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Abstract

Depulped seeds of Liriope muscari (Decne.) L. H. Bailey pretreated with GA₃ and/or kinetin and placed at 21°C for warm stratification, showed increased germination over unpulped seeds. Germination rates ranged from 87 to 100%. Identical growth regulator treatments resulted in no germination when the depulped seeds were cold stratified (5°C). Unpulped seed, pre-soaked in water for 24 hours or not soaked and given warm stratification germinated 38 and 25%, respectively. This suggested that the inhibition in unpulped seed is influenced by a water soluble inhibitor in the fruit wall.

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.

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).

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.

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.

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.

Abstract

Germination responses of creeping bentgrass (Agrostis palustris Huds.) and Kentucky bluegrass (Poa pratensis L.), and annual bluegrass (Poa annua L.) to elevated temperature were evaluated by germinating seed in sustained temperature regimes or by moving imbibed seed from high to intermediate or from intermediate to high temperatures. ‘Penncross’ creeping bentgrass germinated well at 40°/30°C (day/night) temperature or when moved from 40/30° to 25°/18° or from 25°/18° to 40°/30°. ‘Baron’ Kentucky bluegrass seed germination was decreased by 34°/28° and there was no germination at 40°/30°. Moving imbibed seed from 40°/30° to 24°/18° resulted in a high germination percentage, while imbibition for 12 or 24 hours at 25° resulted in some germination at 40°/30°. Annual bluegrass seed germination was significantly less at 34°/28° than at 25°/18° and was prevented at 40°/30°. Imbibition at 40°/30° prior to 25°/18° decreased germination and there was no annual bluegrass germination at 40°/30° regardlessf of pretreatments at 25° for up to 24 hours.

The autointoxication of chrysanthemum was studied using water extract of Dendranthema morifolium's rhizospheric soil. Results of bioassays showed that the water extract inhibited chrysanthemum seed germination and the activities of some important root enzymes. The seedling nitrate reductase activity was decreased linearly with increasing concentration of the extract. The activity of root dehydrogenase was inhibited only at the highest concentration tested [3.2 g·mL^-1, dry weight (DW)], but was stimulated at a lower concentration tested (1.6 g·mL^-1, DW). Malondialdehyde content increased at higher than 1.6 g·mL^-1, DW concentrations of the extract. The autointoxication phenomenon might be related to the difficulties in continuous plantings of chrysanthemum at the same location.

Abstract

Soaking palm seed in water for 1 to 21 days prior to planting reduces the number of days required for germination (3). Loomis (1) found soaking seeds of Acrocomia scierocarpa and Astrocaryum mexicanum palms for 2 to 3 weeks following hot water scarification at 100°C for 3 min hastened seed germination. Rees (3) reported soaking Copernicia cerifera (Mart.) seeds in water for 7 days at 38° to 42° also accelerated germination after planting. Presoaking Alexandra palm [Archontophoenix alexandrite (F.J. Muell.) H. Wendl & Drude] seed in water for 24 to 72 hr at 25° was reported by Nagao and Sakai (2) to stimulate germination. The purpose of this study was to determine the effect of temperature during a 7-day preplanting period on imbibed and nonimbibed seed and to compare seed soaking in water with moist peatmoss on germination percentages and numbers of days required to achieve 50% final germination.

Abstract

Seeds of 29 terrestrial orchid species representing 15 genera were surface sterilized by immersion in 0.5% sodium hypochlorite containing a wetting agent, washed, sown on a completely defined, semisolid embryo culture medium containing macro- and microelements, sucrose, amino acids, and vitamins, and incubated in the dark at 25°C. Six months after sowing, 16 species from 9 genera germinated and continued development while 13 species from 10 genera failed to germinate. Species of Cypripedium, Goodyera, Platanthera and Spiranthes differed in response in that one or more of each germinated and one or more did not. Seedling development was similar for most germinating species and progressed to the formation of a shoot or shoot initial in all but one. Apparently the mycorrhizal association thought to be required for terrestrial orchid seed germination and early seedling development can be replaced with aseptic culture on a completely defined medium for many terrestrial orchids.