DISTINGUISHING THE EFFECTS OF GENOTYPE AND SEED PHYSIOLOGICAL AGE ON LOW TEMPERATURE TOLERANCE OF RICE (ORYZA SATIVA L.)

2006 ◽  
Vol 42 (3) ◽  
pp. 337-349 ◽  
Author(s):  
M. G. ALI ◽  
R. E. L. NAYLOR ◽  
S. MATTHEWS
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Oryza Sativa L ◽  
Ageing Time ◽  
Physiological State ◽  
Thermal Time ◽  
Physiological Age ◽  
Base Temperature ◽  
Seed Moisture Content ◽  
Rice Genotypes

When differences are observed between genotypes in their response to low temperatures at germination, it has been generally assumed these are purely genetic. Laboratory experiments were carried out to evaluate the effects of physiological age on the temperature responses of 13 rice genotypes from Bangladesh in order to clarify whether (a) differences in seed germination at low temperature represented genetic differences or differences in the physiological state of the particular seed lot used and (b) whether genotype performance at higher temperatures was indicative of performance at lower temperatures. A higher initial seed moisture content (mc) was associated with lower initial viability (Ki). The base temperature for germination differed by less than 1 °C between genotypes. Seeds remaining ungerminated at low temperatures usually germinated when transferred to 21 °C. The thermal time requirement to reach t50 (θ) differed widely between genotypes. Lower optimum temperatures for germination were associated with lower thermal time requirements. Ageing seeds for 24 hours at 24 % mc and 45 °C significantly reduced final germination on a thermal gradient table at all temperatures below 20.8 °C in genotype BR29 but only below 16.5 °C in BR11. The rates of germination (seeds d−1) of aged seeds were also lower at all temperatures. Germination of high quality seeds of four genotypes were compared at 21 °C and 11 °C both before and after ageing (at 24 % mc and 45 °C). Ageing consistently reduced the rates of germination at both 21 °C and 11 °C. Increased ageing time progressively reduced the rate of germination of all seed lots at both temperatures. The rates of germination at 11 °C and 21 °C were positively and significantly (p < 0.01) related to final germination at the lower temperature of 11 °C. These results demonstrate that seed physiological quality as well as genotype might influence the final germination and rate of germination of rice genotypes at low temperatures. This information will be useful for breeders involved in selection of lines suitable for growing in cooler seasons.

Low temperature induced spikelet sterility in rice. II. Effects of panicle and root temperatures

2003 ◽  
Vol 54 (10) ◽  
pp. 947 ◽  
Author(s):  
T. A. Gunawardena ◽  
S. Fukai ◽  
F. P. C. Blamey
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Oryza Sativa L ◽  
Pollen Grains ◽  
Development Stage ◽  
Dominant Factor ◽  
Microspore Development ◽  
Root Temperature ◽  
Spikelet Sterility ◽  
Germinated Pollen

Low temperatures impose restrictions on rice (Oryza sativa L.) production at high latitudes. This study is related to low temperature damage that can arise mid-season during the panicle development phase. The objective of this study was to determine whether low temperature experienced by the root, panicle, or foliage is responsible for increased spikelet sterility. In temperature-controlled glasshouse experiments, water depth, and water and air temperatures, were changed independently to investigate the effects of low temperature in the root, panicle, and foliage during microspore development on spikelet sterility. The total number of pollen and number of engorged pollen grains per anther, and the number of intercepted and germinated pollen grains per stigma, were measured. Spikelet sterility was then analysed in relation to the total number of pollen grains per spikelet and the efficiency with which these pollen grains became engorged, were intercepted by the stigma, germinated, and were involved in fertilisation. There was a significant combined effect of average minimum panicle and root temperatures on spikelet sterility that accounted for 86% of the variation in spikelet sterility. Total number of pollen grains per anther was reduced by low panicle temperature, but not by low root temperature. Whereas engorgement efficiency (the percentage of pollen grains that were engorged) was determined by both root and panicle temperature, germination efficiency (the percentage of germinated pollen grains relative to the number of engorged pollen grains intercepted by the stigma) was determined only by root temperature. Interception efficiency (i.e. percentage of engorged pollen grains intercepted by the stigma), however, was not affected by either root or panicle temperature. Engorgement efficiency was the dominant factor explaining the variation in spikelet sterility. It is concluded that both panicle and root temperature affect spikelet sterility in rice when the plant encounters low temperatures during the microspore development stage.

OsSIG2A is required for chloroplast development in rice (Oryza sativa L.) at low temperature by regulating plastid genes expression

2019 ◽  
Vol 46 (8) ◽  
pp. 766 ◽  
Author(s):  
Yang Yu ◽  
Zhenling Zhou ◽  
Hanchun Pu ◽  
Baoxiang Wang ◽  
Yunhui Zhang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Chloroplast Development ◽  
Oryza Sativa L ◽  
Photosynthetic Apparatus ◽  
Development Stage ◽  
Specific Gene ◽  
Genes Expression ◽  
Young Leaves

The chloroplast is an essential photosynthetic apparatus that is more sensitive to low temperatures than other organelles. Sigma factors were revealed regulating specific gene expression for maintaining photosynthetic efficiency and adapting to physiological and environmental conditions. However, the regulatory mechanisms of SIG genes supporting chloroplast development under low temperature in rice have not yet been reported. Here, we uncovered the essential role of OsSIG2A in rice chloroplast development at low temperatures by a newly reported thermo-sensitive chlorophyll deficient 12 (tcd12) mutant, which exhibited albino leaves with decreased chlorophyll content and malformed chloroplasts at seedling stage under low temperature. OsSIG2A is a typical chloroplast-localised RNA polymerase sigma factor, and constitutively expresses in different rice tissues, especially for young leaves and stems. Moreover, the transcription level of both PEP- and NEP- dependent genes, which are necessary for chloroplast development at early leaf development stage, was greatly affected in the tcd12 mutant under low temperature. Taken together, our findings indicate that OsSIG2A is required for early chloroplast differentiation under low temperatures by regulating plastid genes expression.

scholarly journals Screening for Cold Tolerance during Germination within Sweet and Fiber Sorghums [Sorghum bicolor (L.) Moench] for Energy Biomass

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 620
Author(s):  
Cristina Patanè ◽  
Salvatore L. Cosentino ◽  
Valeria Cavallaro ◽  
Alessandro Saita
Keyword(s):  
Seed Germination ◽  
Low Temperature ◽  
Cold Tolerance ◽  
Fiber Type ◽  
Warm Season ◽  
Early Spring ◽  
Thermal Time ◽  
Base Temperature ◽  
Biomass Sorghum ◽  
Germination Response

Within the project “BIOSEA” funded by the Italian Ministry of Agriculture and Forestry, a preliminary laboratory test was conducted to assess the variability for cold tolerance during germination in 30 cultivars of biomass sorghum, among fiber and sweet types. Seed germination (%) and mean germination time (MGT) were examined at seven constant temperatures (from 8 °C to 35 °C) and base temperature (Tb) and thermal time (θT) for 50% germination were calculated. A wide genetic diversity in the germination response of sorghum was ascertained at 8 °C (CV 45%) and 10 °C (CV 25.4%). At 8 °C, in cultivars of ‘Padana 4’, ‘PR811F’, ‘PSE24213’, ‘PR849’ and ‘Zerberus’, seed germination exceeded 80%. Seeds of ‘Zerberus’ were also the fastest, requiring less than 13 days for final germination at this low temperature. Great differences were found in Tb and θT among cultivars. Tb varied between 7.44 °C (‘PR811F’) and 13.48 °C (‘Nectar’). Thermal time (θT) was, on average, 24.09 °Cd−1, and ranged between 16.62 (‘Nectar’) and 33.42 °Cd−1 (‘PSE24213’). The best combination of the two germination parameters (i.e., low Tb and θT) corresponded to ‘Zerberus’, ‘Sucrosorgo 506’, ‘Jumbo’ and ‘PR811F’. Accordingly, these cultivars are more tolerant to cold stress during germination and, thus, more adapt to early spring sowings in Mediterranean areas (March-April). Cultivars ‘PR811F’ (fiber type) and ‘Sucrosorgo 506’ (sweet type) also combine high cold tolerance with good productivity in terms of final dry biomass, as assessed in open-field conditions (late spring sowing). The genetic variation in the germination response to a low temperature is useful for the identification of genotypes of sorghum suitable to early sowings in semi-arid areas. Selection within existing cultivars for cold tolerance during germination may also contribute to the expansion of biomass sorghum into cooler cultivation areas, such as those of Northern Europe, which are less suitable to this warm season crop.

scholarly journals Analysis of the Effects of Ageing on the Cohesive Strength of Polymer-Modified Bitumen at Low Temperatures

2018 ◽  
Vol 13 (2) ◽  
pp. 156-164 ◽  
Author(s):  
Chuanfeng Zheng ◽  
Genze Li ◽  
Yazhi Xu ◽  
Danni Wang ◽  
Dan Lv
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Decay Curve ◽  
Ageing Time ◽  
Cohesive Strength ◽  
Modified Bitumen ◽  
Styrene Butadiene Styrene ◽  
Styrene Butadiene ◽  
Polymer Modified Bitumen ◽  
Butadiene Styrene

The decay law on the ageing process of the cohesive strength of styrene-butadiene-styrene(SBS)- and polyethylene(PE)-modified bitumens at low temperatures was investigated. The rotated-thin-film oven test was used to age the two types of polymer-modified bitumens. The cohesive strengths at different low-temperature conditions were tested quantitatively according to technology for testing the low-temperature cohesive strength of bitumen. The decay curve of bitumen low-temperature cohesive strengths was drawn, and the embrittlement time of bitumen at different ageing states was obtained according to the decay curve. Results showed that ageing time definitely influenced the attenuation degree of the low-temperature cohesive strength of the two types of polymer-modified bitumens and influenced the appearance of the low-temperature cohesive strength peak, i.e., the bitumen embrittlement time, which advanced after ageing. The lightweight components of polymer-modified bitumen were lost after ageing. The bitumen embrittlement time was advanced, and the sharp attenuation of the low-temperature cohesive strength of bitumen appeared. In the future, bitumen antiageing technology and lighter part pre-supplement technology should be studied in-depth.

Evaluation of rice (Oryza sativa L.) genotypes for cold tolerance at seedling stage

2020 ◽  
Vol 57 (1) ◽  
pp. 43-48
Author(s):  
K Sumayya ◽  
MP Rajanna ◽  
CA Deepak ◽  
KV Shivakumar ◽  
GR Denesh
Keyword(s):  
Oryza Sativa ◽  
Low Temperature ◽  
Cold Tolerance ◽  
Oryza Sativa L ◽  
Early Spring ◽  
Seedling Stage ◽  
Germination Index ◽  
Coleoptile Length ◽  
Crop Establishment ◽  
Rice Genotypes

Cold tolerance during germination is important for ensuring fast and uniform crop establishment. Rice plants are injured at the seedling stage when they are grown in early spring in temperate or subtropical environments. The productivity of rice is particularly low during spring due to cold, which is an important abiotic constraint, where low temperature prevails below 18 ºC. The present study was taken up to evaluate cold tolerance in 86 rice genotypes based on seed and seedling parameters as per Cruz and Milach (2004). Seeds were germinated under two conditions i.e.,160C for 28 days (cold) and 280C for 7 days (control).The genotypes showed highly significant differences forparameters such as germination (%), germination index (%), percentage of seeds with coleoptile superior to 5 mm (PERCOL), percentage of reduction in coleoptile length (REDCOL) and coleoptile regrowth (COLREG, cm).Both REDCOL and COLREG seem to be the most adequate characteristics to be used to evaluate cold tolerance during the germination period in rice. Among those genotypes, AC 35548, JBT 37/164, PS 353, KMP-175 andThanu were adjudged as promising when screened for cold tolerance under laboratory conditions based on the aforementioned parameters.

scholarly journals Effect of Low Temperature on Chlorophyll Biosynthesis and Chloroplast Biogenesis of Rice Seedlings during Greening

2020 ◽  
Vol 21 (4) ◽  
pp. 1390 ◽  
Author(s):  
Yuqing Zhao ◽  
Qiaohong Han ◽  
Chunbang Ding ◽  
Yan Huang ◽  
Jinqiu Liao ◽  
...  
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Aminolevulinic Acid ◽  
Oryza Sativa L ◽  
Chlorophyll Biosynthesis ◽  
Chilling Stress ◽  
Chlorophyll Synthesis ◽  
Rice Seedling ◽  
Rice Seedlings ◽  
Plastid Development

Rice (Oryza sativa L.) frequently suffers in late spring from severe damage due to cold spells, which causes the block of chlorophyll biosynthesis during early rice seedling greening. However, the inhibitory mechanism by which this occurs is still unclear. To explore the responsive mechanism of rice seedlings to low temperatures during greening, the effects of chilling stress on chlorophyll biosynthesis and plastid development were studied in rice seedlings. Chlorophyll biosynthesis was obviously inhibited and chlorophyll accumulation declined under low temperatures during greening. The decrease in chlorophyll synthesis was due to the inhibited synthesis of δ-aminolevulinic acid (ALA) and the suppression of conversion from protochlorophyllide (Pchlide) into chlorophylls (Chls). Meanwhile, the activities of glutamate-1-semialdehyde transaminase (GSA-AT), Mg-chelatase, and protochlorophyllide oxidoreductase (POR) were downregulated under low temperatures. Further investigations showed that chloroplasts at 18 °C had loose granum lamellae, while the thylakoid and lamellar structures of grana could hardly develop at 12 °C after 48 h of greening. Additionally, photosystem II (PSII) and photosystem I (PSI) proteins obviously declined in the stressed seedlings, to the point that the PSII and PSI proteins could hardly be detected after 48 h of greening at 12 °C. Furthermore, the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) and cell death were all induced by low temperature. Chilling stress had no effect on the development of epidermis cells, but the stomata were smaller under chilling stress than those at 28 °C. Taken together, our study promotes more comprehensive understanding in that chilling could inhibit chlorophyll biosynthesis and cause oxidative damages during greening.

In situ Tensile Experiments at Low Temperatures on Niobium Single Crystals by H.V.E.M.

1975 ◽  
Vol 33 ◽  
pp. 58-59
Author(s):  
F. H. Louchet ◽  
L. P. Kubin
Keyword(s):  
Electron Microscope ◽  
Transition Temperature ◽  
Low Temperature ◽  
Slip System ◽  
Low Temperatures ◽  
Tensile Axis ◽  
Image Intensifier ◽  
Screw Dislocations ◽  
Source Operation

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.

INVAR M93

Alloy Digest ◽  
2008 ◽  
Vol 57 (1) ◽  
Keyword(s):  
Fracture Toughness ◽  
Low Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Low Temperatures ◽  
Bend Strength ◽  
Temperature Performance ◽  
Ni Content ◽  
Precision Alloys ◽  
Ni Alloy

Abstract Invar is an Fe-Ni alloy with 36% Ni content that exhibits the lowest expansion of known metals from very low temperatures up to approximately 230 deg C (445 deg F). Invar M93 is a cryogenic Invar with improved weldability. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear and bend strength as well as fracture toughness and fatigue. It also includes information on low temperature performance as well as forming and joining. Filing Code: FE-143. Producer or source: Metalimphy Precision Alloys.

scholarly journals The Candidate Genes Underlying a Stably Expressed QTL for Low Temperature Germinability in Rice (Oryza sativa L.)

Rice ◽  
2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Tifeng Yang ◽  
Lian Zhou ◽  
Junliang Zhao ◽  
Jingfang Dong ◽  
Qing Liu ◽  
...  
Keyword(s):  
Low Temperature ◽  
Differential Expression ◽  
Candidate Genes ◽  
Complex Traits ◽  
Molecular Breeding ◽  
Genome Wide Association Study ◽  
Oryza Sativa L ◽  
Sequence Comparisons ◽  
Cold Environments ◽  
Promising Source

Abstract Background Direct seeding is an efficient cultivation technique in rice. However, poor low temperature germinability (LTG) of modern rice cultivars limits its application. Identifying the genes associated with LTG and performing molecular breeding is the fundamental way to address this issue. However, few LTG QTLs have been fine mapped and cloned so far. Results In the present study, the LTG evaluation of 375 rice accessions selected from the Rice Diversity Panel 2 showed that there were large LTG variations within the population, and the LTG of Indica group was significantly higher than that of Japonica and Aus groups (p < 0.01). In total, eleven QTLs for LTG were identified through genome-wide association study (GWAS). Among them, qLTG_sRDP2–3/qLTG_JAP-3, qLTG_AUS-3 and qLTG_sRDP2–12 are first reported in the present study. The QTL on chromosome 10, qLTG_sRDP2–10a had the largest contribution to LTG variations in 375 rice accessions, and was further validated using single segment substitution line (SSSL). The presence of qLTG_sRDP2–10a could result in 59.8% increase in LTG under 15 °C low temperature. The expression analysis of the genes within qLTG_sRDP2–10a region indicated that LOC_Os10g22520 and LOC_Os10g22484 exhibited differential expression between the high and low LTG lines. Further sequence comparisons revealed that there were insertion and deletion sequence differences in the promoter and intron region of LOC_Os10g22520, and an about 6 kb variation at the 3′ end of LOC_Os10g22484 between the high and low LTG lines, suggesting that the sequence variations of the two genes could be the cause for their differential expression in high and low LTG lines. Conclusion Among the 11 QTLs identified in this study, qLTG_sRDP2–10a could also be detected in other three studies using different germplasm under different cold environments. Its large effect and stable expression make qLTG_sRDP2–10a particularly valuable in rice breeding. The two genes, LOC_Os10g22484 and LOC_Os10g22520, were considered as the candidate genes underlying qLTG_sRDP2–10a. Our results suggest that integrating GWAS and SSSL can facilitate identification of QTL for complex traits in rice. The identification of qLTG_sRDP2–10a and its candidate genes provide a promising source for gene cloning of LTG and molecular breeding for LTG in rice.

FEC-LiTFSI-Pyr1ATFSI Ionic Liquid Electrolyte to Improve Low Temperature Performance of Lithium-Ion Batteries

2014 ◽  
Vol 986-987 ◽  
pp. 80-83
Author(s):  
Xiao Xue Zhang ◽  
Zhen Feng Wang ◽  
Cui Hua Li ◽  
Jian Hong Liu ◽  
Qian Ling Zhang
Keyword(s):  
Low Temperature ◽  
Lithium Ion Batteries ◽  
Low Temperatures ◽  
Freezing Point ◽  
Lithium Ion ◽  
Liquid Electrolyte ◽  
Capacity Retention ◽  
Composite Electrolyte ◽  
Ionic Liquid Electrolyte ◽  
Fluoroethylene Carbonate

N-methyl-N-allylpyrrolidinium bis (trifluoromethanesulfonyl) imide (PYR1ATFSI) with substantial supercooling behavior is synthesized to develop low temperature electrolyte for lithium-ion batteries. Additive fluoroethylene carbonate (FEC) in LiTFSI/PYR1ATFSI/EC/PC/EMC is found that it can reduce the freezing point. LiFePO4/Li coin cells with the FEC-PYR1ATFSI electrolyte exhibit good capacity retention, reversible cycling behavior at low temperatures. The good performance can be attributed to the decrease in the freezing point and the polarization of the composite electrolyte.

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