Different Fresh-keeping Effects of Sugar Aspirin and Vc on Cut Rose Flowers

Jianjun LIU Lijun CHENG Zebing SHU Shimin WANG Rui SHI

Abstract [Objectives]This study was conducted to develop environmentally-friendly effective vase solutions for cut rose flowers convenient for ordinary household use. [Methods]The vase life， flowering stage， flower diameter variation， petal water content， and soluble protein and malondialdehyde contents were determined on cut rose flowers regularly during the vase period， to study the fresh-keeping effects of the vase solutions prepared from such three components as sugar， aspirin and Vc according to L9（33） orthogonal table design on cut rose flowers during the vase period. [Results]20 g/L white granulated sugar+460 mg/L aspirin+50 mg/L Vc was the best combination in this study. [Conclusions]This study provides a reference for the research on the fresh-keeping vase solutions of household cut rose flowers.

Key words Sugar; Aspirin; Vc; Cut rose flowers; Household fresh keeping

Chinese rose （Rosa hybrida） is one of the top ten traditional famous flowers in China[1]. It is widely loved by people from all over the world because of its wide variety， colorful colors， and full and elegant flowers. It is known as the "Queen of Flowers"[2]， and has become one of the world's four major cut flowers[3]. The floral language of "peace"， "friendship" and "love" make cut rose flowers very important in ceremonial occasions[4]， and its splendid figure adorns our home even more colorful.

At present， the preservation of cut rose flowers focuses on the research of chemical preservatives， but the commonly used 8-hydroxyquinoline as a microbicide and silver thiosulfate as an ethylene inhibitor have certain toxicity， and cause pollution to the environment easily[5]. Therefore， in recent years， a few scholars have begun to study environmentally friendly cut rose preservatives. For example， Yang et al.[6]used sucrose， penicillin， citric acid， Al2（SO4）3 and 6-BA to prepare silver-free preservatives， which made the bottle life of Rosa "Salman" reach 10.6 d， and Xu et al.[7]used 75% ethanol for pretreatment and studied the fresh-keeping effects of sucrose， salt， white vinegar， Vc and aspirin on three kinds of fresh cut rose， Gerbera jamesonii Bolus and Dianthus caryophyllus L. The optimal treatment made cut rose flowers' vase life up to 8 d. However， there has been no report on the research on cut rose flower vase solutions that are convenient for ordinary household use and environmentally friendly. In view of the current household fresh-keeping status of cut rose flowers， in this study， orthogonal tests were designed to investigate the different fresh-keeping effects of household vase solutions prepared from three components of sugar， aspirin and Vc on cut rose flowers during the household bottle-keeping period， aiming to develop a convenient， environmentally-friendly and effective fresh-keeping vase solution for cut rose flowers.

Materials and Methods

Experimental materials

Cut rose flowers of variety "Xiangbinjin" in the budding stage were bought from Zhaotong Qicai Flower Shop. Robust flower branches with buds thereon， similar in the degree of flower head openness and stem uprightness， were selected as the test flowers.

The used reagents， edible white sugar， Paracetamol， Caffeine and Aspirin Powder （with aspirin as the main ingredient， the content of which was 230 mg/bag）， and vitamin C tablets （with the Vc content of 50 mg/tablet）， were commercially available.

Experimental design

The purchased cut rose flowers were obliquely cut in the water to remove the base parts of the flower branches， leaving 30 cm. Extra leaves were cut off， leaving only the top pair of compound leaves. The cut flowers were inserted into the vase solutions prepared according to the L9（33） orthogonal table design （Table 1）， with S1 tap water as the control （CK）. Among the 9 treatments， 3 replicates were set for each treatment， and 3 cut rose flower branches were inserted in each replicate vase for testing. During the tests， the relative humidity was 30%-60%， the indoor temperature was （15±3） ℃， and the cut flowers were placed under indoor astigmatism. Various morphological and physiological indexes of cut rose flowers were measured regularly.

Determined indexes and determination methods

Determination of vase life and flowering stages of cut rose flowers

According to the 7-level grading standard of cut rose blooming， the blooming stage of cut flowers was observed and recorded every day. Stage 0 is the bud stage with sepals erect; stage 1 is the bud stage with sepals horizontal; stage 2 is the bud blooming stage with sepals drooping and the outer layer petals becoming loose; stage 3 is the initial blooming period with the outer petals unfolded; stage 4 is the early blooming period with multiple petals unfolded; stage 5 is the end of blooming with the flower heart exposed; and stage 6 is the wilting period， with petals turned over or beginning to wilt， turning blue， showing burnt edges[8]. The vase life is the number of days from the date of vase insertion to the day before the flowering grade of cut rose flowers reaches grade 6[9].

Flower diameter measurement

A vernier caliper was used to measure the maximum opening diameter of the cut rose flowers every day as the flower diameter value of the day. With the first day of vase insertion （that is， the data before the cut rose flower was treated with the vase solutions， the same below） as 100， the flower diameter variation during vase culture was calculated[10].

Determination of petal water content

The petal water content was determined referring to the method for determination of the total water content in plant tissue[11]every other day.

Determination of the soluble protein content in petals

The Coomassie brilliant blue G-250 staining method[11]was used for the determination of the solution protein contents every other day.

Determination of malondialdehyde content in petals

The thiobarbituric acid method[11]was used to determine the malondialdehyde content every other day.

Analysis of the experimental data

Software Excel 2010 and SPSS 25.0 were used to statistically analyze the experimental data and draw charts.

Results and Analysis

Effects of various treatments on the vase life and flowering stage of cut rose flowers

The vase life is the most intuitive expression of the ornamental quality of vase cut flowers in vases[11]. It can be seen from Fig. 1 that the vase life of cut rose flowers treated with S9 was the longest， reaching 10.5 d， which was 4.5 d longer than treatments S1 （CK） and S3; treatments S2， S4 and S5 had the second longest vase life， which was 3.3 d longer; and treatment S8 prolonged the vase life by 3 d; and finally， treatments S6 and S7 prolonged the vase life by 1.3 d. According to Duncan's new double-range method， the vase life of cut rose flowers treated with S9 was significantly different from those treated with S1 （CK） and S3 （P<0.01）.

During the vase period， the longer the cut rose flowers maintain their blooming period （flowering stage 4 and 5）， the higher the ornamental value of the cut flowers is[9]. Fig. 1 shows that treatment S9 had the longest blooming period， up to 7 d， which was 4 d longer than treatment S1 （CK）; treatment S5 maintained the second longest blooming period， which was 6 d; the blooming period of treatments S2， S4 and S8 was 5 d; that of treatment S6 and S7 was 4 d; and treatment S3 maintained the shortest full blooming period of the cut rose flowers， only 2 d， which was 1 d less than treatment S1 （CK）. After the Duncan's new multiple range test， it was concluded that the blooming period of cut rose flowers maintained by S9 was significantly different from those maintained by S1 （CK）， S2， S3， S4， S6， S7， and S8 （P<0.01）.

Effects of various treatments on the variation of cut rose flower diameter

The diameter of cut rose flowers changes from small to large and then to small， reflecting the process of flowers from first blooming， full blooming to wilting and senescence[9]. Fig. 2 shows that the overall trend of the flower diameter of all cut rose flowers treated with vase solutions was to increase gradually in the early stage and slowly decrease in the later stage as the vase time increased. From the perspective of the period of keeping the flower diameter of cut rose flowers increasing， compared with 5 d in treatment S1 （CK）， other treatments all prolonged the period to varying degrees. Among the vase solution treatments， treatment S9 maintained the longest time， reaching 9 d， which was 4 d longer than treatment S1 （CK）; secondly， treatments S2， S4， and S5 maintained 8 d; treatments S6 and S8 maintained 7 d; and treatments S3 and S7 maintained 6 d. When comparing from the flower diameter increase of cut rose flowers， the flower diameter increase of treatment S9 ranked first with 109.65%， and those of treatments S5， S2， S4， S8， S6， S7， S3 and S1 （CK） were 91.83%， 73.82%， 72.06%， 63.51%， 63.37%， 60.22%， 47.39%， and 30.73%， respectively. In summary， from the two aspects of the time of keeping the diameter of cut rose flowers increasing and the increase in cut rose flower diameter， the effects of treatment S9 were better than other treatments.

Effects of various treatments on water content variation in petals of Rosa cut flowers

Cut flowers' high water content can maintain the normal operation of all physiological metabolism in the body. If the water content is deficient， cells will lose tension， and wilting and dimness will appear on the petals， making the cut flowers lose their ornamental value[12]. As shown in Fig. 3， the water contents of petals of all cut rose flowers treated with the vase solutions were maintained at more than 83% during the entire vase culture period， and all showed a trend of rising first and then falling. In terms of the time of maintaining the water content of petals increasing， treatment S9 was the best， and maintained the increase until the 5th d， which was 2 d longer than treatment S1 （CK）. The remaining 7 treatments and S1 （CK） treatments only maintained until the 3rd d. In terms of the daily average water contents of the petals of cut roes flowers treated with various vase solutions during the vase culture period， treatment S1 （CK） was 86.61%， and only treatments S8， S9 and S2 had daily average water contents of petals higher than treatment S1 （CK）， which were 87.08%， 86.98% and 86.76%， respectively. In summary， the cut rose flowers treated with S9 during the vase culture period maintained the longest growth and higher daily average value.

Effects of various treatments on solution protein content variation in petals of cut rose flowers

Soluble protein is an indispensable nutrient for plants， which can keep more water in cells and provide more nutrients for cells to protect plants. It is regarded as an important resistance index[13]. It can be seen from Fig. 4 that the soluble protein content in petals of cut rose flowers treated with each vase solution showed a trend of first increasing and then decreasing with the passage of time. From the perspective of the increase in the soluble protein content in petals of cut rose flowers treated with each vase solution， treatment S1 （CK） was the lowest， with an increase of only 15.4%; treatment S9 had the largest increase of 48.92%， followed in order by treatments S4， S2， S5， S3， S6， S8 and S7， with the increases of 45.61%， 41.87%， 34.72%， 33.68%， 33.04%， 30.81%， and 15.82%， respectively. From the daily average value of the soluble protein content in petals of cut rose flowers treated with each vase solution during the vase culture period， treatment S9 was still the highest， at 110.59 mg/g， 27.8 mg/g higher than treatment S1 （CK）， followed sequentially by treatments S5， S2， S6， S4， S8， S7， S3 and S1 （CK）， the daily average values of which were 107.96， 102.24， 102.15， 101.93， 94.86， 91.58， 85.13， and 82.78 mg/g， respectively. Based on the increase in the soluble protein content in petals of cut rose flowers and the daily average value during the vase culture period， compared with treatment S1 （CK）， all other treatments promoted the synthesis of soluble protein in cut rose flowers in the early stage of vase insertion， and maintained a high level during the entire vase culture period. Among them， treatment S9 had the best effect.

MDA is one of the main products of membrane lipid peroxidation in the process of plant senescence. Its content can reflect the severity of membrane damage and can be used as a sign to evaluate senescence[14]. The changes of MDA content in the petals of cut rose flowers treated with all vase solutions are shown in Fig. 5. All of them first decreased and then decreased， that is， the vase solution treatments delayed the membrane lipid peroxidation in cut rose flowers and reduced MDA generation in the early stage of vase insertion. Among them， treatments S5 and S9 maintained the MDA content in petals of cut rose flowers decreasing for the longest time， which was 5 d， and other treatments maintained the decrease for 3 d. From the daily average value of MDA content in the petals of cut rose flowers treated with each vase solution， treatment S9 was the lowest at 17.18 nmol/g， followed by treatments S4 and S1 （CK）， respectively， at 17.65 and 19.18 nmol/g， and the MDA contents of the remaining treatments S2， S5， S6， S7， S8 and S3 were， respectively， 19.64， 19.99， 20.32， 20.44， 20.48 and 21.85 nmol/g， all of which were higher than S1 （CK）. It can be seen that treatment S9 was most effective among various treatments in slowing down the membrane lipid peroxidation of cut rose flowers， maintaining the stability of membrane quality， and delaying the senescence of cut flowers.

Conclusions and Discussion

In this study， three household daily necessities， edible white sugar， Paracetamol， Caffeine and Aspirin Powder （with aspirin as the main component） and Vc tablets， were used to prepare household vase solutions according to the L9（33） orthogonal table design to study the fresh-keeping effects of vase solutions on cut rose flowers. Among them， edible white granulated sugar is a glycogen material， which can provide nutrition and energy for cut rose flowers and maintain the physiological and biochemical process of cut flowers after harvest[15]; the main component of Paracetamol， Caffeine and Aspirin Powder is aspirin， which produce salicylic acid after being dissolved in water， while salicylic acid can reduce the respiratory metabolism of cut flowers， alleviate the water shortage of flowers， reduce flower membrane damage， and improve the ornamental value of cut flowers during the vase period[16]; and Vc can reduce vase solutions' pH values and inhibit the growth of microorganisms， and can simultaneously eliminate the free radicals produced during the senescence of cut flowers and delay the senescence of cut flowers[17].

According to the experimental results， treatment S9 achieved the longest vase life of the cut rose flowers， reaching 10.5 d; it maintained the longest blooming period， reaching 7 d; the time of keeping the diameter of the flowers increasing was the longest， reaching 9 d， and the increase was the largest， reaching 109.65%; and treatment S9 maintained the petal water content increasing and the MAD content decreasing for longest time of 5 d， and exhibited the largest petal soluble protein content increase of 48.92% and the largest daily average value of 110.59 mg/g， and the lowest daily average MAD content of 17.18 nmol/g.

In summary， in terms of all the experimental results， the household vase solution S9 prepared from 20 g/L edible white sugar， 460 mg/L aspirin and 50 mg/L Vc had the best fresh-keeping effect on cut rose flower "Xiangbinjin". It maximized the vase life and blooming period of cut rose flowers， and was most effective in promoting flower opening degree and time， regulating cut flower water metabolism， maintaining the maximum growth of petal water content， reducing petal membrane damage and maintaining the normal physiological function of cell membrane， maximizing the content of soluble protein in petals to delay the senescence of cut flowers and increasing the ornamental value of cut flowers. It was the best combination for this study. As there are many varieties of cut rose flowers， whether the household vase solution S9 is also suitable for the preservation of other varieties of cut rose flowers at home remains to be further studied in the future.

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