gum can germinate with pulp of drupes intact, although it is unknown whether pulp enhances or impedes seed germination of Nyssa spp. Fagan et al. (1981) demonstrated that seeds of lily turf [ Liriope muscari (Decne.) L.H. Bailey] with their mealy
Frank Balestri and William R. Graves
Ali O. Sari, Mario R. Morales, and James E. Simon
Echinacea pallida, one of the three medicinal Echinacea species native to North America, is generally wildcrafted, and low and uneven seed germination are obstacles to its widespread cultivation. Nonstratified E. pallida seeds were treated with 2500, 3500, and 4500 mg/L GA3 to increase seed germination. Treated seeds were directly germinated at 25 °C and 25/15 °C (14/10h) or stored at 5 and 10 °C for 4, 8, and 12 weeks before germination at the same temperatures. Seed germination across treatments was higher at 25 °C (19%) than at 25/15 °C (14%). Application of 2500, 3500, and 4500 mg/L GA3 significantly increased seed germination rate and total seed germination of nonstratified seeds of E. pallida and resulted in 44%, 50%, and 63% total seed germination, respectively, while untreated control seeds germinated at only 9%. The effect of GA3 as a germination stimulant increased with cold storage, with maximum germination (83%) occurring after seeds were treated with 4500 mg/L GA3 and an 8-week cold storage period at 10 °C. The effect of cold storage periods of 4, 8, and 12 weeks and cold storage temperatures of 5 and 10 °C on seed germination were generally similar. Seeds collected from the upper rows of the seed heads germinated significantly higher (10.6%) than those collected from the lowest seed rows (2.4%).
Kit L. Chin, Catalino A. Blanche, and V.R. Bachireddy
Rapid and timely production of kiwi (Actinidia deliciosa) seedlings is often hampered by poor and erratic seed germination. This investigation was conducted to assess the effect of gibberellic acid, cold stratification (5° C), and their combinations on seed germination and subsequent radicle elongation. Germination counts and radicle elongation measurements were made two weeks after incubation at 25.4° C under continuous light and approximately 100% RH. GA treatments broke dormancy and increased germination and radicle elongation with increasing concentration up to 2500 ppm. At 5000 ppm, germination and radicle elongation were reduced. Cold stratification (1 and 2 week durations) alone did not affect germination nor break dormancy. Combined cold stratification and GA treatments significantly enhanced seed germination and radicle elongation with the best response at the highest GA concentration (5000 ppm) and longest stratification (2 weeks), regardless of whether the seeds were stratified prior to or after GA treatments.
Yung-I Lee, Nean Lee, Edward C. Yeung, and Mei-Chu Chung
This investigation documents the key anatomical features in embryo development of Cypripedium formosanum Hayata, in association with the ability of embryos to germinate in vitro, and examines the effects of culture media and seed pretreatments on seed germination. A better understanding of zygotic embryogenesis for the Cypripedium L. species would provide insights into subsequent germination events and aid in the in vitro propagation of these endangered species. In seeds collected at 60 days after pollination (DAP), soon after fertilization, no germination was recorded. The best overall germination was found at 90 DAP (≈70%), at which time early globular to globular embryos with a single-celled suspensors can be observed. After 135 DAP, the seeds germinated poorly. At this time the inner integument shrinks and forms a tight layer, which encloses the embryo, the so-called “carapace.” Using Nile red stain, a cuticular substance was detected in the carapace, which may play a role in the impermeability of the mature seed and may help the seeds survive in the stringent environment. At maturity (after 210 DAP), the embryo proper has an average size of eight cells along its length and six cells across the width. Lipids and proteins are the main storage products within the embryo. To improve seed germination, experiments were conducted to test the suitability of various media and pretreatments of seeds. When different media were used, except for the Harvais medium at 120 DAP, there was no significant difference in seed germination at three different developmental stages tested. Soaking mature seeds in 1% NaOCl or treating them with ultrasound may slightly increase the germination percentage. For seed germination, our results indicate that the timing of seed collection outweighs the composition of medium and the seed pretreatments.
Moo R. Huh, Beyoung H. Kwack, and Leonard P. Perry
In this experiment, the effects of salinity from 0.0%, 0.5%, 1.0%, and 5.0 % NaCl on Hibiscus syriacus L. and Hibiscus hamabo Sieb. & Zucc. seed germination with various temperature and Ca treatments was investigated in petri dishes with 10 ml of distilled water or with the appropriate saline solution. At 11 days after treatment, the highest germination rate was obtained at 20C with H. syriacus and 25C with H. hamabo without NaCl and Ca treatments. At 25C, only H. hamabo seeds germinated with 1% NaCl, with dry and fresh weight increasing as Ca concentration increased. With 0.5% NaCl treatment, the germination rate of H. hamabo and H. syriacus increased as Ca concentrations (0.0, 13.35, and 133.5 mM) increased. Without NaCl treatments, hypocotyl and leaf length and width of H. syriacus were longer than those of H. hamabo; with NaCl treatments, the inverse was true.
N. Wartidiningsih and Robert L. Geneve
Germination was evaluated in six seed lots of purple coneflower purchased from four different seed companies. Standard germination percent ranged from 28% to 90% depending on the seed lot. For seed collected in 1989, seed size and stage of development of the seed at harvest could not account for the wide variability in seed germination observed in the purchased seed lots. preconditioning the seed with either cold stratification (10°C for 10 days) or osmotic priming (PEG or salt solution at -5 bars for 5 days) increased the rate of germination and the overall percent germination for all seed lots and dramatically improved germination in the poor germinating seed lots. Preconditioning appears to overcome either a shallow physiological dormancy or compensates for seeds with poor vigor or quality. In either case, seed preconditioning drastically improved seed germination (rate and percent) in greenhouse and field tests for purple coneflower.
John M. Smagula, Michael Michaud, and Paul R. Hepler
A light requirement for improved seed germination of lowbush blueberry (Vaccinium angustifolium Ait.) was partially overcome by GA treatments; GA at 500, 1000, 2000, and 4000 ppm stimulated early germination of seeds kept in the dark. The germination rate of seeds exposed to an 8 hour light period was also enhanced by GA treatments. Continuous exposure to concentrations above 1000 ppm resulted in abnormally curled seedlings with necrotic root tips.
G. C. Sharples
Activated carbon stimulated seed germination of lettuce (Lactuca sativa L.) in soil and vermiculite. Stimulation was strongly dependent upon the moisture potential. Germinating seeds were shown to excrete an inhibitor into the micro-environment which cannot diffuse away rapidly at moisture potentials near the soil field capacity or at analogous potentials in vermiculite. Increasing the moisture potential or adding activated carbon caused rapid removal of inhibitor from the seed micro-environment.
Paul H. Henry and Frank A. Blazich
Two experiments investigated the relationship of light and temperature in seed germination of Fraser fir [Abies fraseri (Pursh) Poir.]. Irradiation during the warm portion of 9/15 hr thermoperiod of 20/10C and 30/20C increased germination percentages after 42 days, and the degree of stimulation depended on the timing of the light exposures. A 1-hr exposure was most effective during the latter part of the warm portion of the thermoperiods, and varying the time of irradiation had the greatest effect at 20/10C. The involvement of phytochrome in this photomorphogenic response was ascertained by demonstration of red/far-red reversibility.
Hae-Jeen Bang, Soo-Jung Hwang, Hyun-Sook Ham, and Jung-Myung Lee
The effectiveness of solid matrix priming (SMP) and seed brushing was further evaluated by using an thermo-gradient table (Seed Processing, Holland) set at 10 different temperatures from 12 to 30 °C. Intact or brushed seeds of gourd (Lagenaria siceraria) were primed with Micorocel E (Celite Corp.) at 25 °C for 3 days in the mixture of 10 seed: 1 Microcel E: 3 water, by weight, and the primed seeds were dried again for long-term storage. SMP treatment significantly increased earlier seed germination at all temperatures. However, the difference in seed germination rate between intact and SMP-treated seeds was most pronounced at somewhat lower temperatures of 18-22 °C. SMP-treated seed showed about 20% final germination rate at 12 °C, whereas intact seeds did not germinate at all. Seed brushing treatment itself did not influenced the germination rate. However, brushing treatment before SMP treatment significantly increased the SMP effect. Combined use of chemicals in solution further increased the early germination. Details of various seed treatment methods will be presented.