PGRs), [gibberellic acid (GA3) and Indole-3-scetic acid (IAA) at 400, 800 and 1200 mg L−1], along with chitosan-based nanofiber (CNF, at 50, 100 and 200 mg L−1) were investigated, individually and in combination, on plant height, calyx fresh and dry weights, number of flowers, total chlorophyll and ß-carotene, soluble sugar, anthocyanin, vitamin C, total polyphenols and flavonoids as well as antioxidant capacity in roselle plants. According to the results, a synergistic effect was observed between employed PGRs. Of interest, CNF was observed inside the calyxes using scanning electron microscopy (SEM) technique. Because of its unique physio-chemical properties, CNF further influenced the PGRs function on most of the traits evaluated. It was found that the combined use of IAA and GA3 could improve plant height, number of calyxes per plant, total chlorophyll, β-carotene, flavonoids and antioxidant activity in roselle. Furthermore, the results clearly demonstrated that PGRs in combination with CNF have a significant impact on various growth parameters in roselle plant. The present results suggest that the use of combined IAA+GA3+CNF (at 800 + 800 + 100 mg L−1) stimulate both growth parameters and health-promoting phytochemicals content in roselle plants.

Cattle manure and bio-nourishing royal jelly as alternatives to chemical fertilizers: Potential for sustainable production of organic Hibiscus sabdariffa L.

For sustainable and organic farming, organic manures such as cattle manure (CMn) and bio-nutritious substances such as royal jelly (RJ) should be used as complete or at least partial alternatives to chemical fertilizers (CFs). Therefore, two consecutive trial seasons (2018 and 2019) were conducted to study the effect of soil fertilization with CMn and/or CFs in combination with foliar spraying with RJ on growth, yield, and chemical composition of roselle (Hibiscus sabdariffa L.) plant and seed. The results indicated that spraying roselle plants with RJ resulted in a significant increase in all parameters studied over the control; however, this increase was enhanced when RJ was combined with soil fertilization. The highest values for most of the growth traits, chemical composition of seeds, sepal anthocyanin and vitamin C contents, and sepal acidity were obtained by applying 2 or 4 g RJ L−1 + (30 m3 CMn ha−1 + 50 % dose CFs). In addition, the highest values for yield components and plant chemical composition were obtained by applying 2 or 4 g RJ L−1 + (0 m3 CMn ha−1 + full dose CFs). The results also indicated that applying CMn in combination with RJ gave values mostly close to those of CFs treatment. In conclusion, the results recommend the use of RJ (2 g L−1 as a foliar feeding) along with CMn (30 m3 ha−1) as a partial alternative to chemical fertilizers for sustainably producing healthy roselle sepals.

Growth, yield, and quality of roselle (Hibiscus sabdariffa L.) plants as affected by nano zinc and bio-stimulant treatments

Growth, yield, and quality of roselle (Hibiscus sabdariffa L.) plants as affected by nano zinc and bio-stimulant treatments

Effect of Pinching Date and Potassium Fertilizer rate on Growth and Productivity of Roselle (Hibiscus sabdariffa, L.) Plant

To enhance growth and productivity of roselle plant, two field experiments were done during the two consecutive summer season of 2019 and 2020 at Experimental Farm (Ghazala Farm), Faculty of Agriculture, Zagazig University, Egypt. This study included different pinching time treatments (after 4, 6, 8 and 12 weeks from sowing date) as the main factor and potassium fertilization rate (0.0, 25, 50 and 75 kg K2O/ feddan) as sub-factor as well as their combinations to improve growth, yield, anthocyanin content and some chemical contents of Hibiscus sabbdariffa plant. Results could be summarized as follow: The longest roselle plants were recorded with the control treatment (pinched after 4 weeks from sowing date), whereas pinching after 12 weeks from sowing date increased number of branches/plant. Also, apical bud pinching after 12 weeks from sowing date recorded the highest number of fruits per plant, dry sepals yield/plant and per feddan. Delaying pinching date from 4 to 8 weeks gradually increased anthocyanin content. In addition, total chlorophyll content as well as total carbohydrates, total nitrogen, total phosphorus and potassium percentages were increased with delaying pinching date especially after 12 weeks, in most cases. Potassium fertilization rate at 75 kg per feddan recorded the highest values of growth, yield components and the chemical constituents with significant differences between this rate and the other rates under study. Generally, the combination treatment between pinching after 12 weeks from sowing date and 75 kg potassium fertilization rate had significant effect in most parameters compared to the other combination treatments during both seasons.

Effect of Some Microorganisms on Controlling Fusarium Wilt of Roselle (Hibiscus sabdariffa L.)

Roselle (Hibiscus sabdariffa L.) is one of the most crucial medicinal plants all over the world. The present study was carried out with the intention of solving some problems related to soil-borne diseases. Fusarium oxysporum is associated with wilt disease of roselle plant. The application of some microbiota i.e., a mixture of Pseudomonas fluorescens (PSR-11), Bacillus subtilis (BSR-8), Pleurotus ostreatus and mycorrhizeen® individually or in combination were investigated for controlling wilt disease, growth, and yield of roselle plant. The study was conducted in sandy textured soil under sprinkler irrigation of Ismailia Agricultural Research Station, Ismailia, Egypt. Under greenhouse conditions, all the tested bioagents reduced wilt incidence and increased the percentage of survived plants. The conglomeration of the bacterial mixture of Pseudomonas fluorescens and Bacillus subtilis, Pleurotus ostreatus and mycorrhizeen® was more effective in controlling wilt disease than using any of them individually. The application of the investigated bioagents showed a significant increase in phenol, photosynthetic pigments, and dehydrogenase contents, as well as root colonization percent. The obtained results showed the ability of B. subtilis and P. fluorescens to produce lytic enzymes such as β-1-3 glucanase, β-1-4 glucanase, chitinase and protease, in addition to their production of siderophore and HCN. The consortium of all microbiota gave the best results for growth and yield parameters of roselle plant.

Response Surface Regression with LTS and MM-Estimator to Overcome Outliers on Red Roselle Flowers

The surface response method is similar to the regression analysis method which uses procedures or ways of estimating the response function regression model based on the Ordinary Least Square (OLS) method. Unfortunately, using the quadratic method has no drawbacks because it is easily sensitive to assumption deviations due to outlier cases. One of the solutions to the outlier problem is using robust regression. The method of parameters in the regression is very diverse, but the methods used in this study are the Least Trimmed Square (LTS) and MM-estimator methods because both methods have a high breakdown point of nearly 50%. The variables studied were the response variable consisting of red roselle plant height (Y1) and red roselle flower weight (Y2). While the independent variables were soil moisture factor (X1) and NPK fertilizer application factor (X2). The purpose of this study is to estimate the response surface regression parameters. using the LTS and MM-estimator methods on data that contains outliers. The resulting model in data analysis shows the same result that the best model is using the LTS estimation method. The modeling result of plant height obtained an R-Square value of 98,27% with an error is 1,243. Meanwhile, for the red rosella plant flower weight model, the R-Square value was 97,31% with an error is 0.6632.

Biochar and compost enhance soil quality and growth of roselle (Hibiscus sabdariffa L.) under saline conditions

Soil amendments may increase the slate tolerance of plants consequently; it may increase the opportunity of using saline water in agricultural production. In the present pot trial, the effects of biochar (BIC) and compost (COM) on roselle (Hibiscus sabdariffa L.) irrigated with saline water (EC = 7.50 dS m−1) was studied. Roselle plants were amended with biochar (BIC1 and BIC2) or compost (COM1 and COM2) at rates of 1 and 2% (w/w), as well as by a mixture of the two amendments (BIC1+). The experiment included a control soil without any amendments. Biochar and compost significantly enhanced the soil quality and nutrients availability under saline irrigation. Compost and biochar improved the degree of soil aggregation, total soil porosity and soil microbial biomass. BIC1 + COM1 increased the soil microbial biomass carbon and nitrogen over the individual application of each amendments and control soil. BIC1 + COM1 increased the activity of dehydrogenase and phosphatase enzymes. Growth of roselle plants including: plant height, shoot fresh and dry weight, and chlorophyll were significantly responded to the added amendments. The maximum sepal’s yield was achieved from the combined application of compost and biochar. All the investigated treatments caused remarkable increases in the total flavonol and anthocyanin. BIC1 + COM1 increased the total anthocyanin and flavonol by 29 and 17% above the control. Despite the notable improvement in soil and roselle quality as a result of the single addition of compost or biochar, there is a clear superiority due to mixing the two amendments. It can be concluded that mixing of biochar and compost is recommended for roselle plants irrigated with saline water.

IMPACT OF TYROSINE AND GLUTAMINE ACIDS ON YIELD AND SOME CHEMICAL CONSTITUENTS OF HIBISCUS SABDARIFFA PLANTS UNDER DIFFERENT SOWING DATES

Two field experiments were carried out at experimental farm of Faculty of Agriculture, Zagazig University, Egypt, during the two summer consecutive seasons of 2018 and 2019. To study the impact of sowing dates and some amino acids on the roselle (Hibiscus sabdariffa L.) yield in terms of number of fruits per plant, dry sepal’s yield per plant and per feddan as well as its chemical constituents in terms of total chlorophyll (SPAD) and anthocyanin (mg/100g as dry weight) contents. A split-plot experiment was carried out in the field based on a randomized complete block design with three replications. The main plot was four sowing dates (15th April, 1st May, 15th May and 1st June) and the sub-plot was five amino acids treatments (tap water as control, tyrosine and glutamine acids each at 100 or 200 ppm concentrations). The results showed that the early in sowing from June1 to April 15 increased fruit number per plant, dry sepals yield per plant (g) and per feddan (kg) as well as total chlorophyll content and anthocyanin content. Also, all the values of the studied parameters were significantly increased when the roselle plants sprayed with glutamine acid at 200 ppm compared to control. In final, planting roselle seeds in 15th April and sprayed with 200 ppm glutamine four times per season manifests to enhance yield and is adequate for fulfilling the highest anthocyanin contents in sepals of roselle under Sharkia Governorate conditions.