(pp. 7-20)
Cold Test and Saturated Cold Test Reliability for Testing Carryover Corn Seed Treated with Seed-applied Insecticides
A. Susana Goggi,* Daniel Curry, and Jeff Daniels
ABSTRACT:
The cold test germination percentage of carryover seed corn lots treated with a seed-applied insecticide (SAI) can be below the seed industry’s sale standard. However, the same seed lots have good emergence (80 to 90%) when planted in the field.
The objectives of this study were to 1) evaluate the extent of cold test germination differences between carryover seed lots treated with fungicide + SAI or fungicide-only; 2) determine if an alternative preparation can be made to a seed lot prior to the cold test and the saturated cold test; and 3) address the accuracy of the conventional cold versus the saturated cold testing method in predicting field emergence. Nineteen seed lots treated with fungicide-only or fungicide + SAI were tested in the laboratory and the field. The cold test germination percentage of carryover seed lots treated with fungicide + SAI was lower than fungicide-only treated seed. When the treatments were removed with Tween 20, the cold test germination of the fungicide + SAI-treated seed was not significantly different from the fungicide-only treated control. The cold test of fungicide-only treated and fungicide + SAI-treated seed correctly estimated emergence under all field conditions. After the fungicide + SAI seed treatment was removed, the saturated cold test accurately predicted field emergence under “poor” field conditions but underestimated field emergence under “average” or “good” field conditions. Removing the fungicide + SAI treatment before conducting the cold test may help seed companies better predict field
emergence of the seed lots.
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(pp. 21-36)
How Variables Like Parent, Seed Size and Desiccation Time Affect Seed Deterioration of Quercus macrocarpa L.
Valasia Iakovoglou,* Richard B. Hall, Allen D. Knapp, Manjit K.Misra and Susan A. Duvick
ABSTRACT:
Desiccation sensitivity is the main characteristic of recalcitrant seeds that poses limitations to practices such as storage and direct seeding. This study investigated the effect of parent tree, seed size, and desiccation time on seed variables, seedling growth, and starch thermal properties for Quercus macrocarpa. We expected to find an effect of parent tree, but not for the seed size due to narrow size ranges available for the study.
We hypothesized that desiccation time would negatively affect seed variables and seedling growth, while starch thermal properties would also be altered. Two parent trees with distinctive pericarp characteristics (Type-1 with tougher/darker pericarp than Type-2), and two seed sizes (19.5 and 20.5 mm in diameter) for each parent were selected. Seeds were placed to desiccate in a room at ambient relative humidity, and temperature > 21 °C, with seeds being sampled every two days. Parent tree and seed size affected almost all seed variables and the onset of starch gelatinization, with larger values for larger seeds. Parent tree also affected seedling growth, with larger values for the Type-1. Desiccation time negatively affected the majority of the studied variables. Respiration decreased with desiccation time, with greater values for larger seeds. Our results suggest that practices such as direct seeding could be enhanced by proper parent tree and seed size selection, since those variables could delay the deleterious effects of desiccation. Starch thermal properties also proved to be indicators in tracking metabolic alterations during desiccation.
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(pp. 37-42)
Heritability of Seed Components in “Egusi”Melon (Colocynthis citrullus L.)
P. E . Ogbonna
ABSTRACT:
Egusi melon Colocynthis citrullus L. is an important food crop in Nigeria and other West African countries where it is cultivated for its seed that is rich in oil and protein. This study was carried out to estimate the components of variation in seed moisture, fat, ash, protein, and fiber.
Eight inbred lines of egusi melon cultivars (NS-B, NS-W, NS-E, NS-R, Ov-1, Sewere, W.SE and B.SE) were used. Crosses were made with these inbreds and F1s, F2s and BCs were obtained. The result revealed extensive genetic variation in the seed components. Percentages of protein and ash had higher coefficient of variation than the other components measured indicating higher variability. High broad sense heritability was recorded in all seed components implying the potential for improvement through selection. This was confirmed by the high expected genetic advance in selection recorded.
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(pp. 43-54)
Response of Rocky Mountain Juniper (Juniperus scopulorum) Seeds to Seed Conditioning and Germination Treatments
Jill R. Barbour* and João P. F. Carvalho
ABSTRACT:
Rocky Mountain juniper (Juniperus scopulorum Sarg.) seeds are difficult to germinate in the laboratory and nursery due to multiple dormancies. The response of Rocky Mountain juniper to different seed conditioning and germination treatments were examined. The viability of the original seedlot was increased through seed sizing and weight separation. Following this, 21 germination treatments were tested to determine their effectiveness in promoting germination.
Fifteen new germination treatments were evaluated and compared with the six best germination treatments cited in the literature. Seed sizing did not affect seed viability significantly, but weight separation increased viability about 7 to 10% for medium to heavy weight classes. Three germination treatments yielded the highest germination ranging from 45 to 55%. A warm stratification period followed by a cold stratification period produced the best germination; increasing the warm stratification from8 to 12 and 16 weeks improved germination. The best germination treatment, proposed by Clark Fleege (Manager, USDA Forest Service Bessey Nursery), was a 3 d water soak, followed by 16 weeks warm stratification and then 13 weeks cold stratification. Reducing the warm stratification period by 4 weeks was the second best germination treatment. The third and fourth best germination treatments were VanHaverbeke and Comer’s 90min peroxide soak and a 6 d 10,000 ppm citric acid soak followed by warm and then cold stratification. The study shows that additional seed sizing and weight separation coupled with germination treatments are required to increase germination for Rocky Mountain juniper seeds.
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(pp. 55-65)
Stratification, Gibberellic Acid, Scarification, and Seed Lot Influence on Rosemary Seed Germination
Angela M.Madeiras,* Thomas H. Boyle, andWesley R. Autio
ABSTRACT:
Seeds of Rosmarinus officinalis L. (rosemary) exhibit slow and irregular germination. Improvement of germination rate and percentage may enable commercial propagation from seed instead of cuttings. To this aim, the effects of constant and alternating temperatures following cold stratification, incubation with GA3 under different temperature regimes, chemical scarification with sulfuric acid, and seed lot on the germination of rosemary seeds were studied.
Prolonging the cold stratification period increased germination after 28 d (G28), and decreased days to 50% germination (T50). Temperature following cold stratification interacted with stratification period to increase germination rate. GA3 increased G28, and reduced T50, and the number of days between 10% and 90% germination (T90 − T10). Temperature regime influenced all three parameters, but did not interact with GA3. Germination was greatest after 15 min exposure to H2SO4, while T50 decreased from 17.8 d in the untreated control to 11.5 d after 120 min exposure to H2SO4. Extract of rosemary seeds did not inhibit germination and growth of Lepidium sativum L. (garden cress) seedlings, indicating inhibitory chemicals in the rosemary seed coat are not likely to be responsible for germination irregularities in rosemary. Differences in percentage of filled seeds and embryo lengthmay account for differences in germination among seed lots. Our study demonstrates multiple mechanisms are likely responsible for release from physiological dormancy and irregular germination in rosemary seeds.
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(pp. 66-75)
Distinguishing Glyceria Species of Western North America
B. Shaun Bushman,* Mohammed Sedegui, Nancy K. Osterbauer
ABSTRACT:
There are seven North American and three introduced European Glyceria species growing in western North America, yet distinguishing among the species is morphologically challenging. As contaminants in agronomic grass seed lots, the introduced species
G. declinata and G. fluitans are undesirable domestically, while North American species are undesirable in seed grown for international trade. In order to distinguish between the western North American and introduced European Glyceria species we designed PCR, Taqman® SNP, and DNA sequencing assays.
The PCR assays are co-dominant markers in which a larger sized amplification product is detected in G. declinata, G. fluitans, and G. fluitans-like G. occidentalis than is detected among the other species. The Taqman® SNP assay shows VIC hybridization signal for G. declinata and FAM hybridization signal for G. fluitans and G. fluitans-like G. occidentalis. DNA sequencing of the chloroplast trnK region and the nuclear ribosomal ITS-1 region provide several SNPs that identify each of the individual species. However, Glyceria occidentalis samples contain chloroplast and ITS-1 sequences identical to either G. leptostachya or G. fluitans, thus currently cannot be distinguished with DNA markers.
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(pp. 76-86)
Effects of Salinity and Temperature on Germination, Seedling Growth and Ion Relations of Two Lentil (Lens culinaris) Cultivars
Asghar Rahimi,* Rob Norton, David McNeil and Shahab Maddah Hoseini
ABSTRACT:
The general responses to salt stress have been investigated in two lentil cultivars (Lens culinaris Med.) ILL6788 and Nugget, which have been identified as being salt tolerant and susceptible as adult plants, respectively. This research investigated the response of these cultivars to different salinity levels during germination.
Germination medium (filter paper) was treated with aqueous solutions of 0, 2, 4 and 6 dS∙m−1 NaCl and distilled water (control) prior to planting. The highest salt concentrations caused a longer delay in germination and after seven days, germination percentage was 20% and 45% for the tolerant and sensitive lentil seeds respectively in 6 dS∙m−1 solution. Germination rate was decreased with increasing salt concentration and all treatments of NaCl were inhibitory to root and shoot elongation of seedlings in both cultivars compared to the distilled water controls. The Na+ concentration of two lentil cultivars in shoots and roots increased significantly as salinity concentration increased. Shoots accumulated much more Na+ than roots in both cultivars. Concentration of K+ in roots and shoots was reduced significantly with increasing NaCl concentration. The K+ concentration in roots and shoots increased significantly as incubation temperature increased up to 25 °C. It was concluded that the tolerant lentil cultivar, ILL6788, was more sensitive than the susceptible cultivar, Nugget, to salinity over 2 dS∙m−1 during germination. It is therefore important to consider salinity response at different stages of growth when selecting for crop tolerance.
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(pp. 89-94)
Effect of Pre-sowing Treatments on the Germination of Pleurospermum angelicoides (DC.) Cl.
Arvind Bhatt,* I.D. Bhatt, Kailash Gaira, Komal Tripathi, R.S. Rawal and Uppeandra Dhar
ABSTRACT:
A simple seed germination protocol for Pleurospermum angelicoides (DC.) Cl., an endemic medicinal plant of west Himalaya has been developed. Among the various treatments (GA3, IAA, KNO3 and Chilling), chilling at 4 °C for 7 d was found to be best with respect to percentage germination (55%) and seedling survival (77.8%). The other treatments (GA3, IAA, KNO3) reduced the percentage germination of the seeds as compared to control (40%). Improved percentage germination to chilling treatments corresponds well with natural condition where P. angelicoides seeds are covered with snow during the winter.
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(pp. 95-100)
Evaluation of Priming Effects on Sweet Corn Seeds by SVIS
Francisco G. Gomes-Junior,* Vitor H.V.Mondo, Silvio M. Cicero, Miller B.McDonald and Mark A. Bennett
ABSTRACT:
Two sweet corn seed lots of each hybrid sh2 (‘SWB 551’ and ‘Obsession’) were primed by a non-osmotic method (drum priming) at 25 °C for 6 h. During each cycle, 125 g of seeds were exposed to 6.0 mL of distilled water and then rotated in the drum for 1 h to ensure uniform absorption. After hydration, the seeds were incubated at 25 °C for 0, 12, 24 and 36 h and dried under ambient conditions (25 °C, 50% RH).
Seed Vigor Imaging System (SVIS) evaluations were compared with standard germination and seedling emergence tests. The results obtained in this study confirmed that SVIS is a practical, valuable approach to evaluating the efficacy of priming treatments in sweet corn seeds when using a vigor index ratio of 70% growth index and 30% uniformity index for evaluating seed lots considered commercially valuable, but possessing low vigor.
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(pp. 101-107)
Breaking Seed Dormancy of Clematis ispahanica Bioss. a Medicinal Plant of Iran
Khorshid Razmjoo,* Nahid Khodaeian, Arefeh Razzazi and Ehsan Askari
ABSTRACT:
Aerial parts of Clematis ispahanica Bioss., a medicinal plant, are being collected indiscriminately, thus it is an endangered species. Seeds were collected in 2007 and tested for germination and viability. The tetrazolium chloride test showed the seeds to be 93% viable, however the germination was 0% indicating nearly 100% dormancy. The objectives of this study were to investigate several methods for breaking dormancy and improving germination of this species.
Fifteen seed treatments [sulfuric acid (98%, 15 and 30 sec), sulfuric acid (75%, 30 sec), GA3 (1500, 2000, 2500 ppm, 48 h), ethephon (250, 500 ppm, 48 h), IBA (500 ppm, 15 sec and 250 ppm, 30 sec), ethanol (96%, 24 h), 2,4-D (250, 500 ppm, 48 h), dry heat (60 °C, 12 h) and chilling (5 °C, 7 d)] were used. Sulfuric acid (98%, 15 sec), sulfuric acid (98%, 30 sec), GA3 (2500 ppm, 48 h),GA3 (2000 ppm, 48 h),GA3 (1500 ppm,
48 h), ethephon (250 ppm, 48 h), ethephon (500 ppm, 48 h), 2,4-D (500 ppm, 48 h) and chilling (5 °C, 7 d) increased germination to 52, 28, 59, 41, 44, 40, 57, 7 and 7%, respectively. Whereas, 2,4-D (250 ppm, 48 h), sulfuric acid (75%, 30 sec), IBA (250 and 500 ppm, 30 and 15 sec), dry heat (60 °C, 12 h) and ethanol (96%, 24 h) had no effect on germination. The results revealed that seed of C. ispahanica had nearly 100% dormancy, which may be both exogenous and endogenous. The treatments with the greatest degree of success in breaking dormancy were GA3 (1500–2500 ppm, 48 h), sulfuric acid (98%, 15 sec) and ethephon (250–400 ppm, 48 h). However, the effectiveness of the methods depends on compound, concentration and treatment temperature and duration.
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