Effect of Metal Elements on Microstructure and Mechanical Properties of Ultrafine Cemented Carbide Prepared by SPS.

To satisfy the needs of precision machining, ultrafine tungsten carbide (WC)-based cemented carbide with fine grain size and excellent mechanical properties was prepared. Ultrafine cemented carbide was prepared by spark plasma sintering (SPS) using WC, Co as raw materials and metal elements V, and Cr as additives, and the effects of metal elements on the microstructure and mechanical properties of cemented carbide were investigated. The results show that the specimen (91.6WC-1.2V-1.2Cr-6Co) prepared at 1350 °C, 6 min, 25 MPa has the best mechanical properties (HV 2322.9, KIC 8.7 MPa·m1/2) and homogeneous microstructure. The metal elements could react with WC to form a (W, V, Cr) Cx segregation layer, which effectively inhibits the growth of WC grains (300 nm). The combination of SPS and metal element additives provides a new approach for the preparation of ultrafine cemented carbides with excellent properties.

Propyrisulfuron plus cyhalofop butyl as one-shot herbicides provide high weed control efficiency and net economic performance in mechanically transplanted rice.

Propyrisulfuron is a novel pyrimidinylsulfonylurea herbicide with good activity for controlling annual weed in rice fields. To evaluate the economic performance of propyrisulfuron, a field study was conducted in 2021 and 2022 on a farm of the Jiangsu Academy of Agricultural Sciences, China. Eight different herbicide treatments were employed, including CB (cyhalofop butyl), Py (propyrisulfuron), CBPy (cyhalofop butyl plus propyrisulfuron), PrBe 3, PrBe 10, and PrBe 3+PrBe 10 (pretilachlor plus bensulfuron applied at different times [at 3 (PrBe 3) and 10 (PrBe 10) d] or sequentially, respectively), 2PrBe+PeCBBz (pretilachlor plus bensulfuron [applied sequentially] followed by penoxsulam plus cyhalofop butyl plus bentazone), 2PrBe+MeCBBz (pretilachlor plus bensulfuron [applied sequentially] followed by metamifop plus cyhalofop butyl plus bentazone), along with weed-free and nontreated weedy check treatments. Herbicide treatments did not cause visual phytotoxicity to rice, and bending and leaf rolling were not observed. Only the two propyrisulfuron treatments had temporary negative effects on rice height, but rice recovered quickly. Compared with the weed-free treatment, CBPy did not affect rice tiller number or dry matter accumulation. Compared with the nontreated weedy check, herbicide treatments reduced total weed density by 29.4% to 99.1% and dry biomass by 32.2% to 98.7%. The CBPy treatment provided the best weed control, reducing weed density and biomass by 96.7% and 95.9% in 2021 and 97.4% and 95.6% in 2022, respectively. Rice grain yield was not significantly different between CBPy and the weed-free treatment in either year. Economic analysis showed that CBPy provided the highest net profit, followed by that in 2PrBe+PeCBBz and 2PrBe+MeCBBz, with the lowest net profit in the nontreated weedy check. Thus, CBPy provides good weed control and could be promoted in mechanically transplanted rice fields in China.

Triose phosphate utilization in leaves is modulated by whole-plant sink-source ratios and nitrogen budgets in rice.

Triose phosphate utilization (TPU) is a biochemical process indicating carbon sink-source (im)balance within leaves. When TPU limits leaf photosynthesis, photorespiration-associated amino acid exports probably provide an additional carbon outlet and increase leaf CO2 uptake. However, whether TPU is modulated by whole-plant sink-source relations and nitrogen (N) budgets remains unclear. We address this question by model analyses of gas-exchange data measured on leaves at three growth stages of rice plants grown at two N levels. Sink-source ratio was manipulated by panicle pruning, by using yellower-leaf variant genotypes, and by measuring photosynthesis on adaxial and abaxial leaf sides. Across all these treatments, higher leaf N content resulted in the occurrence of TPU limitation at lower intercellular CO2 concentrations. Photorespiration-associated amino acid export was greater in high-N leaves, but was smaller in yellower-leaf genotypes, panicle-pruned plants, and for abaxial measurement. The feedback inhibition of panicle pruning on rates of TPU was not always observed, presumably because panicle pruning blocked N remobilization from leaves to grains and the increased leaf N content masked feedback inhibition. The leaf-level TPU limitation was thus modulated by whole-plant sink-source relations and N budgets during rice grain filling, suggesting a close link between within-leaf and whole-plant sink limitations.

Discrete frequency-bin entanglement generation via cascaded second-order nonlinear processes in Sagnac interferometer.

Discrete frequency-bin entanglement is an essential resource for applications in quantum information processing. In this Letter, we propose and demonstrate a scheme to generate discrete frequency-bin entanglement with a single piece of periodically poled lithium niobate waveguide in a modified Sagnac interferometer. Correlated two-photon states in both directions of the Sagnac interferometer are generated through cascaded second-order optical nonlinear processes. A relative phase difference between the two states is introduced by changing the polarization state of pump light, thus manipulating the two-photon state at the output of the Sagnac interferometer. The generated two-photon state is sent into a fiber polarization splitter, and then a pure discrete frequency-bin entangled two-photon state is obtained by setting the pump light. The frequency entanglement property is measured by a spatial quantum beating with a visibility of 96.0±6.1%. The density matrix is further obtained with a fidelity of 98.0±3.0% to the ideal state. Our demonstration provides a promising method for the generation of pure discrete frequency-bin entanglement at the telecom band, which is desired in quantum photonics.

Hertz-rate metropolitan quantum teleportation.

Quantum teleportation can transfer an unknown quantum state between distant quantum nodes, which holds great promise in enabling large-scale quantum networks. To advance the full potential of quantum teleportation, quantum states must be faithfully transferred at a high rate over long distance. Despite recent impressive advances, a high-rate quantum teleportation system across metropolitan fiber networks is extremely desired. Here, we demonstrate a quantum teleportation system which transfers quantum states carried by independent photons at a rate of 7.1 ± 0.4 Hz over 64-km-long fiber channel. An average single-photon fidelity of ≥90.6 ± 2.6% is achieved, which exceeds the maximum fidelity of 2/3 in classical regime. Our result marks an important milestone towards quantum networks and opens the door to exploring quantum entanglement based informatic applications for the future quantum internet.

A SmNiO3 memristor with artificial synapse function properties and the implementation of Boolean logic circuits.

Recently, with the improvement of the requirements for fast and efficient data processing in the era of artificial intelligence, new forms of computing have come into being. Developing memristor devices that can simulate the brain's computing neutral network is particularly important for applications in the field of artificial intelligence. However, there are still some challenges in their biological function simulation and related circuit design. In this work, a memristor based on perovskite rare earth nickelates (RNiO3) is presented with excellent electrical performance, including three orders of magnitude higher current switching ratio and good repeatability, and can achieve bidirectional conductance regulation like weight modulation in bio-synapse. Furthermore, the synaptic like characteristics of the device have been mimicked successfully, such as excitatory postsynaptic current (EPSC), paired pulse facilitation (PPF), classical double pulse spike time-dependent plasticity (classical pair-STDP), triplet spike time-dependent plasticity (triplet-STDP), short-term plasticity (STP), long-term plasticity (LTP), the refractory period phenomenon and learning and forgetting rules. In particular, two synaptic devices and a leaky integrate-and-fire (LIF) neuron device are used to achieve a logic gate circuit to realize "AND", "OR", and "NOT" functions. The device paves the way for the application of high-density circuits in artificial intelligence.

Mechanism of metamifop resistance in Digitaria ciliaris var. chrysoblephara from Jiangsu, China.

Digitaria ciliaris var. chrysoblephara is one of the most competitive and problematic grass weeds in China. Metamifop is an aryloxyphenoxypropionate (APP) herbicide that inhibits the activity of acetyl-CoA carboxylase (ACCase) of sensitive weeds. Following the introduction of metamifop to China in 2010, it has been continuously used in rice paddy fields, thereby substantially increasing selective pressure for resistant D. ciliaris var. chrysoblephara variants. Here, populations of D. ciliaris var. chrysoblephara (JYX-8, JTX-98, and JTX-99) were observed to be highly resistant to metamifop, with resistance index (RI) values of 30.64, 14.38, and 23.19, respectively. Comparison of resistant and sensitive population ACCase gene sequences revealed that a single nucleotide substitution from TGG to TGC resulted in an amino acid substitution from tryptophan to cysteine at position 2,027 in the JYX-8 population. No corresponding substitution was observed for JTX-98 and JTX-99 populations. The ACCase cDNA of D. ciliaris var. chrysoblephara was successfully obtained by PCR and RACE methods, representing the first amplification of full length ACCase cDNA from Digitaria spp. Investigation of the relative expressions of ACCase gene revealed the lack of significant differences between sensitive and resistant populations before and after herbicide treatments. ACCase activities in resistant populations were less inhibited than in sensitive populations and recovered to the same or even higher levels compared to untreated plants. Whole-plant bioassays were also conducted to assess resistance to other ACCase inhibitors, acetolactate synthase (ALS) inhibitors, auxin mimic herbicide, and protoporphyrinogen oxidase (PPO) inhibitor. Cross-resistance and some multi-resistance were observed in the metamifop-resistant populations. This study is the first to focus on the herbicide resistance of D. ciliaris var. chrysoblephara. These results provide evidence for a target-site resistance mechanism in metamifop-resistant D. ciliaris var. chrysoblephara, while providing a better understanding of cross- and multi-resistance characteristics of resistant populations that will help in the management of herbicide-resistant D. ciliaris var. chrysoblephara.

Experimental study on co-culture of DiI-labeled rat bone marrow mesenchymal stem cells and neonatal rat cardiomyocytes to induce differentiation into cardiomyocyte-like cells.

BACKGROUND: Myocardial infarction is a serious clinical disease with high mortality and poor prognosis. Cardiomyocytes (CMs) have limited regeneration abilities after ischemic injury. Their growth and differentiation can be enhanced by contact co-culture with stem cells. OBJECTIVE: The aim was to study the contact co-culture of Dil-labeled bone marrow mesenchymal stem cells (BMSCs) and CMs for inducing differentiation of CMs from stem cells for treating myocardial infarction. METHODS: After contact co-culture, the differentiation of BMSCs into CMs was analyzed qualitatively by detecting myocardial markers (cardiac troponin T and α-smooth muscle actin) using immunofluorescence and quantitatively using flow cytometry. To examine the mechanism, possible gap junctions between BMSCs and CMs were analyzed by detecting gap junction protein connexin 43 (C×43) expression in BMSCs using immunofluorescence. The functionality of gap junctions was analyzed using dye transfer experiments. RESULTS: The results revealed that BMSCs in contact with CMs exhibited myocardial markers and a significant increase in differentiation rate (P < 0.05); they also proved the existence and function of gap junctions between BMSCs and CMs. CONCLUSIONS: It was shown that contact co-culture can induce Dil-labeled BMSCs to differentiate into CM-like cells and examined the principle of gap junction-mediated signaling pathways involved in inducing stem cells to differentiate into cardiomyocytes.

A colorimetric and fluorometric probe for phenylhydrazine and its application in real samples.

A fluorescent probe for phenylhydrazine detection was developed with aldehyde as the recognition group and good selectivity towards phenylhydrazine over hydrazine, hydroxylamine and other amines was observed. Its application in real water samples and fast visualization of phenylhydrazine using a probe-loaded paper strip were demonstrated.

Preparation of myocardial patches from DiI-labeled rat bone marrow mesenchymal stem cells and neonatal rat cardiomyocytes contact co-cultured on polycaprolactone film.

To provide better treatment of myocardial infarction, DiI-labeled bone marrow mesenchymal stem cells (BMSCs) were contact co-cultured with cardiomyocytes (CMs) on polycaprolactone (PCL) film to prepare myocardial patches. BMSCs from Sprague Dawley rats were isolated, cultured, and characterized for expression of surface markers by flow cytometry. CMs were isolated from suckling rats. After BMSCs were cultured for three generations, they were labeled with DiI dye. DiI-labeled BMSCs were co-cultured with CMs on PCL film in the experimental group, while CMs were replaced with the same amount of unlabeled BMSCs in the control group. After 24 h, cell growth was observed by light microscopy and cells were fixed for scanning electron microscopy (SEM). After 7 d of co-culture, cells were stained for immunofluorescence detection of myocardial markers cardiac troponin T (cTnT) andα-actin. Differentiation of BMSCs on PCL was observed by fluorescence microscopy. The efficiency of BMSC differentiation into CMs was analyzed by flow cytometry on the first and seventh days of co-culture. CMs were stained with calcein alone and contact co-cultured with DiI-labeled BMSCs on PCL film to observe intercellular dye transfer. Finally, cells were stained for immunofluorescence detection of connexin 43 (Cx43) expression and to observe the relationship between gap junctions and contact co-culture. BMSCs were identified by flow cytometry as strongly positive for CD90 and CD44H, and negative for CD11b/c and CD45. After co-culture for 24 h, cells were observed to have attached to PCL by light microscopy. Upon appropriate excitation, DiI-labeled BMSCs exhibited red fluorescence, while unlabeled CMs did not. SEM revealed a large number of cells on the PCL membrane and their cell state appeared normal. On the seventh day, some DiI-labeled BMSCs expressed cTnT andα-actin. Flow cytometry showed that the rate of stem cell differentiation in the experimental group was significantly higher than the control group on the seventh day (20.12% > 3.49%,P< 0.05). From the second day of co-culture, immunofluorescence staining for Cx43 revealed green fluorescent puncta in some BMSCs; from the third day of co-culture, a portion of BMSCs exhibited green fluorescence in dye transfer tests. Contact co-culture of DiI-labeled BMSCs and CMs on PCL film generated primary myocardial patches. The mechanism by which contact co-culture promoted differentiation of the myocardial patch may be related to gap junctions and gap junction-mediated intercellular signaling pathways.

Comparative studies on the absorption and fluorescence responses of hemicyanine to HSO3-, CN-, HS- and ClO.

A fluorescent probe Hcy-Im bearing an indolium-hemicyanine structure was designed and synthesized to compare its responses to four anions, namely HSO3-, CN-, HS- and ClO-. The results disclosed that Hcy-Im reacted with all these four anions in 5% DMSO-PBS buffer with different speeds and spectral changes. Hcy-Im responded to HSO3- markedly quicker than CN- and HS-, and it responded to CN- a little quicker than HS- while the response to ClO- was much slower than the other three anions. The detection limits for these four anions were calculated to be 0.15 µM, 1.32 µM, 2.07 µM and 2.29 µM, respectively. The characteristic conjugated CN+ and CC bonds in Hcy-Im were responsible for the responses towards these four anions via a Michael addition-rearrangement reaction, a 1, 2-addition reaction or an oxidation reaction. These different sensing mechanisms were verified by 1HNMR and HRMS. Thus, it could be inferred that hemicyanine-based fluorescent probe could detect HSO3- sensitively and selectively while the interference of HSO3- should not be neglected when it was used for the detection of CN-, HS- and ClO-. Moreover, as HSO3-, HS- and ClO- are anions endogenously generated in human bodies, enough attention should be paid to the presence of physiological level of these three anions in certain tissues when hemicyanine-based fluorescent probe is applied for the detection of biorelevant analytes in biological samples.

A Michael addition reaction-based fluorescent probe for malononitrile detection and its applications in aqueous solution, living cells and zebrafish.

It is highly desirable to detect malononitrile in organisms and human bodies owning to its inherent toxicity. With dicyanovinyl as the recognition site, a Michael addition reaction-based fluorescent probe Hcy-DCV was developed for malononitrile detection. A notable advantage of this probe is that it responds quickly to malononitrile without any additive to speed the sensing reaction. It has a good water solubility and the detection limit was determined to be 6.92 ppb in 100% aqueous solution. In particular, Hcy-DCV exhibited good selectivity towards malononitrile over other interfering substances including hydrazine and other active methylene compounds. The probe was applied successfully to quantitate malononitrile in pure water with satisfying recovery and relative standard deviation. Additionally, the ability of visualizing malononitrile by using probe-coated strip papers was displayed, which may facilitate the on-site detection of malononitrile. Moreover, the bioimaging of malononitrile in living H1975 cells and zebrafish larvae was also demonstrated. All the experimental results suggested the potential of Hcy-DCV for practical detection of malononitrile in both environmental and biological samples.

[Differences in exogenous methyl jasmonate-induced quinclorac resistance between resistant and sensitive barnyardgrass and the underlying mechanism]. / å¤–æºèŒ‰èŽ‰é ¸ç”²é ¯è¯±å¯¼æŠ—æ€§ä¸Žæ•æ„Ÿç¨—è‰å¯¹äºŒæ°¯å–¹å•‰é ¸æŠ—æ€§çš„å·®å¼‚åŠæœºç†.

The effects of exogenous methyl jasmonate (MeJA) on the resistance levels to quinclorac and endogenous hormone levels were examined using the resistant and sensitive biotypes of barnyardgrass with the same genetic background. The results showed that exogenous MeJA could significantly increase the resistance of resistant plants to quinclorac, but did not affect the resistance of sensitive plants. There were significant differences in the contents of indole-3-acetic acid (IAA), abscisic acid (ABA), salicylic acid (SA), and jasmonic acid (JA) among the tested materials. Quinclorac treatment could significantly increase the contents of ABA, SA, and JA in barnyardgrass, with stronger increase of ABA and JA contents in the sensitive plants. Exogenous MeJA could significantly enhance the induction of ABA and JA contents by quinclorac, especially in the sensitive biotypes. These results showed that rapid hormone variations in sensitive plants inhibited their response to herbicide, while gentle hormone variations endowed resistant plants with a strong adapta-bility to herbicide, which closely related to the enhanced resistance by MeJA. ABA and JA hormone signals might play an important role in the resistance of barnyardgrass to quinclorac stress.

Quantitative proteomics reveals ecological fitness cost of multi-herbicide resistant barnyardgrass (Echinochloa crus-galli L.).

Barnyardgrass (Echinochloa crus-galli) is one of the top 15 herbicide-resistant weeds around the world that interferes with rice growth, resulting in major losses of rice yield. Thus, multi-herbicide resistance in barnyardgrass presents a major threat, with the underlying mechanisms that contribute to resistance requiring elucidation. In an attempt to characterize this multi-herbicide resistance at the proteomic level, comparative analysis of resistant and susceptible barnyardgrasses was performed using iTRAQ, both with and without quinclorac, bispyribac-sodium and penoxsulam herbicidal treatment. A total of 1342 protein species were identified from 2248 unique peptides by searching the UniProt database and conducting data analysis. Approximately 904 protein species with 4774 Gene Ontology (GO) terms were grouped into the categories of biological process, cellular component and molecular function. Among these, 688 protein species were annotated into 1583 KEGG pathways, with 980 protein species relating to metabolism and 93 relating to environmental information processing. A total of 292 protein species showed more than a 1.2-fold change in abundance in the resistant biotype relative to the susceptible biotype. Furthermore, herbicide treatment resulted in 157 protein species that showed more than a 1.2-fold change in the resistant biotype. Moreover, physiological analyses demonstrated an ecological fitness cost in the resistant biotype. SIGNIFICANCE: While some studies have shown a fitness cost to be associated with an altered ecological interaction, our understanding of the fitness costs associated with herbicide resistance are limited. Herein, physiological and proteomic analysis demonstrates herbicide resistance associated ecological fitness cost and potential mechanisms of herbicide-resistance in resistant biotypes of E. crus-galli. The results presented herein have revealed differences in ecological adaptation between resistant and susceptible biotypes in E. crus-galli and provide a fundamental basis enabling the development of new strategies for weed control. Lastly, this is the first large-scale proteomics study to examine herbicide stress responses in different barnyardgrass biotypes.

Data for iTRAQ-based quantitative proteomics analysis of different biotypes in Echinochloa crus-galli with multi-herbicide treatment.

Barnyardgrass (Echinochloa crus-galli) is one of the most troublesome herbicide-resistant weeds worldwide that interferes with rice growth and rice yield. Here we provide the data from a comparative proteomic analysis of leaves in resistant (R) and susceptible (S) biotypes of Echinochloa crus-galli both with and without multi-herbicide treatment in two independent biological experiments using iTRAQ. The distribution of length and number of peptides, mass and sequence coverage of proteins were presented, and the repeatability of the replicates was analyzed. 1342 differential accumulated proteins were identified from 2248 unique peptides by searching uniprot database and data analysis. These results are associated with the research article "Quantitative proteomics reveals ecological fitness cost of multi-herbicide resistant barnyardgrass (Echinochloa crus-galli L.)" (X. Yang, Z. Zhang, T. Gu, M. Dong, Q. Peng, L. Bai, Y Li, 2017) [1].

[Effects of different barnyardgrass species on grain yield of rice and their physiological characteristics under alternate wetting and drying irrigation].

In order to investigate the influence of different barnyardgrass species on rice yield and physiological characteristics of rice, two rice cultivars, Liangyoupeijiu (an indica hybrid cultivar) and Nanjing 9108 (a japonica cultivar) , were employed to co-culture with four barnyardgrass species during the period from transplanting to maturity under alternate wetting and moderate drying ir- rigation condition. The treatments were separately designed as follow: weed free ( control) , rice with Echinochloa crusgalli var. mitis (T1), rice with E. crusgalli (T2), rice with E. crusgali var. zelayensis (T3) and rice with E. colonum (T4). The results showed that T1, T2, T3 and T4 treatments reduced the Liangyoupeijiu yield by 13.8%, 10.6%, 23.8% and 0.5%, but the corresponding yield loss of Nanjing 9108 could reach up to 45.5%, 36.9%, 60.7% and 15.1%, respectively. The results above showed that T1, T2 and T3 treatments all significantly reduced grain yield, and T4 treatment only reduced grain yield for Nanjing 9108 but not for Liangyoupeijiu. All treatments elevated malondialehyde contents of rice leaf, but the activities of peroxidase, catalase, superoxide dimutase, dry matter accumulation in maturity stage, root oxidation activities and contents of indole-3-acetic acid as well as zeatin + zeatin riboside in roots during rice grain filling stage were all decreased. The influence degree of four barnyardgrass against physiological indices of rice had the order of T3 > T1 >T2 > T4. It showed that the reductions in enzyme activities of antioxidant system, root oxidation activities, contents of indole-3-acetic acid, zeatin + zeatin riboside during grain filling stage and accumulation of dry matter in maturity as well as increase in contents of malondialehyde of rice during grain filling stage might be important reasons for grain yield reduction when grew with barnyardgrass.

Growth, structure, thermal properties and spectroscopic characteristics of Nd3+-doped KGdP4O12 crystal.

A single crystal of Nd3+-doped KGdP4O12 was successfully grown with the top-seeded solution growth and slow cooling (TSSG-SC) technique. It crystallizes in space group C2/c with cell parameters a = 7.812(2) Å, b = 12.307(3) Å, c = 10.474(2) Å, ß = 110.84(3)° and Z = 4. The IR and Raman spectra also indicated that the phosphoric polyhedra of Nd:KGdP4O12 has a cyclic symmetry. The chemical composition of the crystal was analyzed and the distribution coefficient of Nd3+ was calculated. The crystal morphology of KGdP4O12 was identified using X-ray diffraction. The compound has good thermal stability to 920°C. Its specific heat and thermal conductivity were determined for potential applications. The spectral properties of Nd:KGdP4O12 indicates that it exhibits broad absorption and emission bands, which are attributed to low symmetry of the crystal. The broad absorption band around 798 nm has a full-width at half-maximum (FWHM) of 14.8 nm and is suitable for AlGaAs laser diode pumping. Moreover, 5 at% Nd3+-doped KGdP4O12 crystal has a long luminescence lifetime of 300 µs and a high quantum efficiency of 96%.

[Influence of weeds in Echinochloa on growth and yield of rice].

In order to investigate effects of different barnyardgrass species on growth and yiled of rice, two rice cultivars, Xinliangyou 6 hao (an indica hybrid cultivar) and Nanjing 46 (a japonica cultivar), were co-cultured with four barnyardgrass species grown at a density of six plants · m(-2) from 10 days after transplanting to maturity. The treatments were designed as follow: weed free (control), rice with Echinochloa crusgalli var. mitis (T1), rice with E. crusgalli (T2), rice with E. crusgali var. zelayensis (T3), and rice with E. colonum (T4). The result showed that barnyardgrass-induced reductions in grain yield of rice were obviously different among the four treatments. T1, T2 and T3 treatments reduced the grain yield of indicia cultivar by 19.2%, 10.8% and 21.9%, and the respective reductions in japonica cultivar were 39.7%, 25.3% and 47.3%, re- spectively. However, no significant difference was detected for T4 treatment. During rice co-culture with barnyardgrass, T1, T2 and T3 significantly reduced rice dry matter accumulation at maturity, flag leaf photosynthetic rate, root oxidation activity and the activity of adenosine triphosphate enzyme (ATPsse) in rice grains at the filling stage, and the magnitude of decrease was in the order of T3 > T1 > T2, while no significant difference was observed between T4 and CK. In addition, all treatments had no effects on the final tiller number and plant height of rice. It indicated that the negative effect of barnyardgrass on rice growth and yield differed among the four species of barnyardgrass, in the order of T3 > T1 > T2 > T4. Barnyardgrass reduced the flag leaf photosynthetic rate of rice, both root oxidation activity and ATPsse activity in grains, which resulted in the reduction in final productivity of rice when co-cultured with barnyardgrass.