Effect of process parameters on the morphology of aluminum/copper alloy lap joints by red and blue hybrid laser welding

In order to overcome the problems of many pores,large deformation and unstable weld quality of traditional laser welded aluminumcopper alloy joints,a red-blue dual-beam laser source and a swinging laser were introduced for welding.T2 copper and 6063 aluminum thin plates were lap welded by coaxial dual-beam laser welding.The morphology of weld cross section was compared to explore the influence of process parameters on the formation of lap joints.The microstructure characteristics of the weld zone were observed and compared by optical microscope.The results show that the addition of laser beam swing can eliminate the internal pores of the weld.With the increase of the swing width,the weld depth decreases,and the weld width increases first and then decreases.The influence of welding speed on the weld cross section morphology is similar to that of swing width.With the increase of welding speed,the weld width increases first and then decreases,while the weld depth decreases all the time.This is because that the red laser is used as the main heat source to melt the base metals,with the increase of red laser power,the weld depth increases.As an auxiliary laser source,blue laser reduces the total energy consumption,consequently,the effective heat input increases and the spatter is restrained effectively.As a result,the increase of red laser power has an enhancement effect on the weld width and weld depth.When the swing width is 1.2 mm,the red laser power is 550 W,the blue laser power is 500 W,and the welding speed is 35 mm/s,the weld forming is the best.The lap joint of T2 copper and 6063 aluminum alloy thin plate can be connected stably with the hybrid of blue laser.The effect rules of laser beam swing on the weld formation were obtained,which improved the quality of the joints.

Differing responses of root morphology and physiology to nitrogen application rates and their relationships with grain yield in rice

Root morphology and physiology influence aboveground growth and yield formation in rice.However,root morphological and physiological differences among rice varieties with differing nitrogen(N)sensitivities and their relationship with grain yield are still unclear.In this study,rice varieties differing in N sensitivity over many years of experiments were used.A field experiment with multiple N rates(0,90,180,270,and 360 kg ha^(-1))was conducted to elucidate the effects of N application on root morphology,root physiology,and grain yield.A pot experiment with root excision and exogenous application of 6-benzyladenine(6-BA)at heading stage was used to further verify the above effects.The findings revealed that(1)under the same N application rate,N-insensitive varieties(NIV)had relatively large root biomass(root dry weight,length,and number).Grain yield was associated with root biomass in NIV.The oxidation activity and zeatin(Z)+zeatin riboside(ZR)contents in roots obviously and positively correlated with grain yield in N-sensitive varieties(NSV),and accounted for its higher grain yield than that of NIV at lower N application rates(90 and 180 kg ha^(-1)).(2)The root dry weight required for equal grain yield of NIV was greater than that of NSV.Excision of 1/10 and 1/8 of roots at heading stage had no discernible effect on the yield of Liangyoupeijiu(NIV),and it significantly reduced yield by 11.5%and 21.3%in Tianyouhuazhan(NSV),respectively,compared to the treatment without root excision.The decrease of filled kernels and grain weight after root excision was the primary cause for the yield reduction.Root excision and exogenous 6-BA application after root excision had little influence on the root activity of NIV.The oxidation activity and Z+ZR contents in roots of NSV decreased under root excision,and the increase in the proportion of excised roots aggravated these effects.The application of exogenous 6-BA increased the root activity of NSV and increased filled kernels and grain weight,thereby reducing yield loss after root excision.Thus,the root biomass of NIV was large,and there may be a phenomenon of"root growth redundancy."Vigorous root activity was an essential feature of NSV.Selecting rice varieties with high root activity or increasing root activity by cultivation measures could lead to higher grain yield under lower N application rates.

Responses of maize germination,root morphology and leaf trait to characteristics of lead pollution:a case study

On base of the content of Pb in the soil under different land use patterns in Lanping Lead-zinc mining area,Yunnan in southwest China,the root morphology and leaf traits of maize in different concentration Pb(20,40,60,80,100,150,200,500,1000,2000,3000 mg/L)were analyzed.The results showed that maize germination rate,germination vigor and growth index decreased with the increase of Pb concentration.The root length,surface area of maize increased by 0.21%-81.58%,8.99%-73.43%,1.50%-77.37%,respectively,under 20-500 mg/L Pb concentration.However,these parameters under 1000-3000 mg/L Pb concentration decreased by 37.86%-553.54%,44.99%-766.16%,55.99%-92.81%,respectively,and these lowest value appeared in 3000 mg/L Pb treatment.The root volume of maize increased by 4.57%-89.25%in 20-80 mg/L Pb concentration,and it decreased with the increase of Pb concentration when the Pb concentration was higher than 80 mg/L and decreased by 94.13%in 3000 mg/L Pb.The root surface area and length of 0.50-1.00 diameter class were higher than those of other diameter classes,and these value of maize under 500 mg/L Pb were higher than those of other concentrations.The length and perimeter of maize leaves with the highest value of 220.36 and 962.68 mm,respectively appeared in 60 mg/L Pb treatment.The leaf width and area of maize with the highest value of 15.68 mm and 2448.31 mm^(2),respectively,appeared in 40 mg/L Pb treatment,which indicated that the leaf traits of maize were promoted by low concentration Pb and inhibited by high concentration Pb.

Effect of Different pH-regulating Acids on Root Morphology and Yield of Lettuce in Floating Transplant System

[Objective] The aim was to investigate different effects of two pH-regulating acids on the root morphology and other physiological growth of Lactuca sativa L.in floating plug transplant system.[Method] HNO3 and H2SO4 were used to adjust pH condition of various nutrient concentrations in lettuce floating transplant system,the effect of two acid treatments on root traits of lettuce were investigated.[Result] These two acids made different effects on root system under a series of nutrient gradients.Under HNO3 treatment,the fresh weight of shoot and root were increased with growth of nutrient concentration;root preformed best when EC was 1.0 μs/cm.Under H2SO4 treatment,when EC was 0.8 μs/cm,the total root length and root surface area,projected area,root volume of lettuce were 344.8 cm,40.9 cm2,13.0 cm2,0.4 m3,respectively,which were significantly higher than those in HNO3 treatment.Compared the influences of acid treatments under same nutrient concentration,the result showed that H2SO4 treatment increased root/shoot ratio and all other root morphological characteristics;however,HNO3 treatment promoted the growth of shoot and lateral root,increased transplanting efficiency and facilitated realizing high yield after transplanted into open-field.[Conclusion] This study will provide theoretical reference for improving plug transplant technology of lettuce.

Effects of Root Cutting on Morphological Characteristics and Endogenous Hormone Levels of Quercus variabilis Seedlings

The objective of this study was to investigate the effects of root cutting stress on the dynamic changes of endogenous hormone content and growth characteristics of Quercus variabilis roots,and to explore the physiological role of endogenous hormones in regulating root-crown interactions in the short term.The morphological characteristics and endogenous hormone contents of normal roots(no root cutting,CK)and cut roots(cut by 1/3 of the length of the main root,RP)were determined by liquid chromatography,which was combined with mass spectrometry at different levels of different developmental stages.The results showed that the root growth indexes and root endogenous hormones in the RP group were superior to those in the CK group.Through comprehensive analysis of endogenous hormones,it was found that the crosstalk of IAA,JA,ABA and SA could activate the root growth defense.After the root cutting treatment,the root growth of Quercus variabilis seedlings could compensate for the inhibition of taproot growth by promoting lateral root growth.The growth and development of compensatory lateral roots contribute to the increase the total root length of plants,thus promoting the absorption of water and nutrients.It is speculated that plant hormones may be the key factors affecting their development,but this is not only related to the content of a single hormone,but more importantly,it is the interaction between various hormones.

Root Morphology and Physiology in Relation to the Yield Formation of Rice

Root system is a vital part of plant and regulates many aspects of shoot growth and development. This paper reviews how some traits of root morphology and physiology are related to the formation of grain yield in rice （Oryza sativa L.）. Higher root biomass, root oxidation activity, and cytokinin contents in roots are required for achieving more panicle number, more spikelets per panicle, greater grain-filling percentage, and higher grain yield. However, these root traits are not linearly correlated with yield components. When these traits reach very high levels, grain filling and grain yield are not necessarily enhanced. High numbers of mitochondria, Golgi bodies, and amyloplasts in root tip cells benefit root and shoot growth and yield formation. Proper crop management, such as an alternate wetting and moderate soil drying irrigation, can significantly improve ultra-structure of root tip cells, increase root length density and concentration of cytokinins in root bleedings, and consequently, increase grain-filling percentage, grain yield, and water use efficiency. Further studies are needed to investigate the mechanism underlying root-shoot and root-soil interactions for high grain yield, the roles of root-sourced hormones in regulating crop growth and development and the effects of soil moisture and nutrient management on the root architecture and physiology.

Response of root morphology, physiology and endogenous hormones in maize(Zea mays L.) to potassium deficiency

Potassium （K） deficiency is one of the major abiotic stresses which has drastically influenced maize growth and yield around the world. However, the physiological mechanism of K deficiency tolerance is not yet fully understood. To identify the differences of root morphology, physiology and endogenous hormones at different growing stages, two maize inbred lines 90-21-3 （tolerance to K deficiency） and D937 （sensitive to K deficiency） were cultivated in the long-term K fertilizer experimental pool under high potassium （＋K） and low potassium （-K） treatments. The results indicated that the root length, volume and surface area of 90-21-3 were significantly higher than those of D937 under -K treatment at different growing stages. It was noteworthy that the lateral roots of 90-21-3 were dramatically higher than those of D937 at tasselling and flowering stage under-K treatment. Meanwhile, the values of superoxide dismutase （SOD） and oxidizing force of 90-21-3 were apparently higher than those of D937, whereas malondialdehyde （MDA） content of D937 was obviously increased. Compared with ＋K treatment, the indole-3-acetic acid （IAA） content of 90-21-3 was largely increased under-K treatment, whereas it was sharply decreased in D937. On the contrary, abscisic acid （ABA） content of 90-21-3 was slightly increased, but that of D937 was significantly increased. The zeatin riboside （ZR） content of 90-21-3 was significantly decreased, while that of D937 was relatively increased. These results indicated that the endogenous hormones were stimulated in 90-21-3 to adjust lateral root development and to maintain the physiology function thereby alleviating K deficiency.

Exogenous melatonin improves cotton yield under drought stress by enhancing root development and reducing root damage

The exogenous application of melatonin by the root drenching method is an effective way to improve crop drought resistance.However,the optimal concentration of melatonin by root drenching and the physiological mechanisms underlying melatonin-induced drought tolerance in cotton(Gossypium hirsutum L.)roots remain elusive.This study determined the optimal concentration of melatonin by root drenching and explored the protective effects of melatonin on cotton roots.The results showed that 50μmol L-1 melatonin was optimal and significantly mitigated the inhibitory effect of drought on cotton seedling growth.Exogenous melatonin promoted root development in drought-stressed cotton plants by remarkably increasing the root length,projected area,surface area,volume,diameter,and biomass.Melatonin also mitigated the drought-weakened photosynthetic capacity of cotton and regulated the endogenous hormone contents by regulating the relative expression levels of hormone-synthesis genes under drought stress.Melatonin-treated cotton seedlings maintained optimal enzymatic and non-enzymatic antioxidant capacities,and produced relatively lower levels of reactive oxygen species and malondialdehyde,thus reducing the drought stress damage to cotton roots(such as mitochondrial damage).Moreover,melatonin alleviated the yield and fiber length declines caused by drought stress.Taken together,these findings show that root drenching with exogenous melatonin increases the cotton yield by enhancing root development and reducing the root damage induced by drought stress.In summary,these results provide a foundation for the application of melatonin in the field by the root drenching method.

MORPHOLOGY OF AMORPHOUS SILICA DURING ALUMINUM REACTIVE PENETRATION

The reduction of volume of silica glass during aluminum reactive penetration was observed experimentally. The liquid aluminum infiltrates easily into the cavities while the released silicon is solved in the liquid aluminum, and Al/Al2O3 composites could be obtained. The experimental results show that Al/Al2O3 composites can be transformed into Al2O3 grains by oxygen in the cavities of Al/Al2O3 composites during the longer penetration treatment. The formation of alumina is a sintering process, in which liquid aluminum, particulate alumina and oxygen play an important role. The transformtion process has shown that there is a relationship of σAl2O3-Al2O3 2O3-Al, where σAl2O3-Al2O3 is the grain boundary energy of alumina, and σAl2O3-Al is the interface energy between aluminum and alumina. The formation temperature by aluminum reactive penetration is much lower than that by sintering.

Changes of root morphology and Pb uptake by two species of Elsholtzia under Pb toxicity

Elsholtzia argyi and Elsholtzia splendens, which are Chinese endemic Pb/Zn mined and Cu mined ecotype respec- tively, were investigated on the aspect of their response to Pb toxicity in the presence or absence of EDTA addition. After 8 d’s Pb treatment, root length, root surface area and root volume of E. splendens decreased much more than those of E. argyi, and reduced considerably with increase of Pb, while no marked change was noted for root average diameter. Compared to E. argyi, length of root with diameter (D)<0.2 mm was significantly reduced for E. splendens as Pb increased. D<0.1 mm E. splendens root had cross-sectional surface area at Pb≥10 mg/L, while for E. argyi, it was at Pb≥25 mg/L. With increase of Pb, DW of E. splendens decreased much more than that of E. argyi. E. argyi exhibited much more tolerance to Pb toxicity than E. splendens. Treatment with 100 mg/L Pb plus 50 mmol/L EDTA significantly decreased the length and surface area of D≤0.2 mm root, increased the length and surface area of 0.2≤D≤0.8 mm root for the case of E. argyi, while for E. splendens, length and surface area of D<0.6 mm root reduced, as compared to 100 mg/L Pb treatment, alone. At 100 mg/L Pb, shoot Pb accumulation in E. splendens and E. argyi were 27.9 and 89.0 μg/plant DW respectively, and much more Pb was uptaken by the root and translocated to the stem of E. argyi as compared to E. splendens. Treatment of the plant with 100 mg/L Pb plus 50 mmol/L EDTA increased leaf Pb accumulation from 16.8 to 84.9 g/plant for E.splendens and from 18.8 to 52.5 g/plant for E. argyi, while both root and stem Pb pronouncedly reduced for both Elsholtzia species. The increased translocation of Pb to the leaf of E. splendens being than that of E. argyi after treatment with 100 mg/L Pb plus 50 mmol/L EDTA should be further investigated.

Root canal morphology and configuration of 123 maxillary second molars by means of micro-CT

The aim of this study was to investigate the root canal configuration, accessory canals and number of main foramina of 123 maxillary second molars by means of micro-computed tomography. The teeth were scanned and reproduced with 3D software imaging. The root canal configuration and number of main foramina were evaluated by means of a four-digit system. The morphological complexity of human maxillary second molars is depicted by the number of accessory and connecting canals. The most frequently observed root canal configurations in the mesiobuccal root were 2-2-2/2 （19.5%）, 2-2-1/1 （14.6%） and 2-1-1/1 （13.0%）. A 1-1-1/1 configuration was observed in 93.5% and in 96.7% in the distobuccal and palatal roots, respectively. The MB1 mot canal had one accessory canal （18.7%）, and 8.9% of the MB2 root canal had one or two accessory canals. The distobuccal （11.3%） and palatal （14.6%） root canals had at least one accessory canal, and connecting canals were observed in 16.3% of mesiobuccal roots. The MB1, MB2, distobuccal and palatal root canals had one main foramen in 99.2%, 43.1%, 98.4% and 99.2% of samples, respectively. In the mesiobuccal root, one accessory foramen was detected in 14.6%, two were detected in 7.3%, and three were detected in 5.7%. The distobuccal root showed one or two accessory foramina in 9.1% of samples. The root canal configuration of maxillary second molars is quite heterogeneous; the mesiobuccal root has predominantly two root canal entrances （58.4%, 1 in 41.1%） with one main foramen （54.4%）. Two main foramina were observed in 43.0%. Morphological variations, connecting and accessory canals were observed in all apical thirds.

Effects of drought stress on root morphology and spatial distribution of soybean and adzuki bean

Due to global climate change,Korea is facing severe droughts that affect the planting and early vegetative periods of upland crops.Soybean and adzuki bean are important legume crops in Korea,so it is critical to understand their adaptations to water stress.This study investigated the changes in root morphological properties in soybean and adzuki bean and quantified the findings using fractal analysis.The experiment was performed at the National Institute of Crop Science in Miryang,Korea.Soybeans and adzuki beans were planted in test boxes and grown for 30 days.The boxes were filled with bed soil with various soil moisture treatments.Root images were obtained and scanned every two days,and the root properties were characterized by root length,depth and surface area,number of roots,and fractal parameters(fractal dimension and lacunarity).Root depth,length and surface area and the number of roots increased in both crops as the soil moisture content increased.The fractal dimension and lacunarity values increased as the soil moisture content increased.These results indicated that the greater the soil moisture,the more heterogeneous the root structure.Correlation analysis of the morphological properties and fractal parameters indicated that soybean and adzuki bean had different root structure developments.Both soybean and adzuki bean were sensitive to the amount of soil moisture in the early vegetative stage.Soybean required a soil moisture content greater than 70%of the field capacity to develop a full root structure,while adzuki bean required 100%of the field capacity.These results would be useful in understanding the responses of soybean and adzuki bean to water stress and managing irrigation during cultivation.

Influence of Biochar on Nitrogen Use Efficiency and Root Morphology of Rice-Seedling in Two Contrasting Paddy Soils

Biochar may affect the root morphology and nitrogen(N)use efficiency(NUE)of rice at seedling stage,which has not been clearly verified until now.To clarify it,we conducted a pot experiment regarding to two soil types(Hydragric Anthrosol and Haplic Acrisol),two biochar application rates(0.5 wt%and 1.5 wt%)and two rice varieties(common rice var.Xiushui134 and hybrid super rice var.Zhongkejiayou12-6)meanwhile.Seedling NUE of common rice Xiuhui134 was significantly increased(p<0.05)by 78.2%in Hydragric Anthrosol and by 91.4%in Haplic Acrisol following biochar addition with 1.5 wt%.However,biochar addition exerted no influence on seedling NUE of super rice Zhongkejiayou12-6 in both soils.Overall,0.09–0.10 units higher soil pH and 105–116%higher soil NH_(4)^(+)-N were observed in Xiushui134 growing two soils with 1.5 wt%biochar.In addition,improved root morphology(including longer root length,larger root surface area,bigger root volume,and more root tips)contributed to the higher seedling NUE of Xiushui134 in two soils.The soil pH and NH_(4)^(+)-N content,also the root morphology were influenced by biochar,which though could not thoroughly explained the NUE of Zhongkejiayou12-6.In conclusion,biochar application to paddy soil changed soil pH and NH_(4)^(+)-N content,root growth,and the consequent seedling NUE of rice,which effects are relative with rice cultivar,biochar addition rate,and soil type.

Root Morphology, Plant Growth, Nitrate Accumulation and Nitrogen Metabolism of Temperate Lettuce Grown in the Tropics with Elevated Root-Zone CO2 at Different Root-Zone Temperatures

This paper investigated the effects of root-zone (RZ) CO2 concentration ([CO2]) on root morphology and growth, nitrate (NO3-) uptake and assimilation of lettuce plants at different root-zone temperatures (RZT). Elevated RZ [CO2] stimulated root development, root and shoot growth compared to ambient RZ [CO2]. The greatest increase in root growth was observed in plants grown under elevated RZ [CO2] of 50,000 ppm. However, RZ [CO2] of 10,000 ppm was sufficient to achieve the maximal leaf area and shoot productivity. Lettuce plants exhibited faster shoot and root growth at 20°C-RZT than at ambient (A)-RZT. However, under elevated RZ [CO2], the magnitude of increased growth was greater at A-RZT than at 20°C-RZT. Compared to RZ [CO2] of 360 ppm, elevated RZ [CO2] of 10,000 ppm increased NO3- accumulation and nitrate reductase activity (NRA) in both leaves and roots. NO3- concentrations of leaf and root were higher at 20°C-RZT than at A-RZT in all plants. NRA was higher in root than in leaf especially under A-RZT. The total reduced nitrogen (TRN) concentration was significantly higher in plants grown under elevated RZ [CO2] of 10,000 ppm than under ambient RZ [CO2] of 360 ppm with greater concentration in 20°C-RZT plants than in A-RZT plants. These results imply that elevated RZ [CO2] significantly affected root morphology, root and shoot growth and N metabolism of temperate lettuce with greater impacts at A-RZT than at 20°C-RZT. These findings have practical significance to vegetable production by growing the vegetable crops at cool-RZT with elevated RZ [CO2] to enhance its productivity.

Morphology control of aluminum nitride(AlN)for a novel high-temperature hydrogen sensor

Hydrogen is a promising renewable energy source for fossil-free transportation and electrical energy generation.However,leaking hydrogen in high-temperature production processes can cause an explosion,which endangers production workers and surrounding areas.To detect leaks early,we used a sensor material based on a wide bandgap aluminum nitride(AlN)that can withstand a high-temperature environment.Three unique AlN morphologies(rod-like,nest-like,and hexagonal plate-like)were synthesized by a direct nitridation method at 1400℃usingγ-AlOOH as a precursor.The gas-sensing performance shows that a hexagonal plate-like morphology exhibited p-type sensing behavior and showed good repeatability as well as the highest response(S=58.7)toward a 750 ppm leak of H2 gas at high temperature(500°C)compared with the rod-like and nest-like morphologies.Furthermore,the hexagonal plate-like morphology showed fast response and recovery times of 40 and 82 s,respectively.The surface facet of the hexagonal morphology of AlN might be energetically favorable for gas adsorption–desorption for enhanced hydrogen detection.

Root Morphology and Anatomy Affect Cadmium Translocation and Accumulation in Rice

Paddy fields contaminated with cadmium(Cd)present decreased grain yield and produce Cckcontaminated grains.Screening for low-Cd-accumulating cultivars is a useful method to reduce the amount of Cd in the grains.The present study aimed to examine the roles of the root morphology and an atomy in Cd tran slocati on and accumulati on in rice plants.Twenty・two rice cultivars were used in the first experiment,after which two cultivars[Zixiangnuo(ZXN)and Jinyou T36(JYT36)]were selected and used in subsequent experiments under hydroponic conditions.The results showed that there were significant differences in Cd concentrations in the shoots(ranging from 4 to 100 mg/kg)and the Cd translocation rates(shoot/root)(from 7%to 102%)among the 22 cultivars,and the shoot Cd concentration was significantly correlated with the Cd translocation rate of the 22 cultivars under 0.1 mg/L Cd treatment.Compared with cultivar ZXN,JYT36 had greater root Cd uptake and accumulation but lower shoot Cd accumulation and Cd translocation rate.The number of root tips per surface area of cultivar ZXN was greater than that of JYT36,while the average root diameter was lower than that of JYT36.Compared with ZXN,JYT36 had stronger apoplastic barriers,and the Casparian bands and suberin lamellae in the root endodermis and exodermis were closer to the root apex in both the control and Cd treatments,especially for suberin lamellae in the root exodermis with Cd treatments,with a differenee of 25 mm.The results also showed that,compared with ZXN,JYT36 had greater percentages of Cd bound in cell walls and intracellular Cd but lower Cd concentrations in the apoplastic fluid under the Cd treatment.The results suggested that Cd translocation,rather than root Cd uptake,is a key process that determi nes Cd accumulati on in the rice shoots.The root morphological and an atomical characteristics evidently affect Cd accumulation in the shoots by inhibiting Cd translocation,especially via the apoplastic pathway.It was possible to pre-screen low・Cd・accumulating rice cultivars on the basis of their root morphology,an atomical characteristics and Cd tran slocati on rate at the seedling stage.

Morphology of alpha-lead dioxide electrodeposited on aluminum substrate electrode

Alpha-lead dioxide was deposited by anodization of alkaline solution containing HPbO2- anions. Scanning electron microscopy (SEM) results show that the morphology is remarkably affected by the current density, concentration of HPbO2- anions, bath temperature and electroplating time. Compact and well adherent layers are possibly obtained under conditions of current densities ≤3 mA/cm2, electrolyte containing 4 mol/L NaOH and 0.12-0.14 mol/L lead (Ⅱ ), bath temperature of 40 ℃, and electroplating time of 2 h. EDS analyses show that the PbO2 deposited in alkaline condition is highly non-stoichiometric at high current density.

Genotypic variation in root morphology, cotton subtending leaf physiology and fiber quality against nitrogen

Background:Nitrogen(N)is important for improving various morphological and physiological processes of cotton but their contribution to fiber quality is still lacking.Aims:The current study aimed to explore the relationship between root morphology,subtending leaf physiology,and fiber quality of contrasting N-efficient cotton genotypes in response to N.Methods:We analyzed the above parameters of CCRI 69(N-efficient)and Xinluzao-30(XLZ-30,N-inefficient)under control(2.5 mmol·L^(-1))and high N(5 mmol·L^(-1))conditions.Results:The results showed that root morphological traits were increased in CCRI-69 under control conditions than high N.Subtending leaf morphology,chlorophyll and carotenoid contents,free amino acids,and soluble proteins were higher under high N as compared with the control.However,soluble sugars,fructose,sucrose contents,and sucrose phosphate synthase were higher under control conditions than high N across the growth stages.Irrespective of the N conditions,all morphological and physiological traits of cotton subtending leaf were higher in CCRI-69 than XLZ-30.Except for fiber uniformity,fiber quality traits like fiber length,strength,micronaire,and elongation were improved under control conditions than high N.Between the genotypes,CCRI-69 had significantly higher fiber length,strength,micronaire,and elongation as compared with XLZ-30.Strong positive correlations were found between root morphology,soluble sugars,sucrose content,and sucrose phosphate synthase activity with fiber quality traits,respectively.Conclusions:These findings suggest that CCRI-69 performed better in terms of growth and fiber quality under relatively low N condition,which will help to reduce fertilizer use,the cost of production,and environmental pollution.

Silicon Mitigates Aluminum Toxicity of Tartary Buckwheat by Regulating Antioxidant Systems

Aluminum (Al) toxicity is a considerable factor limiting crop yield and biomass in acidic soil. Tartary buckwheatgrowing in acidic soil may suffer from Al poisoning. Here, we investigated the influence of Al stress on the growthof tartary buckwheat seedling roots, and the alleviation of Al stress by silicon (Si), as has been demonstrated inmany crops. Under Al stress, root growth (total root length, primary root length, root tips, root surface area, androot volume) was significantly inhibited, and Al and malondialdehyde (MDA) accumulated in the root tips. At thesame time, catalase (CAT) and ascorbate peroxidase activities, polyphenols, flavonoids, and 1,1-diphenyl-2-picrylhydrazyl(DPPH) and 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) free-radical scavenging abilitywere significantly decreased. After the application of Si, root growth, Al accumulation, and oxidative damage wereimproved. Compared to Al-treated seedlings, the contents of ·O2− and MDA decreased by 29.39% and 25.22%,respectively. This was associated with Si-induced increases in peroxidase and CAT enzyme activity, flavonoidcompounds, and free-radical scavenging (DPPH and ABTS). The application of Si therefore has positive effectson Al toxicity in tartary buckwheat roots by reducing Al accumulation in the roots and maintaining oxidationhomeostasis.

Characterization of alpine meadow surface crack and its correlation with root-soil properties

Quantifying surface cracks in alpine meadows is a prerequisite and a key aspect in the study of grassland crack development.Crack characterization indices are crucial for the quantitative characterization of complex cracks,serving as vital factors in assessing the degree of cracking and the development morphology.So far,research on evaluating the degree of grassland degradation through crack characterization indices is rare,especially the quantitative analysis of the development of surface cracks in alpine meadows is relatively scarce.Therefore,based on the phenomenon of surface cracking during the degradation of alpine meadows in some regions of the Qinghai-Tibet Plateau,we selected the alpine meadow in the Huangcheng Mongolian Township,Menyuan Hui Autonomous County,Qinghai Province,China as the study area,used unmanned aerial vehicle(UAV)sensing technology to acquire low-altitude images of alpine meadow surface cracks at different degrees of degradation(light,medium,and heavy degradation),and analyzed the representative metrics characterizing the degree of crack development by interpreting the crack length,length density,branch angle,and burrow(rat hole)distribution density and combining them with in situ crack width and depth measurements.Finally,the correlations between the crack characterization indices and the soil and root parameters of sample plots at different degrees of degradation in the study area were analyzed using the grey relation analysis.The results revealed that with the increase of degradation,the physical and chemical properties of soil and the mechanical properties of root-soil composite changed significantly,the vegetation coverage reduced,and the root system aggregated in the surface layer of alpine meadow.As the degree of degradation increased,the fracture morphology developed from"linear"to"dendritic",and eventually to a complex and irregular"polygonal"pattern.The crack length,width,depth,and length density were identified as the crack characterization indices via analysis of variance.The results of grey relation analysis also revealed that the crack length,width,depth,and length density were all highly correlated with root length density,and as the degradation of alpine meadows intensified,the underground biomass increased dramatically,forming a dense layer of grass felt,which has a significant impact on the formation and expansion of cracks.