Postharvest Life of Cut Lisianthus Flowers as Affected by Silicon, Malic Acid and Acetylsalicylic Acid

INTRODUCTION

Short postharvest vase life and senescence are one of the most important problems on the cut flowers (Reid and Wu, 1992; Ichimura et al., 2002; Kader, 2003; Da Silva, 2003; Farokhzad et al., 2005; Reezi et al., 2009). Ethylene reduced the postharvest quality cut flowers, increased respiratory activity and loss of cell membrane fluidity. Inhibitors of ethylene biosynthesis such as SA, Si and MA reduced the effects of senescence cut flowers with reduced ethylene production (Nowak and Rudnicki, 1990; Epstein, 1994; Eason and Webster, 1995; Ansari and Misra, 2007; Mahdavian et al., 2007; Mba et al., 2007; Canakci, 2008; Karlidag et al., 2009; Kazemi et al., 2011b). Kazemi et al. (2010) reported that SA and MA reduced effects ethylene with reduced the number of bacterial in the solution and with decrease ACC-oxidase activity cause delay in senescence. Janda et al. (1999), Ananieva et al. (2002) and Metwally et al. (2003) reported that SA could increased disease resistance in plants. SA treatment alleviates ACO activity and sensitivity (Kazemi et al., 2011a). Therefore, In this study, the preservative effects of silicon, malic aid and acetylsalicylic acid and their interaction on the vase life of cut carnation flowers were studied.

MATERIALS AND METHODS

Plant material: The experiment was started on May 25, 2011 and chlorophyll content, Membrane stability, MDA content and ACO activity were measured. This study was on the effect of silicon, malic aid and acetylsalicylic acid treatments on vase life of lisianthus cut flowers, in a factorial test with complete randomized design with five replications. Cut flowers were harvested in half-open stage from local commercial greenhouses (Iran), in the morning and transported with appropriate covers immediately. Cut flower stems of lisianthus (Eustoma grandiflorum Mariachi. cv. blue (40 cm in length) were placed in solution containing silicon (0, 1.5 and 3 mM), acetylsalicylic acid (0, 1.5 and 3 mM) and malic aid (0, 1 and 2 mM) after cutting. Five cut flowers were placed in a 300 mL bottle with 250 mL of solution. Distilled water was used for the controls and placed in chambers at 19°C. The relative humidity was about 70% while 14 h photoperiod was maintained using fluorescent lamps with a light intensity of 15 μmol m^-2 s^-1 at the top of the corolla.

Vase life: The vase life of the inflorescence was considered terminated when 50% of the open flowers had wilted.

Chlorophyll content measurement: Total chlorophyll (a+b) content was measured by chlorophyll meter (SPAD-502, Minolta Co. Japan) which is presented by SPAD value. Average of 3 measurements from different spots of a single leaves was considered.

Determination of anthocyanin leakage: Anthocyanin leakage was measured based on the method of Poovaiah (1979).

Determination of ACC-oxidase activity: ACC-oxidase activity was measured based on the method of Moya-Leon et al. (2004).

Assays of MDA content (lipid peroxidation): Oxidative damage to lipids was measured based on the method of Heath and Packer (1968).

Superoxide dismutase (SOD) activity: The activity of superoxide dismutase was measured based on the method of Beauchamp and Fridovich (1971).

Carbohydrates determination: Carbohydrates were measured based on the method of Hassan (2005).

Determination of proline: Proline was quantified by using ninhydrin reagent and measured according to Bates et al. (1973).

Experimental design and statistical analysis: Experiment was arranged in a factorial test with complete randomized design with five replications. Analysis of variance was performed on the data collected using the General Linear Model (GLM) procedure of the SPSS software (Version 16, IBM Inc.). The mean separation was conducted by Tukey analysis in the same software (p = 0.05).

RESULTS AND DISCUSSION

Treatment with Si, ASA and MA showed remarkable decreases in Anthocyanin leakage and ACO activity as compared with the control (p = 0.05). The remarkable decreases in Anthocyanin leakage and ACO activity is compared as indicators of the reduction of membrane damage and increased membranes stability. Treatment with 1.5 mM silicon+1.5 mM acetylsalicylic acid+2 mM MA higher delayed the climacteric ethylene production, anthocyanin leakage and extended vase life of the carnation (Table 1), while treatment with Silicon 3 and 3 mM acetylsalicylic acid increased anthocyanin leakage and ACO activity and senescence (p = 0.05). In agreement with our result, Kazemi et al. (2011a) reported that treatment with salicylic acid significantly extends the vase life with reduced the anthocyanin leakage and ACO activity. Also, Kazemi et al. (2010) reported that treatment with malic acid significantly extends the vase life with decrease ACC-oxidase activity. Table 1 show that significant increases in chlorophyll content were recorded in MA treatments followed by the low concentration of Si and ASA (1.5 and 1.5 mM, respectively) (p = 0.05). Chlorophyll content decreased rapidly in present cut flower in solutions containing 3 mM silicon and 3 mM acetylsalicylic acid while flowers in the solutions containing 1.5 mM Si+2 mM MA+1.5 mM ASA showed the minimum decrease in chlorophyll content from day 18 (p = 0.05).

Table 1:	Mean comparisons of chlorophyll content, vase life, MDA, SOD activity, membrane stability and ACC-oxidase activity in Si, ASA and MA treatments and their interaction

Table 2:	Effect of MA with or without Si and SA on carbohydrate content (in mg^-1 DW) for petals and stems of lisianthus cut flowers

The application of different Si, ASA and MA concentrations delayed the senescence with increase SOD activity and decreased accumulation MDA and proline significantly as compared to control (p = 0.05). The best treatment in this regards was 1.5 mM Si+2 mM MA+1.5 mM ASA. There were no significant difference between 1 mM MA and control (p = 0.05). These findings are in agreement with those reported by Jamali and Rahemi (2011), Kazemi et al. (2010) and Kazemi et al. (2011a, d) they reported that treatment with Si, SA and MA significantly extends the vase life with reduced the MDA, proline content and increasing chlorophyll content and superoxide dismutase activity. According to Table 1, fructose, glucose and sucrose were the main soluble carbohydrates in petals and stems of cut lisianthus (Table 2). The results indicate that the carbohydrate content significantly increased as a result of using MA (p = 0.05). Flowers treated with 2 mM MA solution significantly increased carbohydrate content in cut flowers (p = 0.05). Glucose was the major component in the petals as well as in stems but generally, its value was higher than in stems (Table 2). In agreement with our result, Kazemi et al. (2011c) reported that treatment with MA and SA significantly extends the vase life with reduced the anthocyanin leakage and ACO activity. According to Table 1, significant differences were observed among the different treatments in term vase life (p = 0.05). Among the different Si, ASA and MA concentrations, 1.5 mM Si+1.5 mM ASA+2 mM MA with average vaselife of 18 days was better than other treatments and as compared to the control treatment it increased the vaselife more than 12 days (Table 1). These findings are in agreement with those reported by Jamali and Rahemi (2011), Kazemi et al. (2010) and Kazemi et al. (2011a, c, d). They reported that treatment with Si, SA and MA significantly extends the vase life. These findings are similar to previous results reported by Jamali and Rahemi (2011) and Kazemi et al. (2011a, b, c, d).

CONCLUSION

In the present study, results our showed that treatment with Si, MA and ASA extends the vase life of cut carnation flowers. Also, Si, MA and ASA reduced chlorophyll total degradation and preserved chlorophyll total content.