Relative Fresh Weight Research Articles

Prolong the vase life of flower spike of Aster (Symphyotrichum novi-belgii L.) by diphenylamine

ABSTRACT The present study was carried out at Antoniades Research Branch, Horticulture Research Institute, A.R.C. Alexandria, Egypt during the two successive seasons of 2017 and 2018 to study the effects of different concentrations and application methods of Diphenylamine (DPA) on the flower longevity of Aster New York plants (Symphyotrichum novi-belgii). Four concentrations of DPA (0, 25 , 50 and 100 ppm) and three application methods ( pulsing , foliar spray and holding solution ) were used in this experiment . The results showed that the highest significant vase life was obtained after application 50 ppm DPA as pulsing treatment for one hour , this treatment caused the lowest significant loss of flower fresh weight percentage (LFFW %), highest significant flower fresh weight/flower dry weight ratio (FWR), the highest relative fresh weight (RFW ) value and the highest significant reducing sugar content . Moreover, foliar spray treatment of DPA caused the highest significant increase of chlorophyll a and b content along the experiment period.

Methyl Jasmonate Treatment Delays Flower Opening and Petal Wilting of Three Cut Rose Cultivars

Abstract Developing a method for the control of cut flower opening and improvement of cut flower quality is important to meet consumer demand. In this study, we investigated the effects of methyl jasmonate (MeJA) on flower opening of three rose cultivars: ‘Red Star,’ ‘Princes Meg,’ and ‘Madrid’. Shoot bases of cut roses were immersed in water solutions containing 100- or 1000-μM MeJA in addition to 2% weight/volume (w/v) sucrose and 0.02% w/v 8-hydroxyquinoline monohydrate. Subsequently, the vase life, flower opening, petal wilting, petal weight, water uptake, and water evaporation were measured. Flower opening of all three cultivars was clearly delayed following the treatment with MeJA, resulting in prolonged vase life compared with control. In addition, flower wilting was suppressed in all cultivars. Moreover, 7 days following treatment, the petal fresh weight was maintained high in the ‘Red Star’ and ‘Princes Meg’ cultivars. However, there was no significant difference in the ‘Madrid’ cultivar versus control. In all three cultivars, there was a minimal difference in the total amount of water uptake and evaporation. Thus, it is suggested that the total amount of water uptake and evaporation have limited relevance to the changes in the relative fresh weight of cut roses and petal fresh weight observed following treatments. Despite the difference in the sensitivity of the rose cultivars to treatment with MeJA, we conclude that MeJA has high potential as a quality retention agent for cut roses.

Sugarcane Biomass Yield Response to Phosphorus Fertilizer on Four Mineral Soils as Related to Extractable Soil Phosphorus

ABSTRACTThe efficient use of phosphorus (P) fertilizers is very important in South Florida so that the environmental impact is minimal while meeting crop demand. To ensure that this is accomplished, an updated soil test P calibration is needed for sugarcane (Saccharum spp.) grown on Florida mineral soils, which accounts for almost 30% of the total sugarcane planted in the state. An outdoor pot experiment was conducted with the objective of evaluating four soil extractants for potential use in soil test P calibrations. Sugarcane cultivar CL 88–4730 was grown in 26L pots in a randomized complete block design with four replications of four P fertilizer rates (0, 38, 76, and 152 mg P L−1 soil) and four soil series (2 Spodosols, 1 Entisol, and 1 Alfisol). Sugarcane biomass was significantly increased with P fertilizer application and extractable soil P significantly increased with increasing P fertilizer rate. Strongest relationships of extractable soil P with relative fresh weight yield were determined with the water, acetic acid, and ammonium acetate extractants. All extractants tested, including Mehlich 3, had significant relationships with relative yield and leaf P concentration and so all these extractants should be considered in further field calibration studies with sugarcane on Florida mineral soils.Abbreviations: EAA: Everglades Agricultural Area; EREC: Everglades Research and Education Center; OM: organic matter; TSP: Triple superphosphate

Postharvest physiology of cut Gardenia jasminoides flowers

We investigated the postharvest physiology of Gardenia jasminoides, and a range of postharvest treatments that might permit its use as a cut flower. The effects of different vase solution treatments, containing a range of biocides, acidulants, carbohydrate sources and/or growth regulators on the postharvest performance of cut gardenia flowers were studied by measuring water uptake (WU), water loss (WL) and relative fresh weight (RFW) of the flowers during vase life. In deionized (DI) water, gardenia flowers wilted after 2–3 days. Pulse treatment with silver thiosulfate (STS) to inhibit ethylene responses had no effect on vase life. However, abscisic acid (ABA) treatment increased vase life to 5 days by reducing WL and maintaining RFW. Including a cytokinin, benzyl adenine (BA), in the vase solution was the most effective plant growth regulator treatment, doubling vase life to 5.5 days. Vase solutions containing a commercial flower preservative, or combining citric acid, sucrose and aluminum sulfate also doubled the vase life of gardenia flowers. NaOCl in the vase solution provided little benefit, but acidification with aluminum sulfate (AS) or citric acid (CA) increased initial WU and extended vase life. The results suggest that improving water uptake is important for extending the vase life of cut gardenia flowers, and that acidification of the vase solution is an effective tool.

Vase life extension of cut hydrangea (Hydrangea macrophylla) flowers

ABSTRACTThe popularity of cut hydrangea has been increasing in the global floriculture market in recent years. However, vase life of cut hydrangeas is shortened due to sepal browning and wilting. This study was conducted to find out a vase life solution in extending the vase life of cut hydrangea (Hydrangea macrophylla cv. Schneeball) flowers. Cut hydrangea stems were placed in solutions containing 8-hydroxyquinoline sulphate (100, 200 and 300 mgL−1), glycolic acid (9.5, 19 and 28 mgL−1) and distilled water which was used as the control. The vase life, relative fresh weight and solution uptake were measured. Compared to the control, the vase life of cut hydrangeas were significantly increased by all 8-HQS treatments. The best concentration of 8-HQS was 200 mgL−1 and increased the vase life of cut hydrangeas by 11.67 days compared to control (from 4.22. to 15.89 days). It also improved solution uptake and delayed relative fresh weight loss. The results showed that 8-HQS is effective in extending the vase life of cut hydrangeas.

Silica Nanoparticles Enhances Physio-Biochemical Characters and Postharvest Quality of Rosa hybrida L. Cut Flowers

Abstract The effect of silica nanoparticles (SiNPs) preservative solutions on the postharvest quality of rose cut flowers was investigated in this study. SiNPs were used at the concentrations of 0, 1, 2, and 3 mg·dm−3. Treatments of SiNPs increased flower longevity compared to untreated flowers. Relative fresh weight, relative water content, and water uptake were improved because of SiNPs treatments. The enhancement in chlorophyll content, total soluble sugars, as well as total phenol and flavonoid contents were positively correlated with SiNPs treatments. Malondialdehyde (MDA) content significantly increased by control roses relative to treated ones. Activities of peroxidase (POX) and polyphenol oxidase (PPO) enzymes significantly increased because of SiNPs treatments compared to the control. The treatment of 2 mg SiNPs·dm−3 maximized the longevity and improved the postharvest quality of cut roses. The results obtained suggested that SiNPs treatments could improve the longevity and postharvest quality of cut roses by reducing lipid peroxidation and motivating antioxidant machinery, therefore, retaining the membrane integrity.

Association Analysis of Salt Tolerance in Asiatic cotton (Gossypium arboretum) with SNP Markers.

Salinity is not only a major environmental factor which limits plant growth and productivity, but it has also become a worldwide problem. However, little is known about the genetic basis underlying salt tolerance in cotton. This study was carried out to identify marker-trait association signals of seven salt-tolerance-related traits and one salt tolerance index using association analysis for 215 accessions of Asiatic cotton. According to a comprehensive index of salt tolerance (CIST), 215 accessions were mainly categorized into four groups, and 11 accessions with high salinity tolerance were selected for breeding. Genome-wide association studies (GWAS) revealed nine SNP rich regions significantly associated with relative fresh weight (RFW), relative stem length (RSL), relative water content (RWC) and CIST. The nine SNP rich regions analysis revealed 143 polymorphisms that distributed 40 candidate genes and significantly associated with salt tolerance. Notably, two SNP rich regions on chromosome 7 were found to be significantly associated with two salinity related traits, RFW and RSL, by the threshold of −log10P ≥ 6.0, and two candidate genes (Cotton_A_37775 and Cotton_A_35901) related to two key SNPs (Ca7_33607751 and Ca7_77004962) were possibly associated with salt tolerance in G. arboreum. These can provide fundamental information which will be useful for future molecular breeding of cotton, in order to release novel salt tolerant cultivars.

Eucalyptus and Citronella Essential Oils Used in Preservative Solutions Affect the Vase Life of Cut Philodendron Leaves

Cut leaves of Philodendron sp. (philodendron plu jeeb) are often used in bouquets and flower arrangements. Keeping quality is a key criterion for assessing the value of a cut leaf, by growers, traders, and consumers alike. This study set out to determine the influence of the essential oils of Eucalyptus globulus Labill. (eucalyptus) and Cymbopogon nardus Rendle (citronella) on the vase life of cut leaves of the philodendron plu jeeb. Vase life was assessed in terms of relative fresh weight, electrolyte leakage, pigment content, hydrogen peroxide accumulation, and antioxidant activity. Philodendron plu jeeb petioles were treated with preservative vase solutions of distilled water and 12.5 µg·mL-1 eucalyptus essential oil, 25 µg·mL-1 eucalyptus essential oil, 12.5 µg·mL-1 citronella essential oil, and 25 µg·mL-1 citronella essential oil. Cut leaves were held at room temperature (c. 30°C) in daylight and with natural ventilation. Eucalyptus essential oil at 12.5 µg·mL-1 in the vase solution significantly increased leaf vase life and helped maintain relative fresh weight. The essential oils had positive effects on the retention of membrane integrity and antioxidant activity (DPPH radical scavenging assay). They also had inhibitory effects on hydrogen peroxide accumulation and on chlorophyll and carotenoid degradation. The results indicate that 12.5 µg·mL-1 eucalyptus essential oil has potential as a vase-life extender for cut leaves of the philodendron plu jeeb.

Improving the postharvest performance of cut spray ‘Prince’ carnations by vase treatments with nano-silver and sucrose

ABSTRACT The postharvest performance of cut spray-type carnations (Dianthus caryophyllus L.) is often limited by the opening, longevity, and coloration of individual florets, and is apparently related to water stress and sugar deficiency. In this study, we found that, compared with deionised water-treated controls, the vase life of cut spray ‘Prince’ carnations was extended by 2.1–4.6 days when held in vase solutions containing1–5 mg L–1 nano-silver (NS). Moreover, combination treatments with 5 mg L–1 NS and 2%, 3%, or 4% sucrose consistently further prolonged the vase life, prominently promoted floret opening, and increased the bright pink coloration of petals, thereby markedly enhancing quality performance. Overall, the 5 mg L–1 NS plus 3% sucrose treatment provided the longest vase life extension (6.6 days) compared with the control, and significantly increased the anthocyanin content in floret petals. Besides, we also showed that the treatment with 5 mg L–1 NS alone or 5 mg L–1 NS plus 3% sucrose significantly enhanced their vase solution uptake and relative fresh weight. Further, scanning electron microscopy observations revealed that the NS vase treatments evidently alleviated vascular occlusion by inhibiting bacterial colonisation and biofilm formation on their stem-end cut surfaces and in the xylem vessels.

Effects of some preservative solutions on the vase life of cut rose flowers

The vase life of cut rose flowers is generally short due to bent neck and wilting. This study was conducted to determine the effects of different concentrations of citric acid (CA) (100, 200, and 300 mg L(-1)), salicylic acid (SA) (100, 200, and 300 mg L(-1)), succinic acid (SUA) (100, 300, and 500 mg L(-1)), glycolic acid (GA) (76, 152, and 228 mg L(-1)), and benzethonium chloride (BC) (25, 50, and 100 mg L(-1)) on the vase life, relative fresh weight, and water uptake of Rosa hybrida 'Samourai'. Distilled water was used as the control. The results showed that the vase solutions containing 100 mg L(-1) of CA (13.27 days), 100 mg L(-1) of SUA (13.07 days), and 25 mg L(-1) of BC (13.0 days) significantly increased vase life as compared with the control (8.53 days).

Effects of Salicylic Acid and Sucrose Solution on Vase Life of Cut Antigonon leptopus Inflorescences and Their Potential as Cut Flowers for Flower Arrangement

Pink Antigonon leptopus have potential to be commercialized as cut flowers for flower arrangement. In order to determine cut inflorescences' vase life, vase solution treatments containing Artificial Tap Water as control, salicyclic acid (SA) at 100, 200, 300 mg/L and combination of 100, 200, 300 mg/L SA with 2% sucrose were conducted. Parameters observed were vase life, relative fresh weight (RFW), vase solution uptake (VSU), flower drop (FD), flower colour, relative water content (RWC) and pH. The results showed that cut inflorescences in vase treatment containing 200 mg/L SA + 2% sucrose and 300 mg/L + 2% sucrose had 1.6 fold longer vase life than the control, showing higher water uptake and reduced flower drop by 28%.

EFFECT OF GROWTH REGULATORS AND PRESERVATIVE SOLUTION ON VASE LIFE AND WATER RELATION OF Gladiolus hybrida L. AFTER CUT FLOWERS

This experiment was conducted to study the effect of five concentrations of growth regulator of (0, 25 GA3, 50 GA3, 100 Salicylic acid, 150 Salicylic acid) mg.L-1 and three types of preservative solutions on the vase life and water relations for Gladiolus hybrida L. after cut flower. The experiment was conducted as a factorial experiment (3×5) according to Randomized Complete Blocks Design, with three replicates. The results showed that GA3 (50 mg.L-1) significantly excelled in relative fresh weight of 155.33%, absorbed water 59.00 g /flower /day, the lost water 32.99 g /flower /day, water balance 26.01 g /flower /day, vase life 16.96 days, dry weight of flowers 22.89 g, and carbohydrate content in petals 22.34 %, and total carotenoids content in petals 7.84 mg/100 g dry weight. The second solution (5% sucrose + 200 mg.L-1 8.HQS + 200 mg.L-1citric acid) is significantly excelled in most studied traits. The interaction treatment that consisted of (50 mg.L-1 + second solution) is significantly excelled in traits of the relative fresh weight 168.47%, absorbed water 66.32 g/flower /day, the lost water 23.39 g/flower /day, water balance 42.93 g/flower /day, vase life 21.25 days, dry weight of flower 26.11 g, carbohydrate content in petals 20.78% and total carotenoids content in petals 10.06 mg/100g dry weight.

Effects of postharvest relative humidity and various re-cutting on vase life of cut rose flowers

Studies were conducted to evaluate the effects of different relative humidity levels (60%, 75%, and 90%) and re-cutting (0 cm, 1 cm, 2 cm, 3 cm, 4 cm, and 5 cm re-cutting end of flower stem) treatments on vase life of cut rose flower. Two separate experiments (bucket and vase experiments) were conducted based on completely randomised design with factorial arrangement with eight replications in bucket experiment and five replications in vase experiment. Analysis of variance revealed that two ways effect of various RH and re-cuts did not significantly (P ≤ 0.05) affected flower vase life, relative fresh weight, solution uptake, and bacterial populations. Cut rose flower stored in chamber with 90% relative humidity had the longest vase life, while those one kept in 60% showed the shortest longevity. The result of mean comparisons revealed with increasing relative humidity from 60% to 90%, bacterial populations was increased too.

Effects of postharvest relative humidity and various re-cutting on vase life of cut rose flowers

Studies were conducted to evaluate the effects of different relative humidity levels (60%, 75%, and 90%) and re-cutting (0 cm, 1 cm, 2 cm, 3 cm, 4 cm, and 5 cm re-cutting end of flower stem) treatments on vase life of cut rose flower. Two separate experiments (bucket and vase experiments) were conducted based on completely randomised design with factorial arrangement with eight replications in bucket experiment and five replications in vase experiment. Analysis of variance revealed that two ways effect of various RH and re-cuts did not significantly (P ≤ 0.05) affected flower vase life, relative fresh weight, solution uptake, and bacterial populations. Cut rose flower stored in chamber with 90% relative humidity had the longest vase life, while those one kept in 60% showed the shortest longevity. The result of mean comparisons revealed with increasing relative humidity from 60% to 90%, bacterial populations was increased too.

CADMIUMIONSINCELLSELECTION FOR OBTAINING WHEAT CELL FORMS TOLERANT TO WATER STRESS

Introduction. Water deficit significantly decrease the plant development and crop production. Genetic effects that increased the genotype tolerance abilities are the aims of various investigations. Cell selection is the appropriate biotechnology for obtaining plant forms that challenged abiotic stresses. It is known that Cd 2+ cations significantly destroy various plant compartments and tissues. There was detected that Cd 2+ injures the water status of the organism. Purpose. The aim of the investigation was the promotion of cell selection with Cd 2+ cations for obtaining wheat cell lines tolerant to water stress. Methods. Selective systems with lethal doses of cadmium ions (Cd 2+ ) for obtaining wheat cell forms tolerant to water stress are proposed and elaborated. The minimum Cd 2+ concentration that eliminates wild type cell population was established as lethal doses. The water stress was conducted by the addition of manitol. Manitol is usually used for simulation water deficit in vitro. Callus and suspension cultures were initiated from immature embryos of winter wheat, ( Triticum aestivum L .), cv. Favoritka. Cell suspension (wild type) was placed on agar cultural B5 medium with the addition of lethal doses of cadmium ions (“plating procedure”). Such doses were deduced during preliminary tests. Only Cd-resistant cell survive under lethal ion stress pressure. In Cd 2+ resistant cell lines relative fresh weight and free proline levels were estimated. Result. Resistant cells formed primary minicolonies. Such colonies are considered to be wheat resistant cell lines (Cd-RCL). Cd-RCL grew at Cd 2+ ions presence during 3 passages. Then callus was cut and transferred to fresh media: basal medium (normal conditions) and selective media (stress conditions). There were established two variants of selective systems: medium with the addition of Cd 2+ cations, (stress I); cultural medium with the addition of manitol (stress II). Cd-RCL maintained their viability under any stress pressure. Genetic basis of Cd-RCL combined stress resistance was confirmed via media rotations. The changes were: normal conditions → stresses I, II; stresses I, II → normal conditions; stress I → stress II or other way roads. The type of cultural medium and the number of passages were always free. As proliferation marker calli relative fresh mass growth (RFW, Δm) was used. It was always positive. This parameter measured under normal conditions exceeded (40-45%) biomass RFW estimated under manitol pressure. But normal data were lower (more than three times) than data measured during calli cultivation at Cd 2+ presence. It is assumed that such events are the exhibitions of combined resistance. The levels of free proline (pro) were estimated in Cd-RCL. Under normal conditions wheat cell cultures accumulated pro in various amounts. In wild type callus the proline level was the highest. In Cd-RCL cultivated at manitol presence pro contents increased. We suppose that elevated pro levels in Cd-RCL under water stress were due to activity of system of its synthesis. The wild type cell cultures eliminated at the end of any passage. Proline levels were lower than level of determination. Conclusion . Cell lines of winter wheat with combined stress resistance were obtained via cell selection with Cd 2+ cations. Cd 2+ -resistant cell lines tolerated both lethal ion and water stresses. Under water stress pressure callus RFW of Cd 2+ -resistant cell lines was lower and under Cd 2+ affect was higher than normal parameters. The growth under water was cooperated with free proline accumulation. Cell selection with heavy metal ions is the perspective approach for obtaining cell variants with higher tolerance to osmotic stresses.

Salicylic acid modulates cutting-induced physiological and biochemical responses to delay senescence in two gerbera cultivars

The postharvest longevity of gerbera (Gerbera jamesonii) flowers has a critical importance in determining their commercial value; and therefore, there is a commercial demand for prolonging their vase life (VL). Here, we tested the efficacy of salicylic acid (SA, 150 µM) preservative in extending longevity of cut flower of two gerbera cultivars, namely the ‘Sunway’ and ‘Bayadere’, of which water-held ‘Bayadere’ has longer VL than water-held ‘Sunway’. The results indicated that exogenous SA could significantly prolong the VL of cut flowers of both ‘Sunway’ and ‘Bayadere’ cultivars, with better preservative effect being observed on ‘Sunway’. SA preservative was more effective in ameliorating relative water uptake and relative fresh weight in ‘Sunway’ than in ‘Bayadere’, which was accompanied by a greater decrease in proline accumulation. Application of SA prolonged the VL of two cut gerbera flower cultivars by inhibiting the activity of polyphenol oxidase involved in browning reaction, and decreasing oxidative stress through improving reactive oxygen species-scavenging antioxidant capacity, which included accumulation of total phenolic compounds and total flavonoids, and enhancement of enzymatic antioxidant activities. As a result, membrane lipid peroxidation levels were reduced in cut flowers of both cultivars, with higher reduction level being observed in ‘Sunway’ than in ‘Bayadere’. Additionally, SA preservative was more efficient in maintaining a greater content of total soluble proteins in ‘Sunway’ than in ‘Bayadere’. These findings clearly demonstrated that SA has higher preservative effects on extending VL of ‘Sunway’ than that of ‘Bayadere’. Taken together, SA can be recommended to farmers for postharvest treatments to maintain quality and delay senescence of gerbera flowers.

Nano-silver pretreatment delays wilting of cut gardenia foliage by inhibiting bacterial xylem blockage

Gardenias (Gardenia jasminoides Ellis var. ‘fortuniana’) have commercial importance as cut foliage but are prone to severe postharvest water deficit and quick wilting. Herein, we investigated the efficacy of pretreatment with nano-silver (NS), a strong antibacterial agent, in enhancing water relations and the vase life of cut gardenia foliage. Compared with the deionized-water controls, pretreatment with NS at 10, 15, 20, 25, or 30 mg L−1 for 24 h significantly extended the vase life of cut gardenias. The most effective NS concentration was 15 mg L−1, which promoted the longest (15.2 days) vase life extension, i.e., 310.2% of that of the control treatment. In addition, pretreatment with 15 mg L−1 NS effectively delayed wilting by maintaining a higher water balance value and relative fresh weight when compared with untreated cut foliage. Scanning electron microscopy revealed that these higher values were due to an improved water uptake as a result of the alleviation of bacterial xylem blockage at the stem-ends. Furthermore, Ag concentration was remarkably higher at the stem-ends of NS-pretreated cut gardenias than in any other tissues. Overall, these results demonstrate that NS pretreatment effectively inhibited bacterial growth at the cut stem-ends, and helped maintain a favorable water balance, thereby delaying wilting and extending the vase life of cut gardenias.

Biochemical, physiological changes and antioxidant responses of cut gladiolus flower 'White Prosperity' induced by nitric oxide

Sodium nitroprusside (SNP), as nitric oxide (NO) donor, has been considered by postharvest researchers as one of the best option for slowing the processes controlling senescence in cut flowers. Here, we investigate the role of NO on postharvest physiology and vase life of the Gladiolus grandiflorus cv. White Prosperity. Vase life markedly extended by SNP at 150 μM from 3 day to 7.33 day and thus those inducer effects were dose- and time-dependent. SNP at 125 μM interdependent on vase life time period was observed to be the optimal dose for improving of relative fresh weight (RFW), peroxidase (POD), and total monomeric anthocyanin (TMA) in cut flowers. Supplementing vase solution with SNP indicated significant increase in water uptake of cut flowers and consequently protected to decline in RFW due to alleviate water losses stress. SNP was maintained the level of total soluble protein, lipid peroxidation, and POD, whereas it enhanced the level of catalase (CAT) and TMA in flower petals. Summary of our results revealed that SNP exogenous prolongs vase life via maintaining protein degrade, scavenging free radical in term of anthocyanin and enzymes antioxidant, decreasing polyphenol oxidase, inhibiting lipid peroxidation, and improving membrane stability in ‘White Prosperity’ cut flowers.

Postharvest characteristics of two flowering stages of torch ginger (Etlingera elatior) inflorescences

Torch ginger (Etlingera elatior), a flourish in tropical and subtropical climates crop, with extravagant and showy inflorescence may be used as cut flower at each developmental stage. Limited studies have been undertaken to reveal the postharvest performance of this leafless inflorescence, especially at advanced developmental stages. Therefore, the objective of this study was to elucidate the postharvest performance of the torch ginger inflorescence treated with different vase solutions. Inflorescences at two flowering stages i.e., tight bud stage and torch shows stage at about 35 and 58 days, respectively, after emergence from rhizome, were used in this study. Sucrose (20 g L-1), 8-hydroxyquinoline sulfate (8-HQS, 0.1 g L-1) and distilled water were used as vase solution treatment. Postharvest characteristics, including vase life, relative fresh weight (RFW), dry weight, solution uptake rate, respiration and ethylene production rate were evaluated. Results showed that vase life of tight bud stage inflorescence was significantly higher than torch shows stage irrespective of treatments used. In contrast, significantly higher solution uptake rate was shown in the torch shows stage inflorescence. There was no significant difference in dry weight and respiration rate measured. No ethylene was detected in all treated inflorescences throughout the study. Prolongation of vase life was associated with the increase in RFW. Increase of RFW was found in tight bud stage inflorescence but reduction of RFW was shown in torch stage inflorescence at the end of vase life. The decrease of RFW could be due to the breakdown of stored carbohydrates in peduncle for the development of true flowers for pollination purpose. Supplementation of sucrose promoted the opening of true flowers. The use of 8-HQS and distilled water enabled the development of true flowers, but they failed to open. Sucrose treated inflorescences both in tight bud and torch stage showed better postharvest quality compared to 8-HQS and distilled water.

Elicitation of Stevia Glycosides Using Salicylic Acid and Silver Nanoparticles Under Callus Culture

Development of biosynthesis of phytochemicals, especially medicinal products, is highly important due to their broad bioactivity properties. In this study, optimization of callus growth was initially carried out using various combinations of plant growth regulators. Callus with the highest fresh weight was produced on Murashige and Skoog (MS) medium containing 1 (mg/l) naphthalene acetic acid + 0.5 (mg/l) benzyl aminopurine. The effect of different concentrations of salicylic acid (SA) (0.25, 0.5 and 0.75 mg/l) and silver nanoparticles (Ag NPs) (15, 30, 45 and 60 mg/l) on callus growth as well as the possibility of stevia glycosides (SGs) production in callus culture was subsequently evaluated. The SA elicitation, at a concentration of 0.75 (mg/l), resulted in the highest level of callus growth rate (0.1 cm/day), callus diameter (0.79 cm) and relative callus fresh weight (0.085). Likewise, 45 (mg/l) of Ag NPs led to the highest amount of stevioside (32.34 mg/g dry weight callus). The addition of 0.25 (mg/l) of SA to the MS medium led to production of the highest amount of rebaudioside A (3.40 mg/g dry weight callus). The results of this study may enhance the commercial application of important glycosides prevalent in Stevia by highlighting that the nano-elicitors and SA should be utilized at optimized concentrations.