Progress 10/01/98 to 09/30/03
Outputs
The predictive value of electrical impedance spectroscopy (EIS), a nondestructive analytical test, was considered when EIS results were used as a pre-germination indicator of bean seed viability and vigour. Impedance spectra of individual snap bean (Phaseolus vulgaris L.) and soybean (Glicine max L. (Meer)) seeds of 45 percent moisture content (fresh weight basis) and of differing seed quality at a frequency range from 60 Hz to 8 MHz both in longitudinal and lateral position were obtained. Each seed was given a germination evaluation subsequent to this electrical scan. The impedance spectra of germinated and non-germinated seeds differed both in magnitude and in characteristic shape for both positions and for both crops when plotted in the complex plane. With the exception of snap bean seeds measured along the longitudinal axis, seeds spectra were well characterized using a circuit modeled with three distributed elements. Longitudinally oriented snap bean spectra were
best approximated with two distributed circuit elements in series with a resistor (Voigt model). Several parameters of these equivalent electrical models were sensitive to the likelihood of subsequent successful germination, particularly those obtained at low frequency and in a lateral orientation. Sensitive model parameters included R3, and others . The receiver-operating-characteristic (ROC) curves were used to evaluate these parameters, and the resulting high (very nearly to 1) accuracy values suggested that good threshold values in forecasting viability and vigour were measurable.
Impacts
Biophysical markers that can be used to assess seed viability and can be used to elucidate mechanisms responsible for loss of germination during aging. Electrical impedance spectroscopy has the potential to be both rapid and non-invasive, so seeds can be used for other purposes.
Publications
- Bicanic D., Persijn S., Taylor A., Cozijnsen J., van Veldhuyzen G. Lenssen G. and Wegh H. 2003. Quality assessment of cabbage (Brassica olearacea) seeds by the CO laser photoacoustic and FTIR detection of ethylene and acetaldehyde. Review of Scientific Instruments 74, 689-693.
- Taylor, A. G. 2003. Seed quality. In: Thomas, B, D. J. Murphy and B. G. Murray. Encyclopedia of Applied Plant Sciences. Elsevier Acad. Press. p. 1284 - 1291.
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Progress 01/01/02 to 12/31/02
Outputs
Seed coating technologies serve as delivery systems for biological and chemical seed treatments. Application uniformity and longevity / efficacy of systemic seed treatments were studied. Seed treatments must be applied uniformly over the seed surface for maximum efficacy. Application uniformity was studied using a fluorescent tracer mixed with Rhizobium inoculant and applied to pea (Pisum sativum L) seeds. A digital camera with UV illumination was used to examine application uniformity. Imaging software discriminated between nontreated, properly treated and over-treated portions of seeds. Seeds treated with an `on-farm' auger had better uniformity of coverage compared to hand mixing. Doubling the amount of liquid improved the coverage for both methods. New chemistry seed treatments with systemic activity have the ability to control foliar pests. Bean (Phaseolus vulgaris L) seeds were treated with imidacloprid or thiamethoxam at 63 and 30 mg ai/100 grams of seeds,
respectively. These systemic insecticidal seed treatments were analyzed from leaf tissue in time course studies, and potato leafhoppers were counted during the growing season. Both systemic seed treatments were detected in leaves, and a decline in concentration was measured 21 days after sowing. Both imidacloprid and thiamethoxam significantly reduced potato leafhopper numbers 34 days after sowing, but showed no differences at 42 or 52 days after sowing. Thus, both plant protectants provided early season control of potato leafhoppers.
Impacts
A fluorescent tracer with the liquid inoculant facilitated the visualization and assessment of application uniformity. The digital camera with imaging software provided a method to quantify application uniformity, and this system could be used for many other purposes. Both imidacloprid and thiamethoxam were detected at parts per million in leaf tissue. Thus the concentration of small concentrations of pesticides applied as systemic seed treatments can be related to pest management efficacy.
Publications
- Kuhar, T. P., L. J. Stivers-Young, M. P. Hoffmann, and A. G. Taylor. 2002. Control of corn flea beetle and Stewart's wilt in sweet corn with imidacloprid and thiamethoxam seed treatments. Crop Protection 21: 25-31.
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Progress 01/01/01 to 12/31/01
Outputs
Electrical impedance spectroscopy techniques were developed for use on single seeds of snap beans (Phaseolus vulgaris L.) to assess and predict their germination potential. These seeds were aged in a manner that provided a range of seed qualities for testing. The test protocol established was noninvasive, requires careful moisture content regulation and can be completed in 24 hours. Two distinct dispersions were observed of which a low frequency dispersion correlated best with seed quality, and centered between 9.5 and 13.4 kHz with a real resistive component between 7 and 18 k ohms. The low resistive values corresponded to seeds of low quality compared with seeds having high values. The Voigt impedance model represented the data well enough to provide parameters that could predict germination with an accuracy of 0.93 (ROC). An ROC (receiver operating characteristic) of 0.5 is simply a prediction by chance, while a value of 1.0 would indicate a perfect prediction with
no false negatives or false positives.
Impacts
Electrical impedance spectroscopy (EIS) is a technique that has been used in medical diagnostics, with limited research in the plant sciences. EIS was adapted as a nondestructive and noninvasive method to predict seed viability, prior to the completion of germination. The technique has applications for germination testing of germplasm, plant breeding lines and other valuable seed materials.
Publications
- Kataki, P. K. and A. G. Taylor. 2001. Time course study of ethanol production by corn and soybean to optimize the use of ANA ethanol index as an accurate seed quality test. J. New Seeds 3: 1-17.
- Taylor, A. G., and J. Kwiatkowski. 2001. Polymer film coatings decrease water uptake and water vapour movement into seeds and reduce imbibitional chilling injury. British Crop Protection Council Symposium Proceedings No. 76. p. 215-220.
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Progress 01/01/00 to 12/31/00
Outputs
A biophysical method was developed to rapidly and nondestructively assess seed viability of individual seeds. Electrical impedance spectroscopy (EIS) was studied as a noninvasive method on snap bean (Phaseolus vulgaris L.) seeds. Seeds were hydrated for 24 h and the optimal range of moisture content (MC) was determined for detecting non-aged from aged seeds. The most sensitive EIS parameters were determined from the spectra data within a frequency range from 60Hz to 8MHz. The highest differentiation in the EIS parameters between the aging groups occurred between MC 40 to 45% (fr. basis), a water concentration insufficient for the completion of germination. Since the EIS procedure was non-destructive, studies were performed from the same seeds on actual germination. Several EIS parameters were the most useful for predicting seed quality. Further studies were conducted on relative electrolyte leakage (REL), an established (but destructive) alternate test. The EIS
parameter values were directly compared to REL values on a seed by seed basis. The results of EIS and REL measurements support each other well. There was an exponential relation between the relative electrolyte leakage and the EIS parameters. EIS has the potential to predict seed viability, prior to the completion of visible germination. Thus seeds could be used for other uses or be dried and stored.
Impacts
Electrical impedance spectroscopy (EIS) is a technique that has been used in medical diagnostics, with limited research in the plant sciences. Our research on seeds is novel and offers tremendous potential in seed testing and in studying seed biology. EIS can be used as a nondestructive and noninvasive method to predict seed viability, prior to the completion of germination. The technique has applications for germination testing of valuable germplasm, and plant breeding lines.
Publications
- Taylor, A. G., T-G. Min and D. H. Paine. 2000. Maillard reactions cause browning in bean seed coats during ageing: Inhibition by aminoguanidine. In: Black, M, K. J. Bradford and J. Vazquez-Ramos. (eds.) Seed biology: Advances and applications. CABI Pub.
- Lee, P. C., A. G. Taylor, M. Zhang, and Y. Esashi. 2000. Volatile compounds and accumulation of acetaldehyde-protein adducts in relation to seed quality and storage conditions. J. New Seeds 2: 59-76.
- Lee, P. C., A. G. Taylor, M. Zhang, and Y. Esashi. 2000. Evolution of volatiles during seed aging: Exogenous gas application. J. New Seeds 2: 77-91.
- Johnson, C. F., A. G. Taylor, D. H. Paine, C. H. Roe and L. W. Konikiewicz. 2000. Hardware analysis for non-destructive individual seed conductivity measurements: Implications for detecting glass-phase transitions. NASA Technical Memorandum 2000-208566.
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Progress 01/01/99 to 12/31/99
Outputs
Water uptake was studied in Phaseolus vulgaris in laboratory investigations with the objective to achieve elevated seed moisture contents and the examine seed-to-seed variation. A moisture isotherm was developed for relative humidities >70%, and a curvilinear relationship existed between RH and seed moisture content. Controlled hydration was performed on single seeds by adding a calculated amount of water to a seed of known weight and initial moisture content. Kinetic studies were attempted; however, considerable seed-to-seed variation was measured. The variation was attributed to differential permeability of the seed coat and the contact of the water on the seed surface. The rape-chalaza region was found to imbibe water faster than other areas of the testa. Along with single seed method, bulk methods similar to priming were used to elevate seed moisture. Liquid systems had severe limitations as the water potential desired ranged from -5 MPa to -1.5 MPa. The
solubility of mannitol in water limited its application to about -2 MPa and higher. Glycerol and water could achieve a wide range of water potentials; however, it was found to be toxic to seeds. PEG from 200 to 8000 was investigated, and PEGs <3400 MW were lethal to seeds. Humidification in custom designed chamber equipped with air circulation required several days for water uptake and microbial growth was observed at very high RH values. Solid particulate systems are currently being investigated.
Impacts
(N/A)
Publications
- Taylor, A. G., C. F. Johnson, P. K. Kataki, and R. L. Obendorf. 1999. Ethanol production by hydrated seeds: A high resolution index of seed quality. Acta Horticulturae 504: 153-160.
- Taylor, A. G., P. C. Lee and M. Zhang. 1999. Volatile compounds as indicators of seed quality and their influence on seed aging. Seed Technology. 21: 57-65.
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Progress 01/01/98 to 12/31/98
Outputs
Rapid seed quality tests are needed that are able to detect early stages of aging. A test that employs two measurements, in which a response increases under one condition and decreases in another with aging, should provide a sensitive index or ratio. Changes in respiratory activity (measured by ethanol production) were examined with respect to seed quality, water and oxygen availability and seed integrity. Specific combinations of water availability and seed integrity were needed to result in a reversal in ethanol production trends with aging. Brassica oleracea seeds were aged under mild conditions to provide different levels of seed quality. Ethanol production increased with aging from intact seeds under aerobic conditions, which was attributed to uncoupling of mitochondrial electron transport, thus enhancing alcoholic fermentation. Ethanol production decreased with aging from ground seeds under anaerobic conditions, which was hypothesized to be related to hydration
damage. Hydration damage would be exacerbated by aging thereby resulting in decreased ethanol production. On a practical basis, the ratio of ANaerobic to Aerobic (ANA) ethanol production decreased sharply with mild aging. The ANA ratio decline with seed quality preceded a reduction in germination. Testing methods are needed that can detect the early phases of aging prior to a significant loss in germination. Quality was assessed using both germination speed and uniformity on non-primed and primed as well as non-aged and aged lettuce (Lactuca sativa L) seed. Speed and uniformity was quantified using time to 50% (T50) germination and one standard deviation (Tsd). Embryo elongation was developed as a rapid test by first soaking seeds for 2 hours, then cutting and removing the distal 1/3 of the seed, and finally observing the percentage of visibly elongated embryos from the seed coverings over time. The mild aging conditions employed in this study (45 C and 50% relative humidity for up to
three weeks) had little influence on viability (all treatments had > 98% germination), but decreased germination rate (increased the time for T50 and Tsd). Primed seeds aged faster than non-primed seeds under the same aging conditions. The percentage of elongated embryos was calculated at hourly intervals after cutting, and treatment differences were observed after five hours. The percent elongated embryos at five hours was significantly correlated with T50 (r = 0.81*). The embryo elongation test detected both enhancement in embryo growth due to priming and retardation due to aging.
Impacts
(N/A)
Publications
- Taylor, A. G., P. S. Allen, M. A. Bennett, K. J. Bradford, J. S. Burris and M. K. Misra. 1998. Seed enhancements. Seed Science Research 8: 245-256.
- Taylor, A. G., A. P. M. Bay, D. H. Paine and M. C. Bourne. 1998. Physical and chemical properties of bean seed coats in relation to mechanical damage resistance. p. 248-256. In A. G. Taylor and X-L Huang, eds., Progress in seed research: Proceedings of the second international conference on seed science and technology. Communication services of the New York State Agricultural Experiment Station, Geneva, NY. p. 348.
- Taylor, A. G. and X-L Huang (eds.). 1998. Progress in seed research: Proceedings of the second international conference on seed science and technology. Communication services of the New York State Agricultural Experiment Station, Geneva, NY. p. 348.
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Progress 01/01/97 to 12/31/97
Outputs
Research was performed on volatile compounds in relation to seed quality in soybean (Glycine max), a high lipid seed, and snap beans (Phaseolus vulgaris), a starch storing seed. Qualitative and semi-quantitative analysis revealed more than 30 compounds from dry seeds as measured by gas chromatography and a thermal desorption method, including aldehydes, alcohols, ketones, alkanes, alkenes and furans. Alcohols, in particular methanol and ethanol, were abundant in both species. Acetaldehyde was the major aldehyde, but was detected at lower levels than ethanol and methanol. Research was then focused on the evolution of methanol, ethanol and acetaldehyde in relation to seed aging. Ethanol evolution increased while acetaldehyde decreased as soybean seed aged in an open storage condition. Snap beans produced about two times the concentration of volatiles as soybeans; however, the evolution trends were similar for both species. Ethanol and methanol were measured at higher
concentrations from seeds in closed compared to open storage conditions. Methanol evolution with respect to seed quality paralleled ethanol production. Alcohol dehydrogenase (ADH) activity was indirectly studied by applying exogenous ethanol or acetaldehye in closed containers. ADH was shown to be active from intact seeds in the range of storage relative humidities tested (12 to 75%). Exogenous ethanol and, in particular, acetaldehye were detrimental to seed germination. Ethanol toxicity was partially attributed to the formation of acetaldehyde. Acetaldehye-protein adducts (APA) formation in vitro and in vivo were quantified using a competitive ELISA. An exogenous reducing agent was essential to form stable adducts in vitro, and an endogenous supply of reducing agents appeared to be present in dry seeds. APA formation coincided with the sigmoidal loss of germination during storage, and was negatively correlated percent germination.
Impacts
(N/A)
Publications
- Taylor, A. G., M. B. Beresniewicz and M. C. Goffinet. 1997. Semipermeable layer in seeds. In R. H. Ellis, M. Black, A. J. Murdoch and T. D. Hong, eds., Basic and applied aspects of seed biology: Proceedings of the Fifth International Workshop on Seeds, Reading, 1995. Kluwer Academica Publishers. p. 429-436.
- Kataki, P. K., M. Horbowicz, A. G. Taylor and R. L. Obendorf. 1997. Changes in sucrose, cyclitols and their galactosyl derivatives with seed aging. In R. H. Ellis, M. Black, A. J. Murdoch and T. D. Hong, eds., Basic and applied aspects of seed biology: Proceedings of the Fifth International Workshop on Seeds, Reading, 1995. Kluwer Academica Publishers. p. 515-522.
- Lee, P. C. 1997. Volatile compounds and acetaldehyde-protein adducts in relation to seed aging and removal of off-colored seeds by color sorting. Ph.D.
- Taylor, A. G., D. F. Grabe and D. H. Paine. 1997. Moisture content and water activity determination of pelleted and film-coated seeds. Seed Technology 19: 24-32.
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Progress 01/01/96 to 12/30/96
Outputs
Modification of a single channel color sorter (model 10R MP, Xeltron, Costa Rica) was performed to sort fluorescent from non-fluorescent seeds or coated seeds. Three basic changes were performed on the conventional sorter to detect a fluorescent product; UV light source, photomultiplier tube detector and NIR filter. A custom designed and manufactured UV source was purchased and a machined housing was constructed at Geneva to hold the lamp. The UV source produced an emission with a maximum at 365 nm and was equipped with a 24 kHz power supply. A photomultiplier tube (PMT) with power supply was adapted to enhance sensitivity to the weak fluorescece emission. A custom designed housing was constructed at Geneva to hold the PMT as this detector was larger than the standard detectors. Preliminary tests revealed erratic detection and sorting with the UV lamp. The light emission from the UV lamp was measured with a spectralradiometer (model Li-1800, Li-Cor). Non-uniform
emission in the NIR was measured that caused the erratic sorting. A filter was then added to remove the near infrared (NIR) reflectance from the seeds and only fluorescence in the visible region could be used for sorting. In summary, the color sorter now has the capability to perform fluorescence sorting as well as traditional color sorting. In addition, three detectors are available for low and high sensitivity light emission detection.
Impacts
(N/A)
Publications
- Taylor, A. G., M. B. Beresniewicz and M. C. Goffinet. 1997. Semipermeable layer in seeds. In R. H. Ellis, et al., eds., Basic and applied aspects of seed biology: Kluwer Academica Publishers. (in press)
- Kataki, P. K. and A. G. Taylor. 1996. Production of ethanol by germinating soybean and sweet corn seeds under aerobic and anaerobic conditions: An index of seed quality. Search 30: 3-8.
- Kataki, P. K. and A. G. Taylor. 1996. The influence of exogenous glucose and seed coat integrity on ethanol production from aged cotton, lettuce and rice seeds: An index of seed quality. Search 30: 9-13.
- Kataki, P. K. and A. G. Taylor. 1997. Ethanol. A respiratory by-product: an indicator of seed quality. In R. H. Ellis, et al., eds., Basic and applied aspects of seed biology: Kluwer Academica Publishers. (in press)
- Kataki, P. K., et al. 1997. Changes in sucrose, cyclitols and their galactosyl derivatives with seed aging. In R. H. Ellis, et al, eds., Basic and applied aspects of seed biology: Kluwer Academica Publishers. (in press).
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Progress 01/01/95 to 12/30/95
Outputs
Ethanol production by seeds was developed as a rapid biochemical test, and foundto be a sensitive indicator of seed quality. Seeds of maize, soybean, cotton, rice and lettuce were aged at 75% relative humidity and 45C to obtain five aged samples for each species including a nonaged control. Aging reduced the percent germination and the coefficient of the rate of germination (CRG). Samples of differentially aged seed lots were subjected to aerobic and anaerobic conditions. Maize and soybean seeds were imbibed in distilled water while seeds of cotton, rice and lettuce were imbibed with 50 mM glucose in 5 mM potassium phosphate buffer adjusted to a pH of 5.6. Cotton seeds were ground and particles from 3.35 to 4.76 mm were used, while lettuce was scarified. Ethanol was analyzed using immobilized enzyme electrode technology and verified by gas chromatography. Anaerobiosis induced greater amounts of ethanol production compared to aerobic treatments. In general, the ethanol
production increased with aging under aerobic conditions while the reverse trend was measured under anaerobic conditions. The anaerobic to aerobic ethanol ratio (ANA ethanol ratio) was calculated and was correlated with the CRG.
Impacts
(N/A)
Publications
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Progress 01/01/94 to 12/30/94
Outputs
Semipermeability may be defined as the ability of seed coverings to allow water uptake and gas exchange while solute diffusion is restricted or prevented. The presence and location of a semipermeable layer was studied in seed coats of cabbage, leek, onion, tomato, and pepper. Seed coat thickness varied by species, although all species readily imbibed water. Cabbage seeds had permeable seed coats and non-germinable seeds readily leaked amino acids and non-aged seeds showed positive staining with tetrazolium chloride (TTC) without pre-treatment. Tomato and pepper seeds had relatively impermeable seed coats, while leek and onion were intermediate with respect to amino acid leakage and TTC uptake. The semipermeable layer of the seed coat was studied by uptake of Lanthanum salts to be adjacent to the endosperm in leek, onion, tomato and pepper, while morphological studies did not reveal a semipermeable layer in cabbage. The chemical nature of the semipermeable layer in seed
coats of non-germinable leek, onion, tomato, and pepper was further studied. Histochemical analyses were performed with stains, however, traditional stains were not able to differentiate between cutin and suberin. Therefore, digestion procedures were included by either enzymatic or chemical hydrolysis with cutinase or NaOH, respectively, to remove cutin or the cutin portion of suberin, followed by different stains. The semipermeable layer in seed coats of leek and onion was composed of cutin, while in tomato and pepper the layer.
Impacts
(N/A)
Publications
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Progress 01/01/93 to 12/30/93
Outputs
Sinapine leakage has been developed to predict seed germinability on a single-seed basis in BRASSICA. The major source of errors in this procedure are false negatives (F-), the method predicted a seed was germinable since the seed did not leak, and it did not germinate. The sinapine leakage index (SLI) was used to assess F- for any seed lot by dividing the number of non-germinable seeds that leaked by the total number of non-germinable seeds. The SLI for 13 lots including cabbage, cauliflower and broccoli (B. OLERACEA., Capitata, Botrytis and Italic groups, respectively) ranged from 0.2 to 0.91. Different staining patterns were observed from the tetrazolium test performed only on the F- seeds and the most common staining was dead tissue on the axis. The leakage rate as measured by the time for 50 percent of the nonviable seeds to leak revealed that seed coat permeability was negatively correlated with SLI. Therefore, at least two factors are responsible for the
presence of F- seeds: the seed coat restricted leakage from diffusing from the embryo to the environment and the presence of dead tissues on the axis that directly affect germinability without greatly contributing to total leakage.
Impacts
(N/A)
Publications
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Progress 01/01/92 to 12/30/92
Outputs
Research was conducted on leakage of specific compounds in relation to seed quality. Leakage of sugars was studied in association with different levels of seed germinability in leek, onion, and cabbage aged at 45C and 90 percent RH. Mono- and oligosaccharides from control (nonaged) and non-germinable seeds sampled after 24 hours of soaking were analyzed. Glucose and sucrose were, generally, the major mono- and oligosaccharides leaked from non-viable seeds as determined by HPLC. Glucose, sucrose and total sugars were quantified from leachates after 1, 4, 8, 16, and 24 hours at 25 degrees C. The amount of total sugars leaked from non-germinable treatments was greatest for cabbage followed by leek and onion (35, 12, and 5 mg/g seed, respectively), while control seeds of all three crops leaked <2 mg/g seed and aged seeds were intermediate. The percent of total sugars as glucose and sucrose varied with both sampling time and species. Cabbage mostly leaked glucose, leek
exuded roughly equal portions of glucose and sucrose and onion leaked a greater amount of sucrose than glucose. Leakage of total sugars was correlated with the proportion of germinable seeds in the sample from all crops. In a similar manner as described for sugars, amino acids were analyzed from the same species and seed qualities. The predominant amino acid found in the leachate was alanine. There was from 5 to 10 times more sugars leaked than amino acids and amount of total amino acids was correlated with the total sugars for each crop.
Impacts
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Publications
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Progress 01/01/91 to 12/30/91
Outputs
The purpose of this project was to study variation in sinapine leakage from nonviable Brassica seeds and develop a method to enhance leakage rate. Six seedlots were studied; two seedlots from one cultivar of cabbage, broccoli and cauliflower. Sinapine content was determined spectrophotometrically and ranged from 0.74 to 1.24% of the seed weight. Sinapine expressed on a single seed basis ranged from 24 to 51 ug per seed. After a 24 hour soak, the amount of leakage differed among seedlots, however, conducting the experiment with a constant seed number, seed weight or sinapine content did not correct for these measured differences. Studies conducted with either cracked testa or embryos revealed that the major factors regulating the leakage rate was the testa. The leakage pattern of sinapine differs from electrolyte leakage which is biphasic. Intact seeds exhibits a sigmoidal leakage pattern of sinapine with a distinct lag phase. Pretreatment of seeds with a 1.0% NaOCl
for 10 minutes accelerated subsequent leakage and generally increased uniformity of leakage.
Impacts
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Publications
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Progress 01/01/90 to 12/30/90
Outputs
There is a need for higher quality seedlots which ideally will produce one productive (vigorous) plant from each sown seed. Crop seeds rarely have 100 percent germination capacity after harvesting. Therefore, it is necessary to upgrade seed quality by eliminating non-viable seeds and those seeds which would produce abnormal seedlings from a seed population. The objective of this research project was to develop a seed coating system to detect poor quality seeds in the Brassicaceae. The crops studied represented three horticultural Brassicas, one agronomic Brassica and one flower species. Imbibition studies revealed that all seedlots imbibed > 90 percent water after a four hour soak. Sinapine, an indigenous fluorescent compound, leaked more (42 to 300 percent) from deteriorated than non-deteriorated seeds. A system was developed to effectively upgrade seed quality by exploiting leakage of sinapine. Seeds were first hydrated, then coated with an adsorbent to trap the
sinapine leakage. Coated seeds were dried, then sorted into two fractions: fluorescent and non- fluorescent. Sowing the non-fluorescent seeds resulted in a greater percent normal seedlings than sowing non-coated seeds in all seedlots. The fluorescent fraction contained a high percentage of the dead and abnormal seedlings.
Impacts
(N/A)
Publications
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Progress 01/01/89 to 12/30/89
Outputs
Research conducted on lettuce seed quality revealed that slow-to- germinate seeds generally produce abnormal seedlings. Methodoloy was needed to monitor the germination process and time sequence photography (TSP) was employed to record germination events. A camera equipped with an intervalometer and automatic flash attachment were placed over a plexiglas chamber. The entire apparatus was kept at 20 degrees centigrade in a growth chamber. There were 12 moistened blotters (10 x 10 cm) with 50 lettuce seeds per blotter within the plexiglas chamber. Data (photos) were recorded at 2 hour intervals. Studies have shown little variability within the chamber and among runs. Volatile compounds, such as acetaldehyde and ethanol are released during germination and have been shown to be negatively correlated with seed vigor in several crops. The methods most commonly used to quantify volatiles is to imbibe seeds in a closed vessel and either withdraw a sample from the head
space or trap the volatiles within the vessel. A technique was developed to leach volatiles present in the germination medium and provide an aerobic environment for seeds. Disposable plastic chromatography columns filled with coarse quartz sand and lettuce were employed. Lettuce seeds were loosely packed in the column with the sand.
Impacts
(N/A)
Publications
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Progress 01/01/88 to 12/30/88
Outputs
Seeds leak a wide range of compounds during the early phases of germination. Non-viable cabbage seeds were observed to have a fluorescent leakage where viable seeds did not. The major compound responsible for the fluorescent leakage was sinapine, the choline ester of sinapic acid. Sinapine leakage was further studied as a rapid viability test. Detection of sinapine was a better predictor of cabbage seed viability than the conductivity test. Solid matrix priming (SMP) is a method to osmotically prime seeds by mixing seeds, a finely ground solid medium and water in known proportions. Seedling emergence trials were conducted on primed tomato, carrot and onion. An improvement in the earliness of emergence and greater plant dry weight was recorded from SMP treated than non-primed seeds. Thermodormancy was overcome by priming. SMP was also found to be an effective carrier for biological control agents to control soil-born pathogens.
Impacts
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Publications
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Progress 01/01/87 to 12/30/87
Outputs
Priming seeds in aerated osmotic solutions has been shown to increase the speed of germination for many vegetable crops. However, little increase in viability has been observed after priming. A specialized seed conditioning procedure has been developed to upgrade seed quality while seeds are imbibed. The combination of priming with a separation procedure would increase both the rate and total percent germination. Lettuce, tomato and onion seeds were primed in solutions of polyethylene glycol 8000. After priming, seeds were separated into density fractions with aqueous solutions of Maltodextrins. The percent germination increased as density increased. The time to 50 percent radicle emergence (T50) decreased as density increased in onion and tomato. Imbibitional chilling injury may occur when low moisture content snap bean seeds are sown in a cold, wet soil. The seedling emergence forces of snap bean seeds equilibrated to 8 or 12 percent (fresh weight basis) were
recorded for a period of up to 72 hours. Seeds of both moisture contents were imbibed at 5 or 25 degrees centigrade. Seedling emergence forces were influenced by the interaction of imbibition temperature and initial seed moisture content. No differences were observed in total seedling force and percentage seedling emergence from 12 percent moisture seeds imbibed at either temperature. A decrease in force and a longer duration to obtain the maximum force was recorded from low moisture seeds imbibed at low temperatures.
Impacts
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Publications
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Progress 01/01/86 to 12/30/86
Outputs
Chilling injury is a physiological disorder which occurs in warm season crops. Large seeded legumes are susceptible to imbibitional chilling if seeds of low initial moisture content are sown in cold, wet soil. One strategy to alleviate chilling injury is to reduce the imbibition rate. A seed technology approach to decrease seed coat permeability and alleviate chilling is to treat seeds with a material which would retard imbibition. Proprietary hydrophobic polymers were obtained which were in an aqueous carrier. Polymer were applied on snap bean (Phaseolus vulgaris) seeds in a tumbling drum apparatus. Field emergence was improved from sowing coated compared to noncoated seeds. Polmeric coatings were found to decrease imbibition and solute leakage in laboratory studies.
Impacts
(N/A)
Publications
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