Comparative Cytohistological Studies on Inhibition and Promotion of Stem Growth in Chrysanthemum Morifolium

Abstract

Sachs, R. M. (U. California, Davis), and A. M. Kopranek. Comparative cytohistological studies on inhibition and promotion of stem growth in Chrysanthemum morifolium. Amer. Jour. Bot. 50(8): 772‐779. Illus. 1963.—The present study with Amo, CCC, and Phosfon,3 3 substances which inhibit stem elongation, shows that all inhibit subapical cell expansion and division in Chrysanthemum morifolium var. ‘Indianapolis Yellow.‘ Furthermore, GA,3 in preventing the inhibition of stem elongation, maintains subapical activity at normal or greater than normal levels. For comparative purposes concentrations of the retardants and GA have been selected which completely prevent or promote the maximum rate of stem elongation. Phosfon causes complete inhibition of root growth and almost completely prevents dry matter accumulation in the tops. However, GA does not prevent such deleterious effects. Thus, GA and the growth retardants are mutually antagonistic only with respect to stem elongation and not to other aspects of growth. Furthermore, none of the retardants inhibits transverse stem growth; on the contrary transverse cell expansion and division in the subapical tissues are stimulated by the retardants, and as a result the stems of such plants are thicker than normal. GA not only prevents the thickening effect of the retardants, but, at the doses applied, GA‐treated stems are considerably thinner than those of the controls, having fewer and smaller cells across the pith, cortical, and vascular tissues. Apparently, then, there is a relationship between longitudinal and transverse growth in the subapical tissues such that if one is promoted, the other is inhibited.

Effects of Phosfon-S on Nucleic Acid Metabolism in Pisum sativum Alaska

“…Others (4,9,14,20,21), however, have found many instances in which there was little or no mutual antagonism between the retardants and gibberellins or auxins. They have felt that the inhibitory effects should not be restricted to the hormonal level.…”

Action of Gibberellic Acid on Cell Proliferation in the Subapical Shoot Meristem of Watermelon Seedlings

“…These values are 10-12 hr longer than those which we obtained from normal or GA-treated dwarf watermelon seedlings. In the rosette plant Samolus parviflorus, Sachs et al (1959) reported a cell generation time of 24 hr in subapical meristem cells partially synchronized by GA treatment. Cell cycle times obtained from root meristems of several species at temperatures between 20-30 C (Burholt and Van't Hof, 1971;Evans and Savage, 1959;Van't Hof and Sparrow, 1963;Wimber, 1966) are generally shorter than the above values for shoot meristems.…”

“…Studies employing GA-responsive genetic dwarfs (Basford, l 1961;Greulach and Haesloop, 1958;Loy and Liu, 1974;Okuda, 1964), rosette plants (Bernier, Bronchart, and Jacqmard, 1964;Sachs, Bretz, and Lang, 1959), and plants treated with growth retardants (Sachs and Kofranek, 1963;Sachs et al, 1960) have provided convincing evidence that stimulation of cell division in the subapical meristematic zone is a common feature of gibberellinmediated increases in stem elongation. Burholt and Van't Hof (1971) emphasize the need to examine several parameters, such as mitotic index, duration of the cell cycle and the number of proliferating cells to provide an accurate assessment of cell kinetics in meristematic tissues.…”

Chrysanthemum and Gaillardia as Stunted Winter Annuals I. Tricolor Chrysanthemum (Chrysanthemum Carinatum Schousb.)

“…Such gains may be explained by the direct role of growth retardants used in retarding stem elongation by reducing cell division and extension in the subapical meristematic zone of the stem (Sacks and Kofranek, 1963) or by inhibition of cytokinin and gibberellin biosynthesis (Million et al, 1999). Similar observations were also postulated by Wei and Han (1997), Yewale et al (1997) and Yoo et al (1999) on chrysanthemums.…”

“…Among of these plants may be chrysanthemums which usually need staking to stay upright. In this respect, Sacks and Kofranek (1963) have shown that Amo-1618, CCC and phosphon-D, all inhibite subapical cell expansion and division in Chrysanthemum morifolium. Qrunfieh and Al-Wir (1987) elicited that PP-333 at 1000, 2000 and 4000 ppm as soil drench significantly reduced shoot length in five chrysanthemum cvs., namely: Tom Pearce, PR.…”