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10 July 2025, Volume 39 Issue 4 Previous Issue   
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Special Focus: Mechanization and Intelligentization in Rice Production
Reviews and Special Topics
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Special Focus: Mechanization and Intelligentization in Rice Production

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Research on Path Tracking Control Methods for Tractor Operating Units: A Review XIAO Maohua, TIAN Fengyu, WEI Wenbo, ZHU Yejun, LI Dongfang, ZHANG Pengcheng, GENG Guosheng 2025, 39(4): 423-439.  DOI: 10.16819/j.1001-7216.2025.250104 Abstract ( )   HTML ( )   PDF (1823KB) ( )   The tractor operating unit refers to an agricultural machinery system with a unique articulated tractor structure composed of a tractor and supporting implements, and the path tracking control method is the key technology to realize the unmanned operation of this unit. However, limited by the variability of the agricultural environment and the complex steering structure of the articulated frame, the existing methods still face challenges in terms of adaptability, robustness, and control efficiency. The aim of this work is to provide a systematic overview of current research status on path tracking control methods for tractor operating units by analyzing their models and path tracking control algorithms. In addition, this review discusses the main problems in research on path tracking control methods for tractor operating units and possible solutions, with a view to providing useful references for related research in this field.

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Design and Testing of an Adaptive Rear-hitch Leveling Control System for Tillage Depth Using Fuzzy PID Algorithm LI Huijie, YUAN Haoyu, XIE Chenshuo, XIAO Maohua, HUANG Weixing, CAO Yuxuan, TANG Cungan 2025, 39(4): 440-450.  DOI: 10.16819/j.1001-7216.2025.250317 Abstract ( )   HTML ( )   PDF (1756KB) ( )   【Objective】 In response to the current challenges in agricultural production, where traditional tillage implements are susceptible to variations in terrain and workload, leading to limited terrain adaptability and in accurate leveling control. 【Method】 This work proposes an intelligent adaptive leveling control method for tillage depth based on a fuzzy PID algorithm. A four-bar electronically controlled hydraulic rear-hitch leveling device is designed to achieve adaptive tillage depth regulation, and ensure depth uniformity during rotary tiller operations. The four-bar hydraulic rear-hitch leveling device is modeled using 3D modeling software, and simulation analysis is conducted to verify its safe and stable operation under apecified load conditions. Field operation tests are carried out to validate the system's performance. 【Result】 The results show that when the tractor operates at low, medium, and high speeds in the field, the hydraulic rear-hitch leveling device using the fuzzy PID algorithm achieves average leveling response times of 2.2 s and 5.3 s on slopes of 10° and 20°, respectively, with leveling errors less than 0.5° and no overshoot. 【Conclusion】 The system effectively ensures the qualified rate and uniformity of tillage depth, enabling real-time adaptive control of tillage depth during rotary tiller operations.

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Design and Optimization of a Terminal Shunting Acceleration Device for Rice Side Deep Fertilization LIN Yi, SUN Liang, CHEN Dongshun, ZHU Guangfei, KONG Ziyang, YU Gaohong 2025, 39(4): 451-464.  DOI: 10.16819/j.1001-7216.2025.250209 Abstract ( )   HTML ( )   PDF (1746KB) ( )   【Objective】 Addressing the slow fertilizer falling speed and susceptibility to clogging at the fertilizer tube outlet in rice side-deep fertilization devices, 【Method】 a terminal shunt-type acceleration device was developed based on the physical properties of universal granular compound fertilizers. Utilizing the gas-solid two-phase flow theory, the device separates the air stream and fertilizer particles. The diverted air stream is accelerated through a variable-diameter tube and then reintroduced at the fertilizer outlet, thereby increasing the outlet air velocity to accelerate fertilizer descent and prevent blockages. 【Result】 A coupled Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM) simulation model was established. The inclination angle of the mixing tube, the bend-to-diameter ratio, and the inclination angle of the air induction port in the air-fertilizer shunting device were selected as influencing factors. Using the fertilizer misentry rate into the air induction port and the air flow velocity as response variables, a Box-Behnken experimental design (a three-factor, three-level response surface methodology) was employed to conduct simulation experiments and identify the optimal structural parameters. The results indicate that the optimal structural parameter combination is a mixing tube inclination angle of 10°, an air induction tube inclination angle of 16°, and a bend-to-diameter ratio of 2. Bench tests conducted under these optimal conditions yielded an average accelerated air velocity of 19.74 m/s, a fertilizer misentry rate of 7.74%, and an average fertilizer falling velocity of 2.14 m/s. 【Conclusion】 This device effectively enhances the air velocity at the fertilizer tube outlet and the fertilizer falling speed, providing a valuable reference for research into pneumatic rice fertilization technology.

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Analysis and Design of Wide and Narrow Row Transplanting Mechanism with Direct Picking and Direct Planting ZHOU Bin, HUANG Jiangjun, XUE Xiaodi, GU Wei, FENG Tao, SUN Liang, YU Gaohong 2025, 39(4): 465-476.  DOI: 10.16819/j.1001-7216.2025.250303 Abstract ( )   HTML ( )   PDF (1333KB) ( )   【Objective】 In order to solve the problem of lateral inclination of seedlings during the seedling pushing and transplanting process by the existing spatial trajectory wide-narrow row transplanting mechanism, this work presents a spatial trajectory transplanting mechanism evolved from a planar trajectory. 【Method】 Firstly, based on the requirements of rice seedling planting, key positions and postures on the trajectory of the planting arm claw tip were determined. A motion parameter solving model for the simplified mechanism of the planetary gear train (planar 2R mechanism) was established. The transmission ratio of the transplanting mechanism's non-circular gear was distributed using the solved whole-cycle angular displacement of the 2R mechanism. Then, a swing-arm type seedling-pushing device was introduced, where a conjugate cam drives the lateral motion of the planting arm and a split fork realizes seedling pushing. The planar angle between the swing shaft of the planting arm and the claw was determined according to the attitude angle of the claw during seedling picking. With the requirements of straight seedling picking in the planar trajectory segment and lateral swing planting for upright seedling establishment, the conjugate cam profile and structural parameters were designed. This achieved zero offset during the seedling picking process of the transplanting mechanism and upright seedlings after pushing for wide-narrow row mechanical transplanting. Finally, a physical prototype test of the transplanting mechanism was conducted. 【Result】 The actual trajectory and posture of the prototype were basically consistent with the theoretical design: seedling picking angle β1=0.75°; seedling pushing angle in the xoy plane β2=55.25°; seedling pushing angle in the yoz plane β3=34.42°; total lateral displacement during pushing ΔS=39.26 mm; trajectory height h1=318.86 mm; loop height h2=179.83 mm; hill-opening width d1=19.97 mm. These meet the agronomic requirements for wide-narrow row planting, verifying the correctness of the design of the straight-picking and straight-planting wide-narrow row transplanting mechanism

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Effects of Seeding Rate and Seedling Picking Area on Establishment of High-yield Populations and Energy Efficiency in Precision Drill-Sown and Machine-transplanted Hybrid Rice CAO Yun, CHEN Xuefang, HUANG Xinghai, HE Ziting, TANG Jingsha, CHEN Kun, WANG Ailing, LUO Guanzhou, LIAO Qin, SUN Yuanyuan, GUO Xiang, YANG Zhiyuan, MA Jun, SUN Yongjian 2025, 39(4): 477-490.  DOI: 10.16819/j.1001-7216.2025.250311 Abstract ( )   HTML ( )   PDF (2255KB) ( )   【Objective】 This study aimed to investigate the effects of drill seeding rate and seedling picking area on mechanical transplanting quality, high-yield population establishment, and energy efficiency in hybrid rice under precision drill sowing, thereby optimizing cultivation parameters for enhanced yield and resource utilization efficiency. 【Method】 A two-factor split-plot design was conducted with hybrid rice cultivar Chuankangyou 6308 under 18-row precision drill sowing. The design comprised four main-plot drill seeding rates: 100 (M1), 130 (M2), 160 (M3), and 190 grains/row (M4), and three seedling picking areas under mechanical transplanting of 1.25 cm² (S1), 2.03 cm² (S2), and 2.81 cm² (S3) were established as subplots to represent differential seedling picking quantities, systematically evaluating their impacts on seedling quality, mechanical transplanting performance, population dynamics, yield formation, and energy utilization efficiency. 【Results】 At a seedling age of 25 d and different drill seeding rates, the differences between M1 and M2 treatments were not significant. Plant height (17.05-17.95 cm), stem base width (1.78-1.84 mm), number of green leaves (3.41-3.57 leaves), seedling establishment rate (74.15%-77.75%) and number of roots (7.04-7.71 roots/plant) were all significantly better than those in M3 and M4 treatments by 1.36% to 21.46%. However, the M2 treatment showed better root-shoot ratio and root intertwining force than the M1 treatment. Under the treatments of drill seeding rate and seedling picking area, the experimental combination M2S3 achieved the best results, with optimum mechanical transplanting quality and slower leaf area decline in the later stages of reproduction. Its population growth rate and net population assimilation rate were higher than those of the other treatments by 0.77% to 70.59% and 2.54% to 55.79%, respectively, and its yield reached 10768.79 kg/hm², which was 4.01% to 37.23% higher than that of the other treatments. In addition, its net energy, energy utilization efficiency, and energy productivity were significantly increased by 3.70% to 34.41%, 0.04% to 1.80%, and 2.5% to 24.24%, respectively, and its net return and output/input ratio increased by 335.13 to 3935.06 yuan/hm² and 0.36% to 18.93%, respectively. 【Conclusion】 For precision drill-sown and machine-transplanted hybrid rice with 18 rows, using a drill seeding rate of 130 grains/row and a seedling age of 25 d can cultivate seedlings with superior quality. Combined with a seedling picking area of 2.81 cm², this approach facilitates the establishment of a high-yield population, reduces costs, improves efficiency, and synergistically increases both yield and energy efficiency ratio.

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Response of Machine-transplanting Quality and Yield Formation of Hybrid Rice Pot-mat Seedlings to Pot Depth TANG Chenghan, CHEN Huizhe, HUAI Yan, SUN Liang, ZHANG Yuping, XIANG Jing, ZHANG Yikai, WANG Zhigang, XU Yiwen, WANG Yaliang 2025, 39(4): 491-500.  DOI: 10.16819/j.1001-7216.2025.241106 Abstract ( )   HTML ( )   PDF (1345KB) ( )   【Objective】 Pot-mat seedlings can effectively constrain root system, thereby reducing damage during rice mechanical transplanting. Elucidating the impact of pot depth on the machine-transplanting quality and yield formation of hybrid rice pot-mat seedlings will lay a theoretical basis for developing suitable hybrid rice pot-mat seedling trays. 【Method】 The experiment selected the indica-japonica hybrid rice Yongyou 1540 as material. An ordinary mat seedling tray (CK, blanket seedling tray, pot depth of 0 cm) was used as the experimental control. Four pot depth types were set as treatments: T1 (pot-mat seedling tray, pot depth 0.4 cm, pot volume 1.6 cm³); T2 (pot-mat seedling tray, pot depth 0.8 cm, pot volume 3.2 cm³); T3 (pot-mat seedling tray, pot depth 1.2 cm, pot volume 4.8 cm³); T4 (pot-mat seedling tray, pot depth 1.6 cm, pot volume 6.4 cm³). All treatments use seedling trays of the same size(length×width×height=58 cm×28 cm×2.8 cm). The sowing specifications were 14 holes horizontally and 29 holes vertically per tray, 3 seeds per hole, and the seeding rate per tray was 30.94 g. Comparative analysis was conducted on different treatments for mat-forming ability, rice seedling quality, machine-transplanted quality, mechanical root damage, physiological indexes of seedlings after machine transplanting, and yield formation of rice populations. 【Results】 (1) The increase in pot depth reduced root damage from machine transplanting and increased root vitality, leaf soluble sugar, and chlorophyll content in rice seedlings after machine transplanting. Seedlings with a pot depth of 1.6 cm had poor mat-forming properties; this treatment had a high seedling leakage rate and low planting uniformity after machine transplanting. (2) The increase in pot depth promoted tillering, increased leaf area index, and increased dry matter accumulation. (3) Higher pot depth resulted in higher yield of rice populations, attributed to more productive panicles. 【Conclusions】 Increasing pot depth can reduce root damage in rice seedlings and increase productive panicle number in rice populations to achieve high yield. However, pot-mat seedlings with too deep pots are difficult to form a mat and have poor machine-transplanted quality. The pot depth of the pot-mat tray should not exceed 1.2 cm at large pot volume and low sowing rate. In actual production, it is suggested to increase pot depth of the pot-mat tray while ensuring successful mat formation, to facilitate the establishment of high-yield populations through mechanized transplanting of hybrid rice pot-mat seedlings.

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Effects of Weed Control Methods on Grain Yield and Quality of Herbicide-resistant Rice Under Direct Seeding ZHU Peng, LING Xitie, WANG Jinyan, ZHANG Baolong, YANG Yuwen, XU Ke, QIU Shi 2025, 39(4): 501-515.  DOI: 10.16819/j.1001-7216.2025.241001 Abstract ( )   HTML ( )   PDF (1819KB) ( )   【Objective】 The aim of this study was to investigate the effects of different weed control methods on herbicide-resistant rice growth and yield formation. 【Method】 Field experiments were carried out with the ALS herbicide-resistant varieties of conventional glutinous rice Zhennuo 19 (Z19), indica restorer line rice Huazhan (HZ), conventional japonica rice Zhendao 18 (Z18), soft rice K6 (K6) and their corresponding herbicide sensitive wild-type varieties as materials. The method of direct seeding was adopted. Three weeding methods were employed, including, artificial-weeding (T1), imazamox-weeding (T2) and conventional-weeding (T3). 【Result】 The control effect of artificial weeding was the best, followed by metomiazol treatment, with weed control efficacies of 95.43% and 86.34%, which were 34.32% and 24.23% higher than that of conventional weeding at 40-day after treatment. In addition, the agronomic traits of tested rice varieties (number of tillers, heading rate, leaf area index, leaf area decay rate and dry matter accumulation) increased to different degrees, with no significant effect on SPAD value or rice quality. Compared with the conventional-weeding(T3), the yield of Zhennuo 19, Huazhan, Zhendao 18 and K6 in T1 increased by 35.0%, 34.8%, 31.9% and 28.8%, respectively, and the yield of corresponding rice varieties in T2 increased by 17.6%, 15.9%, 14.1% and 15.2%, respectively. 【Conclusion】 The above results indicate that selecting ALS herbicide-resistant rice varieties and applying corresponding herbicide control technology under mechanical direct seeding conditions can effectively control weeds and maintain high grain yield, which is a high-yield cultivation method worthy of promotion.

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Effect of Dense Sowing Nursery on Seedling Quality and Picking Characteristics for Mechanized Transplanting in Northern japonica Rice DONG Liqiang, ZHANG Yikai, YANG Tiexin, FENG Yingying, MA Liang, LIANG Xiao, ZHANG Yuping, LI Yuedong 2025, 39(4): 516-528.  DOI: 10.16819/j.1001-7216.2025.250105 Abstract ( )   HTML ( )   PDF (1657KB) ( )   【Objective】 To study the effects of dense sowing on rice seedling quality and seedling-picking characteristics under mechanized transplanting, and to explore its role in enhancing rice nursery efficiency and mechanized transplanting performance. 【Method】 In 2024, using Liaojing 419 as the test variety, a seedling nursery experiment was conducted. The control treatment (CK) used the conventional farmer sowing rate of 100 g per tray (58 cm × 28 cm). Four dense-sowing treatments were established: 125 g (ISR1), 150 g (ISR2), 175 g (ISR3), and 200 g (ISR4) per tray. The study investigated the effects of different sowing rates on rice seedling quality and seedling-picking characteristics during mechanized transplanting, aiming to elucidate the relationship between the physiological and biochemical changes in dense-sown seedlings and the operational quality of mechanized transplanting. 【Result】 The whole-tray biomass of rice seedlings increased significantly with increasing sowing rate, reaching its maximum at 175 g per tray(ISR3). The root intertwining force of seedlings also significantly increased under ISR3, averaging increases of 35.6% and 29.1% compared to CK, respectively. The individual seedling biomass decreased significantly due to high sowing rates, accompanied by reduced antioxidant enzyme activities, lower soluble sugar content, and altered expression of stress resistance-related genes. The uniformity of plant height and stem base width decreased by 1.3%-2.6% and 0.6%-3.7% in ISR1-ISR3 compared to CK, respectively, and decreased significantly by 7.2% and 9.3% in ISR4, respectively. The injured seedling rate during mechanized transplanting showed a linear positive relationship with sowing rate. The average injury rate was 4.1% for ISR1-ISR3 and 9.8% for ISR4. Treatments ISR2 and ISR3 maintained relatively higher seedling plumpness, seedling vigor index, and lower seedling injury rates. The actual number of seedling trays used per hectare for mechanized transplanting in ISR1-ISR4 decreased by 53.2-148.1 trays/hm² compared to CK. Consequently, the manual operational efficiency during mechanized transplanting significantly improved by 17.2%-40.2%. 【Conclusion】 Dense-sowing nursery increases whole-tray biomass and root intertwining force. A sowing rate of 150-175 g per tray maintained relatively high individual seedling quality, significantly reduced tray usage by 36.2%, and greatly improved the operational efficiency of mechanized transplanting. This approach can be adopted as a high-quality and efficient mechanized transplanting option for japonica rice in Northern China.

Reviews and Special Topics

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Research Progress of Typical Plant Growth-promoting Microorganism Enhancing Salt Stress Resistance in Rice ZHOU Yang, YE Fan, LIU Lijun 2025, 39(4): 529-542.  DOI: 10.16819/j.1001-7216.2025.240814 Abstract ( )   HTML ( )   PDF (1685KB) ( )   Soil salinization is one of the main challenges facing global food security. Rice is the preferred grain crop for the reclamation of coastal tidal flats and saline-alkaline land. Enhancing salt tolerance is essential to ensuring stable saline-alkaline soil rice production. Plant growth-promoting microorganisms (PGPMs) are a crucial part of the biological improvement of saline-alkaline soils. Salt-tolerant PGPMs, such as arbuscular mycorrhizal fungi, Bacillus, and Pseudomonas, can alleviate the adverse effects of salt stress on the growth and development of rice by activating soil enzyme activity, producing extracellular polysaccharides, enhancing antioxidant enzyme activity, regulating osmotic metabolism osmoprotectants, and regulating plant hormones. This work summarizes different pathways and related mechanisms by which the three aforementioned PGPMs enhance rice resistance under salt stress, highlights the current research gaps in this field, and provides an outlook for future research, thereby offering theoretical and practical bases for the improvement of saline-alkaline soils and high-yield rice production.

Research Papers

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Phenotypic Analysis and Gene Mapping of a Floury Endosperm Mutant we1 in Rice ZHU Jianping, LI Xia, LI Wenqi, XU Yang, WANG Fangquan, TAO Yajun, JIANG Yanjie, CHEN Zhihui, FAN Fangjun, YANG Jie 2025, 39(4): 543-551.  DOI: 10.16819/j.1001-7216.2025.240508 Abstract ( )   HTML ( )   PDF (1407KB) ( )   【Objective】 The study of floury endosperm mutants is helpful for elucidating the molecular mechanisms underlying rice grain quality formation. 【Method】 A stably inherited floury endosperm mutant we1 (white endosperm 1) was isolated from a 60Co-irradiated mutant pool of japonica rice cultivar Nipponbare. Phenotypic characterization and physicochemical analyses of we1 were conducted. An F2 population derived from a cross between we1 and indica variety 9311 was used for fine mapping. 【Result】 Compared with the wild type, we1 exhibited white, shrunken endosperm with irregularly shaped and loosely packed compound starch granules. The mutant showed significant reductions in 1000-grain weight, plant height, total starch content, and amylose content, along with a marked increase in lipid content. Genetic analysis indicated that the mutant phenotype was controlled by a single recessive nuclear gene. For map-based cloning, we1 was crossed with 9311 and recessive F2 individuals were selected. The WE1 locus was initially mapped to chromosome 6 and fine-mapped to a 181-kb physical interval. Twenty-three open reading frames (ORFs) were predicted in this region. qRT-PCR analysis revealed altered expression levels of starch synthesis-related genes in the we1 mutant. 【Conclusion】 WE1 likely encodes a novel gene involved in starch synthesis, providing a foundation for further elucidating its molecular regulatory mechanisms in rice.

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Natural Variation of OsNF-YC10 and Its Correlation with Grain Width in Rice CHEN Jiale, YU Qingtao, ZHENG Chenfan, WANG Qing, TAN Yuanyuan, CHEN Baicui, LI Chengxin, JIANG Meng, SHU Qingyao 2025, 39(4): 552-562.  DOI: 10.16819/j.1001-7216.2025.240713 Abstract ( )   HTML ( )   PDF (1904KB) ( )   【Objective】 Grain width is an important determinant of grain type and grain weight, which can affect rice yield and appearance quality. So far, a large number of genes have been found to affect grain width, but only a limited number of genes have breeding value because mutations of other genes often have negative collateral effects. Hence, it is of great significance to explore new grain width genes and uncover natural variations that have no negative effects on quality and yield. DR610 is a small-grain indica rice and Hagengdao 7 (HG7) is a large-grain japonica rice. 【Method】 In this study, a QTL-seq was performed using the extreme grain weight individuals of the DR610×HG7 F2 population. Through the combined analysis of QTL-seq results and known genes affecting grain type, we found that a nonsense mutation of OsNF-YC10 in DR610 is likely to be the underlying genetic basis of its narrow grain. To determine the correlation between OsNF-YC10 variation and grain width, we analyzed the natural variation of OsNF-YC10 in more than 4000 rice germplasm accessions and its correlation with grain width. 【Result】 A total of 10 major OsNF-YC10 haplotypes were identified with HG7(Hap1) being the predominant haplotype (1464/1509) in japonica rice (1464 of 1509 accessions). The Hap5 (represented by DR610) contains a C(HapC)→T(HapT) nonsense mutation at nucleotide site 1048. The grain width of rice varieties with HapC (3.036 mm, n=1596) was significantly wider than that of HapT (2.938 mm, n= 309), indicating that this natural variation significantly affected the grain width. Further analysis showed that Hap1 and Hap5 are significantly differentiated between japonica and indica, with the latter mainly distributed in the low latitude regions. A molecular marker to distinguish C→T variants was developed using four tetra-primer ARMARMS-PCR, which can be used for marker-assisted selection of grain type. 【Conclusion】 In summary, this study determined the natural variation of OsNF-YC10, which is significantly correlated with the grain width. The finding is of importance to providing an important reference for breeding by design of grain type and weight in rice.

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Transcriptome Analysis of Top Second Leaf Sheath of Rice Under Different Nitrogen Fertilizer Levels HUANG Fudeng, WU Chunyan, HAO Yuanyuan, HAN Yifei, ZHANG Xiaobin, SUN Huifeng, PAN Gang 2025, 39(4): 563-574.  DOI: 10.16819/j.1001-7216.2025.250306 Abstract ( )   HTML ( )   PDF (2200KB) ( )   【Objective】 The leaf sheath is an important organ that simultaneously serves the functions of “source, sink, and transport”, playing a crucial role in the growth and development of rice plants. Identifying important genes in leaf sheaths in response to nitrogen will provide scientific evidence for the genetic improvement of nitrogen use efficiency in rice. 【Method】 The japonica rice cultivar Xiushui 134 was planted in percolation ponds at low nitrogen (LN), medium nitrogen (MN), and high nitrogen (HN) levels. The top second leaf sheaths were collected on the 10th day after heading for transcriptome sequencing analysis to identify important genes involved in the nitrogen response of rice leaf sheaths. 【Result】 Comparative analysis of the transcriptome data revealed 1,791 differentially expressed genes at the three nitrogen levels. The number of upregulated and downregulated genes between HN and MN, MN and LN, and HN and LN were 312 and 155, 263 and 160, and 1,059 and 542, respectively. The common upregulated and downregulated genes at the three nitrogen levels were 15 and 53, respectively, involved in physiological and biochemical processes such as nutrient element absorption and transport, responses to biotic and abiotic stresses, plant hormone responses, and light regulation. Based on GO enrichment analysis, KEGG metabolic pathway analysis, a total of 6 known functional genes related to nitrogen utilization and 4 genes related to photosynthesis, as well as 50 genes of unknown function, were identified. It is speculated that these genes play important roles in the nitrogen response of the second leaf sheath in rice. 【Conclusion】 The research results preliminarily clarify the important genes involved in the leaf sheath's response to different nitrogen levels, which may play significant roles in signal transduction pathways of nitrogen utilization.