Download abstracts (free download) from oral and poster presentations given at the 99th Association of Official Seed Analysts and the 86th Society of Commercial Seed Technologists (AOSA/SCST) Annual Meeting held in Ft. Collins, Colorado on May 31st–June 5th, 2009
Seed Germination Differences between Glyphosate-Resistant and -Susceptible Italian Ryegrass Populations
Vijay K. Nandula*, Daniel H. Poston and Krishna N. Reddy
Influence of environmental factors on germination and emergence of Italian ryegrass [Lolium perenne L. subsp. multiflorum (Lam.) Husn.], including glyphosate-resistant populations, is lacking. Such knowledge would help improve our understanding of the biology and ecology of this problem species, which could in turn, aid in its management.
The objective of this study was to determine the effects of temperature, light, pH, salt and osmotic stress, shikimic acid and planting depth on germination of glyphosateresistant (R) and susceptible (S) Italian ryegrass populations. Overall, germination of both populations of Italian ryegrass was highest at 13 °C and decreased when temperature increased to 20 or 27 °C under both light and dark conditions. Light stimulated germination (57%) compared to darkness (41%) at 13 °C, but light had no effect on germination at 20 and 27 °C. The resistant population had higher germination (69–87%) compared to the susceptible (37–57%) at a pH range of 4–7. Seed germination decreased as NaCl concentration increased from 20–160 mM and osmotic potential increased from 0 (distilled water) to −0.8 MPa in both populations. Germination of the R and S populations decreased from 76% to 25% and 67% to 12%, respectively, as shikimic acid concentration increased from 0–16 mM. Seedling emergence was highest from seed placed on the soil surface. Seedling emergence was less than 7% from seed planted at a 0.5 cm depth and no seedlings emerged from seed planted below 2.5 cm for both populations. Both populations germinated under a broad range of environmental conditions used in the study, however, the R population was higher than the S population.
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(pp. 134-143) Overcoming Seed Dormancy in Cleome gynandra L. to Improve Germination
R.M.Muasya*, J.N. Simiyu, C.W.Muui, N.K. Rao, M.E. Dulloo and L.S. Gohole
Cleome gynandra L. is a traditional semi-domesticated leafy vegetable grown in East Africa. It belongs to the family Cleomaceae. Farmers save seed from each harvest for planting in the next season. C. gynandra seeds fail to germinate when planted immediately after harvest. Studies were conducted to determine appropriate seed treatments to overcome dormancy in freshly harvested C. gynandra seeds.
Seeds were subjected to various dormancy breaking treatments including: potassium nitrate (KNO3), leaching, light, gibberellic acid (GA3) and chilling. Additional studies were carried out to determine the degree of dormancy in seeds harvested from pods at different positions on the plant. Among all treatments studied, application of GA3 at a concentration of 500 ppm resulted in the highest final germination. Stratification for two weeks at 5 °C and germination in dark also improved germination significantly. While leaching had no significant effect, treatment with KNO3 and light reduced germination. Seeds from lower and middle positioned siliques germinated readily compared to those from upper siliques. We suggest for commercialization of C. gynandra seed that have high potential germination, treating seeds immediately after harvest with GA3 at a concentration of 500 ppm before being packaged and sold to farmers is a possibility that can be explored.Download entire article
(pp. 144-155) Promoter Analysis of Soybean Seed Coat Peroxidase Gene Ep
Huabang Chen and Richard A. Vierling*
High peroxidase activity in the soybean seed coat is controlled by a single dominant allele Ep. This peroxidase isoform represents up to 5% of the soluble protein in the dry seed coat of EpEp genotypes. The promoter and regulatory sequences of the soybean seed coat peroxidase gene could be used to drive expression of proteins of human and industrial importance.
Soybean seed coats have unique features that make them ideal sites for this purpose. Several features were noticed in the 1524 bp upstream Ep promoter including four directed repeats, the as1 element of CaMV 35S promoter and a G-box like sequence. Transient assay results indicated that the 1524 bp 5´ flanking promoter region was capable of driving GUS expression in the seed coat. Availability of the epep genotype and the nature of peroxidase activity enabled us to use peroxidase itself as a reporter to conduct the 5´ sequential promoter deletion analysis. Promoter deletion analysis from −1524 to −467 of the Ep allele did not significantly affect peroxidase activity, and further deletion from−467 to −207 resulted in a sharp decrease in peroxidase activity in the seed coat. Two promoter fragments A4 (−467/−310) and A6 (−207/−1) were identified that interact with seed coat nuclear proteins. No DNA-protein complex was detected when these two fragments were incubated with root and leaf nuclear extracts, indicating that the binding of Ep promoter fragments and seed coat nuclear proteins was tissue specific.Download entire article
(pp. 156-163) Cardinal Germination Temperatures of Some Medicinal Plant Species
F. Nadjafi*, L. Tabrizi, J. Shabahang and A. M.Mahdavi Damghani
The germination behavior of 11 medicinal plant species under different temperatures was studied. Seeds of all species were exposed to eight constant temperatures ranging from 5–40 °C. A linear model was applied to describe the germination rate-temperature relationship. Tested species showed clear differences in temperature requirements for seed germination.
The highest germination percentage was observed within the ranges of 15–25 °C for Marrubium vulgare L., 15–30 °C for Origanum majorana L., 10–30 °C for Hyssopus officinalis L. and Silybum marianum L., 10–25 °C for Thymus daenensis Celak subsp. daenensis and Ocimum basilicum L. Germination of most species ceased or highly declined at temperatures of 35 °C. The highest germination rate was observed within temperature ranges of 15–30 °C for Nepeta racemosa Lam., Oenothera biennis L. and H. officinalis, 10–25 °C for O. basilicum and Salvia nemorosa L., 20–25 °C for O.majorana L. and T. daenensis and 10–30 °C for S.marianum. The lowest base temperature was observed for Salvia sclarea L., S. nemorosa, H. officinalis and Centaurea benedicta (L.) L. All medicinal species studied in this research had a low, below 5 °C, base temperature. Optimum temperature ranged from 13–24 °C, and the lowest optimum temperature belonged to C. benedicta. These germination requirements are insufficient to make a general conclusion for introducing the species into cultivation, however, these data provide basic temperature requirements for further research.Download entire article
(pp. 164-176) Effect of Provenance, Temperature and Pretreatment on Germination of Albizia chinensis
C.S. Dhanai* and A.K. Uniyal
To improve percent germination in seed lots of Albizia chinensis, seeds collected from 13 different provenances were examined under different temperature regimes (20, 25, 30, and 35 °C) in the laboratory. Percent germination was optimal at 25 °C. Seed lots were also pretreated with tap water (control), hot water, sulfuric acid (H2SO4), and rumen egesta (fresh sheep fecal matter as an incubation medium).
Treatments with hot water, rumen egesta, and tap water considerably enhanced percent germination, irrespective of provenance. Soaking in H2SO4 or boiled water was ineffective in improving percent germination of the seed lots of A. chinensis. Seeds subjected to 25 °C. and a hot water pretreatment had the highest germination and took the least time for germination as compared to other temperature regimes and pretreatments. Among all the provenances compared, Josiara consistently had the highest germination across all treatments. Download entire article
Altitude (provenance) had an influence on germination, however there was little to no relationship between altitude and germination following laboratory treatments.
(pp. 179-188) How to Prepare a Master Calibration Sample: Procedure and Applications Using Tall Fescue as a Model
Adriel Garay, Sabry Elias* and Heather Nott
Standard calibration samples are used in the uniform blowing procedure to calibrate General-type seed blowers to even out the physical variation among themand achieve uniformity in separating lightweight inert matter from pure seed. Currently, there is no standardized procedure for production of calibration samples for tall fescue (Festuca arundinacea Schreb.), one of the main cool season forage crops in the U.S. The objective of this study was to develop a stepwise procedure to prepare standard calibration samples for tall fescue (TF) with proven uniformity, i.e.,master calibration samples (MCS).
The optimum blowing point (OBP) for tall fescue was identified. It was defined as the point at which almost all lightweight inert matter was removed via blowing (light fraction) and the pure seed remained in the heavy fraction. Various tall fescue samples representing different varieties, production years, and growing conditions were used to produce the light and heavy fractions of nine master calibration samples. Uniformity of the MCS developed in this study was tested. The MCS identified the OBP across several blowers, and, samples with different levels of inert matter were uniformly separated. The prescribed procedures can be used as a guideline to prepare master calibration samples for other species because the principles of preparation are the same.
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(pp. 189-193) Laboratory Tests for Predicting Seedling Emergence of Safflower (Carthamus tinctorius L.) Cultivars
Farhad Khavari, Farshid Ghaderi-Far* and Elias Soltani
The lack of information about predicting seedling emergence of safflower (Carthamus tinctorius L.) in field conditions prompted us to study the relationship between laboratory tests and field emergence. This experiment was conducted at Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran. Seeds from five cultivars of safflower (‘Abade’, ‘Hartman’, ‘Kino76’, ‘PI19829’ and ‘Zarghan279’) were used in these experiments.
Laboratory tests included standard germination (SG), accelerated aging (AA), seedling growth rate (SGR) and electrical conductivity (EC). The results revealed that the AA and EC tests provided better separation of safflower seed vigor levels than SG and SGR. Seed from ‘Zarghan279’ was the lowest quality with no difference in seed quality among the other cultivars. The fitted regression of the laboratory tests and field emergence trials showed that germination percentage after aging (R2 = 0.92**) and EC (R2 = 0.94**) were better related to field emergence than any of the other tests. Thus, EC and AA tests were the most successful in predicting the emergence potential of the safflower seeds.Download entire article