Germination-dormancy and promoter-inhibitor relationships in Setaria lutescens seeds

Physiological and ultrastructural investigations of caryopsis dormancy in Setaria lutescens (Gramineae)

“…The presence of hull dormancy has not been associated with any easily dis cernible morphological characteristic such as hull color (Nieto-Hatem, 1963;Rost, 1975). Dormancy does not appear to be caused by impermea bility of the hulls to water, since florets exhibiting hull dormancy take up similar amounts of water as nondormant florets (Nieto-Hatem, 1963;Kollman, 1970). Hull dormancy could be caused by a restriction of oxygen supply to the embryo, but such a hypothesis has not been investigated.…”

“…Thus, the inhibitor hypothesis of hull dormancy is cur rently unsubstantiated. Hull dormancy can also be relieved by simply physically removing the lemma and palea or by other treatments which appear to destroy the integrity of the hull itself (Nieto-Hatem, 1963;Biswas et al, 1970;Kollman, 1970). For example, Kollman (1970) has demonstrated that acid scarification effectively removes hull dormancy.…”

“…Nieto-Hatem (1963) was the first to demonstrate that innate dormancy in mature yellow foxtail florets was separable into two types, (1) that which is associated with the hulls (lemma and palea) and (2) that which is associated with the caryopsis. In a single floret, both of these types of dormancy may be expressed simultaneously or separately (Kollman, 1970).…”

“…Hull dormancy could be caused by a restriction of oxygen supply to the embryo, but such a hypothesis has not been investigated. It has been suggested that hull dormancy is caused by inhibitors present in the hulls themselves (Kollman, 1970). This hypothesis is based primarily on the observation that leaching of hulls with cold water (2° C) relieves hull dormancy (Kollman, 1970).…”

“…It has been suggested that hull dormancy is caused by inhibitors present in the hulls themselves (Kollman, 1970). This hypothesis is based primarily on the observation that leaching of hulls with cold water (2° C) relieves hull dormancy (Kollman, 1970). However, water leachates of hulls from florets expressing hull dormancy are not significantly inhibitory to germination of nondormant caryopses (NietoHatem, 1963).…”