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- Author or Editor: H. F. Wilkins x
Abstract
Ethylene (C2H4) and CO2 levels and callus formation were influenced by photoperiods (8 hours-SD; 16 hours-LD) under which ‘Nita’ dahlia stock plants were grown and leaf segments incubated in vitro. Larger callus and higher levels of C2H4 and CO2 were detected when tissues from stock plants under SD were incubated under SD (SD-SD) than when incubated under LD (SD-LD). Tissue under LD-LD or LD-SD formed similar amounts of callus to SD-LD cultures, but C2H4 and CO2 levels were higher. Compared to water-sprayed controls, 2500 mg/liter butanedioic acid mono-(2,2-dimethylhydrazide) (daminozide) sprayed on SD stock plants one day before explant removal promoted callus formation, and C2H4 and CO2 production in tissue incubated under either SD or LD. Daminozide sprayed on LD stock plants had no influence on callus or C2H4, but CO2 was increased under SD or LD incubation.
Abstract
Pretreatment of excised leaves of Petunia hybrida L. with AgNO3 permitted shoot formation equal to the control, when explants were cultured on a medium containing 6-benzylamino purine (BA), but increased callus formation, chlorophyll content, and ethylene production. When explants were cultured on a medium containing α-naphthaleneacetic acid (NAA), pretreatment with AgNO3 promoted callus growth, root formation and extension, and ethylene production, but inhibited root hair formation. Pretreatment of explants with CuSO4 suppressed ethylene production and chlorophyll content. Inclusion of AgNO3 partially overcame the effects of CuSO4 alone. When the rhizobitoxine analog, L-2-amino-4-(2-aminoethoxy)-trans-3-butenoic acid (Rh), was used for pretreatment, ethylene emanation was inhibited for 2 or 3 weeks. Number of shoots and roots, root length, root hair and callus formation were not affected by Rh except that callus growth was reduced on a medium containing NAA. NAA (1.0 mg/liter) promoted callus and root formation and induced high levels of ethylene, while kinetin (0.2 mg/liter) stimulated shoot formation but simultaneously induced much lower levels of ethylene.
Abstract
Plants of Freesia hybrida Bailey ‘Moya’, grown from corms and ‘Royal Crown’ from seed flowered when the temperature was 13°C continuously or with 13° during an 8 hour light span or with 13° during a 16 hour dark span both of which were alternated with 24°. Flower quality was poor but marketable on plants treated a 13° light or dark temperature alternated with 24°. Results suggest that the commercial production season could be extended into warm seasons by maintaining 8 hours of inductive temperature (13°) in greenhouses or coolers. Flowering or corm filling did not occur at continuous 24°.
Abstract
Lily plants were exposed to natural daylight (ND), 50% ND (50% saran), ND plus 16 hours of incandescent (Inc) or ND plus 16 hours of high pressure sodium discharge (HID) lamp light at both University of Minnesota and Michigan State University. Light intensity had no significant horticultural effect on plant development rate that could not be readily explained by temperature. The Inc or HID light source hastened flowering by 5 to 8 days over the ND plants when given from emergence to flower. However, the rate of development from visible bud to flower was not influenced by light intensity. Plant heights were increased by all light treatments when compared to the ND plants. These increases appeared due to photoperiod for the HID treated plants, photoperiod and light quality for the Inc treated plants, and light quantity for the 50% saran-treated plants. The number of flower buds initiated was not affected by light treatment but Inc lighting increased flower bud abortion. Final plant height was highly correlated with height at visible bud; final height being about double the height at visible bud when plants were grown continuously under ND, HID, or 50% saran.
Abstract
Dormancy of non-cooled Lilium longiflorum Thunb. cv. Ace bulbs was broken with GA3 (1000 ppm), while ABA (500 ppm) partially negated the effect of vernalization on dormancy breaking. Infusion of bulbs with GA3 or ABA had little effect on days to anthesis. Injections of GA3, GA4, or GA7 into shoots from non-cooled bulbs did not substitute for vernalization or affect days to anthesis. ABA injections into shoots from cooled bulbs partially negated the effect of vernalization and delayed anthesis. Injections of GA3 or GA7 into shoots from cooled bulbs decreased days to anthesis, while GA3, GA4 or GA7 increased plant height. ABA delayed anthesis and reduced stem elongation. The major effect of exogenous GA applications appears to stimulate bolting.
Abstract
Lilium longiflorum Thunb. cv. Nellie White shoots rapidly emerged and flowered when bulbs were given a 4.5°C/40 day treatment. However, GA levels in the bulbs did not increase during the 4.5°C/40 day cold storage, but increased afterwards in the greenhouse with a GA maximum 30 days past storage. ABA activity patterns were similar to GA. Bulbs first treated at 4.5°C/30 days and then followed by 21°C/30 days had higher GA activity and their shoots were slower to emerge and flower than those of bulbs first treated at 21°C/30 days then given 4.5°C/30 days. Bulbs from 4 harvest dates had greater GA activity in the inner scales while ABA activity was greater in the outer scales.
Abstract
Easter lily (Lilium longiflorum Thumb. ‘Nellie White’) bulbs forced under an 8-hr duration of fluorescent light at 400 μmol·s−1·m−2 were acceptable for commercial sales. The total number of flowers initiated were not influenced by light intensity or duration during forcing. The number of flowers reaching anthesis was influenced by light duration. Ancymidol was effective in reducing internode elongation.
Abstract
Corms of Freesia hybrida Bailey ‘Moya’ and F. hybrida ‘Maria’ were stored at 2°, 13°, or 30°C immediately after harvest and sampled at 0, 6, or 13 weeks for fresh weight, sprouting ability, free indoleacetic acid (IAA), free abscisic acid (ABA) and conjugated ABA (conj-ABA). High performance liquid and gas-liquid chromatography methods were used for identification and quantification of the extractable IAA, ABA, and conj-ABA. Shoots from corms planted immediately after harvest emerged in 33 to 57 days. It is suggested that freshly harvested F. hybrida corms exhibit physiological dormancy for not more than 4 to 6 weeks and subsequently enter a state of imposed dormancy in storage at 30° or 2°. Physiological dormancy was released more rapidly and corm shoots emerged more rapidly during imposed dormancy when stored at 30° versus 2°. The 30° treatment did not appear to be mandatory for shoot emergence since corms stored at 2° or 13° for 6 weeks emerged within 5 or 20 days, respectively. Extended storage at 13° promoted pupation whereas storage at 30° and 2° prevented pupation. Pupated corms did not emerge when planted. The IAA, ABA, and conj-ABA levels in the corms during storage did not correspond with growth inhibition but rather appeared to relate to the formation of the new corm during pupation.
Abstract
Freesia hybrida Bailey ‘Moya’ corms were analyzed for extractable indole-3-acetic acid (IAA), abscisic acid (ABA) and conjugated ABA (conj.-ABA) before and after 13 weeks of storage at 30°C. After 13 weeks of 30° storage, which is required for emergence, IAA levels did not change in the apical node + bud; however, there was a decrease in ABA and no statistically significant change in the conj.-ABA levels. IAA level increased (0.5 to 14 ng/g fresh weight) in the lateral buds after 13 weeks of heat while the ABA and conj.-ABA did not statistically change. Over the same period, IAA increased slightly (3 to 7 ng/g fresh weight) in the remaining corm tissue while ABA and conj.-ABA levels remained statistically constant.
Abstract
Corm, shoot, and flower development in seed grown Freesia hybrida Bailey cv. Super Emerald Mixture were compared with levels of endogenous indoleacetic acid (IAA), abscisic acid (ABA) and conjugated ABA (conj-ABA) in the developing corm tissue. Lowering the forcing temperature to below 15°C stimulated floral initiation and corm filling. IAA levels decreased midway through corm filling in 1977 whereas in 1978 the decrease was not statistically significant. During the period of rapid corm filling, ABA levels increased as the temperature decreased below 15° suggesting an association between temperature, corm filling, and ABA.