Seed Quality of High-Germinability Soybean Lines After Six Months of Ambient Storage.

Soybean seed produced in high-temperature, high-humidity environments during maturation and harvest are prone to have substandard seed quality.  Such seed can have low germination and vigor, and high incidences of Phomopsis seed decay, seed wrinkling, and hardseededness.  Previous research identified multiple soybean accessions with high germinability in high-temperature, high-humidity environments in the early soybean production system (ESPS).  Six high-germinability accessions and four cultivars from maturity groups II and III were grown in the ESPS at Stoneville, MS.  Seed was harvested from mid-late July to mid-late August in 2004 and 2005, and stored for approximately six months (from the first week of October to the first week of April) in a cold room and three commercial seed warehouses with ambient temperature and humidity.  As an example of the storage conditions, the mean high temperature and mean high relative humidity for the period were 21 degrees C and 77 percent relative humidity in the warehouse at Glen Allan, MS.  After harvest and after storage for six months, standard germination and accelerated-aging germination for five of the six high-germinability accessions were greater than 90 percent.  Interestingly, germination and vigor improved after six months of storage for some cultivars.  For example, the germination percentages of IA 2052, Croton 3.9, and AG 3905 increased from 68 to 87, 64 to 74, and 55 to 66, respectively, at Glen Allan.  In addition, the incidence of Phomopsis dropped significantly after storage for all four cultivars.  For example, from October to April at Glen Allan, the percentage of Phomopsis seed infection dropped from 61 to 35, 51 to 21, 34 to 18, and 27 to 14 for cultivars Macon, AG 3905, Croton 3.9, and IA 2052, respectively.  Some soybean accessions can produce high quality seed in high-temperature high-humidity environments, and maintain that quality after six months of storage at ambient temperature and humidity.  Hence, the production and storage of seed beans with high seed quality may be possible in environments with high temperature and high humidity.