Effects of the Growth Retardant CCC on Floral Initiation and Growth in Pharbitis nil

Abstract

Growth-retarding chemicals such as Amo-1618 (2,12 ), CCC [(2-chloroethyl No specific effects of growth retardants on floral initiation in short-day plants (SDP) have heretofore been reported. The present paper concerns the effects of the growth retardant CCC on flower formation and growth of the SDP Pharbitis nil and the rev-ersibility of these effects by gibberellin A3. Materials and MethodsSeeds of Pharbitis nil Chois., strain Violet, were treated with concentrated sulfuric acid for 60 minutes ancl subsequently washedl overnight with tap water.The swollen seeds were planted in vermiculite and kept at 300 for 2 days. The emerging seedlings were theni transplanted to 10-ml vials containing half strength Hoagland's nutrient solution. If necessary the pH of the solution was adjusted to 5.6 with KOH. 100 ml of deionized water. Before and after this application, nutrient solution was applied sparsely so that the containers were never drained.The quantitative criteria for measurement of flowering were used as previously described (1, 14). Internodes were measured when fully mature.Plants grown continuously in LD were measured at regular intervals and the number of leaves produced was counted. Young leaves were not counted until their blades had begun to unfoldl.

Effect of some (2-chloroethyl) trimethylammonium chloride analogs and other growth retardants on gibberellin biosynthesis in Fusarium moniliforme.

“…For example, they strongly support the conclusion that these gibberellins play a part in the regulation of flower formation (1,17,18), of sex expression in cucumbers (10) Ho-wever, in the barley-endosperm system B-995 was quite ineffective in modifying the GA-induced response (12). Further experiments on the action mechanism of B-995 and related compounds are clearly needed.…”

“…The most common response is reduction of stem elongation which in extreme cases can result in almost rosette-like growth habit but which, apart from a deeper-green color and greater thickness of the leaves, is usually not associated with pronounced anomalies of development or structure, as is, for example, growsvth inhibition by high doses of .auxins or related compoun(ls. Another effect, observe(l in some plants, is suppression of the flowerinducing effect of favorable photoperiods (1,17,18). This effect is also selective, vegetative growth, as expressed by the rate of leaf formation, not being affected at all, or affected to a much lesser extent.…”

“…A number of investigators have emphasized that the response of plants to the growth retardants tends to be the opposite of that to gibberell-ins, and have shown that the effects of the retar plants can be overcame by treatment with gibberellins (GAs) (1,7,14,16,17,18). Lockhart (7) has proposed, on the basis of kinetic studies, that the retardants are genuine GA antagonists, exerting their effect by reducing the activity of GA in plant tissues in a specific manner.…”

Role of Gibberellins in Stem Elongation and Flowering in Radish

“…Dwarfing agents, such as 2-chloroethyltrimethyl amnmonium chloride (CCC) and (4-hvdroxy-5-isopropyl-2-methylphenyl) trimethyl ammonium chloride-i-piperidine carboxvlate (AMO-1618), which inhibit gibberellin production, have been useful in studying the role of endogenous gibberellins in flowering of a long-day plant (2), of a .short-day plant (15), of a long-short-dav plant (17), and of plants requiring low temperature for flower formation (8,13 The plants that remained vegetative formed a rosette after GA treatment was terminated, when a total of 300 yg had been applied per plant. (fig 2).…”

Effect of Photoperiodic Floral Induction on the Metabolism of a Gibberellin Precursor, (-)-Kaurene, in Pharbitis nil

“…Zeevart (14) has shown that 2-chloroethyltrimethylammonium chloride (CCC), an inhibitor of gibberellin biosynthesis, blocks photoperiodically indtuced flowering in the short-day planit, Phlrbitis nil. Since this inhibition wvas completely reversed by application of gibberellic acid (GA.:), it appears that gibberellins are involved at some stage of the flower induction process in this plant.…”