Effect of gibberellin (GA) concentration on Chrysanthemum (Pink Adorn, White Adorn, Daisy Royal, and Target) were investigated. The controlled and noncontrolled were observed. GA 1.5 was applied to the noncontrolled garden mums at 1, 2, 5, and blank ppm concentrations. The controlled and noncontrolled was evaluated after one week. Normal growth rate on controlled. Growth rate on noncontrolled at 1, 2, and 5ppm was evidently accelerated on all varieties, while GA blank decreased the growth rate of all varieties. GA at 1, 2, and 5ppm affected the Target variety more than any other variety.
Abstract
Correlative inhibition of axillary shoot growth is one aspect of apical dominance that has been extensively investigated, but we still have a limited understanding of how this interesting process is controlled (2). Substantial evidence indicates that auxin, especially IAA synthesized in the apical portion of the plant, can inhibit axillary shoot growth (see refs. 2, 14, and 15) and that the inhibitory effect of IAA is most likely exerted indirectly (see ref. 10). In general, when apical dominance is released by surgical removal of the apical portion of a young plant, release of suppressed growth of axillary buds is detectable within 6 to 12 hr. There are three phases of growth, an initial slow phase, a second accelerated growth phase (see ref. 2) and a subsequent slow phase. There is also considerable information indicating that factors from roots, especially cytokinins, may be important for promotion of axillary shoot growth (12).
Abstract
Heading back of 2nd flush growth to basal buds on vigorous young trees at different times of the year indicated that buds were converted from a vegetative to a reproductive state within 4 weeks after they were formed at the shoot apex. Defoliation or defoliation plus etiolation of 7 terminal nodes in July did not deter the buds at these nodes from differentiating pistillate flowers for the next season. Pruning greatly accelerated the differentiation processes.
Abstract
Differences in bract abscission were found among several cultivars of poinsettia either intact or debladed in response to exogenously applied growth regulators. Indoleacetic acid (IAA) delayed the abscission of debladed petioles relative to its concentration, time, and point of application. Gibberellic acid or abscisic acid alone had no effect but interacted with IAA. Ethylene had no influence on abscission. No treatment accelerated the abscission rate of debladed petioles. There was no consistent modification of the relative differences among cultivars.
Abstract
A single application of 10 μg of brassins to a young internode of a ‘Pinto’ bean plant accelerated growth of the treated internode and of other internodes above and below the treated area. The treated internodes grew longer overall and thicker in some areas than comparable untreated ones. These responses involve both cell elongation and cell division. The treatment also caused marked changes in the vascular anatomy of leaves above the site of application.
Abstract
The effects of a magnetic field on biological systems have been studied extensively in recent years. Murphy (1) reported that a magnetic field accelerates seed germination. Boe and Salunkhe (2) suggested that the magnetic field might act upon auxin or enzyme reactions, or influence free radical formation in inducing tomato fruit ripening. Mericle et al. (3) reported that the magnetic field did not affect the rate of germination of barley seeds, but did increase the rate of shoot and root growth. According to Pittman (4), both germination and growth rates of wheat, oat, and barley seeds were enhanced by a magnetic field at certain orientation.
Abstract
Two poinsettia cultivars, ‘Annette Hegg’ and ‘Eckespoint C-l’ were grown at 60° and 65°F night temperatures, and subjected to growth retardant treatments. 2-ChloroethyI trimethyl ammonium chloride (CCC) soil drenches resulted in the shortest plants, but effective height control was achieved with combination spray applications of CCC and succinic acid 2,2-dimethylhydrazide (SADH), or CCC and N-pyrrolidinosuccinamic acid (F 529) applied once, or 2 foliar applications of CCC applied 3 weeks apart. Date of flowering was not appreciably affected by the growth retardants, but was affected by temperature. Flowering was accelerated at the warmer temperature, but plant heights and bract diam were similar at both temperatures.
Abstract
Anatomical changes which take place in conjunction with abscission of cantaloupe fruits (Cucumis melo L. cv. Powdery Mildew Resistant No. 45) include cell separation and cell collapse. Structural modifications in abscission zone cell walls are accompanied by histochemical changes which include losses of pectins and insoluble polysaccharides. Development of a separation cavity is consistently correlated with physiologically defined stages of fruit maturity, and the time of abscission coincides with the peak of the respiratory climacteric. Anatomical and histochemical changes similar to those in cantaloupe also take place in honeydew fruits (Cucumis melo L. cv. Honeydew). However, the abscission zone of honeydews is not structurally well defined, changes are limited to certain parenchyma cells, and the honeydew fruits do not normally abscise. It is suggested that the most desirable growth regulator for use on cantaloupes to accelerate and unify the time of fruit ripening would be one which did not coincidentally accelerate abscission.
Abstract
Trials over five consecutive winter seasons with ornamental crops growing in the greenhouse at split night and constant night temperatures (SNTs and CNTs) showed that a 5-hr period of 17°C minimum temperature during the dark period accelerated development over a CNT minimum of 12° to 13°. Maintaining 17° from 1700-2100 HR accelerated development over a 9° to 12° minimum CNT more than later periods of a 17° minimum with Euphorbia, Hydrangea, Kalanchoe, and Lilium. Continuation of 17° until 0100 or 0200 hr before a 9° to 12° minimum CNT was adequate for flower formation in Chrysanthemum. SNTs improved the bract : stem size ratio in Euphorbia and cyme size in Hydrangea relative to a 17° minimum CNT. Begonia × hiemalis, Begonia semperflorens, Brassaia, Coleus, Fuchsia, and Impatiens showed favorable growth responses or the potential for energy savings through the use of SNTs.
Studies were conducted over eight location-years to evaluate the effects of rowcover material, time of application, and time of removal on `Heritage' red raspberry cane growth, flowering, and fruiting. We anticipated that rowcovers would accelerate fruit maturity so that more of the crop could be harvested before the onset of cold temperatures in autumn. In seven of the eight experiments, rowcovers either increased yields or accelerated harvest. With a March application, harvest began 3 weeks earlier, and August yields of covered plants were 42 times higher than those of noncovered plants. Responses were observed with spunbonded polypropylene and polyester covers, but not with polyethylene covers. Rowcovers placed over the row before primocane emergence and removed when canes were ≈50 cm tall resulted in the greatest plant response. The use of polyester or polypropylene rowcovers with primocane-fruiting raspberries appears to be economically feasible in most years in northern climates.