Agricultural guidelines from Utah State University Extension outline critical protocols for transplant production and seed storage to ensure crop viability and maximize yields. Growers can achieve better stands and more uniform production by optimizing greenhouse conditions, managing growing media, and maintaining strict temperature and humidity controls during seed storage.
Optimizing Transplant Production
Optimizing Transplant Production
Growers utilize transplants to cultivate long-season crops within short-season environments, which helps improve land use efficiency and saves costs when working with expensive hybrid seeds. According to Utah State University Extension, using transplants can also provide early production for early markets, improve water savings, and allow for more efficient management of early weed problems.
To produce high-quality transplants, growers typically utilize heated greenhouses with carefully managed environmental conditions. Success depends on optimizing various inputs, including water, temperature, fertilization, spacing, and growing media. The University notes that quality plants are achieved through the use of appropriate trays and soil media, controlled germination, and proper conditioning before the plants are moved to the field.
Managing Media and Equipment
Managing Media and Equipment
The selection of growing media is a vital component of transplant success. Utah State University Extension states that most commercial mixes produce quality transplants when combined with good management practices, particularly when using lightweight, disease-free media made from peat and vermiculite. Growers are advised to avoid fine particle mixes, as these may hold excessive water and suffer from poor aeration.
When switching between different media types, the University recommends testing the new mix for nutrient levels and pH. Some growers choose to blend their own media to reduce costs and ensure a consistent, uniform composition. Recommended mixtures include combinations of sphagnum peat moss, vermiculite, perlite, and various fertilizers like bone meal, kelp meal, and blood meal.
To prevent the spread of pathogens such as damping-off, the University recommends using new flats and liners for transplant production. If growers choose to reuse old trays or liners, they must be thoroughly cleaned by dipping them in 10% chlorine bleach several times. The bleach solution must be kept below a pH of 6.8 to remain effective at killing disease pathogens, and the solution should be refreshed every two hours or whenever contamination or dilution occurs. All exposed surfaces, including benches, frames, and walls in the greenhouse, should also be washed to ensure sterilization.
Seedling Performance and Germination
Seedling Performance and Germination
Seedling performance is heavily influenced by the size of the cells used during production. Generally, transplants grown in larger cells, such as 50s or 72s, produce earlier yields. While smaller cells (128s or 256s) allow for more plants per unit area of greenhouse space and can lower costs, they may not be suitable for certain vegetables, such as melons.
Proper temperature control during germination is essential for healthy growth. While research shows that germinating seeds at higher-than-recommended temperatures for extended periods can result in weak seedlings with elongated hypocotyls, a germination chamber can be used to maintain heat if floor or bench heat is unavailable. When using a germination chamber, trays must be removed and unstacked before the seedlings emerge.
For seeds that require being pricked out and repotted at a later date, the University suggests germinating them in 100% horticultural-grade coarse sand-size vermiculite or a high-quality commercial mix. Fertilization should be added after the seed leaves, or cotyledons, have fully expanded. Seedlings can be held for three to four weeks if fertilization is withheld until a few days before the pricking out process.
Seed Storage and Handling
Seed Storage and Handling
Proper handling is critical for maintaining seed viability, particularly for large vegetable seeds like beans, peas, and sweet corn. Utah State University Extension warns that these seeds are susceptible to mechanical damage if handled roughly. Loading or unloading these crops should be done carefully to avoid throwing or dropping bags, as damage to the seed coats and embryos can significantly decrease germination or reduce the vigor of germinated seedlings.
Environmental conditions play a major role in seed longevity. High temperatures and high relative humidity can reduce both germination and vigor. The University recommends that seeds should not be stored in areas where temperatures exceed 70 degrees Fahrenheit or where humidity levels are greater than 60%. The ideal storage environment for seeds is a temperature between 35 degrees Fahrenheit and 40 degrees Fahrenheit, with a relative humidity of less than 40%.
Because most refrigerators maintain a temperature of approximately 40 degrees Fahrenheit but have high relative humidity, seeds stored in a refrigerator should be kept in containers with a good seal to maintain low humidity levels. Additionally, growers should be aware that primed seeds do not store well and should be used during the current planting year. For pelleted seeds, large fluctuations in relative humidity can damage pellet integrity, making them difficult to plant. Because pelleted seed stored for more than two years may show a reduced germination percentage, the University recommends performing a germination test to assess viability before planting.
Greenhouse Management
Greenhouse management is essential for maintaining the environmental controls required for effective germination and growth. A well-maintained greenhouse should provide maximum light, soil heating capabilities, and efficient heating and ventilation systems. These systems ensure that proper growing temperatures are maintained, which in turn facilitates uniform growth throughout the production cycle.
Conclusion
By adhering to these standards for media composition, equipment sterilization, and climate-controlled storage, growers can mitigate the risks of disease and poor germination, ensuring a more reliable and efficient production cycle for various vegetable crops.
