Flower and seed storage rooms are designed to store the product or product groups together in a way that provides the desired storage conditions. While there is not much variation in storage conditions for seeds, this is not the case with live plants and cut flowers. Therefore, we will focus more on ornamental plants and cut flowers.

Factors Affecting Post-Harvest Lifespan in Cut Flowers

Approximately 25% of the cut flowers produced in the world are lost due to different reasons in the chain from the producer to the consumer. Quality losses in flower stem, leaves and flower organs either reduce the market value of the product or prevent the sale of the product. For this reason, both the preservation of quality and the prevention of post-harvest losses in the chain from the producer to the consumer are important in terms of producer-consumer satisfaction.

One of the most important quality criteria in cut flowers is vase life, and the length of vase life depends on pre-harvest factors in 2/3 and postharvest factors in 1/3. It was stated that the vase life of the flowers decreased by 32% on average after 4 days of transportation in different cut flower species.

Pre-harvest Factors

Conditions affecting pre-harvest quality loss in cut flowers; genetic factor (variety) and growing conditions. Factors such as vase life, susceptibility to gray mold (botrytis), blooming, occlusion of vascular bundles, and sensitivity to ethylene vary depending on the variety. Growing conditions such as temperature, light, relative humidity, CO ₂ , soil, irrigation, fertilization, disease and pest control, harvest time and pruning have a significant effect on vase life. Flowers obtained from plants grown under optimal conditions have both better quality and longer vase life.

Post Harvest Factors

The main factors affecting the post-harvest quality loss and durability in cut flowers; temperature, ethylene, water loss and blockage of vascular bundles, pre-cooling, water transport, geotropism, yellowing of leaves and disease (botrytis).

Water loss and clogging of the transmission bundles

One of the most important factors affecting the post-harvest life and quality of cut flowers is the water balance. If the water lost through transpiration cannot be met with the water drawn from the stem, wilting occurs in the flowers. Insufficient water intake is mostly caused by physical and microbial blockages at the bottom of the flower stalks. In addition, in species such as cut roses with woody stems, waxflower and acacia (Acacia holosericea) used as cut greens, physiological clogging develops as a result of some enzyme activities in response to post-cut injury in the vascular bundles. Aluminum sulfate (200-300 ppm), 8-HOC (8-hydroxyquinoline citrate) (200-600 ppm), 8-HQS (8) are added to flower solutions in order to both improve water uptake in cut flowers and prevent stem clogging as a result of bacterial growth in vase water. -hydroxyquinoline sulfate) (200-600ppm), silver nitrate (10-200ppm) or silverthio sulfate (0.2-4ppm) are added. The problem of clogging of the vascular bundles is most frequently encountered in cut rose and gerbera species. While lilies and chrysanthemums are moderately sensitive to occlusion of vascular bundles, this problem is not encountered in cloves, freesia, tulips and iris. Dewatering of cut flowers is usually done in warm and low pH (3-5.5) water at an ambient temperature of 4˚C for 6-12 hours.

Before placing the flowers in a solution, cutting the stem bases from 1-2.5 cm and removing the leaves remaining in the water prolongs the vase life. The cutting of the stem bottoms is usually done in the air. However, since the air inlet to the handle transmission bundle after dry storage and transportation causes clogging, it is recommended that the cuttings be made under water, especially after dry storage and transportation, and the water must be clean.

Heat

As the post-harvest storage temperature increases in cut flowers, the respiratory rate increases, and the increase in the respiration rate shortens the vase life.

While there is a linear relationship between storage temperature and respiration rate, there is a negative relationship between respiration rate and vase life. Breathing with low temperature, etc. metabolic events slow down, loss of water and sugar/starch decreases, aging events such as ethylene synthesis and leaf yellowing are delayed, and the development of diseases such as bacterial and botrytis slows down. This is why many types of cut flowers are stored at 0°C just above freezing. Since tropical flowers (orchids and anthuriums, etc.) will suffer from chilling damage at temperatures below 10°C, the storage and transportation temperatures of such flowers should be above 10°C.

Ethylene

Ethylene ; It reduces the vase life of cut flowers by causing shedding of flowers, leaves and petals, yellowing, wilting, necrosis and aging of leaves, incomplete opening and deformity of buds. In some species (Iris hollandica), however, ethylene plays an important role in the opening of flower buds.

To prevent and/or reduce ethylene damage in cut flower species sensitive to ethylene; flowers should be harvested at the optimum development stage, physical damage to flowers should be avoided during processing, flowers should be cooled in a short time after harvest, ventilation and air circulation should be provided in processing and storage areas, flowers should not be stored together with ethylene producing fruits and vegetables, and anti-ethylene products should be used. Products used as anti-ethylene: GTS , STS (silver thiosulfate); It is applied in the form of pulling from the handle. Due to the fact that the silver ions it contains is a heavy metal that pollutes groundwater, its use is prohibited in many countries today, but its use continues in our country. The application dose is 1-3 ml per 1 liter of water. 1-MCP (1-methylcyclopropane); This product, which has a production license under the trade name EthylBloc, gives a gas to the environment when water or buffer solution is added, therefore the flowers to be applied 1-MCP should be kept in a closed place. In practice, the ambient temperature of 24-25°C is ideal, and the application time (6-24 hours) varies depending on the dose and temperature. The disadvantage of 1-MCP is that the effect time depends on the ambient temperature and after a certain time the flower becomes sensitive to ethylene again. The application dose is 2.5 nl-1 µl per 1 liter of water. AOA (aminooxyacetic acid) and AVG (aminoethoxyvinylglycine); Both anti-ethylene products prevent the intrinsic ethylene synthesis of the flower, and are applied as extractor or spray from the stem. potassium permanganate; Products that absorb ethylene in the environment are sold in the market as filters, wraps, linings or covers.

Pre-cooling

The process of taking the heat of flowers after production or harvest in a short time and reducing them to storage temperature is called pre-cooling. For an effective cooling, flower boxes should have opposite air holes, packaging and stacking should not block the air flow. With a suitable cooling method (passive cooling, forced air cooling) in cut flowers, the temperature is reduced to the lowest temperature (0-1°C) where the flowers will not be damaged. In tropical species, the temperature should be above 10°C.

SOURCE where the relevant article was published: Türktob (Turkish Seed Association Journal), April-June 2015, Year:4, Issue:14, pp:42-45.
Title of Article: FACTORS AFFECTING POST-HARVEST LIFE IN CUT FLOWERS Author: SONER KAZAZ, Ankara University Faculty of Agriculture, Department of Horticulture.