Effects of Bacillus subtilis Var. Natto Products on Capillary Blood Flow in Healthy Subjects with Peripheral Coldness: A Double-Blind, Placebo-Controlled, Randomized Parallel Study

Purpose: NKCP®, a natto-derived dietary food supplement whose main component is bacillopeptidase F produced by Bacillus subtilis var. natto, has antithrombotic, fibrinolytic, and pressure-lowering effects, and also is suggested to improve peripheral coldness. However, existing data are based on subjective evaluations with no scientific basis about the effects on peripheral coldness. Therefore, we aimed to investigate the effectiveness of NKCP®for peripheral coldness by measuring changes in blood flow using a laser doppler rheometer and biochemical indices. Patients and Methods: This was a double-blind, randomized, controlled study of individuals aged 30 - 70 years who complained of subjective symptoms of cold hands and feet. They were randomly divided into the NKCP®group and the placebo group to receive NKCP®250 mg once daily and dextrin 250 mg as placebo once daily, respectively. The experiment lasted 8 weeks, with an intervention period of 4 weeks and a washout period of 4 weeks. Results: One-month intake of NKCP®significantly increased blood flow rate for 1 min between 4 and 5 minutes after the end of cold loading compared to that before feeding (p = 0.038). Also, analysis of the 5-minute blood flow rate before and after 4 weeks of feeding showed a significant improvement in the NKCP®group (p = 0.007), although there was no significant difference in the placebo group (p = 0.215). Furthermore, the 5-minute blood flow at 4 weeks after the end of feeding was significantly improved compared to that before feeding in the NKCP®group (p = 0.049). Therefore, the effect continued for at least 1 month after discontinuation of administration. Conclusions: It is possible that NKCP®intake effectively improves blood flow in subjects with peripheral coldness. Therefore, continuous intake of NKCP®is expected to reduce the symptoms of peripheral coldness. In the future, it needs to investigate whether the effect of increasing blood flow after ingestion of NKCP®is effective in improving the symptoms of peripheral coldness.

Interpretation of the prevention and treatment of COVID-19 in Jiangxi based on"unified coldness and warmness"

`Since the outbreak of COVID-19,various regions have introduced their own TCM prevention and treatment methods.However,there are two opposing views on the nature of cold and temperature.Since modern times,the thought of the unification of cold and temperature has developed rapidly,and many doctors gradually realized the importance and practicability of the unification of cold and temperature,and began to advocate the unification of cold and temperature syndrome.The prevention and treatment of COVID-19 in Jiangxi was developed by Professor Wu Bingcai,a master of Chinese medicine,based on the unified idea of cold and temperature,according to the characteristics of humid climate in Jiangxi,and in combination with the characteristics of COVID-19,the anti-toxin prescription for dispelling cold and desiccating dampness and the anti-toxin prescription for clearing heat and dehumidifying,which achieved exact and satisfactory results in clinical application.

Discuss ion on the Correlation Between Yang Deficiency&Cold-dampness and Malignant Tumors Based on"Diseases producing the liquid that is clear and chill all result from coldness"

Tumor is defined as a kind of chronic diseases by the World Health Organization.The integrative traditional Chinese and western medicine works well on the treatment of tumors,even in advanced patients or patients with recurring and metastatic tumor.However,the pathogenic mechanism of tumors is still unclear.Therefore,based on the 19 th pathogenesis in Yellow Emperor's Internal Class that"Diseases producing the liquid that is clear and chill all result from coldness",the paper explore s the etiology pathogenesis of malignant tumors,and the correlation between which and tumor recurrence and metastasis,and also discusses the rules for the treatment of tumors at various stages with great method of warming yang for dispelling cold.

The UDP-glycosyltransferase OsUGT706D2 positively regulates cold and submergence stress tolerance in rice

In a genome-wide association study,we identified a rice UDP-glycosyltransferase gene,OsUGT706D2,whose transcription was activated in response to cold and submergence stress and to exogenous abscisic acid(ABA).OsUGT706D2 positively regulated the biosynthesis of tricin-4’-O-(syringyl alcohol)ether-7-O-glucoside at both the transcriptional and metabolic levels.OsUGT706D2 mediated cold and submergence tolerance by modulating the expression of stress-responsive genes as well as the abscisic acid(ABA)signaling pathway.Gain of function of OsUGT706D2 increased cold and submergence tolerance and loss of function of OsUGT706D2 reduced cold tolerance.ABA positively regulated OsUGT706D2-mediated cold tolerance but reduced submergence tolerance.These findings suggest the potential use of OsUGT706D2 for improving abiotic stress tolerance in rice.

Dietary fat supplementation relieves cold temperature-induced energy stress through AMPK-mediated mitochondrial homeostasis in pigs

Background Cold stress has negative effects on the growth and health of mammals, and has become a factor restricting livestock development at high latitudes and on plateaus. The gut-liver axis is central to energy metabolism, and the mechanisms by which it regulates host energy metabolism at cold temperatures have rarely been illustrated. In this study, we evaluated the status of glycolipid metabolism and oxidative stress in pigs based on the gut-liver axis and propose that AMP-activated protein kinase(AMPK) is a key target for alleviating energy stress at cold temperatures by dietary fat supplementation.Results Dietary fat supplementation alleviated the negative effects of cold temperatures on growth performance and digestive enzymes, while hormonal homeostasis was also restored. Moreover, cold temperature exposure increased glucose transport in the jejunum. In contrast, we observed abnormalities in lipid metabolism, which was characterized by the accumulation of bile acids in the ileum and plasma. In addition, the results of the ileal metabolomic analysis were consistent with the energy metabolism measurements in the jejunum, and dietary fat supplementation increased the activity of the mitochondrial respiratory chain and lipid metabolism. As the central nexus of energy metabolism, the state of glycolipid metabolism and oxidative stress in the liver are inconsistent with that in the small intestine. Specifically, we found that cold temperature exposure increased glucose transport in the liver, which fully validates the idea that hormones can act on the liver to regulate glucose output. Additionally, dietary fat supplementation inhibited glucose transport and glycolysis, but increased gluconeogenesis, bile acid cycling, and lipid metabolism. Sustained activation of AMPK, which an energy receptor and regulator, leads to oxidative stress and apoptosis in the liver;dietary fat supplementation alleviates energy stress by reducing AMPK phosphorylation.Conclusions Cold stress reduced the growth performance and aggravated glycolipid metabolism disorders and oxidative stress damage in pigs. Dietary fat supplementation improved growth performance and alleviated cold temperature-induced energy stress through AMPK-mediated mitochondrial homeostasis. In this study, we high-light the importance of AMPK in dietary fat supplementation-mediated alleviation of host energy stress in response to environmental changes.

Frontogenesis and Frontolysis of a Cold Filament Driven by the Cross-Filament Wind and Wave Fields Simulated by a Large Eddy Simulation

The variations of the frontogenetic trend of a cold filament induced by the cross-filament wind and wave fields are studied by a non-hydrostatic large eddy simulation. Five cases with different strengths of wind and wave fields are studied.The results show that the intense wind and wave fields further break the symmetries of submesoscale flow fields and suppress the levels of filament frontogenesis. The changes of secondary circulation directions—that is, the conversion between the convergence and divergence of the surface cross-filament currents with the downwelling and upwelling jets in the filament center—are associated with the inertial oscillation. The filament frontogenesis and frontolysis caused by the changes of secondary circulation directions may periodically sharpen and smooth the gradient of submesoscale flow fields.The lifecycle of the cold filament may include multiple stages of filament frontogenesis and frontolysis.

Transcription factor CabHLH035 promotes cold resistance and homeostasis of reactive oxygen species in pepper

Plant basic helix-loop-helix(bHLH)transcription factors(TFs)play central roles in various abiotic stresses.However,its role in plant cold resistance is largely unknown.Previously,we characterised CaNAC035 in pepper,which positively regulates tolerance to cold,salt and drought stresses tolerance.Here,we identified CabHLH035,a CaNAC035-interacting protein in pepper.To explore its functions in cold stress tolerance,we silenced the gene in pepper via virus-induced gene silencing(VIGS)and overexpressed the gene in Arabidopsis.The results showed that CabHLH035 expression was induced by cold treatment,and silencing of CabHLH035 decreased cold stress tolerance.Conversely,overexpression of CabHLH035 in Arabidopsis increased cold stress tolerance.To investigate homologs genes of C-repeat binding factor(CBF)pathway proteins and reactive oxygen species(ROS)marker gene expression blocking by CabHLH035,we performed yeast one-hybrid(Y1H),dual luciferase and electrophoretic mobility shift assay experiments.The results showed that CabHLH035 bound to the region upstream of the CaCBF1A and CaAPX promoters.Additionally,CaCBF1A bound to the CaDHN4 promoter.Taken together,our results showed that CabHLH035 plays a crucial role in cold stress tolerance and its potential as a target for breeding cold-resistant crops.The findings provide a basis for studying the functions and regulatory network of cold stress tolerance in pepper.

Heterogeneous expression of stearoyl-acyl carrier protein desaturase genes SAD1 and SAD2 from Linum usitatissimum enhances seed oleic acid accumulation and seedling cold and drought tolerance in Brassica napus

Flax(Linum usitatissimum L.)is a versatile crop and its seeds are a major source of unsaturated fatty acids.Stearoyl-acyl carrier protein desaturase(SAD)is a dehydrogenase enzyme that plays a key role in oleic acid biosynthesis as well as responses to biotic and abiotic stresses.However,the function of SAD orthologs from L.usitatissimum has not been assessed.Here,we found that two LuSAD genes,LuSAD1 and LuSAD2,are present in the genome of L.usitatissimum cultivar‘Longya 10’.Heterogeneous expression of either LuSAD1 or LuSAD2 in Arabidopsis thaliana resulted in higher contents of total fatty acids and oleic acid in the seeds.Interestingly,ectopic expression of LuSAD2 in A.thaliana caused altered plant architecture.Similarly,the overexpression of either LuSAD1 or LuSAD2 in Brassica napus also resulted in increased contents of total fatty acids and oleic acid in the seeds.Furthermore,we demonstrated that either LuSAD1 or LuSAD2 enhances seedling resistance to cold and drought stresses by improving antioxidant enzyme activity and nonenzymatic antioxidant levels,as well as reducing membrane damage.These findings not only broaden our knowledge of the LuSAD functions in plants,but also offer promising targets for improving the quantity and quality of oil,and the abiotic stress tolerance of oil-producing crops,through molecular manipulation.

MIR1868 negatively regulates rice cold tolerance at both the seedling and booting stages

Low temperature causes rice yield losses of up to 30%–40%,therefore increasing its cold tolerance is a breeding target.Few genes in rice are reported to confer cold tolerance at both the vegetative and reproductive stages.This study revealed a rice-specific 24-nt miRNA,miR1868,whose accumulation was suppressed by cold stress.Knockdown of MIR1868 increased seedling survival,pollen fertility,seed setting,and grain yield under cold stress,whereas its overexpression conferred the opposite phenotype.Knockdown of MIR1868 increased reactive oxygen species(ROS)scavenging and soluble sugar content under cold stress by increasing the expression of peroxidase genes and sugar metabolism genes,and its overexpression produced the opposite effect.Thus,MIR1868 negatively regulated rice cold tolerance via ROS scavenging and sugar accumulation.

Artificial ground freezing of underground mines in cold regions using thermosyphons with air insulation

Current practice of underground artificial ground freezing(AGF)typically involves huge refrigeration systems of large economic and environmental costs.In this study,a novel AGF technique is proposed deploying available cold wind in cold regions.This is achieved by a static heat transfer device called thermosyphon equipped with an air insulation layer.A refrigeration unit can be optionally integrated to meet additional cooling requirements.The introduction of air insulation isolates the thermosyphon from ground zones where freezing is not needed,resulting in:(1)steering the cooling resources(cold wind or refrigeration)towards zones of interest;and(2)minimizing refrigeration load.This design is demonstrated using well-validated mathematical models from our previous work based on two-phase enthalpy method of the ground coupled with a thermal resistance network for the thermosyphon.Two Canadian mines are considered:the Cigar Lake Mine and the Giant Mine.The results show that our proposed design can speed the freezing time by 30%at the Giant Mine and by two months at the Cigar Lake Mine.Further,a cooling load of 2.4 GWh can be saved at the Cigar Lake Mine.Overall,this study provides mining practitioners with sustainable solutions of underground AGF.

Avian responses to an extreme weather event:The case of the‘Filomena’snowstorm in Madrid(central Spain)

Cold spells and severe weather may have detrimental effects in wild birds,but owing to the stochastic nature of these events,it is not always possible to measure their impacts.In January 2021,a strong snowstorm known as‘Filomena’affected Spain,mainly the region of Madrid(Central Spain),which was fully covered with snow and suffered freezing temperatures for a fortnight.Using bird surveys conducted in the winter-spring of 2020 and 2021(before and after Filomena)at same locations,we addressed the possible impact of the cold spell in three widespread gamebirds:Wood Pigeon(Columba palumbus),Eurasian Magpie(Pica pica)and Red-legged Partridge(Alectoris rufa).No significant abundance differences were found between years for none of the species and hunting pressure was only significantly reduced for Partridges,hence this species may have been negatively affected by Filomena.Results suggest that in response to Filomena,Pigeons conducted partial migration in search of better conditions,while Magpies aggregated in certain areas of Madrid and Partridges endured the harsh conditions within their home ranges.Our results highlight the importance to alleviate negative impacts of extreme weather events in wild birds through management actions,especially for sedentary species.

Melatonin mitigates cold-induced damage to pepper seedlings by promoting redox homeostasis and regulating antioxidant profiling

This study assessed the influence of exogenous ME in the mitigation of cold damage in pepper seedlings. Melatonin(ME) is a dynamic molecule that helps plants cope with stress in several ways. Cold stress(CS) is one of the most important environmental factors that restrict plant growth and yield. Pepper(Capsicum annuum L.) is a valuable commercial crop, highly sensitive to CS. Thus, identifying an efficient strategy to mitigate cold damage is critical for long-term pepper production. For this purpose, the roots of pepper seedlings were pretreated with ME(5 μmol · L^(-1)) and exposed to CS for 7 d. The results indicated that CS suppressed pepper growth, hampered photosynthetic capacity, and damaged root architecture in pepper plants. In contrast, the production of reactive oxygen species(ROS), malondialdehyde(MDA), electrolyte leakage(EL), proline, and soluble sugars were enhanced in plants under CS. ME(5 μmol · L^(-1)) pretreatment reduced the negative effects of CS by recovering plant growth, root traits, gas exchange elements, and pigment molecules compared to CS control treatment. Furthermore, ME application efficiently reduced oxidative stress markers [hydrogen peroxide(H_(2)O_(2)), superoxide ion(O_(2)^(·-)), EL, and MDA] while increasing proline and soluble sugar content in pepper leaves. ME application combined with CS further increased antioxidant enzymes and related gene expression. Collectively, our results confirmed the mitigating potential of ME supplementation for CS by maintaining pepper seedling growth,improving the photosynthesis apparatus, regulating pigments, and osmolyte content.

Long-term thinning decreases the contribution of heterotrophic respiration to soil respiration in subalpine plantations

Interest in the dynamics of soil respiration(R_(S))in subalpine forest ecosystems is increasing due to their high soil carbon density and potential sensitivity to environmental changes.However,as a principal silvicultural practice,the long-term impacts of thinning on R_(S) and its heterotrophic and autotrophic respiration components(R_(h) and Ra,respectively)in subalpine plantations are poorly understood,espe-cially in winter.A 3-year field observation was carried out with consideration of winter CO_(2) efflux in middle-aged sub-alpine spruce plantations in northwestern China.A trench-ing method was used to explore the long-term impacts of thinning on Rs,Rn and R_(a).Seventeen years after thinning,mean annual Rs,Rn and R_(a) increased,while the contribu-tion of R_(h) to R_(s) decreased with thinning intensity.Thinning significantly decreased winter R,because of the reduction in R_(n) but had no significant effect on Ra.The temperature sensitivity(Q_(10))of R_(h) and R_(a) also increased with thinning intensity,with lower Q_(10) values for R_(h)(2.1-2.6)than for Ra(2.4-2.8).The results revealed the explanatory variables and pathways related to R_(n) and R_(a) dynamics.Thinning increased soil moisture and nitrate nitrogen(NO_(3)^(-)-N),and the enhanced nitrogen and water availability promoted R_(h) and R_(a) by improving fine root biomass and microbial activity.Our results highlight the positive roles of NO_(3)^(-)-N in stimulating R_(s) components following long-term thinning.Therefore,applications of nitrogen fertilizer are not recommended while thinning subalpine spruce plantations from the perspective of reducing soil CO_(2) emissions.The increased Q_(10) values of R_(s) components indicate that a large increase in soil CO_(2) emissions would be expected following thinning because of more pronounced climate warming in alpineregions.

Local Torrential Rainfall Event within a Mei-Yu Season Mesoscale Convective System:Importance of Back-Building Processes

An extreme rainfall event occurred over Hangzhou,China,during the afternoon hours on 24 June 2013.This event occurred under suitable synoptic conditions and the maximum 4-h cumulative rainfall amount was over 150 mm.This rainfall event had two major rainbands.One was caused by a quasi-stationary convective line,and the other by a backbuilding convective line related to the interaction of the outflow boundary from the first rainband and an existing low-level mesoscale convergence line associated with a mei-yu frontal system.The rainfall event lasted 4 h,while the back-building process occurred in 2 h when the extreme rainfall center formed.So far,few studies have examined the back-building processes in the mei-yu season that are caused by the interaction of a mesoscale convergence line and a convective cold pool.The two rainbands are successfully reproduced by the Weather Research and Forecasting(WRF)model with fourlevel,two-way interactive nesting.In the model,new cells repeatedly occur at the west side of older cells,and the backbuilding process occurs in an environment with large CAPE,a low LFC,and plenty of water vapor.Outflows from older cells enhance the low-level convergence that forces new cells.High precipitation efficiency of the back-building training cells leads to accumulated precipitation of over 150 mm.Sensitivity experiments without evaporation of rainwater show that the convective cold pool plays an important role in the organization of the back-building process in the current extreme precipitation case.

Design and implementation of the monochromator shielding for the cold neutron spectrometers XINGZHI and BOYA

An innovative monochromator shielding is designed and implemented for the cold neutron spectrometers XINGZHI and BOYA operated by Renmin University of China at China Advanced Research Reactor.Via Monte Carlo simulations and careful mechanical designs,a shielding configuration has been successfully developed to satisfy safety requirements of below 3μSv/h dose rate at its exterior,meanwhile fulfilling space,floor load and nonmagnetic requirements.Composite materials are utilized to form the sandwich-type shielding walls:the inner layer of boron carbide rubber,the middle layer of steel-encased lead and the outer layer of borated polyethylene.Special-shaped liftable shielding blocks are incorporated to facilitate a continuous adjustment of the neutron energy while preventing radiation leakage.Our work has demonstrated that by utilizing composite shielding materials,along with the sandwich structure and liftable shielding blocks,a compact and lightweight shielding solution can be achieved.This enables the realization of advanced neutron scattering instruments that provide expanded space of measurement,larger energy and momentum coverage,and higher flux on the sample.This shielding represents the first of its kind in neutron scattering instruments in China.Following its successful operation,it has been subsequently employed by other neutron instruments across the country.

Characteristics and Mechanisms of Persistent Wet–Cold Events with Different Cold-air Paths in South China

We investigate the characteristics and mechanisms of persistent wet–cold events(PWCEs)with different types of coldair paths.Results show that the cumulative single-station frequency of the PWCEs in the western part of South China is higher than that in the eastern part.The pattern of single-station frequency of the PWCEs are“Yangtze River(YR)uniform”and“east–west inverse”.The YR uniform pattern is the dominant mode,so we focus on this pattern.The cold-air paths for PWCEs of the YR uniform pattern are divided into three types—namely,the west,northwest and north types—among which the west type accounts for the largest proportion.The differences in atmospheric circulation of the PWCEs under the three types of paths are obvious.The thermal inversion layer in the lower troposphere is favorable for precipitation during the PWCEs.The positive water vapor budget for the three types of PWCEs mainly appears at the southern boundary.

LPCS Ni-Zn-Al_(2)O_(3) Intermediate Layer Enhanced SPS NiCr-Cr_(3)C_(2) Coating with Higher Corrosion and Wear Resistances

The double-layer NiCr-Cr_(3)C_(2)/Ni-Zn-Al_(2)O_(3) coatings with sufficient corrosion and wear resistance were prepared on low carbon steel substrates.The intermediate layers Ni-Zn-Al_(2)O_(3) were fabricated by using low-pressure cold spray (LPCS) method to improve the salt fog corrosion resistance properties of the supersonic plasma spray (SPS) NiCr-Cr_(3)C_(2) coatings.The friction and wear performance for the double-layer and single-layer NiCr-Cr_(3)C_(2) coatings were carried out by line-contact reciprocating sliding,respectively.Combined with the coating surface analysis techniques,the effect of the salt fog corrosion on the tribological properties of the double-layer coatings was studied.The results showed that the double-layer coatings exhibited better wear resistance than that of the single-layer coatings,due to the better corrosion resistance of the intermediate layer;the wear mass losses of the double-layer coatings was reduced by 70%than that of the single layer coatings and the wear mechanism of coatings after salt fog corrosion conditions is mainly corrosion wear.

Evolution Mechanism of a Severe Squall Line Triggered by the Coupling of a Sea Breeze Front and a Gust Front

In the present study, a severe squall line(SL) was analyzed by using intensive observational surface data and radar monitoring products. In this process, mesoscale convergence lines, such as the sea breeze front(SBF), gust front and dry line, served as the main triggering and strengthening factors. The transition from convection triggering to the formation of the initial shape was mainly affected by the convergence line of the SBF, which combined with thermal convection to form the main parts of the SL. In the later stage, the convergence line of the gust front merged with other convergence lines to form a series of strong convective cells. The SBF had good indicative significance in terms of severe convective weather warnings. The suitable conditions of heat, water vapor and vertical wind shear on the Shandong Peninsula were beneficial to the maintenance of the SL. Before SL occurrence, tropopause folding strengthened, which consequently enhanced the baroclinic property in the middle and upper troposphere. The high sensible heat flux at the surface easily produced a positive potential vorticity anomaly in the low layer, resulting in convective instability, which was conducive to the maintenance of these processes. In the system, when precipitation particles passed through the unsaturated air layer, they underwent strong evaporation, melting or sublimation, and the cooling effect formed negative buoyancy, which accelerated the sinking of the air and promoted the sustained development of the surface gale. Together with the development of lowlevel mesocyclones, the air pressure decreased rapidly, which was conducive to gale initiation.

Therapeutic effect of San Bi Tang combined with glucosamine sulfate capsules in cold-dampness-type knee osteoarthritis

BACKGROUND Cold-dampness-type knee osteoarthritis is a common middle-aged and elderly disease,but its pathogenesis is not fully understood,and its clinical treatment has limitations.Glucosamine sulfate capsules are commonly used for treating arthritis,and San Bi Tang is a classic formula of traditional Chinese medicine(TCM)that has the effects of warming yang,dispelling dampness,relaxing muscles,and activating collaterals.This research hypothesized that the combination of modified San Bi Tang and glucosamine sulfate capsules could enhance the clinical efficacy of treating cold-dampness-type knee osteoarthritis through complementary effects.AIM To analyze the clinical efficacy of San Bi Tang combined with glucosamine sulfate capsules when treating cold-dampness-type knee osteoarthritis.METHODS A total of 110 patients with cold-dampness-type knee osteoarthritis were selected as research subjects and randomly divided into a control group and an experimental group of 55 cases each.The control group received only treatment with glucosamine sulfate capsules,while the experimental group received additional treatment with modified San Bi Tang for a duration of 5 wk.The patients’knee joint functions,liver and kidney function indicators,adverse reactions,and vital signs were evaluated and analyzed using SPSS 26.0 software.RESULTS Before treatment,the two groups’genders,ages,and scores were not significantly different,indicating comparability.Both groups’scores improved after treatment,which could indicate pain and knee joint function improvement,but the test group had better scores.The TCM-specific symptoms and the clinical efficacy of the treatment in the test group were higher.Before and after treatment,there were no abnormalities in the patients’liver and kidney function indicators.CONCLUSION The combination of modified San Bi Tang and glucosamine sulfate capsules is superior to treatment with sulfated glucosamine alone and has high safety.

Effects of Silicon Formulations on Cold Tolerance of Rice Seedlings

To investigate the effects of silicon formulations on the cold tolerance of rice seedlings,Song Japonica 16(not cold tolerant)and Dongnong 427(cold tolerant)rice varieties were used as test materials and four different types of silicon formulations,Si-50-G,Si-60-G,Si-T-G,and Si-E-G,were applied as foliar sprays at the seedling stage,and a control group CK(equal amount of distilled water)was set up.One week after the first silicon spray,two types of rice were subjected to low-temperature stress treatments at day/night temperatures of 12℃/10℃for 2,4,6,and 8 days.The effects of different silicon formulations on the chlorophyll,proline(Pro)and soluble sugar contents as well as superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)activities of rice seedlings under low-temperature stress were compared to find out the effects of silicon formulations on the cold tolerance of rice seedlings.The results showed that silicon formulations could significantly increase the chlorophyll content of rice seedling leaves,with Si-50-G being the most effective,with a significant increment of 40.17%compared to the CK at 2 days of low temperature.Four silicon formulations significantly increased the proline content and soluble sugar content of rice leaves at low temperature for 4-8 days.For Song Japonica 16,the most significant increment in leaf POD activity was observed in Si-E-G treatment at 2,4 and 8 days of temperature stress,with 73.58%,20.95%and 217.24%increases compared to the CK,respectively.For 4 and 6 days of temperature stress,the most significant increase in CAT activity was observed in Si-E-G treatment,with 25.70%and 75.78%increases compared to the CK,respectively.For Dongnong 427,the Si-60-G treatment showed the highest increase in leaf SOD activity for 4 and 8 days of temperature stress,with significant increases of 58.15%and 82.76%compared to the CK,respectively,and the Si-E-G treatment showed the highest increase in leaf POD activity for 2 and 8 days of temperature stress,with significant increases of 97.75%and 245.10%compared to the CK,respectively.It showed that the spraying of silicon formulations could significantly enhance the cold tolerance of rice.This study provided a scientific basis for the rational use of silicon formulations to enhance cold tolerance in rice and had important theoretical and practical significance for ensuring sustainable high and stable rice yields in Heilongjiang Province,as well as for the development of silicon fertilizers.