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ARS Home » Pacific West Area » Corvallis, Oregon » National Clonal Germplasm Repository » Research » Publications at this Location » Publication #167210


item Reed, Barbara

Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2004
Publication Date: 2/1/2005
Citation: Aynalem, H., Reed, B.M. 2005. Iron formulation affects in-vitro cold storage of hops. Acta Horticulturae. 668:257-262.

Interpretive Summary: The National Clonal Germplasm Repository (NCGR) stores the US collection of wild and cultivated hops. Hops are usually stored as trellised plants in field collections. These plants are susceptible to loss from environmental stresses and insect or disease attacks. To insure the safety of the collection, a subset of the field collection was established as virus-free tissue cultures stored at refrigerator temperatures. Storage of cultures at refrigerator temperatures averages 14 months, but can vary from 6 months to 2 years depending on the plant type stored. In this study we tested 12 hops cultivars to determine the effect of the iron formulation in the growth medium on the length of storage. For most cultivars the plants grown on the standard formulation (EDTA-chelated iron) were healthier after 9 months than either of the two treatments with a different formulation (EDDTA-chelated iron).

Technical Abstract: Improving the duration of cold storage of in vitro germplasm collections is important to safeguarding plant diversity available for plant breeding. In this study we characterized the response of 12 diverse Humulus lupulus L. genotypes to the iron formulation used in the growth medium during storage. Treatments were standard MS iron alone (EDTA chelated) or with 100 or 200 mg/L sequestrene 138 iron (EDDTA chelated). In standard storage conditions the average length of storage for hops on MS medium is 14.1 ± 3.5 months. Evaluation of 12 genotypes after 3, 6 and 9 months indicated that the plantlets grown with standard MS iron had generally higher condition ratings than those on sequestrene iron. Plants on either concentration of sequestrene iron declined at all rating periods and by 9 months all were near death. When all 12 genotypes were considered as a group, the growth-condition ratings for plantlets stored on MS iron were not significantly different from those on either sequestrene iron concentration due to the large amount of variation among the genotypes. Plants stored for 9 months on 1X sequestrene iron declined from mean ratings of 5 to ratings of 1.2 ± 1.1 and those on 2X declined to 0.8 ± 0.9 while plants on MS were rated 2.7 ± 1.5. Significant differences among treatments were noted for several genotypes. These results indicate that 4° C storage of in vitro hops germplasm should be on medium with the standard MS iron formulation.