title: The Involvement of Endogenous Cytokinin-like and Gibberellin-like Substances in Germination and Early Seedling Growth of Cucurbita pepo L.
abstract: Mature dry seeds of Cucurbita pepo contained measurable quantities of both gibberellin-like and cytokinin-like materials. During germination, levels of endogenous gibberellin-like substances initially fell, but subsequently increased again. At no time, however, was there more endogenous gibberellin activity present than in the dry seeds. In terms of the amounts of gibberellin reported in other tissues, the levels in these seeds were low. Most of the cytokinin-like activity present was in the form of free bases, although small amounts of bound cytokinin-like. material were consistently present. Free cytokinin-like activity was appreciably reduced during imbibition, partly as a result of leaching, and did not increase again until late in the germination sequence. The increases in levels of both gibberellin-like and free cytokinin-like activity occurred much later than germination, as measured by radicle protrusion, and corresponded more closely with a rapid acceleration of extension growth in both the radicle and hypocotyl.
authors.affiliation: Department of Botany, the University, Bristol BS8 1UG, U.K.
authors.forename: N J
authors.initials: NJ
authors.lastname: Pinfield
authors.forename: J O
authors.initials: JO
authors.lastname: Sanchez-Torres