Discussion on Preservation, Storage and Transportation Technology of Flower after Harvest (1)

First, the post-harvest life of flowers

After the flower is harvested, it is still a “living organism”. It absorbs O2 from the surrounding air and releases CO2 and heat. The main factors influencing the post-harvest life of ornamental plants are: physiological decline, physical factors (plant wilting caused by water loss), pathological decline, etc. Specific impact factors include:

1. Factors affecting the post-harvest life of flowers

1) maturity

Since potted plants can continue to grow after being transported and sold, when they are sold depends on the ornamental nature of the plant and market factors. In general, flowering plants can be sold after the flowers have changed color, and the foliage plants are sold after they are ornamental. Since the cut flower is separated from the mother, the minimum harvest maturity should be that the flower bud can be completely opened after sale, and the ornamental period is longer for sale. Different varieties of flowers have different collection dates, and some varieties have an early harvest period. Roses and gladiolus can be harvested when the calyx is first opened, and can be fully opened when reaching the hands of consumers. These flowers should be harvested as soon as possible after ensuring that the flowers are harvested, such as harvesting at the flowering stage. It not only saves space for transportation, but also flowers are not easily damaged by machinery and ethylene is less released, which can prolong post-harvest life. This is often overlooked by flower farmers. Many flowers often lag behind, affecting shelf life and vase life. Some flowers need to be harvested when the calyx is fully open (eg chrysanthemum), otherwise the flowers cannot be completely opened. In general, the maturity of flower harvesting for local consumption is greater than that of off-site consumption.

2) Temperature

(1) Low temperature slows respiration.

Plants breathe heat and provide energy for growth and maturation. When the ambient temperature rises, the respiration rate increases. For example, when the ornamental plants were at 30°C, the respiration rate was 145 times that at 0°C, and the respiration rate increased, which accelerated the aging of the plants. In the cold environment of flowers, the metabolic process is significantly slowed down, which can delay aging. Rapid cooling and a suitable cold environment extend the viewing period. Usually the majority of cut flowers stored at a temperature of 0 °C, the daily rate of decline of flowers is very small, and stored at 30 °C, can only store 3-4 days.

(2) Low temperature reduces moisture loss.

The lower the temperature, the slower the transpiration of the plants, thus reducing the loss of water, and the plants are not susceptible to wilting. In addition, the relative humidity has a greater impact, and the relative humidity in the air is high. At the same temperature, the water loss of the plants is small. Assuming that the water loss of the plants at 0°C and a relative humidity of 40% is doubled, the relationship between the relative humidity, temperature, and water loss of the plants is shown in the table.

(3) Reduced disease transmission. The low temperature suppresses the activity of microorganisms and reduces the spread of the disease.

(4) Reduced unfavorable growth. Plants still have life activities after harvesting. Low temperatures suppress unfavorable growth activities. Maintain the state of the plant when it is harvested.

Low-temperature storage and transportation also have their disadvantages. When plants approach their freezing point, they will produce cold and cold damage. The optimum storage temperature for most flowers is 0-5 degrees, and the best storage temperature for tropical flowers is 8-12 degrees, which is lower than this temperature, which may cause freezing damage to tropical plants such as genus Anthurium. If it is below 10 degrees, the symptoms of frost damage appear as darkening, damage, loss of flowers, leaves, and hair shafts. Most of the foliage plants are tropical plants. They adapt to a warm, moist environment. In the short-term exposure to temperatures below 10 degrees, they are usually subjected to freezing injury. Some flower-seeking plants are also sensitive to low temperatures, such as poinsettia, pineapple, gerbera, and so on. The low-temperature chilling causes changes in the color of the petals, the loss of petals or flowers, and failure to flower normally. Take the carnation as an example to illustrate the relationship between storage temperature and number of flower failures.

3) Nutrition supply

Flowers still need nutrition after harvest. In general, starch and sugar are stored in stems, leaves and flowers to provide nutrients for flowering. For cut flowers, such as providing sugar in bottled solutions, post-harvest life can be increased. For potted plants, nutrition can be provided by photosynthesis, and therefore, a light environment is still required after sale to enable plants to perform photosynthesis.

4) Light

Low light causes yellowing of cut flowers. Chrysanthemums, chrysanthemums, daisies, lilies and other long-day plants are indispensable for color formation and floral development. Low light causes premature aging after flowering.

5) Water supply

Most of the cut flowers have a large surface area and are wilting quickly. Thus, after leaving the matrix, it is best stored in an environment with a relative humidity higher than 95% to reduce moisture loss, especially during long-term storage. Because the low temperature can significantly reduce the loss of water, the loss of flowers during low-temperature storage is less, which is one of the important reasons for the cooling of cut flowers and potted plants during storage and transportation.

6) Ethylene

Most ornamental plants have adverse effects when exposed to ethylene gas. This is a common atmospheric pollution. When ethylene is at a low level, it causes unripe flowers to wilt or accelerate leaves, flowers and flowers. In foliage plants, ethylene also produces adverse reactions that cause the leaves to fall off and the leaves to turn yellow or fade. Therefore, cut flowers should also pay attention to ventilation and ventilation after harvest. In addition, low temperature can reduce ethylene activity and enhance plant resistance to ethylene, which is also a method to slow the aging of plants.

7) Direction of growth

After the cut flower leaves the mother, it continues to grow and responds to environmental stimuli. For example, if cut flowers are stored horizontally and stored horizontally, they can sense changes in the direction of gravity, and try to grow vertically. This can lead to poor stem bending and reduce flower quality. Such as gladiolus, if placed horizontally during transportation, 15 minutes later it will be found that the stem will be bent upwards, causing the stem to be straight, which will affect the quality of sales. Therefore, some flowers sensitive to nature should be placed vertically in order to keep the stem straight.

8) Mechanical damage

The effects of damage on ornamental plants are obvious, making them less ornamental and damaging leaves, flowers, and stems, which not only reduces the ornamental quality of ornamental plants, but also accelerates the aging of plants and makes them more susceptible to diseases.

9) Disease

Cut flowers are susceptible to disease, as cut flowers still consume nutrients, and incision wounds make the bacteria more susceptible to invasion. At the same time, when the flowers are moved from the cold room to the treatment room, the water will condense on the plants or flower tissue, making the bacteria more likely to breed. If the humidity is high, gray mold easily occurs.

(to be continued)