Hypogeal germinators

Fig. 4.11. Seedling development I. Two species in which the cotyledons are the storage organs but one showing hypogeal germination and the other epigeal germination...

Let us look first at those seeds in which the cotyledons are the storage organs. A number of researchers have used pea seeds (a hypogeal germinator) for their experiments. Unfortunately, variable, sometimes contradictory results have been found, possibly because different varieties have been employed or, more likely, because the experimental conditions were not standardized. Respiration, differentiation of mitochondria, and other sub-cellular changes are all impaired in detached pea cotyledons [10, 112]. The cotyledons therefore seem to require a factor from the axis for the development and maintenance of respiratory metabolism—this can be supplied even by a small piece of attached axial tissue [112, 119]. As far as protein and starch mobilization in peas are concerned it is unclear if the presence of the axis is necessary. In some cases protein and starch breakdown proceed equally well in detached and attached cotyledons [10] but in others both the development of proteinase activity and... 

Table 4.5. Some examples of hypogeal and epigeal germinators...

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