Influence of O-O formation pathways and charge transfer mediator on lipid bilayer membrane-like photoanodes for water oxidation

Inspired by the function of crucial components in photosystemⅡ(PSⅡ),electrochemical and dyesensitized photoelectrochemical(DSPEC)water oxidation devices were constructed by the selfassembly of well-designed amphipathic Ru(bda)-based catalysts(bda=2,2'-bipyrdine-6,6'-dicarbonoxyl acid)and aliphatic chain decorated electrode surfaces,forming lipid bilayer membrane(LBM)-like structures.The Ru(bda)catalysts on electrode-supported LBM films demonstrated remarkable water oxidation performance with different O-O formation mechanisms.However,compared to the slow charge transfer process,the O-O formation pathways did not determine the PEC water oxidation efficiency of the dyesensitized photoanodes,and the different reaction rates for similar catalysts with different catalytic paths did not determine the PEC performance of the DSPECs.Instead,charge transfer plays a decisive role in the PEC water oxidation rate.When an indolo[3,2-b]carbazole derivative was introduced between the Ru(bda)catalysts and aliphatic chain-modified photosensitizer in LBM films,serving as a charge transfer mediator for the tyrosine-histidine pair in PSⅡ,the PEC water oxidation performance of the corresponding photoanodes was dramatically enhanced.

Fate and Behavior of Tetracycline Resistance Genes in Activated Carbon Adsorption

The accessibility of tetracycline resistance gene (tetG) into the pores of activated carbon (AC), as well as the impact of the pore size distribution (PSD) of AC on the uptake capacity of tetG, were investigated using eight types of AC (four coal-based and four wood-based). AC showed the capability to admit tetG and the average reduction of tetG for coal-based and wood-based ACs at the AC dose of 1 g·L-1 was 3.12 log and 3.65 log, respectively. The uptake kinetic analysis showed that the uptake of the gene followed the pseudo-second-order kinetics reaction, and the uptake rate constant for the coal-based and wood-based ACs was in the range of 5.97 × 10-12 - 4.64 × 10-9 and 7.02 × 10-11 - 1.59 × 10-8 copies·mg-1·min-1, respectively. The uptake capacity analysis by fitting the obtained experiment data with the Freundlich isotherm model indicated that the uptake constant (KF) values were 1.71 × 103 - 8.00 × 109 (copies·g-1)1-1/n for coal-based ACs and 7.00 × 108 - 3.00 × 1010 (copies·g-1)1-1/n for wood-based ones. In addition, the correlation analysis between KF values and pore volume as well as pore surface at different pore size regions of ACs showed that relatively higher positive correlation was found for pores of 50 - 100 Å, suggesting ACs with more pores in this size region can uptake more tetG. The findings of this study are valuable as reference for optimizing the adsorption process regarding antibiotic resistance-related concerns in drinking water treatment.

Feasibility of a novel vermitechnology using vermicast as substrate for activated sludge disposal by two epigeic earthworm species

This study was conducted to investigate the feasibility of vermicomposting by using vermicast as the substrate for the stabilization of municipal activated sludge, called hereafter as direct vermistabilization, in which the pre-treatment and bulking materials required in previous practices were all omitted. For this purpose, two epigeic earthworm species, namely Eisenia foetida and Bimastus parvus, were inoculated into substrate for composting fresh dewatered activated sludge. Direct vermistabilization resulted in significant reductions in pH, TOC, C/N ratio and the content of heavy metals, as well as increases in EC, total N, total P and total K in the final vermicast. Moreover, both Eisenia foetida and Bimastus parvus showed faster growth rate and higher cocoon production. The results of this study suggest that the direct vermistabilization has the advantages of being simple, cost-effective and efficient, and can thus be used as a feasible vermicomposting approach to convert fresh dewatered activated sludge into a valuable product for agricultural use. The results also suggest that Bimastus parvus can be used as a new potential candidate for vermicomposting of municipal activated sludge.

Tuning the O–O bond formation pathways of molecular water oxidation catalysts on electrode surfaces via second coordination sphere engineering

A molecular [Ru(bda)]-type(bda = 2,2’-bipyridine-6,6’-dicarboxylate) water oxidation catalyst with 4-vinylpyridine as the axial ligand(Complex 1) was immobilized or co-immobilized with 1-(trifluoromethyl)-4-vinylbenzene(3 F) or styrene(St) blocking units on the surface of glassy carbon(GC) electrodes by electrochemical polymerization, in order to prepare the corresponding poly-1@GC, poly-1+P3 F@GC, and poly-1+PSt@GC functional electrodes. Kinetic measurements of the electrode surface reaction revealed that [Ru(bda)] triggers the O–O bond formation via(1) the radical coupling interaction between the two metallo-oxyl radicals(I2 M) in the homo-coupling polymer(poly-1), and(2) the water nucleophilic attack(WNA) pathway in poly-1+P3 F and poly-1+PSt copolymers. The comparison of the three electrodes revealed that the second coordination sphere of the water oxidation catalysts plays vital roles in stabilizing their reaction intermediates, tuning the O–O bond formation pathways and improving the water oxidation reaction kinetics without changing the first coordination structures.

Behavior of Cesium in Dam Reservior-Investigation Based on Sediment Columns

To generate information for better understanding of the behavior of cesium in relatively closed water bodies, experiments using four columns consisted of the sediment phase and the overlying water phase, together with batch sorption experiments were conducted, and the kinetics and the binding potential of cesium by sediment were investigated. Through model analysis with both the first order and the pseudo-second order reaction models, the kinetic parameters of cesium within the four columns were determined. In addition, by analyzing batch equilibrium data with both Freundlich and Langmuir isotherm models, associated sorption parameters were also generated. Comparisons of the models’ suitability for description of both kinetics and binding capacity of cesium were thus made, and the effects of pH and EC on the binding capacity were also studied.

ISSR Polymorphism Analysis of Eight F_1 Hybrids of Erianthus fulvus and Saccharum spp.

In this study, twelve primers were used for ISSR （ inter simple sequence repeat） analysis of eight F1 hybrids of Erianthu.sfulvus and sugarcane （ Saccha- rum spp. ）. The results showed that totally 133 bands were amplified, including 111 polymorphic bands, showing a polymorphic rate of 83.46%, which indicated that there are abundant genetic variations among F1 progenies derived from crossing between cultivated sugarcane and E. fu/vus. The average genetic similarity coef- ficients between F1 progenies and female parent Yacheng 89-9, F1 progenies and male parent E. fidvas were 0.67 and 0.44, respectively. UPGMA clustering result of F1 progenies showed that all the progenies were clustered with female parent, suggesting that the genetic material of female parent was predominated in F： proge- nies, which also revealed that the chromosome number of F, progenies was not directly related to the clustering results based on ISSR analysis.

Chromosomal Transmission in F_2BC_1Hybrid Progenies between Sugarcane and Erianthus fulvus

[ Objective ] This study aimed to provide a scientific basis for breeding new sugarcane varieties with hybrid progenies of Erianthus fulvus and modifying existing sugarcane cultivars. [ Method] Chromosomal slides of the F2 and F2 BC1 hybrid progenies between sugarcane and E. fu/vus （2n = 20） and those of parental materials were prepared with the wall degradation hypotonic method, to further analyze the chromosomal transmission in the F2 and F2BC1 hybrid progenies and to investigate the chromosome transmission mechanism. [ Result ] The results showed that, somatic chromosome number varied in various hybrid progenies; chromo- somes from parents were transmitted into the somatic cells of F2 hybrids in ＂2n ＋ n＂ pattern and transmitted into the somatic cells of F2BC1 hybrids in ＂n ＋ n＂ pattern. [ Conclusion ] This study provided a preliminary cytological basis for further use of these materials in sugarcane breeding.

A hybrid nickel/iron-pyromellitic acid electrocatalyst for oxygen evolution reaction

The migration of protons during the oxygen evolution reaction(OER)is a key factor that affects the performance of OER catalysts.To enhance proton transportation,we designed a catalyst based on nickel/iron-pyromellitic acid(NiFe-PMA)prepared by the electrochemical deposition method.This catalyst exhibited a low overpotential of 188 mV at a current density of 10 mA·cm^(-2),a Tafel slope of 28.2 mV·dec^(-1),and long-term stability for 30 days with a current of 50 mA·cm^(-2).We characterized the NiFe-PMA catalyst using various techniques,including Fourier transform infrared(FTIR)spectroscopy,Raman spectroscopy,X-ray photoelectron spectroscopy(XPS),X-ray absorption spectroscopy(XAS),transmission electron microscopy(TEM),scanning electron microscopy(SEM),and inductively coupled plasma-optical emission spectrometry(ICP-OES).Our results showed that NiFe-PMA contains nickel,iron atoms,and both coordinated and uncoordinated carboxylate groups.Additionally,XPS data confirmed that carboxylate ligands could adjust the outer electronic structure of metal ions,resulting in the high valence state of Ni in NiFe-PMA.The result of XAS indicated that the nickel atoms present in the catalyst might be easier to maintain a higher chemical state.Further investigations using kinetic isotope effects(KIEs)and proton inventory revealed that the uncoordinated carboxylic protons played a crucial role in receiving protons during the OER,which promoted the proton transfer of the rate-determining step of the OER.Our novel electrocatalysts provide a new strategy for designing more active and cost-effective catalysts for the OER.

Effect of Elastic Modulus on Biomechanical Properties of Lumbar Interbody Fusion Cage

This work focuses on the influence of elastic modulus on biomechanical properties of lumbar interbody fusion cages by selecting two titanium alloys with different elastic modulus. They were made by a new β type alloy with chemical composition of Ti-24Nb-4Zr-7.6Sn having low Young＇s modulus -50 GPa and by a conventional biomedical alloy Ti-6Al-4V having Young＇s modulus -110 GPa. The results showed that the designed cages with low modulus （LMC） and high modulus （HMC） can keep identical compression load -9.8 kN and endure fatigue cycles higher than 5× 10^6 without functional or mechanical failure under 2.0 kN axial compression. The anti-subsidence ability of both group cages were examined by axial compression of thoracic spine specimens （T9-T10） dissected freshly from the calf with averaged age of 6 months. The results showed that the LMC has better anti-subsidence ability than the HMC （p〈0.05）. The above results suggest that the cage with low elastic modulus has great potential for clinical applications.

Biodegradation of Natural Estrogens by Biofilms from Biological Activated Carbon: Effect of Temperature

In order to obtain information on the biodegradation potential of biofilms involved in the removal of natural estrogens by biological activated carbon (BAC) columns, batch degradation of estrone (E1) and 17β-estradiol (E2) at temperature of 5℃, 20℃ and 35℃ by biofilms from four BAC columns (packed with activated carbon of particle size ranging from 0.5 - 0.59 mm and 1.0 - 1.19 mm into two bed depths) was studied. The results indicated that E2 was degraded faster by than E1 at all three temperatures and with the increasing of temperature, the amount of E1 converted from E2 increased. By fitting observed concentration data with a first-order rate expression, the bio-mass based degradation rate constants (kVSS) for E1 and E2 under all experimental conditions were estimated and linear relationship between lnkVSS and 1/T (T = absolute temperature) was demonstrated, resulting that with the increasing of the experimental temperature, degradation rate of biofilms for both E1 and E2 increased, and the increasing rate for E2 was higher than that for E1.

Karyotype Analysis of BC_1 and BC_2 Progenies between Sugarcane and Erianthus fulvus

In this study, karyotype analysis of F2BCl progenies between sugarcane （Saccharum spp. ） and Erianthusfulvus was conducted. The result showed that most chromosomes of YAU04/14, YAU09/02, YAU09/05, YAU09/26 and YAU09/52 are median region （m） chromosomes, while only a small amount of chromosomes are submedian （sin） chromosomes and median point （M） chromosomes. The karyotype formulae of five experimental materials are 2n = 106 = 98m ＋ 8sm, 2n = 106 - 2M ＋ 104m, 2n = 106 = 4M ＋ 96m ＋ 6sin, 2n = 102 = 2M ＋ 92m ＋ 8sin and 2n = 106 = 4M ＋ 96m ＋ 6sin, respectively. The karyotypes of all materials belong to symmetrical 2B type, indicating that the chromosomes of progenies are primitive.

Karyotype Comparison of F_1 and F_2 Hybrids of Sugarcane and Erianthus fulvus

Chromosome specimens of sugarcane, Erianthus fu/vus and their progenies were prepared with wall degradation hypotonic method to analyze the karyotypes of parents and Fl, F2 hybrids. The results showed that most chromosomes of experimental materials are median region （m） chromosomes, while only a small amount of chromosomes are submedian （sm） chromosomes. The karyotype of YAU04/102 belongs to 2C type, while other materials belong to 2B type. In addition, the karyotypes of hybrids are asymmetrical and the chromosomes of hybrids show an evolutionary trend compared with parental chromosomes.

Polymeric viologen-based electron transfer mediator for improving the photoelectrochemical water splitting on Sb_(2)Se_(3) photocathode

The photogenerated charge carrier separation and transportation of inside photocathodes can greatly influence the performance of photoelectrochemical(PEC)H2 production devices.Coupling TiO_(2) with p-type semiconductors to construct heterojunction structures is one of the most widely used strategies to facilitate charge separation and transportation.However,the band position of TiO_(2) could not perfectly match with all p-type semiconductors.Here,taking antimony selenide(Sb_(2)Se_(3))as an example,a rational strategy was developed by introducing a viologen electron transfer mediator(ETM)containing polymeric film(poly-1,1′-dially-[4,4′-bipyridine]-1,1′-diium,denoted as PV^(2+))at the interface between Sb_(2)Se_(3) and TiO_(2) to regulate the energy band alignment,which could inhibit the recombination of photogenerated charge carriers of interfaces.With Pt as a catalyst,the constructed Sb_(2)Se_(3)/PV^(2+)/TiO_(2)/Pt photocathode showed a superior PEC hydrogen generation activity with a photocurrent density of−18.6 mA cm^(-2) vs.a reversible hydrogen electrode(RHE)and a half-cell solar-to-hydrogen efficiency(HC-STH)of 1.54%at 0.17 V vs.RHE,which was much better than that of the related Sb_(2)Se_(3)/TiO_(2)/Pt photocathode without PV^(2+)(−9.8 mA cm^(-2),0.51%at 0.10 V vs.RHE).

A chromosome-level genome assembly for Erianthus fulvus provides insights into its biofuel potential and facilitates breeding for improvement of sugarcane

Erianthus produces substantial biomass,exhibits a good Brix value,and shows wide environmental adaptability,making it a potential biofuel plant.In contrast to closely related sorghum and sugarcane,Erianthus can grow in degraded soils,thus releasing pressure on agricultural lands used for biofuel production.However,the lack of genomic resources for Erianthus hinders its genetic improvement,thus limiting its potential for biofuel production.In the present study,we generated a chromosome-scale reference genome for Erianthus fulvus Nees.The genome size estimated by flow cytometry was 937 Mb,and the assembled genome size was 902 Mb,covering 96.26%of the estimated genome size.A total of 35065 proteincoding genes were predicted,and 67.89%of the genome was found to be repetitive.A recent wholegenome duplication occurred approximately 74.10 million years ago in the E.fulvus genome.Phylogenetic analysis showed that E.fulvus is evolutionarily closer to S.spontaneum and diverged after S.bicolor.Three of the 10 chromosomes of E.fulvus formed through rearrangements of ancestral chromosomes.Phylogenetic reconstruction of the Saccharum complex revealed a polyphyletic origin of the complex and a sister relationship of E.fulvus with Saccharum sp.,excluding S.arundinaceum.On the basis of the four amino acid residues that provide substrate specificity,the E.fulvus SWEET proteins were classified as monoand disaccharide sugar transporters.Ortho-QTL genes identified for 10 biofuel-related traits may aid in the rapid screening of E.fulvus populations to enhance breeding programs for improved biofuel production.The results of this study provide valuable insights for breeding programs aimed at improving biofuel production in E.fulvus and enhancing sugarcane introgression programs.

Lipid-Based Poly(I:C) Adjuvants Strongly Enhance the Immunogenicity of SARS-CoV-2 Receptor-Binding Domain Vaccine

Background The outbreak of the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has greatly threatened public health.Recent studies have revealed that the spike receptor-binding domain(RBD)of SARS-CoV-2 is a potent target for vaccine development.However,adjuvants are usually required to strengthen the immunogenicity of recombinant antigens.Different types of adjuvants can elicit different immune responses.Methods We developed an RBD recombinant protein vaccine with a polyriboinosinic acid–polyribocytidylic acid[poly(I:C)]adjuvant to evoke a strong immune response.The delivery of poly(I:C)was optimized in two steps.First,poly(I:C)was complexed with a cationic polymer,poly-l-lysine(PLL),to form poly(I:C)–PLL,a polyplex core.Thereafter,it was loaded into five different lipid shells(group II,III-1,2-distearoyl-sn-glycero-3-phosphocholine[DSPC],III-1,2-dioleoyl-sn-glycero-3-phosphoethanolamine[DOPE],IV-DOPE,and IV-DSPC).We performed an enzyme-linked immunosorbent assay and enzyme-linked immunosorbent spot assay to compare the ability of the five lipopolyplex adjuvants to enhance the immunogenicity of the SARS-CoV-2 RBD protein,including humoral and cellular immune responses.Finally,the adjuvant with the highest immunogenicity was selected to verify the protective immunity of the vaccine through animal challenge experiments.Results Recombinant RBD protein has low immunogenicity.The different adjuvants we developed enhanced the immunogenicity of the RBD protein in different ways.Among the lipopolyplexes,those containing DOPE(III-DOPE and IV-DOPE)elicited RBD-specific immunoglobulin G antibody responses,and adjuvants with four components elicited better RBD-specific immunoglobulin G antibody responses than those containing three components(P<0.05).The IC50 and IC90 titers indicated that the IV-DOPE lipopolyplex had the greatest neutralization ability,with IC50 titers of 1/117,490.Furthermore,in the challenge study,IV-DOPE lipopolyplex protected mice from SARS-CoV-2 infection.On the fourth day after infection,the average animal body weights were reduced by 18.56%(24.164±0.665 g vs.19.678±0.455 g)and 0.06%(24.249±0.683 g vs.24.235±0.681 g)in the MOCK and vaccine groups,respectively.In addition,the relative expression of viral RNA in the vaccinated group was significantly lower than that in the MOCK group(P<0.05).Interstitial inflammatory cell infiltration was observed in the MOCK group,whereas no obvious damage was observed in the vaccinated group.Conclusions The IV-DOPE–adjuvanted SARS-CoV-2 recombinant RBD protein vaccine efficiently protected mice from SARS-CoV-2 in the animal challenge study.Therefore,IV-DOPE is considered an exceptional adjuvant for SARS-CoV-2 recombinant RBD protein-based vaccines and has the potential to be further developed into a SARS-CoV-2 recombinant RBD protein-based vaccine.

Role and mechanism of radiological protection cream in treating radiation dermatitis in rats

OBJECTIVE: To explore the role and mechanism of a radiation protection cream(Rp) in the treatment of radiation dermatitis, and to accumulate necessary technical information for a new drug report on Rp.METHODS: High-performance liquid chromatography was used to establish the method of measuring the main effective ingredients of sovereign and adjuvant herbs of Rp drugs, and to formulate the draft quality standards of Rp. A total of 48Sprague-Dawley male rats were randomly divided into the Model,Trolamine cream(Tc), Rp and Blank groups according to a random number table method.The skin of each rat's buttocks was irradiated using an electron linear accelerator to establish an acute radiation dermatitis model. The histological changes were observed under light microscopy and electron microscopy during wound healing and the effect of Rp on rat fibroblast Ku70/80 gene expression was detected at the transcriptional level.RESULTS: Pathological examination revealed that Rp protected the cellular and subcellular structures of skin after irradiation, promoting the proliferation and restoration of collagen fibers. Ku70/80 mRNA expression levels in the Rp and Tc groups were higher than that in the model group(P<0.05).Moreover,The majority of grade radiation dermatitis relative to the Model, Rp and Tc groups for reducing grade Ⅲ and Ⅳ dermatitis efficiency were 85.7%and 69.2%(P<0.05), respectively.The efficacy of Rp group in treating radiation dermatitis was better than the Trolamine cream group by16.5%(P<0.05).CONCLUSION: Compared with Tc, Rp had certain advantages in the efficacy and performance to price ratio.Thus, Rp is considered an effective alternative formulation for the prevention and treatment of radiation dermatitis.

Effects of irrigation and nitrogen management on hybrid maize seed production in north-west China

Scientific irrigation and nitrogen management is important for agricultural production in arid areas. To quantify the effect of water and nitrogen management on yield components, biomass partitioning and harvest index(HI) of maize for seed production with plastic filmmulching, field experiments including different irrigation and N treatments were conducted in arid north-west China in 2013 and 2014. The results indicated that kernel number per plant(KN) was signi ficantly affected by irrigation and N treatments. However, 100-kernel weight was relatively stable. Reducing irrigation quantity signi ficantly increased stem partitioning index(PI_(stem)) and leaf partitioning index(PIl_(eaf)), and decreased ear partitioning index(PI_(ear)) at harvest, but lowering Nrate(from 500 to 100 kg N$hm^(–2))did not signi ficantly reduce PI_(stem), PI leaf, andPIl_(eaf) at harvest. HI was signi ficantly reduced by reducing irrigation quantity, but not by reducing Nrate. Linear relationships were found between KN, PI_(stem), PI leaf,PIl_(eaf) at harvest and HI and evapotranspiration(ET).

Promotion of the oxygen evolution performance of Ni–Fe layered hydroxides via the introduction of a proton-transfer mediator anion

Developing efficient catalysts with high durability and activity for the oxygen evolution reaction(OER)is imperative for sustainable energy conversion technologies,including hydrogen generation and CO_(2) reduction,as well as other electrochemical energy storage systems.To this end,a comprehensive understanding of the mechanism for the water oxidation reaction is vital.Herein,a surfactant,nonafluoro-1-butanesulfonate(FBS),was introduced into Ni-Fe layered double hydroxide(Ni Fe-FBS/CFP)via electrochemical deposition on the surface of a carbon fiber paper(CFP)substrate.The as-prepared Ni Fe-FBS/CFP electrode exhibited excellent catalytic activities for OER compared to the Ni-Fe layered double hydroxide based electrode(Ni Fe-LDH/CFP),an excellent stability of 15 h,and an ultralow Tafel slope of 25.8 m V dec-1.Furthermore,by combining the results of p H-dependent kinetics investigations,chemical probing,proton inventory studies,and isotopic and atom-protontransfer measurements,it was observed that a proton-transfer process controls the reaction rates of both the Ni Fe-LDH and Ni Fe-FBS catalysts,and the residual sulfonate groups serve as proton transfer mediator to accelerate the proton transfer rate.

Switching the O-O Bond Formation Pathways of Ru-pda Water Oxidation Catalyst by Third Coordination Sphere Engineering

Water oxidation is a vital anodic reaction for renewable fuel generation via electrochemical-and photoelectrochemical-driven water splitting or CO_(2)reduction.Ruthenium complexes,such as Ru-bda family,have been shown as highly efficient wateroxidation catalysts(WOCs),particularly when they undergo a bimolecular O-O bond formation pathway.In this study,a novel Ru(pda)-type(pda^(2–)=1,10-phenanthroline-2,9-dicarboxylate)molecular WOC with 4-vinylpyridine axial ligands was immobilized on the glassy carbon electrode surface by electrochemical polymerization.Electrochemical kinetic studies revealed that this homocoupling polymer catalyzes water oxidation through a bimolecular radical coupling pathway,where interaction between two Ru(pda)–oxyl moieties(I2M)forms the O-O bond.The calculated barrier of the I2M pathway by densityfunctional theory(DFT)is significantly lower than the barrier of a water nucleophilic attack(WNA)pathway.By using this polymerization strategy,the Ru centers are brought closer in the distance,and the O-O bond formation pathway by the Ru(pda)catalyst is switched from WNA in a homogeneous molecular catalytic system to I2M in the polymerized film,providing some deep insights into the importance of third coordination sphere engineering of the water oxidation catalyst.

Alternate partial root-zone irrigation with high irrigation frequency improves root growth and reduces unproductive water loss by apple trees in arid north-west China

Alternate partial root-zone irrigation(APRI)can improve water use efficiency in arid areas. However,the effectiveness and outcomes of different frequencies of APRI on water uptake capacity and physiological water use have not been reported. A two-year field experiment was conducted with two irrigation amounts(400 and500 mm) and three irrigation methods(conventional irrigation, APRI with high and low frequencies). Root length density, stomatal conductance, photosynthetic rate,transpiration rate, leaf water use efficiency, midday stem and leaf water potentials were measured. The results show that in comparison with conventional irrigation, APRI with high frequency significantly increased root length density and decreased water potentials and stomatal conductance.No differences in the above indicators between the two APRI frequencies were detected. A significantly positive relationship between stomatal conductance and root length density was found under APRI. Overall, alternate partial root-zone irrigation with high frequency has a great potential to promote root growth, expand water uptake capacity and reduce unproductive water loss in the arid apple production area.