Multiphasic observations in this study resulted in unexpected identification of Hydrocoleum sp. (Oscillatoriales) is a common epiphytic and benthic bloom-former in tropical and subtropical shallow water systems but shares high phylogenetic similarity with the planktonic, globally important diazotroph Trichodesmium. But one would need to identify and exclude those seedlots for which alternating temperature greatly depresses germination.The nitrogen-fixing, non-heterocystous cyanobacterium Hydrocoleum sp. AT could be a useful application to all seed germination assays in the genebank if it facilitated a better assessment of the potential viability of trickle-germinating seedlots. RT germination without gibberellin had RAUGPC of only 13% of RT control, but AT without gibberellin pretreatment increased this to 65%, showing AT substantially substitutes for gibberellin pretreatment. Also in 2017, two seedlots known to be very dependent on gibberellin pretreatment were tested. In a separate trial in 2017, four seedlots most responsive to AT were shown to germinate significantly better in constant cold than their RT controls, but not as well as seeds germinated under AT. Some species’ seedlots’ RAUGPC germination in AT was nearly zero, some were about 50% of RT control, and some in AT germination had RAUGPC double or even triple that of RT control. When Relative Area Under the Germination Progress Curve (RAUGPC) was calculated, normal germinating seedlots’ germination in AT was not significantly different from RT control. Twelve seedlots with trickle germination even after at least 2 years of storage and 2 robustly-germinating positive control seedlots encompassing 9 species were germinated in petri plates, and subjected to day/night = 10h/14h = 20C/6C alternating temperature (AT) trials along with constant room temperature (RT) controls, in the spring of 20. This is especially true for problematic seedlots that have slow and low (“trickle”) germination even when subjected to germination techniques that give optimal results in most other seedlots in the genebank. Technical Abstract: Potato has about 100 wild species relatives that are multiplied in the form of botanical seed populations by genebanks, and distributed for use in research and breeding, so understanding factors that affect seed germination is valuable. So for seedlots that respond, applying AT should prevent the inadvertent de-selection of that trait and other useful traits that are linked to it. In the genebank, we want to avoid any selection that narrows diversity of populations. Alternating temperature to promote rapid, full germination could have a payoff for breeding projects that need rapid cycling of generations, like a backcrossing or selfing program. We discovered that alternating temperature during germination greatly increases the onset, rapid burst, and final percent germination. About 90% of the collection consists of botanical seedlots, so knowing how to maximize seed germination is important. Our national genebank responsible for keeping this resource is the US Potato Genebank, near Sturgeon Bay, Wisconsin. Interpretive Summary: Potato (Solanum tuberosum) is the most important vegetable crop in the US and world, and has a rich resource of about 100 wild relative species that can be used for breeding and research to improve the crop. Diurnal alternating temperature improves germination of some wild potato (Solanum) botanical seedlots. Submitted to: American Journal of Potato ResearchĬitation: Bamberg, J.B.
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