Showing papers in "Seed Science and Technology in 2001"

Effect of salinity on seed germination and early seedling growth of sugar beet (Beta vulgaris L.)

Abstract: Five varieties of sugar beet (Beta vulgaris L.) were studied in order to assess the effect of NaCl on seed germination and growth of young seedlings. Five salt treatments, 0, 50, 100, 150, and 200 mM NaCl were applied and germination was carried out at 21°C for 14 days. The results showed that germination percentage, rate of germination, and the relative germination percentage, were all inhibited by NaCl treatments. The strongest inhibition of germination occurred at the higher salt concentrations. Growth of young seedlings was also reduced, especially at the higher salt concentrations. The use of isotonic mannitol solutions indicated that the inhibitory influence of NaCl on sugar beet seed germination was principally a specific ionic effect and only a small portion of the inhibition could be attributed to an osmotic effect.

A system for automated seed vigour assessment

Abstract: Seed vigour testing provides valuable information for assessing seed lot quality. However, vigour testing has not experienced widespread use because of its labor intensiveness, high cost and variability in test results from laboratory to laboratory. An automated seed vigour assessment system is presented in this report that is objective, economical and easy to perform. The system interfaces an imaging device that captures digital images of germinating seedlings to a computer. The images are processed by a computer to generate numerical values that collectively represent the quality of a seed lot (vigour index) based on various statistics acquired from morphological features of the imaged seedlings. These statistics include the sample mean of hypocotyl and radicle lengths and sample standard deviation of the hypocotyl length, radicle length, total length (hypocotyl length plus radicle length) and radicle-to-hypocotyl-length ratio that indicate speed and uniformity of seedling development. The system was tested on lettuce seedlings grown for three days in the dark. The results indicated that the imaging system accurately quantified these parameters to yield reproducible, objective vigour assessments.

Effect of salinity and temperature on the germination of Urochondra setulosa (Trin.) C. E. Hubbard

Abstract: Urochondra setulosa (Trin.) C.E. Hubbard is a halophytic grass occurring in coastal areas of Sind Province and in a pure stand at the upper end of Manora creek at Hawkes Bay, Karachi, Pakistan. Seeds were collected from a salt flat situated at the Hawkes Bay location and germinated under a range of salinity and temperature regimes. Highest germination percentages were obtained under non-saline conditions and increases in salinity inhibited seed germination, with less than 10% of the seeds germinating at 500 mM NaCl. Germination was inhibited by either an increase or decrease in temperature from the optimal temperature regime of 20-30°C. The rate of germination, percent recovery germination and rate of recovery were greatest at 20-30°C, with the lowest germination and recovery occurring at the 10-20°C temperature regime. An interaction between salinity and the 10-20°C temperature regime yielded no germination at salinities of 300 mM and higher, whereas, some seeds germinated in up to 500 mM NaCl under the optimal temperature treatment (20-30°C).

Electrical conductivity of soybean seeds after storage in several environments

Abstract: Membrane integrity, as measured by electrical conductivity (EC), is suggested as an indicator of seed vigor in soybean [Glycine max (L) Merrill] seeds This study evaluated the effect of storage time and temperature on EC of six soybean seed lots (two lots each of high, medium and low vigor) All seed lots were adjusted to 120 g kg -1 seed moisture, sealed in aluminum foil packets and placed in storage at 10 and 20°C or stored unsealed in multi-wall paper bags in warehouse (WH) conditions at Lexington, KY, USA for 486 days Four of the six seed lots were also stored unsealed at 10°C All seed lots were sampled at 3-month intervals and evaluated for seed moisture (SMC), standard germination (SG) and vigor [accelerated aging (AA) and EC] After 91 and 204 days in storage, samples initially stored at 20°C and WH were moved to 10°C and sampled at the same intervals Seed moisture content for unsealed samples equilibrated at 107 g kg-' (± 9 g kg -1 ) in both the WH and 10°C environments No change in SG occurred for seeds stored sealed (120 g kg -1 ) at 10°C, except for the low vigor seed lots which declined significantly at the last sample date The AA germination declined significantly for all seed lots stored sealed at 10°C, however the EC did not change during the same storage period Seeds stored sealed at 20°C and unsealed in the WH showed rapid declines in AA and SG and significant increases in EC When these seeds were moved to 10°C, however, the AA continued to decline while the EC remained at the same level (no significant change) for the remainder of the seed storage period Thus whilst the AA declined in all environments, the EC only increased at higher temperatures (20°C, WH) but showed little change during storage at 10°C Thus, precautions must be taken if using EC to measure soybean seed vigor following storage at 10°C

Pre-sowing treatments for improving emergence of bitter gourd seedlings under optimal and sub-optimal temperatures

Abstract: Bitter gourd (Momordica charantia L.) requires high temperature (between 25 and 28°C) for successful seedling emergence, and poor emergence is common at sub-optimal temperature. This study evaluated the effect of suboptimal temperature on seedling emergence and several physiological characteristics related to seedling growth in bitter gourd cultivar Special Six. Priming was achieved by mixing the seeds with moist No. 3 vermiculite, incubating at 25°C for 36 h, then air-drying to the original moisture level. Warm water soaking was achieved by soaking the seeds in water at 50°C for 60 min, and then air-drying to the original moisture level. Seedling emergence from vermiculite was determined at 25, 20 and 15°C. The emergence of non-treated seeds at 25°C was 50%. No seedlings emerged at 20 or 15°C. However, both priming and warm water soaking improved the emergence responses of bitter gourd seeds under 25 and 20°C. The observed decrease and delay in emergence at sub-optimal temperature were linked to the reduced activity of enzymes (i.e. isocitrate lyase, malate-synthase and malate dehydrogenase) involved in lipid and sucrose conversion. Both priming and warm water soaking improved the low temperature (20°C) seedling emergence. These improvement were attributed to the increased enzyme activities. Nevertheless, the morphological changes and softening in seed coat and seed treatment-stimulated embryo growth might also play crucial role in speeding up the seedling emergence.

Effect of scarification, gibberellic acid and temperature on seed germination of two multipurpose Albizia species from Ethiopia

Abstract: Seeds of Albizia grandibracteata and Albizia gummifera possess seedcoat-imposed dormancy hampering complete, rapid and uniform germination. To overcome this dormancy, seeds of both species were pre-treated with mechanical scarification or concentrated sulphuric acid for 10, 20, 30, 40 and 60 minutes or hot water at 60, 70, 80, 90 and ca. 100°C. Besides, scarified seeds of A. grandibracteata were treated with three concentrations of gibberellic acid: 10 -3 , 10 -4 and 10 -5 M. To determine the effects of temperature on seed germination, pre-treated seeds from each species were germinated at 15, 20, 25, 30 and 35°C. All scarification treatments improved the germination capacity and vigour of A. gummifera seeds, the highest being after mechanical scarification followed by sulphuric acid and 80°C hot water treatments. Only mechanical scarification gave the highest germination in A. grandibracteata seeds. GA treatment of mechanically scarified seeds resulted in more than 50% germination, and GA 3 , 10 -4 M was better than the others were. Germination capacity and the speed of germination were higher at 20 and 25°C in both species; but A. gummifera seeds gerntinated well over a wider range of temperatures.

The effects of seed treatments on germination and establishment of Kentucky bluegrass (Poa pratensis L.)

Abstract: Common Kentucky bluegrass seeds were subjected to four hydration treatments: hydropriming, accelerated germination, matric priming and osmotic priming. Seeds from each hydration treatment were subjected to the 15°C or 25°C germination assay either without drying or with drying for 1 week at 25°C. Hydropriming failed to improve germination. Accelerated germination greatly increased germination rate provided the seeds were not dried before sowing. Primed seeds germinated faster than non-treated seeds at either germination temperature, although germination percentage was not increased. Drying the primed seeds slowed germination and this was more pronounced in matrically than in osmotically primed seeds germinated at 15°C. From the subsequent greenhouse seedling emergence test, we conclude that matric priming, using water as the hydrating agent and without postpriming drying was the most satisfactory hydration treatment for KB. Compared to responses of non-treated seeds, this treatment resulted in 49% less time to 50% emergence, 13% greater emergence and 84% higher shoot dry weight.

Genetic variation for and interrelationships among seed vigor traits in wheat from the Caspian Sea coast of Iran

Abstract: This study was undertaken to examine the interrelationships of several seed vigor traits in wheat (Triticum aestivum L.) through path-coefficient analysis, to determine broad-sense heritability, and to estimate genetic advance under selection. Germination rate (R50), germination uniformity, percentage of normal seedling, seedling dry weight, seed dry weight, seed water content, electrical conductivity of seed leachate (membrane integrity), seed reserve utilization ratio (fraction of mobilized seed reserves) and seed reserve utilization efficiency (conversion efficiency of mobilized reserves) of 15 wheat genotypes from the Caspian Sea coast of Iran were used for analyses. The genotypes exhibited significant differences for all traits, except for seed water content. Genetic correlations among R50, germination uniformity and seedling dry weight were not significant, showing that selection for any of them might be possible without hampering any other traits. However, path-coefficient analysis indicated that genetic improvement in fraction of mobilized seed reserve and conversion efficiency of mobilized reserves would have no beneficial effect on seedling dry weight, since it would be compensated for by indirect negative effects via seed dry weight. Moderate to high estimates of broad-sense heritability, genetic coefficient of variation and expected genetic advance were obtained for R50, germination uniformity, seedling dry weight and membrane integrity, indicating the possibility for improving these traits. For successful long-term improvement, crossing programs between the genotypes studied here and genotypes from other parts of the country or overseas might be necessary.

Breaking dormancy in Arbutus andrachne L. seeds by stratification and gibberellic acid

Abstract: To break dormancy and allow germination of Arbutus andrachne L. (Eastern Strawberry tree) seeds, various methods were tested including scarification with hot water, sulphuric acid (H 2 SO 4 ), or potassium hydroxide (KOH), cold moist stratification and treatment of seeds with potassium nitrate (KNO 3 ), thiourea, or gibberellic acid (GA 3 ). None of the seeds in the control or those scarified with H 2 SO 2 or KOH, or treated with KNO 3 or thiourea germinated. Hot water scarification allowed some germination, the greatest being 36% when seeds were soaked in water at 60°C for three minutes. Stratification of seeds at 4°C for three to four months or treatment of seeds with 250 mg/liter GA, was successful as 86% of the seeds germinated for both treatments.

Seed quality in relation to fruit maturation and seed dry weight during development in tomato

Abstract: Variation in seed quality during maturation was determined in tomato (Lycopersicon esculentum Mill.) in two subsequent years in order to relate to changes in seed dry weight and fruit maturity. Seed quality was assessed by germination at low (15, 18°C) and high (35°C) temperatures, germination at low water potential (-0.5 Mpa), emergence percentage and seed quality constant (Ki). Seed dry weight did not change between 60 and 90 and 50 and 80 Days After Anthesis (DAA) in 1998 and 1999, respectively. Whereas, seeds harvested 70 DAA attained not only maximum germination under stress conditions but also maximum emergence and Ki values in both years. Delayed harvests (80, 90 DAA) caused decline in seed quality. Results showed that occurrence of maximum tomato seed quality is related to changes in fruit colour but not in seed dry weight.

Effects of stratification and GA3 on seed germination of a sand stabilising grass Leymus arenarius used in reclamation

Abstract: Seed of the sand-stabilising grass Leymus arenarius is used on a large-scale in dune reclamation in Iceland. Seed which is collected from wild populations is often dormant and methods of alleviating this dormancy were examined. Effects of gibberellic acid (GA 3 : 500 mgl -1 ) and prolonged (i.e. 2, 4 or 6 weeks) stratification (5°C) on seed germination of three refractory coastal populations of L. arenarius were studied under controlled conditions. Different seed coats were tested in order to improve germination in the field. Germination of hulled seed coated with diatomaceous earth with and without the inclusion of GA 3 was compared to those of non-coated hulled or dehulled seed in a glasshouse and field experiments. Prolonged time of stratification (4 to 6 weeks) increased total germination for all populations. Treatment with GA 3 resulted in a significantly higher total germination for two populations but rate of germination was slower than those of 6 weeks stratification. In the field, dehulled seed had significantly the lowest germination. In glasshouse and field experiments, coating hulled seed with diatomaceous earth did not improve germination compared to hulled seed. Adding GA 3 to the seed coat of diatomaceous earth on hulled seed gave significantly the highest germination in the field. It is therefore recommended to include GA 3 to a seed coat of L. arenarius used in reclamation projects.

Development of primary dormancy in seeds of Prunus avium during maturation

Abstract: The development of primary dormancy in seeds of Prunus avium during maturation was studied in selected trees in two consecutive years. Seeds without endocarp were prechilled and germinated at 4°C and the mean time to complete germination was recorded as a relative, quantitative measure of dormancy level. Corresponding levels of germination capacity, dry weight and moisture content of the seeds were determined. Changes in dry weight and moisture content followed the behaviour of general seed development. Seed acquired maximum ability to germinate 4-6 weeks before full maturity, at which point they began to germinate after a few weeks at 4°C, thus displaying a shallow dormancy. Generally, dormancy levels increased with increasing maturity at rates of up to 4 weeks deeper dormancy per week during maturation. Dormancy levels are suggested to reach a final plateau. Both induction rate and final level depend on the tree and year. The levels of dormancy were different in the two years for the same dry weight and moisture content of seeds, which suggests that other factors affect dormancy induction significantly. Environmental factors, especially high temperatures, are hypothesised to be important for dormancy induction.

Hydrophobic-polymer application reduces imbibition rate and partially improves germination of emergence of soybean seedlings

Abstract: A hydrophobic polymer was applied to soybean (Glycine max (L.) Merril.) to seeds to regulate imbibition, reduce imbibition damage and improve germination and seedling emergence. Studies were conducted with genotypes prone to imbibition damage due to either seed coat splitting or low seed vigour. The effect of polymer application on seedling emergence and growth was tested under normal (75% soil water holding capacity: swhc) or short-term flooded (100% swhc for the first 4 days and 75% swhc subsequently) soil conditions. Coating with 24 mg of polymer per seed (Vinamul 3650) regulated the rate of water uptake, reduced imbibition damage and improved percentage germination and seedling emergence. In short-term-flooding soil conditions, low seedling emergence was observed regardless of seed ageing and was particularly evident in seeds that possessed a high proportion of split testas. There was little difference between uncoated and coated seeds in the time to 50% emergence and seedling growth. These results suggest that coating with a hydrophobic polymer can reduce rates of water uptake, lower solute leakage and improve vital tetrazolium chloride staining and partially improve germination or emergence of soybean seedlings.

Effect of germination promoting compounds on the release of primary and salt-enforced seed dormancy in the halophyte Sporobolus arabicus Boiss

Abstract: Sporobolus arabicus Boiss., a perennial stoloniferous grass, is widely distributed in saline areas from Karachi to the plains of the Punjab, Pakistan. It is one of the important components of the vegetation of salt flats and deserts. Experiments were carried out to determine the ability of growth promoter substances to alleviate a primary and salinity- enforced dormancy in seeds of Sporobolus arabicus. Sporobolus arabicus exhibited primary seed dormancy, yielding less than 40% germination in the non-saline control. The growth regulators gibberellic acid (GA 3 ), kinetin and ethephon were unable to break the dormancy of seeds, but nitrate, thiourea, and fusicoccin partially alleviated dormancy. Salinity was not inhibitory at 100 mM NaCl but inhibited germination at higher concentrations, with no seeds germinating at 400 mM NaCl. Salinity-enforced dormancy was not alleviated by kinetin, GA 3 , and ethephon. Fusicoccin, nitrate, and thiourea significantly alleviated salinity-enforced dormancy and the velocity of germination also increased at all salinities in these treatments.

The effect of moisture content and temperature on the longevity of heart of palm seeds (Euterpe edulis)

Abstract: E. edulis, an economically important palm species in southern of Brazil, has been reported to present recalcitrant seeds. The objectives of this paper were to investigate seed desiccation sensitivity under different drying regimes and to evaluate seed storage during 12 months. Germination and moisture content (fresh-weight basis) were assessed periodically during desiccation methods. Viability was maintained when fresh seed was dehydrated from 45 to about 35-30% moisture content; no germination occurred after drying to 24-18% moisture content. Desiccation sensitivity was independent of drying method. These characteristics substantiate previous indication of a “recalcitrant” behaviour. In the storage trials, seeds were tested for germination following storage in polythene bags at 15°, 12° and 5°C and 44, 40 and 36% moisture content. At 15° and 12°C and 40% moisture content no further reduction in germination occurred for 12 months. In contrast, seeds stored with 36% moisture content lost germination independent of the storage temperature used. Chilling damage occurred at 5°C for all seed moisture contents. Partial drying to 40% moisture content before storage at 12°-15°C is recommended in the short term.

Effects of scarification and cold stratification on seed germination of Lupinus sulphureus ssp. kincaidii

Abstract: Propagation methods for Lupinus sulphureus ssp. kincaidii, a threatened host plant for the endangered Fender's blue butterfly, are needed to support restoration efforts and ecological studies. Germination tests were performed to determine the effects of mechanical scarification and cold stratification (4°C for 4 or 8 wk). Seeds from two populations were used to determine whether seed source affected germination. Scarification and stratification both increased germination, but germination rates were highest and fastest when these treatments were applied together. Maximum germination was 95% with seeds from one population, but only 55% from another, suggesting that germination responses differ among wild sources. To optimize germination speed and percentage, a combination of scarification and stratification should be used.

Effects of osmo- and hydropriming on fungal infestation levels and germination of carrot (Daucus carota L.) seeds contaminated with Alternaria spp.

Abstract: The purpose of this research was to study effects of priming on seed infestation with fungi and germination of carrot (Daucus carota L.) seed lots naturally contaminated with seedborne Alternaria spp. Three seed lots of two cultivars, Karita' and 'Nantes Topscore' F1, varying in initial incidence of Alternaria spp., were primed in PEG 6000 or hydroprimed under laboratory conditions. The lots differed in their response to priming, both in terms of germination and presence of Alternaria spp. Priming resulted in a faster germination for all three seed lots. The uniformity of germination was improved in two lots. The overall percentage germination did not increase. Both osmotically and hydroprimed seeds gave rise to a decreased number of normal seedlings compared with untreated seeds. This decrease resulted from an increase in the number of seedlings with fungi and/or decays and dead seeds, which was related to a significant increase in the number of seeds contaminated with fungi after priming. In the seed lots with intermediate or high incidence levels of Alternaria dauci, A. radicina, or A. alternata, priming resulted in significantly higher levels of contamination. Moreover, fungi invaded inner parts of the seeds, especially after PEG priming. These findings indicate that the level of fungal contamination of seeds should be evaluated prior to the selection of seed lots for priming.

Dormancy of yellow cedar seeds is terminated by gibberellic acid in combination with fluridone or with osmotic priming and moist chilling

Abstract: Following dispersal from the parent tree, seeds of yellow cedar (Chamaecyparis nootkatensis D. Don Spach) exhibit a low capacity for germination, primarily as a result of coat-imposed dormancy. Combined warm and cold stratification (generally 4 weeks and 8 weeks, respectively) is often used to break dormancy. Here we investigate the effectiveness of different chemical treatments in replacing warm stratification and in reducing the requirement for cold stratification (moist chilling). Treatments comprised of gibberellic acid (GA3) in combination with osmotic priming (using polyethylene glycol, PEG) or with other hormones (gibberellin 4+7 and benzylaminopurine) had a promotive effect on subsequent germination of whole seeds of yellow cedar after a 60-day moist chilling period. GA 3 had virtually no effect on germination when used alone and even when used with 60 days of moist chilling. Whole seeds exposed to GA 3 and to fluridone (the latter to diminish endogenous abscisic acid, ABA), exhibited increased germination with an increasing time of exposure to fluridone, even in the complete absence of moist chilling, but seedlings were abnormal and unable to survive. Embryos excised from mature seeds which had been subjected to dormancy-breaking treatments (osmotic priming, GA 3 , and moist chilling), exhibited a lowered sensitivity to ABA compared to embryos excised from mature seeds that had received only a 3-day water soak. A decline in ABA within the seed and/or reduced embryo sensitivity to ABA may be two critical factors leading to dormancy breakage of yellow cedar seed.

Evaluation of naturally and artificially aged seeds of Phaseolus vulgaris L.

Abstract: Departamento de Biologia Vegetal e Fitossanidade Universidade do Oeste Paulista, CEP 19067-175 Presidente Prudente, SP

Combined effects of hardening hydration-dehydration and heat shock treatments on the germination of tomato, pepper and cucumber

Abstract: Germinative response of fresh tomato (Lycopersicon esculentum Mill.), pepper (Capsicum annuum L.) and cucumber (Cucumis sativus L.) seeds were tested under heat stress conditions and exposed to pregerminative hydration-dehydration and heat shock treatments. Combinations of a cycle of partial hydration in water with heat shock (36°C or 38°C) for 1 hour produced the optimum increase on germination and thermotolerance in tomato and pepper seedlings. Concerning cucumber seeds, partial hydration in water up to 2 hours before the onset of germination was the best procedure for inducing heat tolerance. Optimal temperature under heat shock was 36°C for all species.

Seed vigour in perennial ryegrass (Lolium perenne L.) : effect and cause

Abstract: Delaying autumn cultivation and sowing of perennial ryegrass seed crops may reduce nitrogen (N) mineralisation and subsequent leaching losses during winter, but may also reduce seedling germination and emergence. Possible relationships between thousand seed weight (TSW), N concentration and seed vigour were investigated by determining seedling emergence from laboratory soil tests at autumn (10°C) and winter (5°C) temperatures, seedling weight from 20°C germination tests, accelerated ageing at different temperatures (40-43°C) and bulk electroconductivity of 48 seed lots from the 1996 and 1997 harvests. Seed lots of perennial ryegrass differed significantly (P 0.90) to laboratory techniques to assess vigour such as accelerated ageing and seedling dry weight. Seed lot electroconductivity was less sensitive and reflected only large vigour differences between harvest year. Seed lot N concentration, TSW and age had significant (P<0.001) effects on seed vigour. N concentration accounted for more variability in laboratory emergence and seedling dry weight than TSW.

Use of flow cytometry to determine ploidy level of ryegrass

Abstract: A more rapid determination of ploidy level in tetraploid ryegrass (Lolium spp.) cultivars than cytological chromosome counting would be beneficial to the grass seed industry. Our objectives were to develop protocols for using flow cytometry in seed testing and to validate ploidy level by using flow cytometry and root tip chromosome counts. DNA content was determined by flow cytometry using leaf tissue of up to 200 seedlings from seed lots of three tetraploid cultivars each of perennial ryegrass (L. perenne), annual or Italian ryegrass (L. multiflorum) and intermediate ryegrass (L. X hybridum). Chromosome numbers were counted using root tip cells from up to 40 plants in each seed lot. Ploidy determined by flow cytometric comparison of G1 peaks from diploid and tetraploid plants was compared with chromosome counts on the same plants. Flow cytometry easily determined ploidy level and was sensitive enough to detect aneuploid plants. Determining chromosome number from root tip cells was slow and laborious; we were unable to detect minor variation of chromosome numbers and counts could not be accomplished on a sufficient number of plants to accurately detect mixtures in ploidy levels. We recommend the acceptance of flow cytometry as a means for determining ploidy level in commercial ryegrass seed testing because of its accuracy, ease of use and greater throughput than classical cytological approaches.

Seed coat regulation of water uptake during imbibition in soybeans (Glycine max (L.) Merr.)

Abstract: Seed coat characteristics of accessions with contrasting imbibition behavior were studied. Seed coat structure was studied by using scanning electron microscopy (SEM), light microscopy and fluorescence microscopy. The effects of different methanol and chloroform pre-treatments on seed coat permeability to water were also assessed. Deposits were possibly hydrophilic material. Deep-circular, deep-elongated and shallow pores on the surface of seeds were observed. In seeds of line VLS-1, that possessed a delayed-permeability seed coat characteristic, there was a lack of pores in the abaxial region of the seed coat. In seeds of lines GC 88037-38-2-2 and SS 87040-2-1, that possessed a rapid-permeability seed coat characteristic, a high density of deep and wide open pores were observed. The water-impermeability barrier was most likely in the subcuticular layer. No callose or suberin was detected in the impermeable soybean seed coat. There were no detected differences in the presence of phenolic material between impermeable and permeable seeds. Prolonged methanol pre-treatments were highly effective in increasing the permeability to water by a reversible way that could not be attributed to either the removal of cuticular waxes or extraction of phenolic material from the seed coat.

Using scanners to improve seed and seedling evaluations

Abstract: Seed analysis requires specific skills such as a thorough knowledge of crop and weed seed morphology for a purity test and an ability to discriminate normal and abnormal seedlings in a germination test. These determinations are subjective and dependent on the competence of the seed analyst. This report forwards the use of inexpensive flat bed scanners as an approach to capture high quality seed and seedling images that can be utilized in the development of comprehensive image libraries and greater understanding of botanical structures for ongoing analyst education as well as quickly sharing captured images via the internet with others more skilled in proper interpretation of the specimens. Employing flat bed scanners for this purpose enhances the standardization of seed testing.

Influence of scarification and temperature on seed germination of Lupinus arboreus

Abstract: Seeds of Lupinus arboreus Sims (bush lupine) were subjected to a variety of scarification and temperature treatments. Without scarification, 80% at germination temperatures between 18 and 24°C within seven days. The most rapid germination occurred between 21 and 24°C. At 32°C, total germination was reduced to approximately 2%. At 35°C, germination did not occur. Our data indicate that seeds of L. arboreus must be scarified to obtain high germination percentages and the most rapid germination occurs between 24-29°C.

Seed development and seed physiological quality of field grown beans (Phaseolus vulgaris L.)

Abstract: In this paper, we tested how sequential anthesis and pod location in the canopy could be sources of heterogeneity of seed development and seed physiological quality for a determinate bean (Phaseolus vulgaris L.). In order to achieve various micro-climatic conditions during seed development different treatments were performed during two years under field conditions near Angers (France). Pods were chosen to differ either by anthesis date or by location in the canopy and were hand harvested at regular intervals. After moisture measurement on a sub-sample and slow drying, seed quality was assessed by standard germination, conductivity and controlled deterioration tests. During seed filling and desiccation, seed moisture was found to be a good indicator of seed development. During the end of seed filling and the beginning of seed desiccation, seed quality increased as seed moisture decreased and levelled off at about 0.4 g.g -1 with no differences between years and treatments or between anthesis date and location of pods. Thus, it was concluded that during this phase, seed quality depended only on seed developmental stage. After the end of desiccation, seed vigour decreased linearly with increasing time from the end of desiccation; rate of deterioration differed between years and treatments but not between anthesis date or location of pods.

Free fatty acid accumulation and quality loss of stored soybean seeds invaded by Aspergillus ruber

Abstract: Soybean seeds with water activity (a w ) varying from 0.66 to 0.86 (moisture content 11.3 to 17% wet basis) and infested with conidia of Aspergillus ruber were stored at 25°C for 140 days. Practically all seeds were colonised by the fungus in less than 20 days independent of the a w . Free fatty acid (FFA) content increased linearly with increase of a w and storage time. The rate of FFA accumulation was slow at lower a w and increased linearly with increase of a w . Seedling emergence started to decrease at a slower rate at lower than at higher a w and its decline followed the pattern of FFA increase. All seeds lost viability in 140 days of storage independent of a w . Regression equations showed strong negative linear relationships between FFA accumulation and emergence percentage and positive relationships with increase of abnormal seedlings characterised by negative geotropism. Seed colonisation by A. ruber accompanied by increase of FFA content and decrease of seed viability at a w of 0.66 warrants revisions of the present recommendations regarding soybean seed moisture for inter-season storage.

Variation in base temperatures for germination in warm season grasses

Abstract: Recently efforts have been made to develop heat unit based growth models for warm season grass production in cool season environments. These models require the accurate determination of base temperatures. Variations in base temperatures for germination of four switchgrasses (Panicum virgatum L.), three big bluestem grasses (Andropogon gerardii Vitman), two indian grasses (Sorghastrum nutans L. Nash) and two prairie sandreeds (Calamovilfa longifolia (Hook) Scribn.) were determined. During the germination study seeds were allowed to germinate in Petri dishes at 4, 8, 12, 16 and 20°C. The germination rates were used in estimating base temperatures using regression techniques. There were variations, among and within species in germination. Estimates of base temperature for germination were 5.5 to 10.9, 7.3 to 8.7, 7.5 to 9.6 and 4.5 to 7.9 for switchgrass, big bluestem, indian grass and prairie sandreed. Absolute values in each case depended on whether linear or non-linear techniques were used. The results also indicated differences between base temperature estimates for germination.

Influence of kinetin and nitrogenous salts on seed germination of red sanders (Pterocarpus santalinus Linn.f.)

Abstract: The effect of different periods (10-50 hrs) of soaking at different concentrations (100-500 ppm) of kinetin and nitrogenous salts on the germination of pods of Pterocarpus santalinus (red sanders) was studied. Generally 400 ppm resulted in the maximum percentage of germination in all imbibition periods except soaking of pods for 10 hrs at 500 ppm of kinetin which resulted in highest germination (80%). However, the germination percentage was decreased with increased duration of soaking at 500 ppm concentration.

Soybean cultivar identification and genetic purity analysis using microsatellite DNA markers

Abstract: Seeds of 11 recommended soybean cultivars and 133 seed accessions from farmers in Thailand was analyzed with nineteen microsatellite DNA markers to determine the genetic purity and diversity of seeds from different sources. Fifteen of the 19 SSR markers (78.9%) revealed high gene diversity above 0.5 in the total plant material studied. Among the 11 reference cultivars, all pairwise comparisons, except one, were well discriminated with distance between 0.353 to 0.598. Only two reference cultivars (SJ4 and SJ5), difficult to distinguish both by field and laboratory methods, were separated with a smaller genetic distance of 0.118. The two cultivars, however, could still be separated by different alleles in three SSR loci SAT20, SATT12, and SATT45. The 11 reference cultivars showed complete genetic purity with only one allele in each cultivar for all 19 SSR loci, whereas farmers' seeds revealed a considerable genetic heterogeneity with an average of 1.29 alleles per SSR locus per cultivar. The public seeds showed better cultivar purity than private and retained seeds with average number of alleles 1.20, 1.30 and 1.31 per SSR locus per cultivar, respectively.