Impaginato 255 Adv. Hort. Sci., 2023 37(3): 255­269 DOI: 10.36253/ahsc­14247 Effect of some chemical and natural preservative solutions on vase life, water relations and some chemical composition of Dianthus caryophyllus L. cut flowers A.M.Z. Sarhan 1, A.A.M. Heikal 1, F.M. Saadawy 2, T.M. Noor El­Deen 2, K.M. Abd Elkareem 2 (*) 1 Ornamental Horticulture Department, Faculty of Agriculture, Cairo University, Cairo, Egypt. 2 Ornamental Plants and Landscape Gardening Research Department, Horticultural Research Institute, Agricultural Research Center, Giza, Egypt. Key words: AgNO3, amino­oxyacetic acid, boric acid, carnation, cv. Turbo, 8­ hydroxyquinoline sulfate, holding solutions, pulsing, silver thiosul­ fate. Abstract: To investigate the effect of some pulsing and holding solutions on the quality of carnation cv. Turbo cut flowers, a laboratory experiment was con­ ducted in the Agricultural Research Center and Cairo University, Egypt during 2020 and 2021 seasons. In this regard distilled water, silver thiosulfate (STS) at 0.4 ppm + sucrose 10% (PS1) and AgNO3 at 10.0 ppm + sucrose 10% (PS2) were employed as a pulsing solution for 15 min while distilled water, sucrose 4% (HS1), boric acid (BoA) at 200 ppm + sucrose 4% (HS2), 8­hydroxyquinoline sul­ fate (8­HQS) at 300 ppm + sucrose 4% (HS3), Amino­oxyacetic acid (AOA) at 250 ppm + sucrose 4% (HS4), 8­HQS + AOA + sucrose 4% (HS5), BoA + 8­HQS + sucrose 4% (HS6), BoA + AOA + sucrose 4% (HS7), BoA + 8­HQS + AOA + sucrose 4% (HS8), rosemary extract at 25% + sucrose 2% (HS9) and thyme extract at 25% + sucrose 2% (HS10) were used as holding solutions. Regarding pulsing solutions, PS2 and PS1 exhibited a positive effect on all studied traits, while the mastery was to HS8 concerning the effect of holding solutions. Pulsing cut car­ nations in a solution containing PS2 followed by holding in HS8 resulted in the highest values in terms of vase life, water balance, chlorophyll a, carotenoids and total sugars, while the highest water uptake and loss and chlorophyll b were obtained by pulsing in PS1 followed by holding in HS8. It is recommended to pulse carnation cv. Turbo cut flowers in AgNO3 at 10.0 ppm + sucrose 10% solution for 15 min followed by holding in BoA + 8­HQS + AOA + sucrose 4% for getting the longest vase life, enhancing water uptake and maintaining water balance. Additionally, this preservative solution effectively reduces chlorophyll degradation and preserves the content of carbohydrates throughout the postharvest period. (*) Corresponding author: koki_assem@yahoo.com Citation: SARHAN A.M.Z., HEIKAL A.A.M., SAADAWY F.M., NOOR EL­DEEN T.M., ABD ELKAREEM K.M., 2023 ­ Effect of some chemical and natural preservative solutions on vase life, water relations and some chemical composition of Dianthus caryophyllus L. cut flowers. ­ Adv. Hort. Sci., 37(3): 255­269. Copyright: © 2023 Sarhan A.M.Z., Heikal A.A.M., Saadawy F.M., Noor El­Deen T.M., Abd Elkareem K.M. This is an open access, peer reviewed article publi­ shed by Firenze University Press (http://www.fupress.net/index.php/ahs/) and distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Competing Interests: The authors declare no competing interests. Received for publication 24 July 2022 Accepted for publication 19 May 2023 AHS Advances in Horticultural Science https://doi.org/10.36253/ahsc-14247 http://www.fupress.net/index.php/ahs/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ Adv. Hort. Sci., 2023 37(3): 255­269 256 1. Introduction Carnation (Dianthus caryophyllus L.; fam. Caryophyllaceae) is native to Southern Europe and the Mediterranean region and is a half­hardy peren­ nial flowering plant with a wide range of colours. Each stem of the carnation forms a terminal flower; hence inflorescence is generally a terminal cyme. The flowering shoots can be single or multiple (stem sprays) (Ponnuswami and Sowmeya, 2015). Moreover, the exceptional keeping qualities of carna­ tions make them an excellent choice for cut flowers. They possess remarkable longevity, the ability to withstand long­distance transportation, and an exceptional capacity to rehydrate even after pro­ longed shipping (Panwar et al., 2022). There is a wide range of techniques applied to extend flower preservation, including the use of flower preservatives, inhibitors of ethylene action, growth regulators, calcium and the control of tem­ perature and flower dehydration (Finger and Barbosa, 2006). Pulsing solutions are used basically to provide sugars (sucrose or glucose at 2­20%) and silver compounds (STS) (Armitage and Laushman, 2003). Pulsing solutions are used on freshly harvest­ ed flowers that are in a bud stage where a short peri­ od (or pulse) in a high­sugar solution will extend the vase life or open buds. Sugar is the main ingredient while STS is used to reduce ethylene sensitivity (Jones, 2001). To promote water uptake, the cut flower’s stems are placed in a holding solution which contains an acidifier for hydration, a biocide of bacte­ rial control and an energy/food source, which is typi­ cally sugar. The flowers usually stay in these solutions for one to several days as they are transported to local distributors and retailers and are used for retail displays (Dole and Faust, 2021). A lot of chemicals are used in formulations of pulsing or/and holding solutions e.g. STS, AgNO3, 8­ HQS, AOA and boric acid. Ebrahimzadeh et al. (2008) concluded that STS is used to inhibit harmful effects of ethylene and prolong vase life in many ornamen­ tals including carnation, AgNO3 inhibits ethylene syn­ thesis and action and is used as an antimicrobial agent, 8­HQS is an antimicrobial additive in preserva­ tives and is ethylene synthesis inhibitor, AOA inhibits the biosynthesis of ethylene, and boric acid used as anti­ethylene synthesis. Various authors have demonstrated the beneficial effects of the aforemen­ tioned chemicals, integrated either individually or in combinations into preservative solutions, on carna­ tion cut flowers cvs. Dolce Vita, Amstel, Monte Lisa, Aliceo, and Paola (Wawrzynczak and Goszczynska, 2003), cvs. Kristina, Aleda, Master, and Vienna (Krishnappa and Reddy, 2004), cvs. Nelson, Dream, and Delphi (Lopez et al., 2008), cv. Optima (Karimi et al., 2012), cv. Charmant (Darwish et al., 2014), cv. Felice (Madhuri et al., 2016), and cv. Mirella (Adam and Eldeeb, 2021). Certain natural materials e.g. plant extracts and essential oils are used instead of chemicals in cut flowers’ preservative solutions due to the harmful effects of such chemicals (particularly those based on silver compounds) on human health. A lot of studies were carried out to investigate the effect of these natural materials. In this regard, Hashemabadi et al. (2021) on Dianthus caryophyllus L. cv. Yellow Candy stated that both vase life and solution uptake were increased by using dill essential oil in the solution compared to distilled water. Numerous studies have provided evidence of the impact of employing natur­ al substances in preserving solutions for carnation cut flowers. For example, investigations have been conducted on the utilization of dill, clove, and corian­ der oils on cvs. Farida and Madam Collate (Shanan et al., 2010); extracts of lupin and clove and juice of the lemon on cv. Domingo (El­Ashwah, 2011); essential oils of dill, geranium and caraway on cv. Yellow Candy (Rad, 2018) and clove essential oil on cv. Cinderella (Eldeeb and Adam, 2021). Such materials were used in these reported studies either individual­ ly or in combination with other post­harvest chemi­ cals. Therefore, the present study was carried out to investigate the effect of different pulsing (mainly STS, AgNO3 or distilled water) and holding (boric acid, 8­ HQS, AOA, rosemary and thyme water extracts) solu­ tions on vase life, water relations, pigments content and total sugars of carnation cut flowers with the possibility to get the longest vase live with the best quality. 2. Materials and Methods A laboratory experiment was carried out in the Post­harvest Lab., Ornamental Plants and Landscape Gardening Res. Dept., Horticulture Res. Inst., Agricultural Research Center, Giza, Egypt and Ornamental Horticulture Dept., Faculty of Agriculture, Cairo University, Egypt during 2020 and 2021 seasons with the aim to study the effect of some pulsing and holding solutions (containing some natural extracts) on the postharvest quality of carna­ Sarhan et al. ‐ Preservative solutions’ effect on carnation‐cut flowers 257 tion cut flowers. Plant materials Fresh cut flowers of carnation (Dianthus caryophyllus L.) cv. Turbo, at the paintbrush stage with red color were obtained from a local commer­ cial greenhouse farm in Giza, Egypt, in the first week of January each season. Flowers’ stem lengths were adjusted to 60 cm with 3.0­3.5 cm flower diameter, while fresh weight ranged from 18 to 20 g. Immediately, after transferring to the laboratory under dry conditions, about 5 cm of stem bases were recut under water and 4 pairs of leaves were left on each stem and then rapidly precooled by placing them in cold water for three hours. Experiment treatments Pulsing solutions These precooled cut flowers were distributed in 500 ml jars (3 flowers/jar) and then equally divided into three groups, each one containing 300 ml from one of the following applied pulsing solutions: 1. Distilled water 2. STS at 0.4 ppm + sucrose at 10% (PS1) 3. AgNO3 at 10.0 ppm + sucrose at 10% (PS2) STS (silver thiosulfate; 1AgNO3.4Na2S2O3·5H2O) solution was prepared according to Gorin et al. (1985). In this regard, both AgNO3 (0.079 g) and Na2S2O3·5H2O (0.462) were dissolved separately in 500 ml deionized water, then AgNO3 solution was poured into Na2S2O3·5H2O solution with continuous stirring. While the AgNO3 solution was prepared by dissolving 0.01 g of AgNO3 in deionized distilled water to prepare a 10­ppm concentration. Holding solutions Each group of the pulsed cut flowers were divided into 11 subgroups (3 flowers/500 ml jar containing 300 ml of different holding solutions) and kept under lab conditions (light intensity at 1000 lux supplied by fluorescent lamps, the average temperature at 18­ 20°C and relative humidity at 50­55%) as follows: 1. Control (distilled water) 2. Sucrose at 4% (HS1) 3. Boric acid at 200 ppm (BoA) + sucrose at 4% (HS2) 4. 8­hydroxyquinoline sulfate at 300 ppm (8­HQS) + sucrose at 4% (HS3) 5. Amino­oxyacetic acid at 250 ppm (AOA) + sucrose at 4% (HS4) 6. 8­HQS + AOA + sucrose at 4% (HS5) 7. BoA + 8­HQS + sucrose at 4% (HS6) 8. BoA + AOA + sucrose at 4% (HS7) 9. BoA + 8­HQS + AOA + sucrose at 4% (HS8) 10. Rosemary extract at 25% (RE) + sucrose at 2% (HS9) 11. Thyme extract at 25% (TE) + sucrose at 2% (HS10) Extracts preparation Both thyme (Thymus vulgaris L.) and rosemary (Rosmarinus officinalis L.) extracts were prepared by water extraction. In this concern, 250 g of the dry herb was extracted in 250 ml of distilled water with boiling at 100°C and stirring for 30 minutes. After that, the solution was filtered using filter paper, and the remaining solution was completed to 1000 ml with distilled water. Afterwards, 250 ml of each solu­ tion was poured into 1000 ml of distilled water to get a 25% concentration. Experiment design This experiment was laid out as a complete ran­ domized design (CRD) in a factorial experiment. Factor (A) was represented by 3 levels of pulsing solutions, while factor (B) was represented by 11 lev­ els of holding solutions. Thus, a total of 33 treat­ ments were utilized. Each treatment consisted of 3 replicates, with each replicate containing 3 jars. Within each jar, there were 3 flowers, resulting in a total of 27 flowers per treatment. Data collection Vase life Vase life was determined as the number of days to the beginning of flowers wilting. Water relations The total water uptake (g/flower) was calculated by subtracting the weight of water at the end of the experiment from the initial weight. The total water loss (g/flower) was determined by measuring the difference between the weight of jars with spikes and solution at the beginning of the experiment and the weight of jars with spikes and solution at the end of the experiment. The total water balance (g/flower) was obtained by subtracting the total water loss from the total water uptake. Determination of pigments and sugars At the end of flower longevity, pigment and sugar contents were measured on the attached leaves. Contents of chlorophylls a, b and carotenoids were determined colourimetrically in fresh leaves according to the method described by Wellburn and Lichtenthaler (1984). Total sugars in the dry leaves were determined Adv. Hort. Sci., 2023 37(3): 255­269 258 colourimetrically according to Dubois et al. (1956). Statistical analysis The obtained data were statistically analyzed as a factorial experiment using MSTAT Computer Program (MSTAT Development Team, 1989). Duncan’s multi­ ple range test (Duncan, 1955) was used to compare the means between various treatments. 3. Results and Discussion Vase life The data reported in Table 1 clearly show that PS2 significantly increased the vase life of carnation cut flowers to 18.4 and 18.7 days in the first and second seasons, respectively. Conversely, pulsing the cut flowers in distilled water solution recorded only 16.3 and 16.5 days in both seasons, respectively. Preserved carnation cut flowers in different hold­ ing solutions showed a significant influence on vase life (days) as presented in Table 1. The highest num­ ber of days was recorded by holding in HS8 (24.3 and 24.6 days) in the first and second seasons, respec­ tively. The lowest values were obtained by holding the cut flowers in HS9 (12.6 and 12.9 days), HS10 (12.7 and 13.0 days) and distilled water (12.8 and 12.6 days) in both seasons, respectively. Comparing to the control treatment (DW), it was evident that all combined treatments involving both pulsing and holding solutions led to a substantial improvement in the vase life of cut carnation flowers. The key technique employed to achieve this outcome involved pulsing the flowers in a PS2, along with Table 1 ­ Effect of pulsing and holding solutions and their interaction on vase life (days) of Dianthus caryophyllus cv. Turbo cut flowers during 2020 and 2021 seasons PS1= STS at 0.4 ppm + sucrose 10%, PS2= AgNO3 at 10.0 ppm + sucrose 10%, HS10 sucrose 4%, HS2= boric acid at 200 ppm + sucrose 4%, HS3= 8­HQS at 300 ppm + sucrose 4%, HS4= AOA at 250 ppm + sucrose 4%, HS5= 8­HQS + AOA + sucrose 4%, HS6= boric acid + 8­HQS + sucrose 4%, HS70= boric acid + AOA + sucrose 4%, HS8= boric acid + 8­HQS + AOA + sucrose 4%, HS9= rosemary extract at 25% + sucrose 2%, HS10= thyme extract at 25% + sucrose 2%. Holding solutions (B) Pulsing solutions (A) PS1 PS2 DW Mean (B) First season (2020) Control (DW) 13.67 o­q 14.18 op 10.67 t 12.84 f HS1 15.69 l­n 15.98 lm 14.69 no 15.45 e HS2 18.04 ij 18.02 ij 16.71 kl 17.59 d HS3 21.44 de 23.11 bc 17.73 jk 20.76 b HS4 19.09 hi 22.13 c­e 16.38 lm 19.20 c HS5 17.60 jk 18.00 ij 15.60 mn 17.07 d HS6 21.87 de 21.24 ef 20.33 fg 21.15 b HS7 20.11 gh 19.36 gh 19.42 gh 19.63 c HS8 23.98 b 26.67 a 22.40 cd 24.35 a HS9 12.67 qr 13.29 pq 11.84 rs 12.60 f HS10 13.09 pq 11.04 st 14.00 op 12.71 f Mean (A) 17.93 b 18.46 a 16.34 c Second season (2021) Control (DW) 13.00 p­r 14.23 n­p 10.83 s 12.69 f HS1 15.45 l­n 16.00 k­m 14.90 m­o 15.45 e HS2 18.23 g­i 18.10 g­i 17.13 i­k 17.82 d HS3 21.68 de 23.63 bc 17.80 h­j 21.04 b HS4 19.51 fg 22.20 c­e 16.50 j­l 19.40 c HS5 17.93 h­j 18.87 gh 16.33 k­m 17.71 d HS6 22.30 cd 21.50 de 20.80 ef 21.53 b HS7 20.80 ef 19.53 fg 19.50 fg 19.94 c HS8 24.57 b 27.00 a 22.23 c­e 24.60 a HS9 13.43 p 13.60 op 11.83 q­s 12.96 f HS10 13.23 pq 11.63 rs 14.33 n­p 13.07 f Mean (A) 18.19 b 18.75 a 16.56 c Sarhan et al. ‐ Preservative solutions’ effect on carnation‐cut flowers 259 holding them in HS8. This combination resulted in vase lives of 26.6 and 27.0 days in both seasons, respectively. The lowest number of days of vase life in both seasons was recorded by pulsing and holding in dis­ tilled water only (10.6 and 10.8 days), pulsing in PS2 + holding in HS10 solution (11.0 and 11.6 days) and pulsing in distilled water and holding in HS9 solutions (11.8 and 11.8 days), respectively. The aforementioned findings were consistent with the results obtained in previous studies on carnation e.g. Serrano et al. (2001), Lopez et al. (2008), Hashemabadi (2014), Liu et al. (2018) and Gocan et al. (2021). Similar outcomes were observed on roses cut flowers (Elgimabi, 2014; Kumar et al., 2017), ger­ bera (Bhanushree and Rao, 2015; Jafarpour et al., 2015), hydrangeas (Kazaz et al., 2020; Suntipabvivat­ tana et al., 2020), Cymbidium (Usha et al., 2014). Kabari and Soleimandarabi (2019) focused on Alstroemeria cut flowers, while Ichimura et al. (2009) examined cut Eustoma, Delphinium, and snapdragon flowers. In this regard, Darwish et al. (2014) reported that using a solution of 300 ppm 8­HQS + 40 g/l sucrose and 0.4 mM STS + 50 g/l sucrose significantly increased vase life of carnation cut flowers cv. Felice. Also, Badawy et al. (2016) revealed that AgNO3 showed the longest vase life of Chrysanthemum cut flowers cv. Royal Accent. Water relations Water uptake Data reported in Table 2 show that PS1 solution significantly enhanced water uptake of carnation cut flowers resulting in the highest values in both sea­ sons, (48.2 and 49.9 g/flower in 2020 and 2021, PS1= STS at 0.4 ppm + sucrose 10%, PS2= AgNO3 at 10.0 ppm + sucrose 10%, HS10 sucrose 4%, HS2= boric acid at 200 ppm + sucrose 4%, HS3= 8­HQS at 300 ppm + sucrose 4%, HS4= AOA at 250 ppm + sucrose 4%, HS5= 8­HQS + AOA + sucrose 4%, HS6= boric acid + 8­HQS + sucrose 4%, HS70= boric acid + AOA + sucrose 4%, HS8= boric acid + 8­HQS + AOA + sucrose 4%, HS9= rosemary extract at 25% + sucrose 2%, HS10= thyme extract at 25% + sucrose 2%. Table 2 ­ Effect of pulsing and holding solutions and their interaction on water uptake (g/flower) of Dianthus caryophyllus cv. Turbo cut flowers during 2020 and 2021 seasons Holding solutions (B) Pulsing solutions (A) PS1 PS2 DW Mean (B) First season (2020) Control (DW) 36.52 mn 36.55 mn 32.06 p 35.04 g HS1 47.74 h­j 36.20 mn 34.01 op 39.32 f HS2 57.35 d 50.23 fg 46.81 ij 51.46 c HS3 52.18 ef 48.95 gh 48.85 g­i 49.99 d HS4 50.57 fg 40.68 l 40.96 kl 44.07 e HS5 59.70 c 57.10 d 54.11 e 56.97 b HS6 56.49 d 46.68 j 46.54 j 49.91 d HS7 46.71 j 42.77 k 45.90 j 45.12 e HS8 67.61 a 65.47 b 60.15 c 64.41 a HS9 29.31 q 37.80 m 37.53 m 34.88 g HS10 26.79 r 34.56 no 29.95 q 30.43 h Mean (A) 48.27 a 45.18 b 43.35 c Second season (2021) Control (DW) 38.42 mn 38.46 mn 34.10 p 36.99 g HS1 49.42 h­j 38.23 mn 36.11 o 41.25 f HS2 58.75 d 51.85 fg 48.53 ij 53.04 c HS3 53.74 ef 50.60 gh 50.50 g­i 51.61 d HS4 52.17 fg 42.58 l 42.85 kl 45.87 e HS5 61.03 c 58.51 d 55.61 e 58.39 b HS6 57.92 d 48.41 j 48.27 j 51.53 d HS7 48.43 j 44.60 k 47.64 j 46.89 e HS8 68.71 a 66.63 b 61.47 c 65.60 a HS9 31.55 q 39.78 m 39.53 m 36.95 g HS10 29.11 r 36.64 no 32.17 pq 32.64 h Mean (A) 49.93 a 46.94 b 45.16 c 260 Adv. Hort. Sci., 2023 37(3): 255­269 respectively). The lowest significant values were recorded when the cut flowers were pulsed in a dis­ tilled water solution. (43.3 and 45.1 g/flower in 2020 and 2021, respectively). All applied holding solutions positively affect the water uptake of cut carnations as shown in Table 2. The holding solution containing HS8 resulted in the highest water uptake (64.4 and 65.6 days in 2020 and 2021, respectively). On the other hand, holding in solutions containing either rosemary or thyme extracts adversely affected water uptake of carnation cut flowers (34.8 and 36.9 g/flower for rosemary and 30.4 and 32.6 g/flower for thyme extract in 2020 and 2021, respectively). Furthermore, it is noteworthy that when the flowers were held in a distilled water solution alone, it exhibited a similar effect to holding them in a solution containing rosemary extract, with no significant difference observed (35.0 and 36.9 g/flower in the first and second seasons, respectively. With regard to the interaction between pulsing and holding solutions, it can be observed that pulsing in PS1 solution followed by holding in HS8 recorded the highest significant values in both seasons (67.6 and 68.7 g/flower, respectively in 2020 and 2021). Water uptake of carnation cut flowers was decreased by all applied pulsing solutions when combined with holding solutions containing either rosemary, thyme or only distilled water. The lowest values in this regard were obtained by pulsing in PS1 in addition to holding in HS10 solutions (26.7 and 29.1 g/flower in 2020 and 2021, respectively). Water loss As shown in Table 3, the greatest water loss was observed when the flowers were pulsed in PS1 in both seasons. The water loss values recorded were Table 3 ­ Effect of pulsing and holding solutions and their interaction on water loss (g/flower) of Dianthus caryophyllus cv. Turbo cut flowers during 2020 and 2021 seasons PS1= STS at 0.4 ppm + sucrose 10%, PS2= AgNO3 at 10.0 ppm + sucrose 10%, HS10 sucrose 4%, HS2= boric acid at 200 ppm + sucrose 4%, HS3= 8­HQS at 300 ppm + sucrose 4%, HS4= AOA at 250 ppm + sucrose 4%, HS5= 8­HQS + AOA + sucrose 4%, HS6= boric acid + 8­HQS + sucrose 4%, HS70= boric acid + AOA + sucrose 4%, HS8= boric acid + 8­HQS + AOA + sucrose 4%, HS9= rosemary extract at 25% + sucrose 2%, HS10= thyme extract at 25% + sucrose 2%. Holding solutions (B) Pulsing solutions (A) PS1 PS2 DW Mean (B) First season (2020) Control (DW) 38.23 ij 41.25 f­h 37.46 jk 38.98 e HS1 49.26 d 33.77 l­n 33.21 mn 38.75 e HS2 54.14 bc 46.64 e 42.28 f­h 47.69 b HS3 47.32 de 42.61 fg 43.50 f 44.48 c HS4 46.57 e 35.72 kl 37.80 jk 40.03 de HS5 59.81 a 53.39 c 53.53 c 55.58 a HS6 51.81 c 42.04 f­h 39.90 h­j 44.58 c HS7 42.71 fg 38.23 ij 40.46 g­i 40.46 d HS8 60.64 a 56.01 b 51.78 c 56.15 a HS9 35.58 k­m 43.42 f 42.50 fg 40.50 d HS10 29.50 o 41.67 f­h 32.84 n 34.67 f Mean (A) 46.87 a 43.16 b 41.39 c Second season (2021) Control (DW) 39.40 l­n 43.28 hi 42.09 i­k 41.59 d HS1 50.21 c­e 31.40 t 33.73 rs 38.45 e HS2 50.79 cd 43.83 hi 40.89 j­l 45.17 c HS3 42.20 ij 40.25 j­m 42.19 ij 41.55 d HS4 44.50 h 33.28 r­t 35.40 p­r 37.73 e HS5 58.60 a 52.08 c 55.00 b 55.22 a HS6 48.63 d­f 37.05 o­q 37.57 n­p 41.08 d HS7 40.89 j­l 36.97 o­q 38.37 m­o 38.74 e HS8 54.72 b 46.74 fg 47.01 fg 49.49 b HS9 39.95 k­m 48.30 ef 45.33 gh 44.53 c HS10 32.58 st 46.85 fg 35.17 qr 38.20 e Mean (A) 45.68 a 41.82 b 41.16 b Sarhan et al. ‐ Preservative solutions’ effect on carnation‐cut flowers 261 46.9 and 45.7 g/flower, respectively in 2020 and 2021. The lowest values were recorded when the flowers were pulsed in a distilled water solution (41.4 and 41.2 g/flower in 2020 and 2021, respectively). There was no significant difference between pulsing the flowers in a solution of PS2 (41.8 g/flower) and using distilled water in the second season only. Regarding the effect of holding solution, it can be said that holding in HS8 or HS5 solutions resulted in the highest water loss in both seasons. Only in the first season, there was no significant difference between them, while in the second one, HS5 was sig­ nificantly higher than HS8. In the first and second seasons, the results were 56.1 and 49.4 g/flower for HS8 and 55.5 and 55.2 g/flower for HS5 respectively. As for the effect of interaction, the highest water loss was obtained by pulsing in PS1 then holding in either HS8 (60.6 and 54.7 g/flower) or HS5 (59.8 and 58.6 g/flower in 2020 and 2021, respectively). However, in the first season, there was no significant difference between these two combined treatments. In contrast, in the second season, when combined with a holding solution containing HS5, it resulted in a significantly higher water loss compared to the combination of HS8. The lowest significant water loss was obtained by pulsing in PS1 followed by holding in HS10 in the first season (29.5 g/flower) and PS2 fol­ lowed by HS1 only in the second one (31.4 g/flower). Water balance Regarding the impact of pulsing solutions on the water balance of carnation cut flowers, the data pre­ sented in Table 4 revealed that PS2 exhibited superi­ ority in this regard, recording the highest values of PS1= STS at 0.4 ppm + sucrose 10%, PS2= AgNO3 at 10.0 ppm + sucrose 10%, HS10 sucrose 4%, HS2= boric acid at 200 ppm + sucrose 4%, HS3= 8­HQS at 300 ppm + sucrose 4%, HS4= AOA at 250 ppm + sucrose 4%, HS5= 8­HQS + AOA + sucrose 4%, HS6= boric acid + 8­HQS + sucrose 4%, HS70= boric acid + AOA + sucrose 4%, HS8= boric acid + 8­HQS + AOA + sucrose 4%, HS9= rosemary extract at 25% + sucrose 2%, HS10= thyme extract at 25% + sucrose 2%. Table 4 ­ Effect of pulsing and holding solutions and their interaction on water balance (g/flower) of Dianthus caryophyllus cv. Turbo cut flowers during 2020 and 2021 seasons Holding solutions (B) Pulsing solutions (A) PS1 PS2 DW Mean (B) First season (2020) Control (DW) ­1.71 m ­4.69 n ­5.40 no ­3.93 f HS1 ­1.52 lm 2.43 j 0.79 k 0.57 e HS2 3.21 h­j 3.59 g­j 4.53 f­i 3.78 d HS3 4.87 e­g 6.34 c­e 5.35 d­f 5.52 b HS4 4.00 f­i 4.95 e­g 3.17 ij 4.04 cd HS5 ­0.11 kl 3.71 g­j 0.58 k 1.39 e HS6 4.68 f­h 4.65 f­i 6.64 cd 5.32 b HS7 4.00 f­i 4.54 f­i 5.44 d­f 4.66 bc HS8 6.97 bc 9.45 a 8.37 ab 8.26 a HS9 ­6.27 op ­5.62 n­p ­4.97 no ­5.62 g HS10 ­2.70 m ­7.11 p ­2.89 m ­4.23 f Mean (A) 1.40 b 2.02 a 1.96 a Second season (2021) Control (DW) ­0.98 m ­4.82 o ­7.99 q ­4.60 e HS1 ­0.79 m 6.83 ij 2.38 k 2.81 d HS2 7.96 gh 8.01 gh 7.63 gh 7.87 c HS3 11.54 c 10.35 e 8.31 g 10.07 b HS4 7.67 gh 9.29 f 7.46 hi 8.14 c HS5 2.44 k 6.43 j 0.61 l 3.16 d HS6 9.29 f 11.35 cd 10.70 de 10.45 b HS7 7.54 h 7.63 gh 9.27 f 8.15 c HS8 13.98 b 19.89 a 14.46 b 16.11 a HS9 ­8.40 q ­8.52 q ­5.80 p ­7.57 g HS10 ­3.46 n ­10.20 r ­2.99 n ­5.55 f Mean (A) 4.25 b 5.11 a 4.00 c Adv. Hort. Sci., 2023 37(3): 255­269 262 2.0 g/flower and 5.1 g/flower in 2020 and 2021, respectively. Pulsing solution containing distilled water occupied the second position without signifi­ cant differences in the first season only (1.9 g/flower). Regarding the effect of holding solutions, HS8 resulted in the highest significant positive values in both seasons (8.2 and 16.1 g/flower in 2020 and 2021, respectively). The lowest values were obtained when using HS9, which resulted in negative values of ­5.6 g/flower and ­7.5 g/flower in the first and second seasons, respectively. A significant interaction between pulsing and holding solutions was observed. Pulsing in PS2 then holding in HS8 seemed to be the most effective treat­ ment resulting in the highest positive values (9.4 and 19.8, in 2020 and 2021, respectively. The lowest val­ ues, on the other hand, were obtained when using any pulsing solution followed by HS9, HS10, or HS1. Specifically, pulsing the flowers in PS2 followed by holding them in HS10 resulted in the lowest values in this regard, measuring ­7.1 g/flower and ­10.2 g/flower in the first and second seasons, respectively. In this regard, Bhanushree and Rao (2015) con­ ducted a research on Gerbera jamesonii cv. Lomborgini and reported that the application of AgNO3 at 20 ppm resulted in an increase in water uptake and water loss. Khella et al. (2018) reported that water uptake of Limonium sinuatum cv. Girlie Wings cut flowers was enhanced by STS at 500 mg/l for 1/2 h or by STS at 500 mg/l for 1/4 h followed by AgNO3 at 500 mg/l for 1/2 h. In a study conducted by Kazaz et al. (2020) on cut hydrangeas, it was found that the application of 8­HQS at 200 mg/l resulted in an improvement in solution uptake compared to the control group. These findings align with the results reported by Elgimabi (2014) on Rosa damascena cv. Trigintipetala and Usha et al. (2014) on Cymbidium hybrid cv. Red Princess. Determination of pigments and sugars Pigments content The pulsing solution containing PS1 recorded the highest values of chlorophyll a (0.349 and 0.354 mg/g f.w.), chlorophyll b (0.234 and 0.241 mg/g f.w.) and carotenoids (0.184 and 0.182 mg/g f.w.) in both sea­ sons, respectively. The lowest values for chlorophyll a, chlorophyll b, and carotenoids were observed when using distilled water, with recorded values of 0.293 and 0.297, 0.218 and 0.214, and 0.133 and 0.143 in the first and second seasons, respectively (Tables 5, 6, and 7). Concerning the effect of holding solutions, HS8 resulted in the highest values of chlorophyll a (0.626 and 0.641 mg/g f.w.), chlorophyll b (0.435 and 0.434 mg/g f.w.) and carotenoids (0.236 and 0.247 mg/g f.w.) in both seasons, respectively. It could be noticed that the lowest values in terms of chlorophyll a (0.167 and 0.171 mg/g f.w.) and carotenoids (0.110 and 0.116 mg/g f.w.) in both 2020 and 2021seasons were obtained by using a holding solution containing HS9, while HS10 produced the lowest values in case of chlorophyll b (0.105 and 0.116 mg/g f.w. in 2020 and 2021 respectively). In general, all holding solu­ tion formulations involving HS9, HS10 or distilled water resulted in the lowest values for the measured parameters. Combined treatment of PS2 in addition to HS8 resulted in the highest significant values in terms of chlorophyll a (0.642 and 0.655 mg/g f.w.) and carotenoids (0.238 and 0.255 mg/g f.w.) and occu­ pied the second rank in case of chlorophyll b with values of 0.468 and 0.466 in 2020 and 2021, respec­ tively. On the other hand, the highest values of chlorophyll b were obtained when using PS1 in com­ bination with HS8 (0.481 and 0.485 mg/g f.w. in 2020 and 2021, respectively). PS1 combined with HS9 gave the lowest values in terms of chlorophyll a, while pulsing and holding in distilled water resulted in the lowest values of chlorophyll b (0.052 and 0.059 mg/g f.w.) and carotenoids (0.062 and 0.060 mg/g f.w.) in both sea­ sons. In a similar context, Badawy et al. (2016) conduct­ ed a study on Chrysanthemum cut flowers cv. Royal Accent and reported that AgNO3 exhibited the least decrease in chlorophyll content. Khella et al. (2018) reported that STS at 500 mg/l for 1/2 h or STS at 500 mg/l for 1/4 h followed by AgNO3 500 mg/l for 1/2 h enhanced pigments content of Limonium sinuatum cv. Girlie Wings cut flowers. The same results were reported by Elgimabi (2014) on Rosa damascena cv. Trigintipetala. Total sugars content The data presented in Table 8 clearly show that pulsing cut carnations in PS1 resulted in the highest percentage of sugars, with recorded values of 28.0% and 28.5% in 2020 and 2021, respectively. Following closely in the second position, a solution of PS2 showed a percentage of 27.7% in 2020 (not being sig­ nificantly different from the highest) and 28.0% in Sarhan et al. ‐ Preservative solutions’ effect on carnation‐cut flowers 263 2021 (being significantly different from the highest). Conversely, the lowest values were observed when using distilled water, with percentages of 25.8% and 26.0% in 2020 and 2021, respectively. When considering the influence of holding solu­ tions, it was evident that HS8 outperformed other treatments in terms of total sugars, resulting in the highest values in both seasons (47.5% and 48.3% in 2020 and 2021, respectively). Conversely, HS9 exhib­ ited a negative effect, leading to the lowest sugar content (11.4% and 11.7%). Regarding the combined treatments, PS2 in addi­ tion to HS8 produced the highest values, recording 52.0% and 54.6% in 2020 and 2021, respectively. On the other hand, when distilled water was combined with HS9, the lowest values were observed, with per­ centages of 10.5% and 11.1% in 2020 and 2021, respectively. These results align with the findings of Badawy et al. (2016), who reported that AgNO3 exhibited the highest total carbohydrate content in Chrysanthemum cut flowers cv. Royal Accent. Additionally, Khella et al. (2018) demonstrated that STS at 500 mg/l for 1/2 h enhanced the total carbo­ hydrate percentage of Limonium sinuatum cv. Girlie Wings cut flowers, followed by the treatment with STS at 500 mg/l for 1/4 h and AgNO3 at 500 mg/l for 1/2 h. Similarly, Chore et al. (2020) investigated Gladiolus grandiflorus L. cv. Fado and found a signifi­ cant increase in total soluble sugars in spikes pulsed with 600 ppm 8­HQS + 5% sucrose compared to the control. These results are consistent with the findings Table 5 ­ Effect of pulsing and holding solutions and their interaction on chlorophyll a (mg/g f.w.) of Dianthus caryophyllus cv. Turbo cut flowers during 2020 and 2021 seasons PS1= STS at 0.4 ppm + sucrose 10%, PS2= AgNO3 at 10.0 ppm + sucrose 10%, HS10 sucrose 4%, HS2= boric acid at 200 ppm + sucrose 4%, HS3= 8­HQS at 300 ppm + sucrose 4%, HS4= AOA at 250 ppm + sucrose 4%, HS5= 8­HQS + AOA + sucrose 4%, HS6= boric acid + 8­HQS + sucrose 4%, HS70= boric acid + AOA + sucrose 4%, HS8= boric acid + 8­HQS + AOA + sucrose 4%, HS9= rosemary extract at 25% + sucrose 2%, HS10= thyme extract at 25% + sucrose 2%. Holding solutions (B) Pulsing solutions (A) PS1 PS2 DW Mean (B) First season (2020) Control (DW) 0.250 t 0.281 r 0.143 z 0.225 h HS1 0.267 s 0.323 o 0.247 t 0.279 g HS2 0.353 l 0.383 k 0.314 p 0.350 e HS3 0.480 d 0.463 e 0.327 no 0.423 b HS4 0.395 j 0.440 f 0.288 q 0.374 d HS5 0.329 mn 0.398 j 0.187 w 0.305 f HS6 0.416 h 0.429 g 0.430 g 0.425 b HS7 0.408 i 0.410 i 0.333 m 0.383 c HS8 0.636 b 0.642 a 0.601 c 0.626 a HS9 0.120 [ 0.212 u 0.170 y 0.167 j HS10 0.186 w 0.196 v 0.178 x 0.187 i Mean (A) 0.349 b 0.380 a 0.293 c Second season (2021) Control (DW) 0.255 r 0.279 p 0.139 y 0.224 h HS1 0.264 q 0.334 m 0.243 s 0.280 g HS2 0.355 l 0.403 k 0.330 m 0.363 e HS3 0.483 d 0.454 e 0.334 m 0.424 b HS4 0.406 jk 0.458 e 0.295 o 0.386 c HS5 0.329 m 0.417 gh 0.190 v 0.312 f HS6 0.420 g 0.413 hi 0.440 f 0.424 b HS7 0.405 jk 0.408 ij 0.323 n 0.379 d HS8 0.650 b 0.655 a 0.618 c 0.641 a HS9 0.131 z 0.213 t 0.169 x 0.171 j HS10 0.197 u 0.199 u 0.184 w 0.193 i Mean (A) 0.354 b 0.385 a 0.297 c Adv. Hort. Sci., 2023 37(3): 255­269 264 of Elgimabi (2014) on Rosa damascena cv. Trigintipetala and Bhanushree and Rao (2015) on Gerbera jamesonii cv. Lomborgini. The present study exhibited the beneficial role of certain chemicals used in pulsing or holding solutions of carnation cut flowers either individually or in com­ binations. The application of these chemicals resulted in a significant increase in the vase life of cut flowers, more than doubling its duration. Furthermore, these treatments also had a positive impact on water rela­ tions and chemical composition, including chlo­ rophylls a, b, carotenoids, and total sugars. It is well known that the vase life of cut carnation is conside­ red one of the most vital traits for florists (Panwar et al., 2022). Finger and Barbosa (2006) summarized the factors affecting the longevity of cut flowers as (1) their tender nature, (2) a lot of stresses leading to water uptake reduction, stored carbohydrates exhau­ stion and respiration increment (3) the harmful effects of ethylene. Otherwise, the vase life of cut flowers is affected basically by ethylene which enhan­ ces the senescence of many cut flowers as well as microorganisms which reduce the amount of water uptake by causing a vascular blockage (Zencirkiran, 2010). Halevy (1987) reported that carnation cut flowers are highly sensitive to ethylene either endo­ genously produced or exogenously applied. Carnation is known to be highly susceptible to the buildup of microorganisms in the vase solution or at the cut ends of the flower stems. This accumulation can result in blockage of the vascular system and ulti­ mately reduce the vase life of the flowers (Van Doorn Table 6 ­ Effect of pulsing and holding solutions and their interaction on chlorophyll b (mg/g f.w.) of Dianthus caryophyllus cv. Turbo cut flowers during 2020 and 2021 seasons PS1= STS at 0.4 ppm + sucrose 10%, PS2= AgNO3 at 10.0 ppm + sucrose 10%, HS10 sucrose 4%, HS2= boric acid at 200 ppm + sucrose 4%, HS3= 8­HQS at 300 ppm + sucrose 4%, HS4= AOA at 250 ppm + sucrose 4%, HS5= 8­HQS + AOA + sucrose 4%, HS6= boric acid + 8­HQS + sucrose 4%, HS70= boric acid + AOA + sucrose 4%, HS8= boric acid + 8­HQS + AOA + sucrose 4%, HS9= rosemary extract at 25% + sucrose 2%, HS10= thyme extract at 25% + sucrose 2%. Holding solutions (B) Pulsing solutions (A) PS1 PS2 DW Mean (B) First season (2020) Control (DW) 0.105 x 0.174 r 0.052 \ 0.110 j HS1 0.156 t 0.184 q 0.154 t 0.165 h HS2 0.206 p 0.251 n 0.260 m 0.239 f HS3 0.396 d 0.423 c 0.294 l 0.371 b HS4 0.217 o 0.357 ef 0.222 o 0.266 e HS5 0.185 q 0.300 k 0.143 u 0.209 g HS6 0.362 e 0.316 i 0.338 g 0.339 c HS7 0.294 l 0.309 j 0.332 h 0.312 d HS8 0.481 a 0.468 b 0.356 f 0.435 a HS9 0.079 [ 0.163 s 0.119 w 0.120 i HS10 0.088 z 0.098 y 0.128 v 0.105 k Mean (A) 0.234 b 0.277 a 0.218 c Second season (2021) Control (DW) 0.127 n­p 0.181 j­m 0.059 q 0.122 h HS1 0.172 k­n 0.181 j­m 0.168 k­n 0.174 g HS2 0.208 i­k 0.260 gh 0.240 g­i 0.236 e HS3 0.398 bc 0.437 ab 0.285 fg 0.373 b HS4 0.230 h­j 0.368 cd 0.215 h­k 0.271 d HS5 0.188 j­l 0.284 fg 0.144 l­o 0.205 f HS6 0.367 cd 0.324 d­f 0.324 d­f 0.338 c HS7 0.291 e­g 0.337 de 0.316 d­f 0.315 c HS8 0.485 a 0.466 a 0.350 cd 0.434 a HS9 0.088 pq 0.171 k­n 0.124 n­p 0.128 h HS10 0.095 o­q 0.130 m­p 0.123 n­p 0.116 h Mean (A) 0.241 b 0.285 a 0.214 c Sarhan et al. ‐ Preservative solutions’ effect on carnation‐cut flowers 265 et al., 1991). Hence, eliminating ethylene production and microorganism accumulation is a vital procedure to prolong the vase life of cut carnations. All solu­ tions containing sucrose showed a great influence compared to control (distilled water only) or solu­ tions with only 2.0% sucrose. This observation aligns with the well­known fact that sucrose, as a source of sugar, plays a crucial role in preservative solutions. The use of sucrose in pulsing solution or as a consti­ tuent of vase solution may extend the vase life of the flowers by improving the water balance, stimulating flower opening or by delaying the senescence due to lower synthesis of ethylene, as observed in cut carna­ tion (Finger and Barbosa, 2006). This study clearly highlights the significance of using integrated silver thiosulfate (STS) in post­harve­ st solutions. In this regard, treatment with silver thio­ sulfate complex (STS) delayed the senescence of atta­ ched and detached petals of Dianthus caryophyllus cv. Barbara (Ichimura and Niki, 2014). STS is highly mobile in the xylem of carnation flowers and may become a practical treatment for carnation flowers (Reid and Kofranek, 1980). Hashemabadi (2014) revealed that STS treatment extended the longevity of cut carnation ‘Tempo’ flowers by reducing oxidati­ ve stress, improving the antioxidant system, reducing bacterial populations and delaying flowering. Chemicals such as STS, are also effective at the recep­ tor level and prevent the binding of ethylene (Ebrahimzadeh et al., 2008). Using AgNO3 in a pulsing solution of carnation cut flowers showed a great influence. In this regard, Table 7 ­ Effect of pulsing and holding solutions and their interaction on carotenoids (mg/g f.w.) of Dianthus caryophyllus cv. Turbo cut flowers during 2020 and 2021 seasons PS1= STS at 0.4 ppm + sucrose 10%, PS2= AgNO3 at 10.0 ppm + sucrose 10%, HS10 sucrose 4%, HS2= boric acid at 200 ppm + sucrose 4%, HS3= 8­HQS at 300 ppm + sucrose 4%, HS4= AOA at 250 ppm + sucrose 4%, HS5= 8­HQS + AOA + sucrose 4%, HS6= boric acid + 8­HQS + sucrose 4%, HS70= boric acid + AOA + sucrose 4%, HS8= boric acid + 8­HQS + AOA + sucrose 4%, HS9= rosemary extract at 25% + sucrose 2%, HS10= thyme extract at 25% + sucrose 2%. Holding solutions (B) Pulsing solutions (A) PS1 PS2 D.W. Mean (B) First season (2020) Control (DW) 0.139 n 0.179 k 0.062 t 0.127 i HS1 0.179 k 0.207 i 0.123 pq 0.170 h HS2 0.189 j 0.211 hi 0.131 o 0.177 f HS3 0.230 de 0.237 ab 0.133 o 0.200 c HS4 0.210 hi 0.232 b­d 0.125 p 0.189 e HS5 0.188 j 0.214 h 0.119 q 0.174 g HS6 0.234 a­d 0.226 ef 0.232 cd 0.231 b HS7 0.222 fg 0.219 g 0.148 m 0.196 d HS8 0.236 a­c 0.238 a 0.234 a­d 0.236 a HS9 0.091 s 0.172 l 0.065 t 0.110 j HS10 0.110 r 0.135 no 0.086 s 0.110 j Mean (A) 0.184 b 0.207 a 0.133 c Second season (2021) Control (DW) 0.129 n 0.201 i 0.060 r 0.130 h HS1 0.182 j 0.207 h 0.127 n 0.172 g HS2 0.200 i 0.218 g 0.148 l 0.189 e HS3 0.216 g 0.230 de 0.142 m 0.196 c HS4 0.199 i 0.235 c 0.143 m 0.192 d HS5 0.182 j 0.235 cd 0.131 n 0.182 f HS6 0.225 f 0.216 g 0.246 b 0.229 b HS7 0.228 ef 0.209 h 0.158 k 0.198 c HS8 0.236 c 0.255 a 0.249 b 0.247 a HS9 0.089 p 0.179 j 0.079 q 0.116 i HS10 0.118 o 0.141 m 0.093 p 0.118 i Mean (A) 0.182 b 0.212 a 0.143 c Adv. Hort. Sci., 2023 37(3): 255­269 266 AgNO3 is used as an antimicrobial, since the Ag+ ion replaces the hydrogen cations (H+) on surface pro­ teins in the cell membranes of bacteria, which leads to loss of membrane integrity and causes cell death (Feng et al., 2000). This study exhibited a positive influence of 8­HQS addition to the holding solution in extending vase life, enhancing water relations (uptake and balance) and chemical constituents of cut carnation flowers, this effect may be explained by the positive role of 8­HQS as a germicide agent. Preservative solutions of carna­ tion cut flowers containing 8­HQS showed a strong inhibitory effect on fungi, yeasts and bacteria (El­ Ashwah, 2011). Numerous authors have corroborated this fact, supporting the use of 8­hydroxyquinoline sulfate (8­HQS) in vase solutions to effectively reduce microbial counts. One such study by Madhuri et al. (2016) demonstrated that the addition of 8­HQS resul­ ted in the lowest microbial counts in vase solutions. Kabari and Soleimandarabi (2019) on Alstroemeria cut flowers observed the lowest bacterial population in vase solution in the treatment of 200 8­HQS mg/l. In addition, 8­HQS is considered an ethylene synthesis inhibitor (Ebrahimzadeh et al., 2008). To explain the positive role of AOA in the present study, Son et al. (1995) reported that AOA appeared to inhibit the activities of arginine decarboxylase and ACC synthase. Ethylene production was significantly decreased by AOA at concentrations over 100 mg/l, the decline in ACC content was observed after using 100 or 150 mg/l AOA (Karimi et al., 2012). Amino­ oxyacetic acid (AOA) inhibits the synthesis of ethyle­ ne by reducing the competitive and irreversible acti­ vity of 1­Aminocyclopropane­1­carboxylic acid (ACC) Table 8 ­ Effect of pulsing and holding solutions and their interaction on total sugars (%) of Dianthus caryophyllus cv. Turbo cut flowers during 2020 and 2021 seasons PS1= STS at 0.4 ppm + sucrose 10%, PS2= AgNO3 at 10.0 ppm + sucrose 10%, HS10 sucrose 4%, HS2= boric acid at 200 ppm + sucrose 4%, HS3= 8­HQS at 300 ppm + sucrose 4%, HS4= AOA at 250 ppm + sucrose 4%, HS5= 8­HQS + AOA + sucrose 4%, HS6= boric acid + 8­HQS + sucrose 4%, HS70= boric acid + AOA + sucrose 4%, HS8= boric acid + 8­HQS + AOA + sucrose 4%, HS9= rosemary extract at 25% + sucrose 2%, HS10= thyme extract at 25% + sucrose 2%. Holding solutions (B) Pulsing solutions (A) PS1 PS2 DW Mean (B) First season (2020) Control (DW) 20.43 o 18.89 p 9.83 t 16.38 i HS1 23.29 n 22.69 n 23.30 n 23.09 h HS2 29.19 jk 23.43 n 29.95 j 27.52 f HS3 40.87 d 39.72 de 30.28 ij 36.96 b HS4 30.16 ij 33.40 g 27.68 l 30.41 e HS5 25.79 m 28.75 kl 21.26 o 25.27 g HS6 35.63 f 31.12 hi 39.01 e 35.25 c HS7 31.72 h 30.00 ij 32.91 g 31.55 d HS8 47.70 b 52.01 a 42.89 c 47.53 a HS9 11.02 s 12.82 r 10.55 st 11.46 k HS10 13.04 r 12.24 r 16.22 q 13.83 j Mean (A) 28.08 a 27.73 a 25.81 b Second season (2021) Control (DW) 21.39 o 19.20 p 9.98 u 16.86 h HS1 24.71 lm 23.77 mn 22.75 no 23.74 g HS2 31.08 hi 24.35 l­n 31.10 hi 28.84 e HS3 42.73 c 40.24 de 31.64 g­i 38.20 b HS4 29.13 jk 33.06 g 29.10 jk 30.43 d HS5 25.64 l 27.55 k 21.87 o 25.02 f HS6 34.95 f 31.76 g­i 38.94 e 35.22 c HS7 30.38 ij 28.63 k 32.61 gh 30.54 d HS8 48.48 b 54.67 a 41.86 cd 48.34 a HS9 11.23 s­u 12.88 rs 11.10 tu 11.74 j HS10 14.43 qr 12.06 st 16.01 q 14.17 i Mean (A) 28.56 a 28.02 b 26.09 c Sarhan et al. ‐ Preservative solutions’ effect on carnation‐cut flowers 267 synthase, reducing the amount of substrate for ACC oxidase, and therefore the conversion of ACC to ethylene (Finger and Barbosa, 2006). Boric acid also showed a promising influence when it was integrated into the holding solution of cut carnation flowers, this could be explained by its role in preventing the early rise in ethylene produc­ tion and considerably improving carnation vase life (Serrano et al., 2001). While many studies have highlighted the positive impact of natural extracts as a component in preser­ vative solutions, such as El­Ashwah (2011) on carna­ tion cv. Domingo, Khenizy et al. (2014) on Gypsophila paniculata L. “Perfecta,”, Zaky et al. (2014) on carna­ tion cv. America, and Hashemabadi et al. (2017) on carnation cv. White Liberty, our study did not obser­ ve a similar effect. The lack of satisfactory results in our study regarding the effectiveness of rosemary and thyme extracts may be attributed to the fact that these extracts were used in combination with sucro­ se at 2.0% only, without the addition of any germici­ dal agents to the solution. The presence of sugar in the solution without germicidal agents can promote the growth of microorganisms, since these extracts alone may not possess sufficient biocidal properties to effectively control microorganisms (Armitage and Laushman, 2003). Therefore, the outcomes of using natural extracts in our study were not as promising. In future research, it is recommended to consider incorporating germicidal agents along with these extracts, particularly when using extracts obtained through water extraction methods. This approach can help enhance the antimicrobial efficacy and ove­ rall performance of natural extracts as preservatives in cut flower solutions.Adam In conclusion, it is highly recommended to pulse carnation cv. 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