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CTA. 2005. Recalcitrant seeds. Spore 118. CTA, Wageningen, The Netherlands.
Permanent link to this item: http://hdl.handle.net/10568/47883
Internet URL: http://spore.cta.int/images/stories/pdf/old/spore118.pdf
Seeds are said to be recalcitrant when they cannot be stored using traditional techniques. When kept in a cold chamber with low humidity levels, these seeds stop germinating altogether! Several important commercial plants fall into this category, includin
Seeds are said to be recalcitrant when they cannot be stored using traditional techniques. When kept in a cold chamber with low humidity levels, these seeds stop germinating altogether! Several important commercial plants fall into this category, including cocoa and rubber trees and a number of plants that are wide- ly used in traditional African medicine. Patricia Berjak, of the University of KwaZulu-Natal in South Africa, who has been studying these seeds and their storage methods for 30 years, has found a solution to what is becoming an increasingly pressing problem, given that some medicinal plants are threatened with extinction. After much trial and error, and various failed attempts to conserve the seed as a whole, members of her team decided to separate a small part of the seed, the embryonic axis, from its covering. A number of plants (avocado, coconut, lychee, mango, etc.) do in fact have storage difficulties due to the large size of their seeds, which cannot be properly dried before being frozen. The greater part of these seeds is made up of the outer casing, which is simply a store of food for the seed. It is, however, possible to store the embryonic axis on its own, and freeze it without the husk before later grafting it onto a seed that is genetically similar, but which has been harvested fresh from a tree. The technique offers a modern solution, combining elements of both the past and the present to tackle the genetic erosion and extinction of certain plants.