Effect of heat stress during seed development and maturation on wheat (Triticum durum) seed quality. II. Mitochondrial respiration and nucleotide pools during early germination

1995 ◽  
Vol 75 (4) ◽  
pp. 831-839 ◽  
Author(s):  
L. Grass ◽  
J. S. Burris
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Low Temperature ◽  
Oxygen Uptake ◽  
Temperature Regime ◽  
Seed Quality ◽  
Energy Levels ◽  
Medium Temperature ◽  
Mitochondrial Structure ◽  
Temperature Regimes

Marzak and Oum-rabia wheat seeds were produced under three temperature regimes (20:15, 28:21, 36:29 °C) starting 10 d after anthesis through harvest. Nucleotide levels and respiratory activity of mitochondria isolated from imbibing embryos were determined. Mitochondrial structure from the radicle meristem region of imbibed embryos was examined under electron microscopy. Embryos from low-temperature treatments showed rapid accumulation of adenosine triphosphate (ATP) and higher energy levels and rates of oxygen uptake than embryos from high-temperature treatments. Embryos from medium-temperature treatments exhibited intermediate values. Parallel to these metabolic changes during early seed germination, results from electron microscopy revealed visible differences in mitochondrial structure. Mitochondria from the low-temperature regime were well developed with visible membranes and cristae; those from the high-temperature regime were degenerating. These results provide clear evidence of the influence of parent temperature conditions on the seed metabolism during early stages of germination. Key words: Embryo, mitochondria, nucleotide, oxygen uptake, vigor, wheat

Cotton responses to different light–temperature regimes

1998 ◽  
Vol 131 (3) ◽  
pp. 277-283 ◽  
Author(s):  
D. ROUSSOPOULOS ◽  
A. LIAKATAS ◽  
W. J. WHITTINGTON
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Light Intensity ◽  
Leaf Area ◽  
Temperature Regime ◽  
Light Regime ◽  
High Light ◽  
Cultivar Differences ◽  
Low Light ◽  
Temperature Regimes

A series of experiments investigating the interactive effects of light and temperature on vegetative growth, earliness, fruiting, yield and fibre properties in three cultivars of cotton, was undertaken in growth rooms. Two constant day/night temperature regimes with a difference of 4 °C (30/20 and 26/16·5 °C) were used throughout the growing season in combination with two light intensities (75 and 52·5 W m−2).The results showed that significant interactions occurred for most of the characters studied. Although the development of leaf area was mainly temperature-dependent, plants at harvest had a larger leaf area when high temperature was combined with low rather than with high light intensity. Leaf area was least in the low temperature–low light regime. However, the plants grown under the high temperature–low light combination weighed the least.Variations in the number of nodes and internode length were largely dependent on temperature rather than light. Light did, however, affect the numbers of branches, sympodia and monopodia. The first two of these were highest in the high light–high temperature regime and the third in the low light–low temperature regime.All other characters, except time to certain developmental stages and fibre length, were reduced at the lower light intensity. Variation in temperature modified the light effect and vice versa, in a character-dependent manner. More specifically, square and boll dry weights, as well as seed cotton yield per plant, were highest in high light combined with low temperature, where the most and heaviest bolls were produced. But flower production was favoured by high light and high temperature, suggesting increased boll retention at low temperature, especially when combined with low light. Low temperature and high light also maximized lint percentage.Fibres were shortest in the high temperature–high light regime, where fibre strength, micronaire index and maturity ratio were at a maximum. However, the finest and the most uniform fibres were produced when high light was combined with low temperature.Cultivar differences were significant mainly in leaf area and dry matter production at flowering.

Preparation and performance characteristics of reduced graphene oxide modified asphalt

2021 ◽  
Vol 11 (9) ◽  
pp. 1579-1586
Author(s):  
Zixuan Chen ◽  
Xudong Li ◽  
Jie Xie ◽  
Jianzhong Pei ◽  
Chengchao Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
High Temperature ◽  
Low Temperature ◽  
Reduced Graphene Oxide ◽  
Softening Point ◽  
Medium Temperature ◽  
Modified Asphalt ◽  
Reduced Graphene ◽  
And Performance

Reduced graphene oxide (RGO) was self-prepared by the oxidation reduction method and then characterized by several tests known as Fourier Transform Infrared Spectroscopy (FTIR) test, scanning electron microscopy (SEM) test, transmission electron microscopy (TEM) test, elemental analysis, raman measurement and thermogravimetry (TG) analysis to evaluate the properties of RGO. Additionally, RGO modified asphalt was prepared in this research to study the influence of RGO on matrix asphalt. Some of the normal performances of RGO modified asphalt were studied in terms of penetration at medium temperature, penetration index (PI), softening point, equivalent softening point T800 at high temperature and ductility at low temperature. Results showed that the prepared RGO has obvious layer structures and good properties and the performance of RGO modified asphalt at high temperature has increased significantly while the performance at low temperature decreased slightly. This research can provide an insight for the further study of RGO modified asphalt to enhance its road performance.

Glyphosate Activity in Potato (Solanum tuberosum) Under Different Temperature Regimes and Light Levels

Weed Science ◽  
1988 ◽  
Vol 36 (2) ◽  
pp. 137-140 ◽  
Author(s):  
John B. Masiunas ◽  
Stephen C. Weller
Keyword(s):  
Solanum Tuberosum ◽  
High Temperature ◽  
Low Temperature ◽  
Temperature Regime ◽  
Distribution Patterns ◽  
Light Level ◽  
Fresh Weight ◽  
High Temperature Regime ◽  
Light Levels ◽  
Temperature Regimes

The response of potato (Solanum tuberosumL. 'Superior’) to glyphosate [N-(phosphonomethyl)glycine] at rates between 0.28 and 2.24 kg ae/ha was determined in four environments: 24/13 or 13/4 C temperature regimes with light levels of 650 ± 53 or 320 ± 45 μE · m−2· S−1. Light level did not affect phytotoxicity ratings or shoot fresh weight following glyphosate application. Greater phytotoxicity and reduced fresh weight accumulation were observed from glyphosate at rates above 0.56 kg/ha in a high-temperature regime than for comparable plants grown at low temperature. Studies of14C-glyphosate uptake and translocation indicated that the differences in phytotoxicity were due to less glyphosate absorption at low temperature and not a shift in distribution patterns within the plant.

scholarly journals Effects of Double-Ageing Heat Treatments on the Microstructure and Mechanical Behaviour of a Ti-3.5Al-5Mo-4V Alloy

Materials ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 209
Author(s):  
Xuanming Ji ◽  
Panpan Ge ◽  
Song Xiang ◽  
Yuanbiao Tan
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Low Temperature ◽  
Mechanical Behaviour ◽  
Ageing Time ◽  
Two Stage ◽  
Ageing Treatment ◽  
Ω Phase ◽  
Α Phase ◽  
Temperature Ageing

In this work, the effect of double-ageing heat treatments on the microstructural evolution and mechanical behaviour of a metastable β-titanium Ti-3.5Al-5Mo-4V alloy is investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The double-ageing treatments are composed of low-temperature pre-ageing and high-temperature ageing, where the low-temperature pre-ageing is conducted at 300 °C or 350 °C for different times, and the high-temperature ageing is conducted at 500 °C for 8 h. The results show that the phase transformation sequence is altered with the time spent during the first ageing stage, the isothermal ω phase is precipitated in the pre-ageing process of the alloy at 300 °C and 350 °C with the change in the ageing time, and the ω phase is finally transformed into the α phase with the extension of pre-ageing time. The existence time of the ω phase is shortened as the pre-ageing temperature increases. The microhardness of the alloy increases with increasing pre-ageing time and temperature. Compared with single-stage ageing, the ω phase formed in the pre-ageing stage changes the response to subsequent high-temperature ageing. After the two-stage ageing treatment, the precipitation size of the α phase is obviously refined after the double-ageing treatment. A microhardness test shows that the microhardness of the two-stage aged alloy increases with extended pre-ageing time.

scholarly journals Dynamics of phytohormones and their relationship with chalkiness of early indica rice under different post-anthesis temperature regimes

2017 ◽  
Vol 42 (1) ◽  
pp. 53-65
Author(s):  
Mohammed Humayun Kabir ◽  
Qing Liu ◽  
Yi Su ◽  
Zhigang Huang ◽  
Langtao Xiao
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Indica Rice ◽  
Grain Filling ◽  
Flag Leaves ◽  
Content Ratio ◽  
Temperature Regimes ◽  
Head Rice ◽  
Grain Filling Period ◽  
Early Indica Rice

A pot experiment on an early indica rice cv. ‘Shenyou9576’ was conducted in the net house of Hunan Agricultural University, Changsha, Hunan, PR China during the early growing season of 2013 to investigate the influence of varying temperatures on chalkiness rate, head rice rate, and phytohormones, namely indole-3-acetic acid (IAA), gibberellins (GA1 and GA4), zeatin (Z), zeatin riboside (ZR) and abscisic acid (ABA) both in flag leaves and grain endosperm during grain filling period. The treatments comprised three temperature regimes which are designated as the high (35/28oC- day/night), low (25/20oC- day/night) and natural condition as the control (35/25oC- day/night). The results showed that the maximum chalkiness rate was 61.11% under high temperature and the minimum (22.59%) under low temperature. The lowest head rice rate was 42.76% under high temperature followed by 49.91% in the control, while the highest (62.33%) under low temperature. The contents of GA1, GA4, Z and ZR were decreased gradually from 7 to 35 days after anthesis (DAA) irrespective of treatments. IAA content began to decrease from 14 DAA and continued up to 35 DAA and ABA was reduced from 28 to 35 DAA under low temperature in comparison to control and high temperature. ABA content was increased from 7 to 21 DAA and then declined at high temperature. The results showed that contents of GA1, GA4, Z, ZR were high at low temperature compared to high temperature and control. IAA content was also high during grain development period at low temperature except 7 DAA. Higher phytohormone contents were observed in endosperm than in flag leaves. Phytohormone content ratio (endosperm: flag leaves) was found highest in IAA and the lowest in GA1. A significant positive correlation was found between ABA and chalkiness rate during early to mid grain filling period, while significant negative correlations were noticed between chalkiness rate and other phytohormones during grain filling period. Correlation results revealed that increased level of ABA during early to mid grain filing period caused by high temperature was more responsible for development of chalkiness.Bangladesh J. Agril. Res. 42(1): 53-65, March 2017

scholarly journals Growth, flowering and fruiting in tomatoes in relation to temperature, cycocel and GA.

1970 ◽  
Vol 18 (2) ◽  
pp. 105-110
Author(s):  
A.A. Abdalla ◽  
K. Verkerk
Keyword(s):  
Growth Rate ◽  
High Temperature ◽  
High Temperatures ◽  
Root Development ◽  
Temperature Regime ◽  
Low Temperatures ◽  
Fruit Set ◽  
High Temperature Regime ◽  
Temperature Regimes ◽  
Dark Green

The effects were assessed of CCC and GA on tomatoes grown either under a high temperature regime (35 degrees day and 25 degrees C. night) or at normal temperatures (22 degrees and 18 degrees ). CCC (0.4%) was applied to the soil in the pots either 2 days after transplanting or at the start of flowering; G A was applied by dipping the first truss in GA (50 p.p.m.). CCC greatly retarded the growth rate of the stems of the plants under both temperature regimes; this effect persisted for about 17 and 24 days under the high and normal temperature regimes, respectively. With plants grown at high temperatures CCC applied at the start of flowering greatly reduced flower shedding and slightly increased the fruit set and fruit development of hand-pollinated flowers. With plants grown at normal temperatures, however, the effects of CCC were slight. CCC-treated plants were sturdy with dark-green leaves which remained green longer, especially under the high temperature regime. More N accumulated in the tissues of plants grown at high temperatures than at normal temperatures, and the N content of the latter plants was considerably increased by CCC treatment. The root development of the CCC-treated plants was much more extensive than that of the untreated plants. The numbers of seeds in the hand-pollinated fruit were not affected by CCC, but at high temperatures there were considerably less seeds than at low temperatures. GA enhanced fruit set of the high-temperature plants, but the fruits were small and seedless. GA also accelerated fruit ripening by 2 and 3 weeks in the plants grown at high and normal temperatures, respectively.-Agric. Univ., Wageningen. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Starch Morphology and Metabolomic Analyses Reveal That the Effect of High Temperature on Cooked Rice Elongation and Expansion Varied in Indica and Japonica Rice Cultivars

Agronomy ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2416
Author(s):  
Nnaemeka Emmanuel Okpala ◽  
Mouloumdema Pouwedeou Potcho ◽  
Muhammad Imran ◽  
Tianyue An ◽  
Gegen Bao ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Oryza Sativa L ◽  
Effect Of Temperature ◽  
Japonica Rice ◽  
Rice Cultivars ◽  
Starch Granules ◽  
Cooked Rice ◽  
Temperature Regimes ◽  
Badh2 Gene

Rice (Oryza sativa L.) is mainly grouped into indica and japonica varieties. The aim of this study was to investigate the effect of temperature on cooked rice elongation, cooked rice expansion, and rice fragrance. This study was conducted in three growth temperature chambers with indica cultivar Basmati 385 (B385) and japonica cultivar Yunjingyou (YJY). Grains of B385 grown in low-temperature regimes had the highest cooked rice elongation and expansion, whereas the grains of YJY grown in high-temperature regimes had the highest cooked rice elongation and expansion. Starch granules of B385 grown in low-temperature regimes were more compact and bigger, compared to grains grown in medium- and high-temperature regimes. Conversely, the starch granules of YJY grown in high-temperature regimes were more compact and bigger, compared to those grown in medium- and low-temperature regimes. Metabolomic analyses showed that temperature affected the rice metabolome and revealed that cyclohexanol could be responsible for the differences observed in cooked rice elongation and expansion percentage. However, in both B385 and YJY, grains from low-temperature regimes had the highest 2-AP content and the lowest expression levels of the badh2 gene. The findings of this study will be useful to rice breeders and producers.

High-Temperature Ignition Kinetics of Gas Turbine Lubricating Oils

2021 ◽  
Author(s):  
Sean P. Cooper ◽  
Eric L. Petersen
Keyword(s):  
Regression Analysis ◽  
High Temperature ◽  
Low Temperature ◽  
Shock Tube ◽  
Gas Turbine ◽  
Temperature Regime ◽  
Ignition Process ◽  
High Temperature Regime ◽  
Second Stage ◽  
Arrhenius Expression

Abstract Lubricant ignition is a highly undesirable event in any mechanical system, and surprisingly minimal work has been conducted to investigate the auto-ignition properties of gas turbine lubricants. To this end, using a recently established spray injection scheme in a shock tube, two gas turbine lubricants (Mobil DTE 732 and Lubricant A from Cooper et al. 2020) were subjected to high-temperature, post-reflected-shock conditions, and OH* chemiluminescence was monitored at the sidewall location of the shock tube to measure ignition delay time (τign). A combination of an extended shock-tube driver and driver-gas tailoring were utilized to observe ignition between 1183 K and 1385 K at near-atmospheric pressures. A clear, two-stage-ignition process was observed for all tests with Mobil DTE 732, and both first and second stage τign are compared. Second stage ignition was found to be more indicative of lubricant ignition and was used to compare τign values with lubricant A. Both lubricants exhibit three ignition regimes: a high-temperature, Arrhenius-like regime (> 1275 K); an intermediate, negative-temperature-coefficient-like regime (1230–1275 K); and a low-temperature ignition regime (< 1230 K). Similar τign behavior in the high-temperature regime was seen for both lubricants, and a regression analysis using τign data from both lubricants in this region produced the Arrhenius expression τign(μs) = 4.4 × 10−14exp(96.7(kcal/mol)/RT). While lubricant A was found to be less reactive in the intermediate-temperature regime, Mobil DTE 732 was less reactive in the low-temperature regime. As the low-temperature regime is more relevant to gas turbine conditions, Mobil DTE 732 is considered more desirable for system implementation. Chemical kinetic modeling was also performed using n-hexadecane models (a lubricant surrogate suggested in the literature). The current models are unable to reproduce the three regimes observed and predict activation energies much lower than those observed in the high-temperature regime, suggesting n-hexadecane is a poor surrogate for lubricant ignition. Additionally, experiments were conducted with Jet-A for temperatures between 1145 and 1419 K around 1 atm. Good agreement is seen with both literature data and model predictions, anchoring the experiment with previously established τign measurement methods and calculations. A linear regression analysis of the Jet-A data produced the Arrhenius expression: τign(μs) = 6.39 × 10−5exp(41.4(kcal/mol)/RT).

Ignition in the supersonic hydrogen/air mixing layer with reduced reaction mechanisms

1996 ◽  
Vol 322 ◽  
pp. 275-296 ◽  
Author(s):  
H. G. Im ◽  
B. T. Helenbrook ◽  
S. R. Lee ◽  
C. K. Law
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Temperature Regime ◽  
Characteristic Temperature ◽  
Mixing Layer ◽  
Reaction Rates ◽  
Thermal Runaway ◽  
Ignition Process ◽  
High Temperature Regime ◽  
Air Mixing

Asymptotic analysis of ignition within the supersonic hydrogen/air mixing layer is performed using reduced mechanisms. Two distinct reduced mechanisms for the high-temperature and the low-temperature regimes are used depending on the characteristic temperature of the reaction zone relative to the crossover temperature at which the reaction rates of the H + 02 branching and termination steps are equal. Each regime further requires two distinct analyses for the hot-stream and the viscous-heating cases, depending on the relative dominance of external and internal ignition energy sources. These four cases are analysed separately, and it is shown that the present analysis successfully describes the ignition process by exhibiting turning point or thermal runaway behaviour in the low-temperature regime, and radical branching followed by thermal runaway in the high-temperature regime. Results for the predicted ignition distances are then mapped out over the entire range of the parameters, showing consistent behaviour with the previous one-step model analysis. Furthermore, it is demonstrated that ignition in the low-temperature regime is controlled by a larger activation energy process, so that the ignition distance is more sensitive to its characteristic temperature than that in the high-temperature regime. The ignition distance is also found to vary non-monotonically with the system pressure in the manner of the well-known hydrogen/oxygen explosion limits, thereby further substantiating the importance of chemical chain mechanisms in this class of chemically reacting boundary layer flows.

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