Necrotic areas along leaf margins and at leaf tips were observed on Freesia hybrida Bailey when an aqueous application of hydrofhiosilicic acid (H2SiF6) was added to the growing medium. Similar foliar symptoms occurred with the addition of superphosphate or treblesuperphosphate which contains 1.0–1.6% F as a contaminant. Tissue fluoride levels increased when H2SiF6, superphosphate or treblesuperphosphate was added to the soil.
Vacuum infusion or soaking of freshly harvested Freesia hybrida Bailey ‘Moya’ corms in solutions of ethephon, gibberellic acid (GA3), abscisic acid (ABA), benzylamino purine (BA) or indoie-acetic acid (I A A), or in solutions with combinations of these growth regulators, did not decrease the time required for shoot emergence. Ethephon delayed shoot emergence and acted synergistically when combined with GA3, or with GA3 and BA, to further delay shoot emergence. Ethephon or ethephon + B A treatments increased the number of shoots produced per corm. Days to flower and flower quality were not influenced by any of the exogenous growth regulator treatments. Presently, there appears to be little horticultural advantage in applying these growth regulators to freesia corms to hasten shoot emergence prior to planting in order to circumvent the need for 10 to 13 week storage treatment at 28°C to remove dormancy and to ensure rapid shoot emergence.
Seed germination of ‘Royal Mix’ freesia was most rapid and uniform at 15.5° or 18.5°C under clear polyethylene or at 13° or 21.5°C under black polyethylene. Soaking seeds in running water prior to germination or removal of the seed coat did not improve seed germination
Lilium longiflorum Thunb. ‘Nellie White’ flower buds developed from visible bud to open flower more rapidly at constant 27°C than at constant 15°. This increased growth rate was most pronounced when buds were less than 6 cm. Once buds were greater than 10 cm, the differences in rate of flower bud growth at 15° compare to 27° was insignificant. Bud development was biphasic, with a relatively slow growth rate up to 6 cm and then an accelerated rate from 6 cm to open flower. The fitted regression line for buds less than 6 cm was: days to flower (DTF) = 37.969 - 8.945 Ln [bud length (L)] — 0.453 [(Temperature (T)]; for buds greater than 6 cm: DTF = 33.258 — 2.039 (L) - 0.736 (T) + 0.044 (L x T). The correlation coefficients for the 2 equations were respectively: r = 0.82 (R2 = 0.67) and r = 0.93 (R2 = 0.87).
Lilium longiflorum Thunb. cv. Nellie White bulbs were shipped in 1969, 1970, and 1971 from the west coast to St. Paul by air freight from July to October at 15 day intervals. Bulbs were given 0 or 2 weeks of 10°C, 15.5°C or 21 °C followed by 0 or 6 weeks of 4.5°C. Two weeks exposure to 10°C enhanced shoot emergence and flowering of late-harvested non-cooled bulbs and enhanced flowering of cooled bulbs. Treatments of 15.5°C or 21°C had little influence on shoot emergence and flowering of non-cooled bulbs and delayed flowering of early harvested cooled bulbs. With time and with increased bulb growth the degree of dormancy (delay of emergence) decreased and degree of maturity (enhancement of early flowering by 4.5°) increased.
Plants of Chrysanthemum morifolium Ramat. cv. Bright Golden Anne irradiated as a day continuation or night interruption with light from cool white fluorescent tubes wrapped with red cellophane (red) produced more cuttings than plants irradiated with incandescent light. There were no significant differences in cutting production when plants were irradiated just prior to dawn. Increased cutting production from plants irradiated with red light was attributed to increased axillary bud activity, especially at the middle nodal position. When shoots were pruned to 4 or 8 nodes, the apical axillary bud produced the maximum number of cuttings and the basal produced the minimum, irrespective of light quality or time span of irradiation.
Alstroemeria ‘Regina’ plants produced more vegetative shoots when the soil temperature alternated between 15°C (40 days) and 21° (20 days) as compared to a constant 15° soil temperature. However, a higher percentage of the shoots flowered from plants grown at the constant 15° soil temperature. Short days (8 hours light) inhibited flowering irrespective of soil temperature. Plants given a long-day treatment by exposing them to a night break with incandescent light flowered 6 weeks earlier than plants grown under normal day photoperiods during winter and spring and produced 30% more flowering stems. Treatments favoring flower development produced shorter flowering stems with fewer leaves. Maximum flower production resulted from plants grown at a constant 15° soil temperature and irradiated with incandescent lights as a night interruption.
Florida-produced ‘Prize’ azalea plants were shipped to Minnesota with apical floral buds whose individual flowers had styles which had commenced elongating. These plants were ready for rapid forcing if given the traditional 6 weeks at 9°C. However, a single 2000 ppm GA (Pro Gibb3) spray treatment resulted in plants which flowered more rapidly without a traditional cold treatment when forced in a glasshouse under natural daylength (ND) in Minnesota during the spring and summer. Length of the ND in these experiments was considered critical, as plants forced in the spring and summer under an 8-hr short day (SD) treatment did not flower in a uniform manner, or floral abortion occurred in GA treated, uncooled plants forced during the autumn. Under ND conditions, extended to 20-hr by high pressure sodium, cool-white fluorescent or incandescent lamps, plants flowered more rapidly than those plants cooled at 9° for 6 weeks and forced under ND. Uniformity of flowering was enhanced and GA treatment had no effect when 3 weeks of 9° cooling preceded supplemental lighting treatments during autumn forcing. During winter, 20-hr of high pressure sodium + GA treatment or a SD treatment of noncooled plants resulted in more rapid, but similarly uniform flowering, when compared to plants with 6 weeks of cold treatment. These data provide evidence indicating that ‘Prize’ azalea floral buds may not exhibit a physiological dormancy.
When Alstroemeria ‘Regina’ shoots were grown in a continuous 13°C air temperature, and the underground structures (rhizomes and roots) were placed in a 5°, 10°, 15°, 20°, or 25° water bath, plants produced 22%, 33%, 13%, 14%, or 5% generative shoots, respectively (Expt. 1). When the underground structures were grown at 13°, there were no differences in percentages of generative shoots, regardless if shoots were in a 13° or 21° air temperature, and regardless if shoots were under short or long photoperiods. When soil temperature was 21° and air temperature was 13°, 12% generative shoots were produced only with a night interruption photoperiod (Expt. 2). Data from these 2 experiments led us to conclude that floral induction was controlled primarily by temperatures to which the underground structures were subjected, regardless of the air temperature or photoperiod. Storage root and rhizome dry weights were promoted by 13° air, 13° soil temperatures and night interruptions with incandescent light. Treatments which had a high percentage of generative shoots also had high root and rhizome dry weights.
Irradiating the all-green Chlorophytum comosum Thunb. with incandescent or red cellophane wrapped fluorescent lamps during the night increased the mean number of stolons formed per plant. A night interruption was more effective in stimulating stolon formation than irradiating the plants prior to sunrise or at sunset. There were no significant differences in stolon numbers formed between the two light sources within an irradiation treatment. Less and less time was required between the advent of subsequent stolons under all treatments during the 25 week experiment. Photoperiod treatments had no effect on time from visible stolons to anthesis. Plants in all treatments formed stolons and flowered.