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.
N. Wartidiningsih and Robert L. Geneve
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.
D. H. Scott and A. D. Draper
Irregular germination and delayed emergence of blueberry, strawberry, blackberry and raspberry seedlings have been noted by various investigators. Seed treatments such as afterripening (1) and acid scarification of strawberry seed (2) improved rapidity of germination, but neither treatment fully overcame the delay in seed germination. In a study with blueberry seed, after-ripening did not improve germination (2). Sporadic germination and delayed emergence of seedlings complicates a breeding program when uniform size of seedlings is desired.
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.
Timothy W. Miller
Diquat was tested to determine its suitability for use as a preharvest desiccant of selected vegetable seed crops during 1997 and 1998. In separate studies, diquat was applied at 0,0.56, or 1.12 kg·ha-1 ai. to spinach (Spinacia oleracea L.), table beet (Beta vulgaris L.), and coriander (Coriandrum sativum L.) plants at usual swathing time. Except for beet seed in 1998, there was no clear trend toward reduced seed weight with increasing diquat rate. Spinach seed germination in 1998 and coriander seed germination in 1997 were reduced by diquat at 1.12 kg·ha-1 compared to seed from nontreated plants or plants treated with 0.56 kg·ha-1. In all crops, diquat at 0.56 kg·ha-1 was adequate for crop desiccation purposes. However, seed producers should consider the potential benefits from chemical desiccation that may potentially lower germination of the harvested seed. Chemical name used: 6,7-dihydrodipyrido[1,2-α:2′,1′-c]pyrazinediium ion (diquat).
Monica Ozores-Hampton, Thomas A. Bewick, Peter Stoffella, Daniel J. Cantliffe, and Thomas A. Obreza
The influence of compost (derived from MSW and biosolids) maturity on seed germination of several weed species was evaluated. A bioassay was developed by extracting 20 g of compost of different maturities with various volumes of water, then measuring germination percentage of ivyleaf morningglory (Ipomoea hederacea) seeds placed on extract-saturated filter paper in a petri dish. A 20 g (dry weight) compost: 50 mL of water generated an extract that produced the widest percentage seed germination variation in response to composts of different maturity. Ivyleaf morningglory, barnyardgrass (Echinochloa crus-galli L.), purslane (Potulaca oleracea L.), and corn (Zea mays L) were selected as plant indicators to determine the compost maturity stage with maximum germination inhibition. Compost 8-week-old decreased percent germination, root growth, and germination index (combines germination rate and root growth), and increased mean days to germination (MDG) of each plant indicator. Immature 8 week-old compost extract effect on MDG and germination percent of 15 weed species was evaluated. Extract from 8-week-old compost inhibited germination in most weed species, except yellow nutsedge (Cyperus esculentus). Compost extracts derided from immature (3-day, 4-, and 8-week-old) compost resulted in delayed and reduced germination percent of important economic weed species.
Rachel Emrick, D. L. Creech, and G. Bickerstaff
This project tested rates of lignite-activated water (LAW) for its influence on seed germination, cutting propagation, and plant performance. LAW is a product of CAW Industries, Rapid City, S.D. LAW is water-activated by lignite in a process that includes the addition of sulfated castor oil, calcium chloride, magnesium sulfate, sodium meta silicate, and fossilized organics from refined lignite. LAW is reported to improve many plant performance traits. Four rates were used in this study. Seed germination trials indicated no significant differences in germination percentage with LAW applications with the two species tested, Echinacea purpurea and Hibiscus dasycalyx. In a “closed” system, LAW enhanced cutting propagation success of Aster caroliniana, Cuphea micropetala, and Verbena `Homestead Purple', as measured by percent rooting and dry weight of roots produced. Cutting propagation of two woody species, Illicium henryi and Rosa banksiae, was not improved with LAW additions. In the SFASU Arboretum, pansy performance, as measured by plant dry weight, was improved one month after establishment.
Lewis W. Jett, Gregory E. Welbaum, and Ronald D. Morse
Priming, a controlled-hydration treatment followed by redrying, improves the germination and emergence of seeds from many species. We compared osmotic and matric priming to determine which was the most effective treatment for improving broccoli seed germination and to gain a greater understanding of how seed vigor is enhanced by priming. Broccoli (Brassica oleracea L. var. italica) seeds were osmotically primed in polyethylene glycol (PEG 8000) at -1.1 MPa or matrically primed in a ratio of 1.0 g seed:0.8 g synthetic calcium silicate (Micro-Cel E):1.8 ml water at -1.2 MPa. In the laboratory, germination rates and root lengths were recorded from 5 to 42C and 10 to 35C, respectively. Broccoli seeds germinated poorly at >35C. Root growth after germination was more sensitive to temperatures >30C and <15C than radicle emergence. Matric and osmotic priming increased germination rate in the laboratory, greenhouse, and field. However, matric priming had a greater effect on germination and root growth rates from 15 to 30C. Neither priming treatment affected minimum or maximum germination or root growth temperatures. Both priming treatments decreased the mean thermal time for germination by >35%. The greater germination performance of matrically primed seeds was most likely the result of increased oxygen availability during priming, increased seed Ca content, or improved membrane integrity.