Long-Term Subfreezing Storage of Forage Crop Seeds1
- Clarence M. Rincker2
Subfreezing storage of seed is a comparatively new technique; therefore, few reports are available on longterm effects, particularly on retention of viability by forage crop seed lots produced under different environments. This study was based on 291 seed lots from seven forage crop species produced at three locations (Prosser, Wash., Shafter and Tehachapi, Calif.) during 1957-1960. All seed lots were stored in a refrigerator at 5 C from year of harvest until placed in a freezer in told-1960 for long-term storage at -15 C and 60% relative humidity. All seed lots were tested for germination in the year of production and in 1971 and 1978 to determine germinability of each lot in those years. Original high seed quality was more important than location of seed production for retention of germinability although crop species did differ in germinability retention among the three production locations. Most notable was orchardgrass (Dactylis glomerata L.) seed produced at Shafter, which lost 22.5% in mean germinability in 19 years compared to 6.5% for seed grown at Prosser. Combined results for the three locations showed that birdsfoot trefoil (Lotus corniculatus L.), white clover (Trifolium repens L.), and alfalfa (Medicago sativa L.) seed retained germinability best, followed by timothy (Phleum pratense L.) and orchardgrass. Red clover (Trifolium pratense L.) and bromegrass (Bromus inermis Leyss.) suffered the greatest loss in germinability. The bromegrass seed, which had good original mean germination (90%), retained germination reasonably well until 1971 (12 years) but lost 11.8% in mean germination during the 7 additional years of storage. The original mean germination of the red clover seed lots was only 74.7% which undoubtedly contributed to the I 1% loss in germinability the first 12 years of storage. With the exception of bromegrass seed, germinability of forage crop seed can be maintained for up to 20 years if the seed was of high germination before subfreezing storage.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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