?Effects of CCC and of B995 on flowering in oenothera biennis?

Abstract

Oenothera biennis L. is a typical biennial plant with an absolute cold requirement for subsequent floral initiation under long-day conditions. Flowering of vernalized Oe. biennis is associated with transition from a rosette habit to the formation of a long flower-bearing stem. Vernalization in Oe. biennis consists of two consecutive stages: (1) preparation for flowering; (2) preparation of stem elongation. At the end of the second stage, the level of endogenous gibberellin-like substances is sufficient to allow the stem elongation which is requisite for subsequent floral development.Applications of (2-chloroethyl)trimethylammonium chloride (CCC) via the roots, when made after the cold treatment, have no effect on internodal elongation and subsequent flowering of vernalized Oe. biennis. Relatively small amounts of CCC applied onto the apical bud of the rosette promote stem growth. However, 750 μg of CCC act as a growth inhibitor and delay the beginning of stem elongation but this retardant has no effect on the number of flower buds.In contrast, N-dimethylaminosuccinamic acid (B 995), when applied after a cold treatment, delays the beginning of stem growth, this delay increasing with greater amounts of applied B 995. However, with relatively small amounts of B 995, the rate of later stem growth increases rapidly so that treated plants flower at the same time as controls.If gibberellic acid (GA3) is applied on the apical bud just at the same time as B 995, it reverses the effects of the growth retardant, even when the amount of B 995, applied by itself, is sufficient to inhibit entirely stem elongation and flowering.B 995 is particularly effective if the preceding cold treatment was just sufficient for effective vernalization. If the cold treatment was extended beyond this time, a greater amount of retardant was required to obtain the same degree of stem growth inhibition.B 995 probably acts by interference with the metabolism of endogenous gibberellin-like substances. The delay of floral initiation in vernalized Oe. biennis by B 995 is a consequence of the retarded internode elongation; if this retardation exceeds a certain limit, the plant is devernalized and exhibits a cold requirement identical with the original one.

Growth and Development of Oenothera fruticosa Is Influenced by Vernalization Duration, Photoperiod, Forcing Temperature, and Plant Growth Regulators

“…Control of height by plant growth regulator (PGR) treatment may be required to produce high-quality potted plants. Although we have been unable to find any previous reports on the effect of PGRs on O. fruticosa, single applications of up to 3000 µg of chlormequat per pot to the root zone of chilled O. biennis plants reportedly had no effect on stem elongation or flowering (Pickard, 1967).…”

Flowering regulation in the facultative biennial Oenothera biennis L.: Environmental effects and their relation to growth rate

“…spring-summer) had previously been attributed to a non-satisfied absolute cold requirement (Chouard, 1960;Picard, 1967;Grignac, 1988;Reekie, 1997;Berti et al, 2006), the evidence from this study does not support this premise. A high proportion of annual plants occurred in Vn− of PD a and a considerable amount of Vn− plants also behaved as annuals in PD b, both exploring temperatures usually assumed as non-vernalizing (>10 • C) (Fig.…”

“…Biennial behavior could be explained as the consequence of the dissatisfaction of an obligate requirement for one or more developmental factors, like vernalization or long photoperiods (Chouard, 1960;Picard, 1967;Reekie and Reekie, 1991;Lapinskas, 1993;Liu et al, 2003). Besides this, there is evidence that factors usually associated with growth could also be involved (Kromer and Gross, 1987;Roy et al, 1993;Lapinskas, 1999;Król and Berbeć, 2004;Król, 2007).…”

Stimulation of Growth of Peppermint (Mentha piperita) by Phosfon, a Growth Retardant

“…Preston and Link (1958), Cathey (1964), Sachs (1961) and numerous others have reported phosfon as being a growth retardant in agreement with the results stated in this paper. In contrast, phosfon-induced stimulatory growth at low concentrations in soil has been reported by Cathey and Stuart (1961), Kende et al (1963), Knypl (1967), Picard (1967) and several others for a number of plants including zinnia (Z. elegans), morning glory {Ipomoea purptirea Lem.) and sunfiower {Helianthtts anmttts L.).…”