Postharvest physiology
Behzad Kaviani; Mohammad Reza Safari Motlagh; Sara Hataminejad
Abstract
Introduction Chrysanthemum (Chrysanthemum morifolum L.) is one of the most important cut flowers in the world, which currently ranks second in the world after rose in terms of economy and cultivation. Stem end blockage and water stress are two problems in decreasing the vase life of chrysanthemum ...
Read More
Introduction Chrysanthemum (Chrysanthemum morifolum L.) is one of the most important cut flowers in the world, which currently ranks second in the world after rose in terms of economy and cultivation. Stem end blockage and water stress are two problems in decreasing the vase life of chrysanthemum cut flowers. Cut flowers undergo physiological and biochemical alterations which often lead to an early senescence. Steps to delay the senescence process rely on consideration of many aspects of handling process particularly the preservative solution that will influence the quality and longevity of the flowers. Many flowers are harvested before they are fully developed, to ensure a long postharvest life and to minimize mechanical damages which may occur during handling. Many researches have been performed to prolong the vase life of chrysanthemum cut flowers with different treatments like essential oils, organic acids and nanoparticles. Essential oils are aromatic oily liquids obtained from some aromatic plant materials. In vase solution, microorganisms cause stem obstruction and accelerate the aging of petals. Microorganisms and their toxic products restrict water uptake by blocking the end of the stem. Water balance, which is an important factor in maintaining the quality and longevity of cut flowers and the inability to uptake water are the main causes of senescence. The presence of disinfectants in the vase solution prevents the growth of microorganisms, protects the vessels against disintegration, and ultimately increases the vase life. Most of nanoparticles have antibacterial effects and their application in vase solution hinders microorganism growth and vascular blockage. Nanoparticles have high area-to-volume ratio, high efficiency, and low toxicity. Some nanoparticles penetrate into the cells of bacteria, disrupt their respiration chain, and cause disorder in their cell division, thereby killing them. They also inhibit the accumulation of bacteria in vase solution and stem end of cut flowers. Various studies have reported the positive impact of nanoparticles on decreasing microbial load, reducing transpiration from leaf surface, and preserving water uptake. Studies on postharvest longevity of chrysanthemum cut flowers using these compounds is low. Therefore, the aim of the present study was to evaluate the effect of orange spring essential oil, fulvic acid and cupper nanoparticles on vase life and some physiological parameters of chrysanthemum cut flowers. Materials and MethodsThe experiment was performed based on randomized completely design with three replicates in order to investigate the effect of different levels of fulvic acid (50, 100 and 150 mg l–1), orange spring essential oil (10, 30 and 50%) and copper nanoparticles (5, 10 and 20 mg l–1) in comparison to control (distilled water + 3% sucrose + 30 mg l–1 8-hydroxyquinoline sulphate) on postharvest parameters of chrysanthemum cut flowers. Measured parameters included vase life, solution uptake, vase solution bacterial population, stem end bacterial population, decreasing the brix degree, decreasing fresh weight, dry matter, total chlorophyll content, carotenoid content, protein content, and peroxidase and superoxide dismutase activity. Data were analyzed by SPSS statistical software package and means were compared with the LSD test at the probably level of 95%. Results and DiscussionAccording to the obtained results, the effect of treatments on improving the quality characteristics of chrysanthemum cut flowers after harvest was significant. Results showed that the high vase life (16.33-17.00 days) was obtained with all three copper nanoparticles concentrations. The vase life of chrysanthemum cut flowers was extended to 17 days by the addition of 20 mg l–1 copper nanoparticles in preservative solution in compared to control with 14 days’ vase life. Least solution bacteria colonies was obtained through the use of 5 mg l–1 copper nanoparticle. On the other hand, least stem end bacteria colonies was obtained using 10 and 30% orange spring essential oil. Solution uptake in these treatments was high, too. The effects of different treatments on some other physiological traits and antioxidant enzymes activity were measured. Many studies have been carried out on the effect of essences (herbal extracts) as antimicrobial agents on prolonging the vase life of cut flowers. In most of these studies, these essences could prolong postharvest life. Essences have been studied with the intension of incorporating them into integrated pest management to avoid or reduce the use of synthetic bactericides and fungicides. They also have antioxidant properties. Application of herbal extracts improved water absorption in rose cut flowers by preventing the vessel obstruction. The above results are similar to the results of this study. In most cases, when the cut flowers were treated with nanoparticles, they exhibited longer vase life, higher water uptake, and lower stem-end bacteria than the control flowers.
Postharvest physiology
S.A. Razi; D. Hashemabadi; B. Kaviani
Abstract
Introduction
Carnation (Dianthus caryophyllus L.) is one of the most important cut flowers of the world. This flower is sensitive to postharvest ethylene and water stress and has short vase life. The use of retardants or inhibitors compounds of ethylene is an effective way to increase the postharvest ...
Read More
Introduction
Carnation (Dianthus caryophyllus L.) is one of the most important cut flowers of the world. This flower is sensitive to postharvest ethylene and water stress and has short vase life. The use of retardants or inhibitors compounds of ethylene is an effective way to increase the postharvest life of carnation. Polyamines including putrescine (diamine), spermidine (triamine) and spermine (tetraamine) as new groups of plant growth regulators that are involved in various processes including increasing cell division, increasing enzyme biosynthesis, regulation of different developmental stages, differentiation, flowering, embryogenesis, rooting and maturity. These compounds exert their anti-aging properties by competing with ethylene production. Polyamines are low molecular weight organic compounds with aliphatic nitrogen groups that have different hydrocarbon rings and two or more amino groups (positive charge agents). These organic compounds bind to cell membranes, nucleic acids, and other macromolecules and are involved in chromatin formation, ion channel control, free radical neutralization, and gene expression. Cell membrane strength and stability play an important role in increasing the post-harvest life of horticultural crops. Putrescine is the major polyamine in plants, which is a precursor to the synthesis of spermidine and spermine, and its positive effect on increasing the vase life of some cut flowers has been reported. Vase life of cut flowers of chrysanthemum, rose and gladiolus was increased by application of putrescine. The purpose of the present research was to increase the vase life of cut carnation flower using different putrescine concentrations and application methods.
Materials and Methods
A factorial experiment based on completely randomized design with 10 treatments in 3 replicates, 30 plots and 150 cut flowers was employed to investigate the effect of different concentrations of putrescine (0.01, 0.02 and 0.05 mM) and its application methods (continuous, pulse and spray) on vase life of cut carnation (Dianthus caryophyllus L.) flowers. Some other traits such as water uptake, dry mater percentage, decrease of fresh weight, the content of leaf chlorophyll and sepal carotenoid, POD and SOD enzymes activity, MDA, decrease of °Brix (sucrose percentage in flower stalk, soluble sugar in stem end and sepal), ionic leakage, ethylene were also measured. The statistical analysis of data was performed using SAS. The least significant difference (LSD) test at P < 0.05 was used for comparisons of different means of various treatments.
Results and Discussion
Results showed that the maximum vase life was recorded in cut flowers treated with 0.02 mM putrescine as spray application. The lowest ethylene production, the highest water uptake and superoxide dismutase enzyme activity was observed in 0.02 mM putrescine treatment. Some physiological parameters and enzymatic activity were also evaluated. The control treatment generally yielded the minimum values for most of the observed traits. Factors such as water stress, reduced carbohydrate levels, increased ethylene production, and the presence of microorganisms play pivotal roles in reducing the vase life of cut flowers. Polyamines are key in counteracting these stressors and delaying aging. They fulfill this role by fortifying the plasma membrane, suppressing the activity of hydrolytic enzymes, and inhibiting ethylene synthesis. Additionally, polyamines bind to cell wall pectin, safeguarding them from detrimental cell wall enzymes, including pectinase. They further impede flower maturation by inhibiting the production of essential enzymes required for ethylene synthesis and by dampening ethylene activity. Increasing polyamines by inhibiting lipid peroxidation is probably one of the mechanisms responsible for the anti-aging effect of polyamines. Polyamines have antioxidant properties so they reduce the number of oxygen free radicals and the permeability of plasma membranes by decreasing the activity of lipoxygenase, thereby increasing the vase life and quality of flowers. The use of polyamines to increase the vase life of some cut flowers has been reported, which the results of the present study are consistent with the results of these studies. Treatment of 20 mg l–1 spermine and 10 mg l–1 putrescine had the greatest effect on increasing vase life and reducing senescence of cut Alstroemeria flowers. Spermidine delayed the aging of carnation flowers. In cut rose cv. ‘Doles Vita’ flowers, the use of polyamines increased vase life. Treatment of 2 mM spermidine was the most suitable treatment to increase the vase life of cut carnation cv. ‘Red Corsa’ flowers. Cut rose flowers treated with humic acid and putrescine had the highest vase life compared to the control. Polyamines increased the vase life of cut gladiolus flowers by increasing the stability of plasma membranes. The addition of polyamines to the carnation flower preservative solution reduced their aging and prevented the production of ethylene. Polyamines appear to increase vase life in cut flowers by inhibiting ACC-synthase activity and reducing ethylene production. SOD, POD and catalase (CAT) enzymes, as antioxidant compounds, protect plants against reactive oxygen species and free radicals. Polyamines neutralize free radicals and are also involved in the synthesis of enzymes. Binding of polyamines to proteins protects them from the damaging effects of reactive oxygen species and free radicals. Treatment of 20 mg l–1 spermine increased the activity of SOD enzyme in cut Alstroemeria flowers. Concentrations of 10 and 20 mg l–1 putrescine and spermine significantly increased catalase activity. Spermidine treatment significantly increased the activity of free radical scavenging enzymes such as SOD and CAT. Putrescine in sunflower stimulated the catalase enzyme. At the first onset of senescence, antioxidant enzymes such as POD increase in petal cells to reduce the damaging effects of reactive oxygen species.
