Location: Emerging Pests and Pathogens Research
Project Number: 8062-21000-048-015-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2023
End Date: Aug 31, 2024
Objective:
The primary objective is to improve the postharvest performance and longevity (vase life) of cut flowers grown in the U.S. floriculture industry, e.g., dahlia, zinnia, snapdragon, dianthus. Primary factors that accelerate senescence and limit postharvest longevity in cut flowers include, oxidative stress, carbohydrate depletion, and water stress. Oxidation may occur in plant cells under stress conditions (e.g., light, drought, temperature) and as part of senescence. Oxidative stress has been described in cut flowers stored in the dark for long periods of time where reactive oxidative species (ROS), such as H2O2 superoxide anion (O2-.) and hydroxyl radical (OH) are produced and cause cell death and short vase life. Plants have the machinery (enzymes, antioxidant molecules) required to protect their cells against ROS; however, under specific stress, the cell may not have enough antioxidant machinery to protect the cells against ROS. Studies have reported increased vase life of different cut flower species treated with antioxidant compounds (e.g. salicylic acid, sodium nitroprusside, chitooligosaccharides). These products provide benefits such as increased water uptake, increased activity of antioxidative enzymes, and decreased content of ROS in flowers resulting in improved vase life. Light can delay oxidative reactions and regulates stomata functioning. Cut flowers are generally stored under dark, cold (2-5 oC), and humid (relative humidity >80%) conditions that affect stomata functioning and accelerate flower senescence. Studies have reported the loss of stomata functionality on different cut flower species stored in cold, dark conditions for long periods of time. Stomata also play an important role in maintaining the adequate water balance of cut flowers. Correct stomata functionality after storage allows the cut flower to restore water balance once placed under vase life conditions. Carbohydrate depletion leads to physiological disorders that accelerate senescence in some flower species. Carbohydrate supplementation can reduce flower senescence by providing the energy source for petal growth and development, decreasing petal ethylene sensitivity, and decreasing botrytis susceptibility resulting in delayed senescence and longer vase life. This project will investigate (1) the role of antioxidant compounds on cut flower quality; (2) effect of light during storage; (3) water balance: and (4) effect of carbohydrate supply after harvest.
Approach:
The effect of antioxidant compounds on the vase life of different cut flower species will be investigated by applying antioxidant compounds (e.g., salicylic acid, sodium nitroprusside, chitooligosaccharides) before and after storage, considering factors such as type of antioxidant, concentration, and application time. The impact of light applied during prolonged, cold storage on the postharvest performance of cut flowers and the effect of light applied during storage on the stomata functionality during and after storage and its effect on vase life on different cut flower species will be investigated by simulating storage conditions in coolers at Clemson University and providing low-intensity lighting from LEDs after harvest and before shipping to observe the effects on oxidative stress, water relations, and carbohydrate supplies.
To investigate factors that can restore stomata functionality after long storage, e.g., ABA and light will be investigated by harvesting dahlia cut flowers, treating them with anti-transpirant products, and evaluating flower vase life. Factors such as type of anti-transpirant, concentration, and application time will be considered. We will also study the stomata's ability to maintain or restore functionality during and after storage. The effect of ABA and light will be evaluated on stomatal characteristics and will be related to vase life performance on different cut flower species.
The effect of the flower harvest stage on the vase life and the impact of applying carbohydrates after harvest on flower opening, ethylene production and sensitivity, botrytis susceptibility, and vase life will be investigated by evaluating flowers harvested at different stages of development, placing in vase solutions with carbohydrates and evaluating vase life. Factors such as carbohydrate source, concentration, and hydration time will be studied on different cut flower species and imported cut flower vase life before and after storage. The role of carbohydrate supplementation on ethylene sensitivity and botrytis susceptibility will also be studied.
