The influence of NaCl concentration on seed germination in blue grama grass (Bouteloua gracilis), salty alkaligrass (Puccinellia distans) and Kentucky bluegrass (Poa pratensis) were investigated. When seeds were germinated in petri dishes containing 0, 2.5, 5.0, 7.5, 10, 12.5, 15, 17.5, 20, 22.5, 25, 27.5, and 30 g·liter–1 NaCl at 22 C for 4 weeks, blue grama grass was most salt-tolerant with 50% germination at 17.5 g·liter–1. The salt concentrations that provided 50% germination for salty alkaligrass and Kentucky bluegrass were 5 and 1.5 g·liter–1, respectively. The upper limits of salinity that allowed any germination were 30 g·liter–1 (1%) for blue grama grass, 27.5 g·liter–1 (1%) for salty alkaligrass, and 5 g·liter–1 (2%) for Kentucky bluegrass. Germination was quickest in blue grama grass (90% germination in 1 week) followed by salty alkaligrass (50% in 3 weeks) and Kentucky bluegrass (50% in 4 weeks). The tissue contents of Na+ and Cl– as influenced by increasing levels of NaCl were also determined.
Edward S. Dehmer and Chiwon W. Lee
Qudsia Hussaini, Chiwon W. Lee, and Shanqiang Ke
Leaf sections of Echinacea purpurea obtained from greenhouse-grown plants were cultured on Murashige and Skoog (MS) medium supplemented with 0.5 to 4.0 μM benzyladenine (BA) and 0.1 to 10.0 μM naphthaleneacetic acid (NAA). The efficiency of adventitious shoot formation from leaf explants varied depending on growth regulator concentrations. About 90% of leaf tissues cultured with 20 μM BA and 0.1 μM NAA produced shoot differentiation. Initially, the adventitious shoot buds were purplish-red in color; they turned to green shoots as young leaves began to unfold. The individual shoots, when excised and subcultured on the MS basal medium containing 10 μM gibberellic acid (GA3), produced 15 to 20 new shoots per culture within 4 weeks.
Kyu-Min Lee, Qudsia Hussaini, Shanqiang Ke, and Chiwon W. Lee
The influences of NaCl concentration, incubation temperature, and pH on the germination of Echinacea angustifolia seeds were investigated. Dehulled, surface-disinfected seeds were germinated in petri dishes containing 0, 0.5, 1, 1.5, 2.0, 2.5, 3.0, 3.5, or 4.0 g–liter–1 NaCl at 12, 17, 22, or 27C for 10 days. Percent seed germination was the highest at 0 ppm NaCl and was progressively reduced as NaCI concentrations increased to 4 g–liter–1 at all temperatures. The NaCI suppression of germination was most severe when seeds were incubated at 27C. No germination occurred at 12C. When seeds were germinated over a pH range from 4 to 11, the highest percent germination occurred at pHs between 6 and 8 at 25C.
Keun Ho Cho, Chiwon W. Lee, and Kyu-Min Lee
The narrow-leaved purple coneflower (Echinacea angustifolia) produces echinacin and related compounds in the root, which are known to have immune and curative properties against viral, fungal, and bacterial infections. In recent years, cultivation of this species has increased in response to growing market demand for natural medicinal remedies. The objective of this study was to determine the influence of gibberellic acid and light on the germination of E. angustifolia seeds. Seeds soaked for 24 h in 0, 1, 5, 10, 50, 100, 250, 500 or 1000 mg/L GA3 solution were germinated on Whatman #1 filter paper inside petri dishes at 22 °C with or without light (80 μmol·m-2·s-1) for 21 days. The seeds germinated poorly in dark with the final percent germination range from 10% (GA3 1000 mg/L) to 36% (GA3 250 mg/L). Under light, seed germination showed a quadratic response (r = 0.84) to GA3 concentration. Percent germination exceeded 90% at 10, 50, and 100 mg/L GA3 with the mean time (T50) to germinate varying at 10.5, 11.7, and 13.3 days, respectively, under light. Seed germination under light was <10% when treated with 500 and 1000 mg/L GA3. In general, seed germination was best when treated with 10 or 50 mg/L GA3 under light. Results of this research may well be used in enhancing seed germination during field establishment of E. angustifolia.
Kyu-Min Lee, Chiwon W. Lee, and Murray E. Duysen
The influences of elevated nutrient solution Fe++ concentrations on tissue iron contents and toxicity symptom development in Chinese cabbage and leaf lettuce were investigated. Seedling plants established in peat-lite mix in 15-cm plastic pots were fertilized with nutrient solutions containing 0 to 10 mM Fe++ for 6 weeks. Both Chinese cabbage and leaf lettuce produced dark leaf spots on plants grown with 5 mM or higher Fe++ concentrations. Biomass yields were reduced when leaf tissue iron contents in Chinese cabbage and leaf lettuce, respectively, were 551 mg·kg–1 and 379 mg·kg–1 or higher on a dry matter basis. In both species, tissue iron contents increased as the nutrient Fe++ concentration increased. Tissue iron contents in both species may be greatly enhanced to a certain level without causing plant toxicity by micronutrient fertilization.
Chiwon W. Lee, Edward P. Glenn, and James W. O'Leary
Damon C. Johnson, Murray E Duysen, and Chiwon W. Lee
The influences of elevated iron concentrations in the nutrient solution and light intensity on growth and the chlorophyll and chloroplast development in Kentucky bluegrass (Poa pratensis) `Touchdown' (C3), creeping bentgrass (Agrostis palustris) `Penncross' (C3), and buffalograss (Buchloe dactyloides) (C4) were investigated. Plants established in peatlite medium in 11-cm pots were fertilized with a Hoagland solution containing various iron concentrations (0, 0.01, 0.1, 1, 2, 4, 6, 8, 10 mM Fe+2) under two different light regimes. Preliminary results indicated that no biomass reduction or toxic symptoms developed in buffalograss when grown with iron levels up to 8 mM under high light conditions. As Fe+' levels were raised, plants became progressively greener with both the chlorophyll-a and chlorophyll-b contents increased. In Kentucky bluegrass, the sizes of chloroplasts and grana stacks in the cell were larger when grown with 2 mM than 0.05 mM Fe+2 in the fertilizer solution. The interactions of iron concentration and light intensity on pigmentation and photosynthesis of the three species are currently being determined.
Shanqiang Ke, Chiwon W. Lee, and Murray E. Duysen
The effects of the expression of the rolC gene on protein accumulation in the chloroplasts of transgenic Kentucky bluegrass (Poa pratensis L.) were investigated. Coleoptile tissues excised from 3-day dark-grown seedlings were bombarded with tungsten particles coated with DNA of the engineered plasmid, pGA-GUSGF, containing the npt II, gus, and rolC genes. The tissues were cultured on callus induction medium, which consists of MS salts supplemented with 0.2 mg/L picloram, 0.01 mg/L naphthaleneacetic acid (NAA) 250 mg/L kanamycin, and 100 mM acetosyringone. The putative transformants were either albinos or variegated plants composed of white and green sections. These albino plants had little or no stroma-based 56-kDa and 14-kDa subunits of the suspected Rubisco proteins, which are expressed in response to genes in the nucleus and plastid, respectively. The albino plants also lacked the 110-kDa and 57–58-kDa, and 43, 47-kDa polypeptides in PS I, coupling factor, and PS II in thylakoid membranes, respectively. These proteins involved in photosynthesis are translated from plastidbased genes. No light-harvesting complex proteins (LHC) were observed in these albino plants. LHC genes are encoded in the nucleus. The thylakoid membrane proteins in the chloroplasts of the rolC transgenic variegated plants contained these proteins. Our data suggest that the nucleus and plastid gene products for plastid development are concomitantly impaired by expression of genes in the transgenic plants.
Chiwon W. Lee, Chun-Ho Pak, and Jong-Myung Choi
Correlations between the nutrient solution concentration and tissue content of micronutrients were determined for geranium, marigold and petunia. When nutrient solution contained 0.25, 0.5, 1, 2, 3, 4, 5, 6 mM of boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn), the tissue content of each microelement increased linearly with increasing levels of the same micronutrient in the fertilizer. Equations for these correlations were established for the six micronutrients used for each species. Increasing levels of micronutrients did not influence tissue macroelement contents. Increasing levels of one micronutrient had little influence on the accumulation of other micronutrients in the tissue. Plant toxicity symptoms developed when the leaf content of microelements increased to a level 5-10 times that of plants grown with the control (Hoagland) solution.
Chiwon W. Lee, Joel T. Nichols, Lijuan Wang, and Shanqiang Ke
Excised leaf sections of lance coreopsis cultured on Murashige Skoog (MS) medium produced adventitious shoots in response to BA. When the combinations of 0, 0.5, 1, or 2 μm NAA with 0, 5, 10, 20, or 40 μm BA were tested, shoots were induced by any of the four BA concentrations used in the medium, regardless of the presence of NAA. The average number of shoots formed per leaf section ranged from 1.4 to 4.3 seven weeks after culture initiation. Roots were induced at the base of individual shoots on the same regeneration medium when cultures were kept longer than 7 weeks. The rooted plants were transferred successfully into soil. The regenerated plants had the same growth and flowering characteristics as the seed-grown plants. Chemical names used: benzyladenine (BA); naphthaleneacetic acid (NAA).