Total Germination Percentage Research Articles

Evaluation of Aegilops tauschii Cosson for preharvest sprouting tolerance

On day 21, total germination percentages of threshed seeds of Ae. tauschii ranged from 0.0 to 92.6, indicating a large variation in preharvest sprouting tolerance. Out of 46 Ae. tauschii accessions, seven had a germination index lower than ten, which indicates good tolerance to preharvest sprouting and usefulness for common wheat (Triticum aestivum L.) improvement. The variety tauschii showed a germination percentage and a germination index much higher than that of var. strangulata. Furthermore, the tough and tenacious glumes of Ae. tauschii also had an effect on tolerance to preharvest sprouting.

Is Ginkgo biloba (Ginkgoaceae) really an oviparous plant?

Germination of Ginkgo biloba seeds with intact and removed sarcotesta was compared to test the role of the seed coat in germination biology. The presence of an intact sarcotesta significantly reduced total germination percentage when compared to seeds with the sarcotesta removed. Some seeds were also cold stratified. This treatment was not necessary for germination, but it did improve total germination percentage. The seeds were collected during the period of natural abscission. Contrary to the accepted literature, we found that Ginkgo seeds contain well-developed embryos at the time of dispersal. These data demonstrate that the seed coat contributes to winter dormancy of G. biloba, and that the phenology of this species is less primitive than popularly believed.

Priming with Salt Solutions Improves Germination of Pansy Seed at High Temperatures

Priming regimes were evaluated on pansy seeds (Viola ×wittrockiana Gam. `Crystal Bowl Sky Blue') in high-temperature germination tests. Priming regimes evaluated included CaCl2, MgCl2, K2HPO4, Na2HPO4, NaCl, KCl, KNO3, Na2SO4, and polyethylene glycol 15,000 (PEG15,000) at –1.0 and –2.0 MPa, for 3, 6, or 9 d at 23 °C. Primed and nonprimed control seeds were then germinated at 25, 30, or 35 °C. Total percent germination of nonprimed control seeds was significantly less at 35 °C than at 25 °C. Seeds primed with CaCl2 at –1.0 MPa for 3 d at 23 °C had significantly higher germination at 35 °C than all other priming regimes tested, including aerated PEG8000 at –1.0 MPa for 7 d at 15 °C. Seed respiration, measured by O2 uptake, during germination of seeds primed with CaCl2 was higher than for control seeds or those primed with PEG8000. Priming pansy seed with CaCl2 at –1.0 MPa for 3 d at 23 °C was effective in increasing seedling emergence and for reducing the time of emergence in summer greenhouse studies.

Differentiation of seed germination and early seedling growth in ten provenances ofEucalyptus microtheca

An investigation of seed germination and early seedling growth ofEucalyptus microtheca was based on seed collection from 10 widely separated provenances in Australia. Genetic variation of seed germination and early seedling growth was observed among a series of provenances whose natural habitats range from different climatic condition. In the ten provenances, both the model of seed relative germination percentage and the model of seed total germination percentage fitted Logistic regression [y=a/(1+exp(-ex+b))]. In comparison with provenances from four high temperature (mean annual maximum temperature >30.0 °C; mean annual minimum temperature >17.0 °C) areas, six low temperature (mean annual maximum temperature <30.0 °C; mean annual minimum temperature <17.0 °C) areas showed the fast germination rate and the high total germination percentage. For each provenance we have 45 seedlings equally divided into three watering levels (100%, 50%, and 25% of field capacity), and studies on relationship between early seedling growth and climatic factors of the natural habitat of provenance. In control treatment, height growth of the seedling has been associated with intrinsically the driest quarter precipitation in the seed collection areas of provenance. In all the treatments, length growth of the biggest leaf of the seedling was related to mean annual maximum temperature and mean annual minimum temperature in origin of provenance. In contrast, basal diameter growth of the seedling was related to mean annual minimum temperature of the seed collection areas in water stress treatment. From an ecological viewpoint, the fast germination rate and the high total germination percentage of the seed and rapid early growth of the seedling appear to be favourable adaptations to the climatic conditions prevailing in the natural habitat of provenance.

Germination of Warm-Season Grasses under Constant and Dynamic Temperatures

Fifteen collections of 10 native and exotic grasses were germinated at constant 25 degrees C, and at gradual and abruptly alternating temperature regimes characteristic of wet seed bed temperatures in the southwest desert grassland in summer, winter, and spring. All species but bristle grass (Setaria macrostachya H.B.K. and S. leucopila Schum.) had high total germination under summer and spring temperatures (mean- 60% and 67%, respectively) and all but bristlegrass and bush muhly (Muhlenbergia porteri Scribn.) had relatively high total germination under winter temperatures (mean-53%). In general, total germination percentage was similar for gradual and abruptly alternating temperature regimes within a season. Constant 25 degrees C and abruptly alternating temperature germination percentages were similar enough to those at more realistic gradually alternating temperatures for most species to permit use of these tests to calculate estimates of summer bulk seeding rates. Time to 50% germination (D50) was slightly less for gradual than abruptly alternating summer temperatures, but was generally similar for these regimes under winter and spring temperatures. To determine if germination responses to constant temperatures could be used to estimate responses to dynamic temperatures, 12 collections of 8 species were tested for germination at constant temperatures of 5.4,10, 20, 25, 30, 35, 40, and 45 degrees C. Total germination and rate of germination (1/D50) increased and decreased as third-order polynomial functions of temperature. Polynomial regression estimates of 1/D50 were used to calculate estimates of D50 for diurnally alternating temperature that were within an average of 0.6 and 13 days of measured values for summer and spring temperatures respectively. Linear regression estimates of 1/D50 for suboptimal to optimal temperatures were similarly used to estimate D50 for dynamic winter temperature regimes that averaged within 3.6 days of measured values for most of the species. Differences between estimated and measured D50 for bush muhly under winter temperatures, and for Lehmann lovegrass (Eragrostis lehmanniana Nees) collections under winter and spring temperatures, indicate sensitivity of these species to extreme temperature in addition to accumulated heat. Similar measured and estimated D50 for most of the collections for summer, winter, and spring temperatures indicates that these species are primarily responding to cumulative heat effects. Even though most of the species have high germination percentages for winter or spring temperatures, field seedling emergence is much less likely in winter and Possibly less likely in spring than in summer. Slower germination rates during these cooler seasons would require long periods of soil water availability at the surface to allow germination.

Seed Germination of Atlantic White Cedar as Influenced by Stratification, Temperature, and Light

Cones of two provenances (Wayne Co., N.C., And Escambia Co., Ala.) of Atlantic white cedar [Chamaecyparis thyoides (L.) B. S. P.], were collected Fall 1994. Cones were dried for 2 months, followed by seed extraction and storage at 4°C for 6 months. Seeds were graded and stratified (moist-prechilled) for 0, 30, 60, or 90 days. Following stratification, seeds were placed at 25°C or 8/16 hour thermoperiods of 25°/15°C or 30°/20°C with daily photoperiods at each temperature of 0, 1/2, 1, 2, 4, 8, 12, or 24 h. At the conclusion of a 30-day germination period, the Alabama provenance exhibited greater germination than the North Carolina provenance for all treatments (74% vs. 46%). There were no significant differences between 25°/15°C and 30°/20°C with regard to total percent germination for both provenances. Germination was lowest at 25°C for each provenance. In some cases, however, there were no significant differences in germination of the North Carolina provenance when stratified for 60 or 90 days and germinated at 30/20°C or 25°C (61% vs. 63%). There was a highly significant quadratic response to stratification for cumulative percent germination for both provenances. The North Carolina provenance required 90 days stratification to maximize germination (66%) in contrast to the Alabama provenance, which only needed 30 days (80%). Seeds of both provenances did not exhibit an obligate light requirement. However, photoperiods ≥1/2 h increased germination greatly over seeds in darkness (29% vs. 62%).

Soilless Growing Media Amended With Sugarcane Filtercake Compost for Citrus Rootstock Production

Seeds of sour orange (Citrus aurantium L.) and Cleopatra mandarin (C. reticulata Blanco) were sown in Speedling trays filled with mixtures (v:v) of 0, 25, 50, 75 or 100 percent sugarcane filtercake compost (a natural waste by-product of sugarcane processing mills; bagasse) and a peat-lite medium. Seeds sown in 100 percent compost resulted in lower total percent germination, but similar mean days to emergence (MDE), seedling heights, and shoot weights and lower root weights than the control (100 percent peat-lite medium). Media amended with 25, 50 or 75 percent compost resulted in similar total percent emergence, (MDE) and root weights, but taller seedlings with heavier shoots than the control. SPAD-502 chlorophyll meter readings, and leaf N, Ca and Zn contents were higher for seedlings produced in compost amended media than in 100 percent peat-lite medium. The results suggest that compost derived from sugarcane filtercake can be successfully utilized as an amended medium for citrus seedling rootstock production.

EFFECT OF SEED PRETREATMENTS ON THE GERMINATION OF SEEDS OF SOME VARIETIES OF SOYBEANS

The effects of two seed pretreatments on the germination of seeds of eight varieties of soybean Glycine max L. were investigated. This is with the aim of improving germination and to determine the effects of these pretreatments on the rate of and total germination of the eight varieties used. Immersing seeds in 100" hot water for 20 and 40 seconds and soaking seeds for 5 and 10 minutes produced a total percentage germination of 70-100 within 4 days of sowing. The untreated but viable seeds of three of the eight varieties gave a total percentage germination of 70 within 8 days of sowing. The three varieties that generally responded to all the treatments by giving 100 per cent total germination include Sam Soy-2, TGX-563-02D and TGX 849-313D.

Seed Mass and Germination Behaviour in Populations of the Dune-building Grass Leymus arenarius

The individual mean seed (caryopsis) mass of 34 natural populations of Leymus arenarius widely distributed in Iceland and one each from Scotland and England showed a six-fold variation. Phenotypic plasticity was a factor in the variation between populations in different environments but there was also likely to have been genetic differentiation. Heavy-seeded populations tended to come from early successional sites, where they also produced longer spikes and more seeds per spike. Individual seed mass was also very variable on spikes within populations and within spikes; lighter seeds were found consistently in the lower third of the spike and in the florets distal to the rachis in the spikelets. Germination was examined using the powerful methods of Survival Analysis. There were striking asymptotic relationships between seed mass and germination: an inverse relationship between median germination time and seed mass and a positive relationship between total germination percentage and seed mass. Samples from small-seeded populations typically achieved half the total germination of large-seeded ones, with up to ten-fold longer median germination times. Similar trends emerged from analysis of large- and small-seeded spikes within populations and large- and small-seeded florets within spikelets. Natural stands of Leymus arenarius are harvested on a large scale in Iceland for sowing in reclamation programmes to combat unstable and eroding sands. The harvest period is short and susceptible to autumn gales and grazing. Mean individual seed mass would provide a rapid and reliable measure of seed quality, in terms of rapid germination and high germination rate. Stands should not be selected for harvest unless the individual seed mass averaged for whole spikes is at least 5 mg and such stands are most likely to be found in early-successional dune sites.

Evaluation of Temperature and Moisture Content during Storage on the Germination of Flowering Annual Seed

Various combinations of temperature and moisture contents were used in evaluating the seed storage of nine genera of annual flowers. Relative humidity (RH) levels of 11%, 32%, 52%, and 75% provided wide ranges in seed moisture during storage at 5, 15, and 25C. At each temperature, total germination percentages (G) generally declined as seed moisture content increased during storage. The seed moisture range giving the highest G after 12 months of storage was determined for each temperature and plant genus. For all genera, seed moisture contents during storage increased as storage temperatures increased at constant RH levels. Moisture contents at 25C storage were 37%, 34%, 29%, and 20% higher than at 5C when RH levels were at 11%, 32%, 52%, and 75%, respectively.

Irradiance Level and Duration Required to Terminate the Dormancy of Begonia ×semperflorens Seed

Begonia ×semperflorens-cultorum Hort. `Prelude Scarlet' seeds varied within irradiance treatments in the irradiance level and duration that they required to reach the light saturation value and germinate. At high photosynthetically active radiation (PAR), seeds required light for only part of the germination period to terminate photodormancy. Germination &gt;90% was achieved after 4 and 1 day of 24 hours/day exposure to PAR at 15 and 150 μmol·m–2·s–1, respectively, but 82% germination occurred after 4 days of irradiance at 1.5 μmol·m–2·s–1 at 27C. Fewer days to 50% of final germination (T50) and between 10% and 90% germination (T90 – T10) were required when light saturation was achieved after 1 day at high PAR rather than after 4 days at a low PAR level. The total PAR that seeds received during 6, 12, or 24 hours of light daily determined the total percentage of the seeds that germinated. Seeds receiving 150 μmol·m–2·s–1 continuously for ≥24 hours achieved 90% germination, but 6 or 12 hours daily at this irradiance level required 4 days and 3 days, respectively. Trends in total germination percentages (G), T50, or T90 – T10 with increased PAR levels, hours of light daily, or days of light were found by fitted regression equations and Tukey's hsd procedure. Begonia seed germination was promoted by PAR levels of 1.5 to 150 μmol·m–2·s–1 for periods ≤4 days, with darkness thereafter until cotyledon emergence.

Variability for Temperature of Germination in Sericea Lespedeza Germplasm

Poor and slow seed germination are major problems in growing sericea lespedeza [Lespedeza cuneata (Dumont de Courset) G. Don.]. Knowledge about the temperatures for optimum seed germination is vital to selecting the best seeding date for this forage legume. The objectives of this study were to determine the variability of sericea lespedeza germplasm for germination under several temperatures and the effect of seed weight on percentage and rate of germination. Germination response to temperature of 54 breeding lines and 26 accessions were tested. Mechanically‐scarified seed of each of the 80 genotypes were weighed and germinated in the dark in a germinator at constant temperatures of I0, 15, 20, 25, and 30°C. An additional temperature (35°C) was included to test the germinability of the accessions. Germination counts were recorded daily for 14 d to calculate total percent germination (TPG) and Maguire germination rate index (GRD. Temperature had a significant effect on TPG and GRI. Optimum germination temperature for sericea lespedeza ranged between 20 and 30°C. Thus, seeding time for this species for a particular location should be selected to match the optimum range of soil temperatures provided that adequate soil moisture is available. Mean TPG and GRI were significantly different among the genotypes at each temperature. However, genotypes with a consistently high TPG and GRI at a wide range of temperatures were found. Seed weight was correlated with TPG at I0 (r = 0.401) and 15°C (r = 0.459), also with GRI (r = 0.388‐0.475) at all temperatures for the breeding lines. However, seed weight was not correlated with TPG or GRI for the 26 accessions. The TPG and GRI were highly interrelated, thus, measuring TPG alone should provide adequate information when describing response to environmental stresses in sericea lespedeza.

Osmotic Priming or Chilling Stratification Improves Seed Germination of Purple Coneflower

High germination seed lots of purple coneflower [Echinacea purpurea (L.) Moench] were evaluated for laboratory germination following osmotic priming or chilling stratification. Compared to nontreated seeds, osmotic priming at 25C in salts (KNO3 + K3PO4; 1:1, w/w) or polyethylene glycol 4000 (PEG) increased early (3-day) germination percentage at 27C of all seed lots, and improved total (10-day) germination percentage of low-germination seed lots. Total germination percentage was unaffected or increased by priming for 4 days compared to 8 days, and by priming at –1.0 MPa compared to –0.5 MPa (except for one low-germination seed lot). Chilling stratification in water at 5 or 10C increased early and total germination of all seed lots, except for that same lot, compared to nontreated seeds. Total germination percentage was unaffected or increased by stratification at 10C rather than at 5C. Neither extending stratification ≥20 days nor lowering osmotic potential with PEG during stratification improved total germination percentage.

Osmotic Seed Priming of Rudbeckia fulgida Improves Germination and Expands Germination Range

Low-vigor seeds of black-eyed Susan (Rudbeckia fulgida Ait.) primed in aerated -1.3 MPa KNO3 for 7 days at 30C in darkness had double the total germination percentage at 30C and one-half the mean time of germination as nonprimed seeds. Priming the seeds in polyethylene glycol rather than KNO3 generally resulted in lower total germination percentage and longer mean time of germination. Osmotic priming increased total germination percentage and germination rate of seeds germinated at 21.9 to 32.2C, but the priming benefit on total germination percentage was greater at ≤27.6C. Total germination percentage of primed and nonprimed seeds was highest at 28.8 to 32.2C.

Light Governs the Germination of Impatiens wallerana Hook. f. Seed

The role of light on impatiens seed germination and radicle emergence was studied. Seeds having a photodormancy require light for only part of the germination period. Germination ≥85% was achieved after 3, 2, or 1 day of irradiance at 1.5, 15, or 75 μmol·s-1·m-2, respectively. Keeping imbibed seeds in darkness for ≥2 days before light exposure caused reduced total germination percentages (G), delayed achieving 50% of the final germination percentage (T50), and increased the days between 10% and 90% germination (T90-T10). Light for 6 hours daily at 1.5, 15, or 150 μmol·s-1·m-2 promoted high G and rapid and uniform germination, but daily 12 to 24 hours of irradiance decreased G and increased T50 and T90-T10. Estimated rates of decline (increase) in G, T50, or T90-T10 with each added day of light (darkness) or increasing daily hours of light were measured by fitting regression equations. Impatiens seed germination was promoted by the initial 1 to 3 days of light, but light inhibited radicle extension in the latter germination stages.

032 EFFECT OF STRATIFICATION AND GIBBERELLIC ACID ON SEED GERMINATION OF NATIVE PLANTS

The Legislative Commission on Minnesota's Resources funded a two year research project to promote expansion of the native wildflower and grass seed industry in Minnesota. Production of seeds and plants for landscaping and restoration is a growing sector of the horticultural industry, yet documentation of production techniques is sketchy due in part to the large number of species. The species Lilium philadelphicum (wood lily), Phlox pilosa (prairie phlox), and Spartina pectinata (prairie cordgrass) were selected for further analysis of germination requirements. These species were noted by producers as having poor and/or unreliable germination. Cold moist stratification and gibberellic acid (GA) treatments were applied Total percent germination and mean days to germination were calculated and analyzed after 30 days under greenhouse growing conditions. Stratification improved total percent and mean days to germination in L. philadelphicum. P. pilosa responded to treatment by both stratification and GA. Four weeks of stratification may be the best method for decreasing mean days to germination while obtaining adequate total percent germination for S. pectinata.

871 PB 223 IMPROVED GERMINATION OF PANSY SEED AT HIGH TEMPERATURES BY PRIMING WITH SALT SOLUTIONS

Pansy (Viola × wiffrockiana cv. Majestic Giant Blue Shades and Crystal Bowl Sky Blue) seeds were primed in various salt sololions at -1.0 MPa for 3, 6 or 9 days at 23C to determine if priming could overcome thermoinhihition at high temperatures (30C and above). Salt solutions tested were KNO3, KCl, NaCl, MgCl2, Na2SO4, Na2HPO4, K2HPO4 and CaCl2, with polyethylene glycol (PEG) serving as a comparison non-salt solution. Total percent germination (G) of non-primed seeds decreased significantly for both cultivars as germination temperature increased from 25C to 35C. Total seed germination and time to 50% germination (TS,) varied widely among the different priming solutions, with all solutions decreasing Tso as compared to non-primed seeds. Seeds primed with PEG for 6 and 9 days, however, germinated during the priming process and were not further examined. Priming did not significantly improve total percent germination versus non-primed seed at 25C. Seeds that had the best G and T50 at temperatures at or above 30C were those primed for 3 days with CaCl2 (for `Crystal Bowl' there was a 40% increase in G at 35C), and MgCl2 (for `Majestic Giant' there was a 15% increase in G at 35C).

The effects of osmoconditioning on the germination, emergence and early plant growth of cucumber under saline conditions

Osmoconditioning improved the rate of germination of cucumber ( Cucumis sativus L. cultivar ‘Telegraph’) seeds at 25°C and 15°C in water and NaCl solutions of upto 200 mM (16.5 dS m −1). At 15°C, the total percentage of germination was also increased. Osmoconditioning promoted the rates of radicle extension, seedling emergence and expansion of the cotyledons and first leaf. However, no effect was observed on the rate of growth of the second leaf or on the photosynthetic activity of either the first or the second leaf. The promotive effects of osmoconditioning on germination were retained by seeds that were stored for 2 months after treatment and were observed in seeds of other cultivars too. It was concluded that although osmoconditioning alleviated NaCl-induced stress during germination, emergence and early growth of cucumber, the benefits of treatment did not persist beyond the seedling stage.

The Role of Light during Phlox drummondii Hook. Seed Germination

The role of light on phlox germination and radicle emergence was studied. Neither light level nor duration affected total germination (G) percentages, which ranged from 93%. to 98%. Increasing light level and lengthening light duration delayed achieving 50% of final germination (T50) and increased the span in days between 10% and 90% germination (T90 - T10). Increasing light duration from 0 to 24 hours during germination at 0.15 μmol·s-1·m-2 progressively increased T50 from 3.5 to 7.1 days and T90 - T10 from 2.6 to 13.1 days. Similarly, lengthening light duration from 0 to 24 hours at 1.5 μmol·s-1·m-2 light increased T50 from 3.7 to 10.8 days and T90 - T10 from 2.8 to 13.4 days, whereas 15 μmol·s -1·m-2 increased T50 from 3.9 to 21.9 days and T90 - T10 from 2.9 to 29.2 days. Increasing the number of days in darkness from 0 to 6 decreased T50 from 14.8 to 4.3 days and T90 - T10 from 20.2 to 3.5 days. Increasing the number of days in light from O to 6 increased T50 from 4.0 to 8.9 days and T90 - T10 from 3.8 to 8.2 days. Estimated rates of decline or increase in T50 and T90 - T10 with each added day in darkness or light were measured by fitting regression equations. Seeds germinated in continuous darkness or in 24 or 48 hours of light followed by total darkness had similar G, T50, and T90 - T10. The results indicate that initial phlox seed germination was not affected by light, but that light inhibited radicle extension in later germination stages.

Germination Response of Hand-Threshed Lehmann Lovegrass Seeds

Germination of Lehmann lovegrass (Eragrostis lehmanniana Nees) was increased by seed after-ripening and by mechanical scarification of the seed coat. Hand-threshed seeds collected from 5 sites in southern Arizona were periodically germinated over the water potential range of 0 to -1.55 MPa for 98 weeks after harvest. Nonscarified seeds exhibited very low germination at all water potentials for the entire length of the study. Total percent germination of scarified seeds peaked after 34 weeks. Seeds scarified before the after-ripening requirement was met germinated without further scarification at 46 weeks after harvest. Measurements of water uptake rates indicate that seed cost permeability to water contributes little to the increased germinability of scarified seeds.