THE EFFECT OF DAYLENGTH AND TEMPERATURE ON THE GROWTH OF SHIELDED AERIAL STEMS OF KENTUCKY BLUEGRASS

1981 ◽  
Vol 61 (3) ◽  
pp. 653-659
Author(s):  
W. E. CORDUKES ◽  
C. J. WILLIAMS
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Leaf Blade ◽  
Growth Traits ◽  
Poa Pratensis ◽  
Growth Period ◽  
Kentucky Bluegrass ◽  
Cultivar Selection ◽  
Origin Group ◽  
Short Days

Stems of 18 cultivars of Poa pratensis L. were shielded and grown in different environments to measure the effects of daylength and temperature with the object of determining the usefulness of this technique for cultivar selection. The four growth environments were: long days, low temperature (LDLT): long days, high temperature (LDHT); short days, low temperature (SDLT); short days, high temperature (SDHT). The mean growth period in the LDLT, LDHT and the SDLT environments was 123 days, but growth ceased in the SDHT regime after 78 days. Daylength and temperature significantly affected growth; cultivars that produced long stems had many nodes and a short upper leaf blade while short-stemmed cultivars had few buds and a long upper leaf blade. These distinct growth traits were stable and can thus be used in cultivar selection. Discriminant analyses assigned the cultivars to three groupings: group A cultivars originated from northern environments while group C cultivars were of southern origin. Group B cultivars were found at locations intermediate to those of A and C. Canadian cultivar performance for turf was closely allied to the three groupings.

EFFECTS OF SHADING OF THE LEAF SHEATH ON THE GROWTH AND DEVELOPMENT OF THE TILLER STEMS OF KENTUCKY BLUEGRASS

1974 ◽  
Vol 54 (1) ◽  
pp. 47-53 ◽  
Author(s):  
W. E. CORDUKES ◽  
JOHN E. FISHER
Keyword(s):  
Growth And Development ◽  
Leaf Blade ◽  
Poa Pratensis ◽  
Growth Period ◽  
Kentucky Bluegrass ◽  
Leaf Sheath ◽  
Selection Program ◽  
Greenhouse Experiments ◽  
Wide Range ◽  
Effect Of Light

Two separate greenhouse experiments were conducted to measure the effects of shading of the leaf sheath on the growth and development of tiller stems of cultivars of Kentucky bluegrass (Poa pratensis L.). In the first experiment, four cultivars were grown as single plants and the initial stem was shielded, allowing the tip of the leaf blade to protrude slightly but retaining the sheath in darkness. As growth of the tiller proceeded, further shields were added in a similar fashion for a growth period of 234 days. The second experiment was similarly conducted but included nine cultivars representing a wide range of latitudinal origin. They were grown for a period of 188 days. All shielded stems were much longer than the unshaded stems and developed into long aerial rhizomes with vegetative rhizome-type buds with cataphylls, indicating the morphogenic effect of light on the leaf sheath and the apparent insensitivity of the leaf blade in this reaction. The growth of the stem and buds of the cultivars Windsor, Merion, Geary, and Belturf was less than the growth of stem and buds of Fylking, Pennstar, and Nugget, whereas growth of the uppermost leaf blade was greater. Fylking, Pennstar, and Nugget produced longer stems with many actively growing side shoots and a shorter upper leaf blade. This method of shading might be used as a screening technique in a selection program, particularly for Kentucky bluegrass.

scholarly journals Silicon Effects on Poa pratensis Responses to Salinity

HortScience ◽  
2010 ◽  
Vol 45 (12) ◽  
pp. 1876-1881 ◽  
Author(s):  
Qi Chai ◽  
Xinqing Shao ◽  
Jianquan Zhang
Keyword(s):  
Leaf Area ◽  
Leaf Blade ◽  
Saline Soil ◽  
Poa Pratensis ◽  
Germination Rate ◽  
Treatment Plant ◽  
Kentucky Bluegrass ◽  
Tiller Number ◽  
Individual Leaf ◽  
Turf Quality

Understanding turfgrass response to silicon (Si) application under salinity conditions is important to find a way to improve turfgrass salt tolerance for turf management. The objective of the study was to investigate effects of increasing amendment concentrations of Na2SiO3 on turf growth and distribution of Na+ and K+ in seedlings of kentucky bluegrass (KBG) (Poa pratensis L.) under salinity stress. This growth chamber experiment was consisted of a control (no salinity and no Si) and five Si amendment treatments (0, 0.24, 0.48, 0.72, and 0.96 g Si/kg saline soil) under 10 g·kg−1 salinity conditions. Seed germination rate was significantly increased after 12 d under 0.48 g·kg−1 Si treatment. Plant height and canopy coverage were increased under 0.72 g·kg−1 Si treatment after 40 and 44 d of treatment, respectively, and tiller number was increased under 0.96 g·kg−1 Si treatment compared with 0 Si under saline conditions. With the supplement of Si at 0.48 to 0.96 g·kg−1, the ratio of Na+/K+ in shoots was decreased and individual leaf area was increased compared with 0 Si under saline conditions. The increase in individual leaf area was mainly the result of the increase in the leaf blade length. The concentration of K+ in shoots was significantly increased, whereas the concentrations of Na+ in roots were significantly decreased under all Si amendment treatments. The content of K+ was higher in shoots than in roots, but the ratio of Na+/K+ in roots was higher than in shoots in all Si amendment treatments. The results indicate that under saline conditions, Si induced the transfer of K+ from roots to shoots but inhibited the absorption and transfer of Na+, which may contribute to better turf quality and growth with Si treatment under saline conditions.

scholarly journals Development of SCAR markers related to heat tolerance in Kentucky bluegrass

2020 ◽  
Vol 48 (2) ◽  
pp. 509-522
Author(s):  
Mingyue TU ◽  
Yali HE ◽  
Xiaoli LI ◽  
Ying ZOU ◽  
Xiaojun YUAN
Keyword(s):  
High Temperature ◽  
Heat Tolerance ◽  
Poa Pratensis ◽  
Kentucky Bluegrass ◽  
Temperature Tolerance ◽  
Scar Markers ◽  
Sequence Characterized Amplified Region ◽  
High Temperature Tolerance ◽  
Significant Difference ◽  
Cool Season Grass

As a high-quality cool-season grass, Kentucky bluegrass (Poa pratensis) is facing increasing threat of high temperature, so improving its heat tolerance (HT) has become an important breeding target. In this study, the HT of 84 materials was identified in the artificial climate chamber, and 15 most heat-tolerant and 15 most heat-sensitive materials were selected respectively to construct two DNA pools. There was a significant difference in high-temperature tolerance time between the plants in the two pools, which was more than 22 days. A total of 304 sequence-related amplified polymorphism (SRAP) and 88 simple sequence repeat (SSR) markers were used to screen the polymorphic bands between the two pools. Then, these bands were transformed into sequence characterized amplified region (SCAR) markers, and finally 12 SCAR dominant markers related to HT were obtained, which could detect the heat-sensitive materials efficiently. Among them, S-me8×em2 and S-me52×em5 had the best identification effect, and the consistency between the absence of these two markers and the heat-sensitive phenotype was 87%. According to the comparison with NCBI database, the sequences of 12 SCAR markers had no homology with known HT related genes. Next, we would further verify the HT identification efficiency of these SCAR markers in single plants within materials, and try to use them in molecular marker-assisted breeding.  

scholarly journals 095 ROSETTING OF LISIANTHUS INFLUENCED BY CULTIVAR, SEEDLING AGE, PHOTOPERIOD, AND TEMPERATURE

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 441f-441
Author(s):  
Brent K. Harbaugh
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Development Stage ◽  
Seedling Development ◽  
Eustoma Grandiflorum ◽  
Short Day ◽  
Long Day ◽  
Temperature Exposure ◽  
Stage 1 ◽  
Short Days

Rosetting response was determined for four lisianthus [Eustoma grandiflorum (Raf.) Shinn.] cultivars exposed to photoperiod and temperature treatments during stage 1(14 to 43 days after sowing) and stage 2 (43 to 79 days after sowing) seedling development. Stage 1 seedlings were exposed to short days (12 h photoperiod) or long days (18 h photoperiod) in combination with high (26C) or low temperatures (12C). After stage 1 treatments, stage 2 seedlings were divided and exposed to the same treatment combinations resulting in 16 treatments. Seedlings were then grown at 22C for 120 days to determine rosetting response. Cultivars responded differently to temperature and photoperiod. Short day-high temperature exposure during either stage 1 or stage 2 resulted in the greatest number of rosetted plants (50 to 100%) for `Yodel White', `HeidiPink', and `BlueLisa'. `GCREC-Blue' did not rosette with short day-high temperature. Low temperature during stage 1 did not prevent rosetting when stage 2 seedlings were subsequently exposed to high temperature, but low temperature during stage 2 decreased rosetting of seedlings exposed to high temperature in stage 1. Less rosetting occurred with long day-high temperature than with short day-low temperature, especially for `Blue Lisa'.

Differential expression of gibberellin 20 oxidase gene induced by abiotic stresses in Zoysiagrass (Zoysia japonica)

Biologia ◽  
2012 ◽  
Vol 67 (4) ◽  
Author(s):  
Xiaomei Dai ◽  
Xiaoxia Cheng ◽  
Yunxia Li ◽  
Wei Tang ◽  
Liebao Han
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Plant Growth ◽  
Differential Expression ◽  
Abiotic Stresses ◽  
Leaf Blade ◽  
Young Leaf ◽  
Zoysia Japonica ◽  
Senescent Leaf ◽  
Oxidase Gene

AbstractThe gibberellin 20-oxidase gene (GA20) plays an important role in plant growth and development. Differential expression of Zoysiagrass (Zoysia japonica Steud.) gibberellin 20 oxidase gene (ZjGA20) induced by abiotic stresses has not been reported. In this investigation, we first reported the differential expression of ZjGA20 in different Z. japonica tissues including root, young leaf, senescent leaf, blade, sheath, and stolon, as well as differential expression induced by abiotic stresses including low temperature (4°C), H2O2(8 μM), salt stress (250 mM NaCl), 25% PEG6000, and high temperature (42°C) by Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR). Higher expression of ZjGA20 was observed in young leaf and sheath, compared to root, senescent leaf, blade, and stolon. Among different abiotic stresses, expression of ZjGA20 decreased under low temperature, 25% PEG6000, and high temperature. The highest expression of ZjGA20 was obtained when plants were treated with 8 μM H2O2 for 10 h and with 250 mM NaCl for 5 h. The analysis of the MDA content, POD activity, and permeability of the plasma membrane demonstrated that application of exogenous GA3 recovered tissue damage derived from low temperature treatment. In addition, the expression of ZjGA20 increased under low temperature stress. These results demonstrated that expression of ZjGA20 was regulated by abiotic stresses and the damage derived from abiotic stresses could be rescued by exogenously applied plant growth regulator GA3. Further more, exogenous gibberellin and salicylic acid (SA) alleviated the growth inhibition and death of the seedlings under stresses. The SA content in the seedlings treated with 80 μM GA3 was far greater than the control (with H2O) and plants under stress treatments. These data suggest that exogenous addition of GA3 is able to counteract the inhibitory effects of these adverse environmental conditions in Zoysiagrass growth through modulation of SA biosynthesis. This is the first study of differential expression of gibberellin 20 oxidase gene and growth regulation of GA3 in Zoysiagrass under stresses.

scholarly journals Trinexapac-ethyl Increases Kentucky Bluegrass Leaf Cell Density and Chlorophyll Concentration

HortScience ◽  
2001 ◽  
Vol 36 (4) ◽  
pp. 787-789 ◽  
Author(s):  
E.H. Ervin ◽  
A.J. Koski
Keyword(s):  
Cell Density ◽  
Leaf Blade ◽  
Poa Pratensis ◽  
Chlorophyll Concentration ◽  
Acid Ethyl Ester ◽  
Kentucky Bluegrass ◽  
Carbohydrate Content ◽  
Cell Length ◽  
Cell Width ◽  
Structural Carbohydrate

The effects of trinexapac-ethyl (TE) on the anatomical and biochemical composition of turfgrasses and their implications for its field use are poorly understood. Two greenhouse experiments were conducted to determine if application of TE increased Kentucky bluegrass (Poa pratensis L.) leaf blade cell density, chlorophyll concentration, or structural carbohydrate content. Kentucky bluegrass (KB) sod was harvested from the field, established in greenhouse pots, and sprayed with 0.27 kg·ha-1 a.i. TE. Leaf blade samples were collected 4 weeks after treatment (WAT), fixed in glutaraldehyde, and embedded in Spurr resin. Photomicrographs of longitudinal leaf blade sections were used to determine cell density, cell length, and cell width. Chlorophyll and structural carbohydrate contents were determined at 2 and 4 WAT. Treatment with TE increased cell density and chlorophyll-b concentration, while reducing cell length, but structural carbohydrate content was unaffected. Chemical name used: 4-cyclopropyl-α-hydroxy-methylene-3,5-dioxo-cyclohexanecarboxylic acid ethyl ester (trinexapac-ethyl).

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

Superconducting Wind Generators with Capacities of 10 MW and Larger

2020 ◽  
Vol 10 (10) ◽  
pp. 59-67
Author(s):  
Victor N. ANTIPOV ◽  
◽  
Andrey D. GROZOV ◽  
Anna V. IVANOVA ◽  
◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Wind Power ◽  
State Of The Art ◽  
Superconducting Materials ◽  
Commercial Application ◽  
Synchronous Generators ◽  
High Temperature Superconducting ◽  
Wind Generators ◽  
Main Factor

The overall dimensions and mass of wind power units with capacities larger than 10 MW can be improved and their cost can be decreased by developing and constructing superconducting synchronous generators. The article analyzes foreign conceptual designs of superconducting synchronous generators based on different principles: with the use of high- and low-temperature superconductivity, fully superconducting or only with a superconducting excitation system, and with the use of different materials (MgB2, Bi2223, YBCO). A high cost of superconducting materials is the main factor impeding commercial application of superconducting generators. In view of the state of the art in the technology for manufacturing superconductors and their cost, a conclusion is drawn, according to which a synchronous gearless superconducting wind generator with a capacity of 10 MW with the field winding made of a high-temperature superconducting material (MgB2, Bi-2223 or YBCO) with the «ferromagnetic stator — ferromagnetic rotor» topology, with the stator diameter equal to 7—9 m, and with the number of poles equal to 32—40 has prospects for its practical use in the nearest future.

SOMERS LTA COPPER

Alloy Digest ◽  
1980 ◽  
Vol 29 (12) ◽  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Physical Properties ◽  
Copper Foil ◽  
Heat Treating ◽  
Dielectric Substrates ◽  
Printed Circuits

Abstract SOMERS LTA Copper is a wrought copper foil that can be annealed at 350 F in 15 minutes to the full-soft condition; its use simplifies the manufacture of printed circuits (LTA = Low-Temperature Annealable). LTA Copper is especially useful for foil weights up to and including one ounce per square foot (0.0014-inch thick) for laminating to high-temperature dielectric substrates. This datasheet provides information on composition, physical properties, and elasticity as well as fatigue. It also includes information on forming, heat treating, and machining. Filing Code: Cu-407. Producer or source: Olin Corporation.

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