Location: Horticultural Crops Production and Genetic Improvement Research Unit
Project Number: 2072-30500-002-009-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2025
End Date: Aug 31, 2029
Objective:
While breeding has generated elite cultivars of berries with superior fruit quality and shelf life, the complementary role of pre- and postharvest practices remains understudied. Currently, there are numerous products available with potential for reducing decay and promoting firmness, ripening, and flavor of small fruits, including smart packaging systems, plant growth regulators, natural edible coatings, and biological control agents. Our goal is to investigate the use of several of these products in blueberries, blackberries, and raspberries and determine how they affect quality and consumer acceptance of the fruit after storage. Specific objectives of the project are to: 1) Quantify the combined impacts of plant and soil water status and new packaging technologies on fresh market quality and shelf life across commercially relevant cultivars; 2) Evaluate the role of pre- and post-harvest plant growth regulators and edible coatings on fresh market quality, shelf life, and consumer acceptance; and 3) Investigate the efficacy of select biological control agents in reducing harvest and postharvest losses. These objectives address several official research priorities listed by the Washington and Oregon berry industries, including improving or extending storage of fruit for fresh markets, controlled atmosphere packaging, physical coatings, and post-harvest handling. The project team has considerable expertise in breeding, production, and physiology of berry crops and is well-equipped with instruments for monitoring plant and soil water conditions, fruit quality, and postharvest longevity. The work will be conducted across Washington and Oregon and include assessments of the growing conditions and the effects of preharvest and postharvest practices on the quality of the fruit following shipping and cold storage.
Approach:
Ripe fruit will be collected from conventional and organic fields of commercially relevant cultivars of blueberry, blackberry, and raspberry located in Oregon and Washington. The water status of the plants and soil at each site will be monitored throughout the growing season. Fruit ripeness indices, including firmness, soluble solids content (SSC), pH, and titratable acidity (TA), will be assessed at harvest. Additional fruit will be stored using three replicates of four different packaging treatments, including: 1) Control - clamshell containers with moisture-absorbing pads, packed as twelve clamshells in one unwrapped carton box; 2) Modified Atmosphere Packaging (MAP) - clamshells with moisture-absorbing pads packed in a carton box wrapped with low-density polyethylene film; 3) MAP with carbon dioxide injection - similar to the second treatment but with carbon dioxide injected into the box at 5%, by volume; and 4) Smart sulfur dioxide releasing (SSDR) film - similar to the second treatment but in a carton box wrapped with a SSDR film. Each treatment will be equipped with smart sensors and shipped to the Postharvest Laboratory at Oregon State University, following a commercial refrigerated air shipping protocol. Upon arrival, the fruit will be stored at 0.5 degrees Celsius and assessed weekly for ethylene production, respiration, antioxidants, firmness, SSC, pH, TA, shrivel, and decay.
In a second trial, plants will be sprayed with 1-aminocyclopropane-1-carboxylic acid (ACC), a naturally occurring precursor to the plant hormone, ethylene, with potential for concentrating fruit ripening in soft fruits. Once harvested, the fruit will be cooled and treated again, along with untreated fruit, with 1-methylcyclopropene (1-MCP). The latter is a plant growth regulator that blocks ethylene receptors and is known to improve firmness and quality of stored fruits. The fruit from each treatment will be stored in clamshells equipped with moisture-absorbent pads, organized into four distinct sets with three replicates per treatment. Another set will be treated with a 1% chitosan coating solution, which can reduce softening and decay of fresh blueberries. Fruit maturity and quality attributes, including firmness, juice SSC, pH, and TA, respiration, ethylene production, shriveling, and decay will be evaluated weekly following 1-10 weeks of cold storage and 1 day at 20 degrees Celsius to simulate market conditions.
A third trial will be conducted using plants grown at the Oregon State University North Willamette Research and Extension Center. Bacillus bacteria and Saccharomyces cerevisiae yeast will be applied as a probiotic spray at 1-7 days before harvest. Harvested fruit will be assessed weekly for quality and decay compared to untreated controls. The epiphytic microbiome will also be isolated from each clamshell on each sampling date. Results are expected to provide practical guidelines for managing Botrytis cinerea and other fruit decay pathogens during harvest and storage.