If it were possible to regulate temperature and relative humidity independently, which control would be most important for preserving seed viability in storage? Why?
Story by:
Sabry Elias, Adriel Garay, Bill Young and Tom Chastain
Maintenance of seed quality in storage from the time of production until the seed is planted is imperative to assure its planting value. Storing seeds, just like storing any other live organism, has its risks. The risks can be high or low depending on the species, the prevailing weather, the market requirements and the management provided during storage. The best alternative to avoid the risks associated with storing seeds is to avoid storing seeds, and in many regions around the world the seed industry has figured out how to do just that. One such example is the grass seed industry in Oregon where most of the seed is shipped in a few months after harvest, or Bolivia where the wheat seed harvested in the highlands in April is being planted in May in the Lowlands, or Colombia where rice can be produced twice a year, which decreases the storage period. These strategies are becoming highly desirable not only because it reduces storage but especially because it makes possible to market and meet the financial obligations in a shorter time. Despite the best strategies, there are times when seed growers and dealers carry over seed lots from one year to the next due to weak market, to insure an adequate supply the following year, because the production system does not provide choices, and other reasons. Under such circumstances the question is how to manage the seeds to maintain a high viability. This may be the case when there is carryover of grass seeds in Oregon beyond a year. Thus, the purpose of this article is to review briefly the basic principles and practices that need to be observed to reduce the risk of a decline in viability during storage.
Historically, grass seeds in Oregon have maintained their viability (measured by TZ and/or germination) for longer periods than one year if the seeds are stored following some basic principles. This track record in Oregon can be attributed to several factors including the dry weather that prevails during seed maturation and harvest that makes it possible to harvest seeds not only with low moisture but also with high initial viability. This is followed up by placing the seeds in cool and dry warehouses provided by the natural environment. Yet accidents can happen and do happen if the seeds are exposed to prolonged rain before threshing which can result in field weathering and physical damage at harvest (bruising, cracked or even broken), piling up moist seeds in a bin or elsewhere which leads to heating, a leak in the roof, etc. This is why it is important to pay attention to the following factors to lower the risks in storage.