Effect of Some Preservative Solutions on Vase Life of Helianthus annuus

INTRODUCTION

Among horticultural exports, cut flowers are one of the most important sources of national wealth. Commercial floriculture has long been recognized as an economic industry that generates jobs and significant foreign exchange in a variety of places across the world. Egypt, with its favorable environmental circumstances, might be a good source of cut flowers for both domestic and international markets. There are a variety of decorative cultivars of the frequently farmed sunflower (Helianthus annuus L.). Cut flowers, potted plants, and gardens are all popular uses for ornamental sunflowers (Kaya et al., 2012). As a result, the ornamental sunflower's breeding is dependent on its application. Breeding for acceptable plant architecture and morphology, floral performances, blossom length, and other features is a common feature of all ornamental sunflowers (Atlagi et al., 2005). The annual cultivated sunflower is Helianthus annuus L. The Helianthus genus had 67 species. Helianthus is derived from the Greek words "helios" and "anthos," which mean "sun" and "flower," respectively. The annual sunflower is a member of the Asteraceae family, which is the biggest flowering plant family (Parmeshwar, 2010). As a result of breeding operations for the cut flower industry, new varieties of attractive sunflowers have been developed. Because of its unusual shape and many hues of flowers, these cultivars have made the sunflower a well-known commodity in flower arrangements, adding energy and activity to the environment. There is minimal research on postharvest technologies for this species when grown for decorative purposes because it is a new product in the floriculture marketplace (Nascimento et al., 2019). Sunflower (Helianthus annuus L.) is a relatively new crop among world field crops, and it is unique in that it has a wide range of applications. It's been used as an oilseed crop, confection, and bird seed, and more recently as an ornamental plant for home gardens and cut flowers in a variety of colours (Schoellhorn et al., 2003). The decorative sunflower (Helianthus annuus L.) has marketing value as a cut flower and ornamental plant due to the beauty of its inflorescence, which comes in a variety of shapes and colours that correspond to a wide range of customer tastes (Baldotto and Baldotto 2015). Sunflower crops have a short growing cycle and hence provide a quick return on investment. It also has a high level of propagation, control, and photosynthetic efficiency. Sunflower is one of the most widely grown crops, adapting well to a variety of settings (Da Silva et al., 2018).

For improving the longevity of cut flowers, several solutions were used as pulsating or preservative solutions. Those chemicals are very expensive and the most dangerous preservative for humans, causing irritation to the skin, eyes, and respiratory tract. Using natural items as safe materials in vase solutions did not receive much attention (Mohamed, 2015). For large-scale applications, an appropriate approach for vase life extension that uses easy-to-use, natural, safe, and economical ingredients is always critical (Soleimany-Fard et al., 2013). Essential oils (EOs) are natural products derived from plant materials that can be utilized as natural additions to a variety of crops because to their antibacterial, antifungal, antioxidant, and anticarcinogenic qualities (Teissedre and Waterhouse, 2000).

Silver nanoparticles are one of the most studied nanomaterials, with unique optical, catalytic, sensing, and antibacterial capabilities that have captivated scientists (Wu et al., 2012). Among the nanoparticles, silver nanoparticles are particularly appealing because of their antibacterial sterilization properties (Solgi, 2014). Nanometer-sized silver (Ag+) particles (NS) are thought to suppress bacteria and other microorganisms more effectively than Ag in various oxidation states, Ag, Ag+, Ag2+, Ag3+, because of their high surface area to volume ratio (Furno et al., 2004).

This research examined the effects of several materials as preservative solutions that are both effective and safe for humans and the environment silver thiosulphate (STS), Nano-silver thiosulphate (NST), 8-hydroxyquinoline sulphate (8-HQS), Mint oil, and Thyme oil). The goal of this study was to use essential oils and certain treatments to enhance the vase life of sunflowers, And also, to determine the most effective concentration among the components used in the production of the highest quality cut flowers with the longest vase life.

MATERIALS AND METHODS

The present study was conducted at Antoniades Research Branch, Ornamental Plants and Landscape Gardening Res. Dept., Hort. Res. Inst., ARC, Alexandria, Egypt during the two successive seasons of   2020 and 2021 in June.

Preparation of cut flowers

Cut flowers Helianthus annuus L. cultivar "Sunbright Supreme" gotten from a well-known commercial nursery arly in the morning, at a consistent length and weight was then wrapped in a polyethylene sheet and swiftly transported to the laboratory, where it was kept at ambient temperature with normal relative humidity and lit by a white fluorescent lamp. All stems were cut back even to 40 cm and the leaves of the lower third part of stems were removed in order to avoid contamination in solutions of postharvest treatments as recommended by (Khimani et al., 2005). For 24 hours, clipped flowers were placed in plastic containers with pulsating liquids containing various chemicals.

Compounds used in the experiments

• Control (distilled water) control cut flowers were pulsed in 1Liter tap water at the same time of the other treatments.
• Silver thiosulphate (STS) at 0.06  and 0.08 mM + 3% sucrose.
• Nano-silver thiosulphate (NST) at 5 and 7.5 mg/l.
• 8-hydroxyquinoline sulphate (8-HQS) at 200 mg/l + 2% sucrose.
• Mint oil at 50 and 75 mg/l + 3% sucrose.
• Thymeoil at 50 and 75 mg/l + 3% sucrose.

Pulsing solutions

For 24 hours, the flowers were pre-treated with pulsing solutions made from different treatments of Silver thiosulphate (STS) (0.06 and 0.08 mM + 3% sucrose), Nano-silver thiosulphate (NST) at (5 and 7.5 mg/l + 3% sucrose), 8 hydroxyquinoline sulphate (8-HQS) at (200 mg/l + 2% sucrose), Mint oil at (50 and 75 mg/l + 3% sucrose), and Thyme oil at (50 and 75 mg/l + 3% sucrose).

Holding solutions

The flowers were moved to Vases which contained 300 ml of distilled water to calculate the vase life and the tested parameters. Every three days, the water in the vases was replenished, and roughly 1 cm of the stems were clipped. Vases were exposed every day at night to light from a white fluorescent lamp for 12 hours and during the day were exposed to daylight. The room temperature was (33°±1 °C) for first experiment, while for the second (25°±1 °C), relative humidity (R.H.) was about (60- 70%).

Experimental layout

The treatments were arranged in a Completely randomized designed (CRD) experiment with three replicates for each treatment each replicate consisted of one glass bottle (vase) in which (3 cut sunflowers) were placed. Then each treatment was represented by 9 cut flowers/ treatment.

The collected data:

Sunflowers vase life (days):

The number of days on the vase until the petals wilt and the stem collapses was regarded as the end of the vase life of sunflowers. (Clark et al., 2010).

Total fresh weight (g):

The average fresh weight of fresh stems carrying leaves and the flowers was calculated (Barakat, 2013).

Water uptake (g):

The volume of water uptake was calculated by subtracting the volume of water evaporated from a control bottle without cut flowers and the amount of water decreased in bottles containing flowers (Zamani et al., 2011).

Total dry weight (g):

At the fading stage the cut flowers were oven dried at 75 ℃ for 48 hours.

Flower diameter

The flower diameter was measured in centimeter at the full opening stage. The average was calculated and recorded.

Chemical analysis:

Chlorophyll (chlorophyll a, b and total) (mg/ g fresh weight) were determined in fresh leaves of sun flower, chlorophyll was determined according (Dawood, 1993). and Carotenoids content in Flowers (mg/100g FW) were determined calorimetrically in 5 g of the fresh petals according to the method described by (Alan, 1994). and reducing sugars content (mg g-1 dry weight) according to Miller (1959) at the end of the vase life of the control. Total sugar content in flowers (%)  was calculated in dry flowers. Sugar were extracted from five grams of flowers and the total sugars were determined colorimetrically using phenol and sulphuric acid according to (Malik and Singh, 1980). Reducing sugar (%) was determined by Nelson arsenate – molybdate colorimetric method (Dubois et al., 1956).

Statistical analysis

Data collected from the current research were statistically analyzed and comparison between means was done according to Duncan Multiple Range Test at probability level 05.0 (Little and Hills, 1978)

RESULTS

A) Physical characters

1-1 Total fresh weight

The effect of some chemicals and essential oil extracts on total fresh weight (g) of sunflower (Helianthus annuus L.) cut flowers are presented in Table (1). Results, generally, showed that all used treatments significantly increased the total fresh weight compared to control from initial time, 5 days, 8 days, 12 days and after 15 days. Results showed that concentrations of nano-silver thiosulphate at 7.5 mg/l applied on total fresh weight (g) recorded the maximum values of total fresh weight after 15 days (48.77 and 51.77 g), followed by STS 0.08 mM (47.55 and 50.55 g), thyme oil at 75mg/l (45.89 and 48.56 g), STS at 0.06  mM (45.29 and 48.29 g), 8 HQS  (45.08 and 48.03 g) and nano-silver thiosulphate at 5 mg/l (44.14 and 47.14 g), during both seasons, respectively, as compared with the control treatment which recorded the minimum values of total fresh weight (42.43 and 45.43 g).

1-2 Total dry weight

Results in table (1) showed that all preservative solution had significant effect on total dry weight in the two experiments (2020-2021). Nano-silver thiosulphate at 7.5 mg/l (16.25-16.06) and STS 0.08 mM (15.83- 15.56) resulted in the greatest total dry weight for the first and second experiments, respectively. The lowest total dry weight was obtained by control (14.16-13.12g) for the first and second experiments, respectively

Table (1): Effect of some preservative solutions on total fresh and dry weight (g) of Helianthus annuus cut flowers in the two seasons of (2020-2021).

STS: Silver thiosulphate, NST: Nano-silver thiosulphate, 8-HQS: 8-hydroxyquinoline sulphate, M: Mint oil, T: Thymeoil and L.S.D: least significant difference at 0.05 level of probability

1-3 Water uptake (g)

Data concerning the effect of some preservative solutions on water uptake of Helianthus annuus sun flower cut flowers in the first and second experiment in June (2020-2021), are listed in Table (2). Data in general showed that all treatments increased water uptake compared with control. In addition, after 15 days of nano sliver thiosulphate application at 7.5 mg/l, STS at 0.08mM and thyme oil at (75mg/l) were more effective on increasing water uptake than other treatments.

1-4 Vase life (days)

The effect of some preservative solutions on vase life of Helianthus annuus in the first and second experiments, data show in Table (2) all the cut sunflowers  had a significant difference in their coordinating age compared to the control. The flowering life is 16.30-16.64 days for the flowers treated with nano-silver thiosulphate concentration of 7.5 mg/l. While it reached the lowest at 8.96-9.06 days at the flowering age of flowers that hadn't been treated (control).

1-5    Flower diameter (cm)

Data presented in Table (3) showed that all treatments with different concentrations promoted flower diameter of Helianthus annuus sunflower. Treatment of 7.5 mg/l nano-silver thiosulphate gave the biggest sunflowers diameter at 5^th day (10.55 and 11.17 cm), followed by 75 mg/l thyme oil (9.45 and 10.37 cm) and 8-hydroxyquinoline at 200 mg/l (9.16 and 10.14 cm), respectively, as compared with the other treatments under study and control.

Table (2): Effect of some preservative solutions on Water uptake (g) and vase life (days) of Helianthus annuuscut flowers in the two seasons of (2020-2021).

STS: Silver thiosulphate, NST: Nano-silver thiosulphate, 8-HQS: 8-hydroxyquinoline sulphate, M: Mint oil, T: Thymeoil and L.S.D: least significant difference at 0.05 level of probability

Table (3): Effect of some preservative solutions on Flower diameter (cm) ofHelianthus annuus cut flowers in the two seasons (2020-2021)

STS: Silver thiosulphate, NST: Nano-silver thiosulphate, 8-HQS: 8-hydroxyquinoline sulphate, M: Mint oil, T: Thymeoil and L.S.D: least significant difference at 0.05 level of probability

A)   Chemical characters

Results of Table (4) showed that all types of treatments, exhibited, highly significant effects on the studied Chlorophyll a 1.24-1.27, Chlorophyll b 1.14-1.06 and total chlorophyll 2.39-2.33. Nano silver thiosulphate (75mg/l) have properties to effectively increase target activity in the two seasons compared to control (0.63-0.65, 0.43-0.44 and 1.06-1.07, respectively)

Carotene pigments (mg/g)

Table (4) showed that Nano sliver thiosulphate 7.5mg/l (6.49-6.59), STS 0.08mM (6.40-6.43), thyme oil 75 mg/l (6.20-6.17) and mint oil 75 mg/l (5.89-5.76) had high significant results compared to control treatment.

Carbohydrates %

As for the treatment of nano sliver thiosulphate in Table (5) it showed that, the higher concentration 7.5 mg/l (2.27-2.15) significantly increase the Carbohydrates % compared to control and the lowest one (control) (1.75-1.78) in two seasons.

Total sugars (%)

Data are presented in Table (5). It has been found that all studied materials had remarkable significant effect on increasing vase life compared to control in both experiments. In addition, nano sliver thiosulphate at (7.5 mg/l) (3.22-3.28), STS at (0.08 mM)(3.23-3.27), thyme oil at (75 mg/l) (3.27-3.17) and mint oil at (75 mg/l) (3.13-3.11) in two experiments were more effective on increasing total sugars(%)  than other treatments.

Reducing sugars (%)

Results in Table (5) showed that, the concentrations of nano sliver thiosulphate at 7.5 mg/l (0.106), significantly decreased the reducing sugars content compared to control in the first seasons. And mint oil at 75 mg/l (0.07) in the second season. And also data showed that the highest significant reduction in sugar content was obtained at control treatments in both seasons (1.39-1.36).

Table (4): Effect of some preservative solutions on chlorophyll a, chlorophyll b, total chlorophyll and carotene pigments (mg/g) of Helianthus annuus sunflower cut flowers in the two seasons of (2020-2021).

STS: Silver thiosulphate, NST: Nano-silver thiosulphate, 8-HQS: 8-hydroxyquinoline sulphate, M: Mint oil, T: Thymeoil and L.S.D: least significant difference at 0.05 level of probability

Table (5): Effect of some preservative solutions on carbohydrates %, total sugars (%), and reducing sugars (%) of Helianthus annuus sunflower cut flowers in the two seasons of (2020-2021).

STS: Silver thiosulphate, NST: Nano-silver thiosulphate, 8-HQS: 8-hydroxyquinoline sulphate, M: Mint oil, T: Thymeoil and L.S.D: least significant difference at 0.05 level of probability