Journal of Shenyang Agricultural University

Retrieval Method of Rice LAI Based on Unified Model of Vegetation Bidirectional Reflectance

[Objective]Leaf Area Index(LAI) is a core indicator for crop growth assessment and plays an irreplaceable key role in precise field management decision-making. In order to break through the limitations of traditional empirical models, this study optimized model parameters according to the differences in canopy structure of rice at different growth stages, reduced the impacts of factors such as soil background, leaf overlap, improved the accuracy and efficiency of retrieval, to achieve rapid conversion from remote sensing data to leaf area index. [Methods]This paper proposes a retrieval method of rice LAI based on the unified model of vegetation bidirectional reflection. Using the Haicheng Precision Agriculture Aviation Research Base of Shenyang Agricultural University as the research area, unmanned aerial vehicle hyperspectral data(400-1 000 nm) and ground measured LAI data were collected during the seedling regreening, tillering, jointing, and heading stages of rice in 2023. The Successive Projection Algorithm(SPA) was used to screen characteristic bands for reducing data redundancy. In terms of model construction, the range of sensitive parameters of the model was determined through global sensitivity analysis, and multiple simulated datasets of LAI and canopy reflectance were established. The inversion models were constructed using the lookup table(LUT) method and the lion swarm optimization algorithm(LSO), and compared and verified with traditional methods such as vegetation index method, BP neural network,extreme learning machine(ELM), and random forest(RF). [Results]The SPPA algorithm can effectively characterize the spectral information of rice canopy by selecting feature bands; the error between the simulated rice canopy spectrum based on the unified model of vegetation bidirectional reflectance and the measured spectrum is small in the range of 400-1 000 nm; the LAI inversion based on LSO has the best performance, with a coefficient of determination(R2) of 0.779 and a root mean square error(RMSE) of0.599, significantly superior to the lookup table method(R2=0.638, RMSE=0.767) and machine learning method(BP neural network R2=0.668, RMSE=0.736; ELM extreme learning machine R2 =0.588, RMSE=0.819; RF random forest R2 =0.649, RMSE=0.756).[Conclusion]With a clear physical mechanism, the unified model of vegetation bidirectional reflection can effectively overcome the over fitting problems of traditional data driven methods and maintain high stability in different growth periods and under complex soil backgrounds. This study provides a reliable technical solution for dynamic monitoring of rice growth and precise farmland management, which is of great significance for promoting the large-scale application of smart agriculture.

Research on Inversion Method of Chlorophyll Content in Rice Leaves Based on PIOSL Model

[Objective]Chlorophyll content is an important indicator for assessing the health of rice plants. Precise monitoring of chlorophyll content in rice leaves is of vital importance. Traditional methods for detecting chlorophyll content in rice leaves require destructive sampling, making it difficult to obtain real-time dynamic changes. With the rapid development of information technology,hyperspectral data combined with machine learning methods can be used to retrieve chlorophyll content in rice leaves. [Methods]Based on the hyperspectral simulation data of leaves output by the PIOSL(PROSPECT considering the internal optical structure of the leaves) model, three methods, namely Successive Projections Algorithm(SPA), Competitive Adaptive Reweighted Sampling(CARS),and Random Frog(RF), were adopted for feature band selection. Then, three algorithms, Particle Swarm Optimization(PSO), Whale Optimization Algorithm(WOA), and Love Evolution Algorithm(LEA), were used to optimize the Extreme Learning Machine(ELM) for the inversion of chlorophyll content in rice leaves. [Results]The research results show that based on the simulated data output from the PIOSL model, using three feature band selection methods, CARS, SPA, and RF, were used to select 19, 9, and 10 feature bands respectively, ELMs optimized by PSO, WOA, and LEA were created. By comparing the performance of the nine models, it was concluded that the CARS-LEA-ELM model had the best effect in inverting the chlorophyll content of rice leaves, with a test set R² of0.929 and RMSE of 4.116 μg·cm^-2.[Conclusion]Through the comprehensive evaluation of the inversion results, the optimal inversion model construction scheme was determined to achieve high-precision inversion of the chlorophyll content of rice leaves and provide support for field management.

A Detecting Method for Maize Tassels Based on UAV RGB Images

[Objective]Accurate identification and detection of maize tassels are crucial for improving detasseling efficiency.Addressing the current limitations of insufficient detection accuracy and poor robustness of deep learning algorithms in complex field environments, this paper proposes an enhanced YOLOv8-based method for efficient maize tassel detection. [Methods]A detection dataset with strong generalization capabilities was constructed by collecting multi-scenario data via UAVs under varying weather conditions and flight altitudes. By incorporating a "Ghost Convolution"(GhostConv) module into the backbone network of YOLOv8, and adding an Attentional Scale Sequence Fusion(ASF)module and a Gather-and-Distribute Mechanism(Gold)module to the neck network,the model can better extract target features and enhances performance in object localization and regression tasks. The improved detection model is named as AG-YOLO. [Results]AG-YOLO demonstrates outstanding performance in maize tassel detection,achieving an Average Precision(mAP)of 89.3% while reducing model size by approximately 18.3% compared to the original model.This performance significantly outperforms other mainstream detection algorithms such as YOLOv3, YOLOv5, YOLOv6, and YOLOv8.Particularly in scenarios such as early tasseling stages, heavy leaf occlusion, dense target distribution, or complex backgrounds, AGYOLO demonstrated outstanding detection capabilities.[Conclusion]The improved AG-YOLO model effectively detects maize tassels in complex and variable field environments, balancing high detection accuracy, lightweight model size, and strong robustness. It exhibits significant practical value in practical applications. This study provides efficient and reliable technical support for automated and intelligent maize detasseling operations, laying a solid foundation for optimizing and promoting precise phenotyping detection models for other crops in future smart agriculture applications.

Distribution Characteristics of Droplet Deposition under Rotor Downwash Airflow of Coaxial Dual-Rotor Plant Protection UAV

[Objective]In the plant protection UAV spraying operation process, the distribution characteristics of the rotor downwash airflow field play a key role in the droplet sedimentation effect. Study was carried out to reveal the airflow distribution patterns of the coaxial dual-rotor UAV, and to explore the influence of rotor airflow on the droplet deposition. [Methods]This study uses the fluid dynamics simulation software Fluent to conduct a numerical simulation of the rotor downwash airflow field and its droplet deposition characteristics of a coaxial dual-rotor UAV, and the simulation results were compared and verified with the field spray test results.[Results]The results of the numerical simulation show that the airflow intensity beneath the rotor decreases with the increase of distance from the rotor. The average speed of the droplet within the area directly beneath the rotor increases with the increase of UAV's rotor speed. When the rotor speeds are 2 000, 2 400, 2 800, and 3 200 r·min^-1, the regions within approximately 2.0,3.5,5.5,and 6.5 m beneath the rotor are high-speed droplet, to the corresponding average droplet speeds of 11.5,13.5,15.5, and 17.5 m·s^-1,respectively. With the increase of the UAV's rotor speed, the drift of droplets initially weakens and then strengthens. The field test results show that the average droplet deposition rate for each collection zone were 1.808, 2.044, 2.434, and 1.774 μL·cm^-2. When the tank capacity increased from 70% to 100%, the average droplet deposition rate decreased significantly from 2.434 to 1.774 μL·cm^-2.The corresponding drift rates were 13.20%, 6.96%, 1.30%, and 19.03% respectively. [Conclusion]Significance analysis shows that there are significant differences in the drift distribution of droplets under different load conditions during spraying. Comparing the test and simulation results, the average droplet deposition rate from the numerical simulation was lower; however, the trend of change in both test and simulation values remains highly consistent. The test verified the reliability of the numerical simulation model and can guide the implementation of field trials, to achie the objectives of precise spraying operations and optimizing spraying effects.

A Lightweight Detection Method for Grape Leaf Diseases in Complex Backgrounds Based on Improved YOLOv10n

[Objective]To address the challenge of balancing model accuracy and deployment efficiency in grape leaf disease detection under complex backgrounds, this study proposes a lightweight real-time detection model based on an improved YOLOv10n. Through structural optimization and attention mechanism enhancement, the model significantly reduces computational complexity while maintaining detection accuracy, facilitating efficient deployment on mobile devices and in practical agricultural scenarios. [Methods]First, a C2f-HFDRB module was designed in the Backbone network to replace the original C2f module. By splitting input features into high-and low-frequency branches, the modeling capability for high-frequency information and local details of disease regions was enhanced. Second, the CAA-HSFPN structure was adopted to replace the Neck network, achieving efficient feature pyramid fusion by streamlining high-computation components. Finally, the TripletAttention module was integrated to precisely focus on disease target areas in complex backgrounds by capturing cross-dimensional dependencies across spatial and channel dimensions. [Results]The proposed model achieved a precision of 92.0%, an improvement of 1.1%; a recall rate of 91.0%; and a mean average precision(mAP@0.5) of 93.3%, an increase of 1.4%. In terms of computational efficiency, the model's computational load was reduced by 60% to 3.4 GFLOPs, and the number of parameters decreased by 0.95 M to only 1.95 M, demonstrating excellent lightweight characteristics.[Conclusion]Compared with mainstream lightweight detection algorithms, the proposed method exhibits significant advantages in balancing accuracy and efficiency. It provides an effective technical solution and important reference for real-time, accurate detection of grape leaf diseases and practical applications in resource-constrained environments.

Interaction Between Water Ecological Resilience and Urban Development in Urban Agglomeration of the Yellow River Basin

[Objective]Promoting high-level synergy between water ecological resilience and urban development is important for achieving the ecological protection and high-quality development of the basin. [Methods]Based on the panel data of the Yellow River Basin urban cluster from 2007 to 2022, the projection tracing model was used to measure the water ecological resilience and the comprehensive level of urban development; and the constraint strength of the two subsystems was calculated using the constrained effect model. Further analysis of the coupling coordination and its driving factors of the water ecological resilience and urban development was conducted using the coupling coordination degree model and the geographical detector model. [Results]The water ecological resilience and overall level of urban growth of the Yellow River Basin urban cluster demonstrated a gradual rising trend during the study period, but there was significant regional variation. The constraint strength of the two subsystems decreased gradually in time sequence, and the overall system remained strongly constrained. The coupling coordination of water ecological resilience and urban development of the Yellow River Basin urban cluster showed an upward trend, and there was a notable spatial imbalance,exhibiting a "south high and north low" pattern. The "near-disbalance" and "barely coordinated" groups accounted for the majority of the coupling coordination level. Population aggregation, water resources, and water utilization efficiency were the core driving factors,and the interaction between these factors showed a non-linear strengthening or double factor enhancement feature, which synergistically promoted the system's coordinated evolution. [Conclusion]A new pattern of water-city synergy determined by water availability and capacity should be constructed by regulating the urban development mode that improves the water ecological resilience.

Soil-sickness Problem in the sustainable Development for the Protected Production of Vegetables

As the development of specialized production of vegetable crops, soil sickness has been a problem for the sustainable production of vegetable crops. Soil sickness is mainly caused by soil--borne pests, disorder of soil physical and chemical properties, and autotoxicity. The present paper discussed possible role of cropping system, biological control and grafting in the soil--borne pest control, role of organic fertilizer, desalting and reasonable fertilization in soil restoration, and the alleviation of autotoxicity by grafting, adsorption with charcoal and degradation by microbes.

Current Situation and Prospects of Green House Industry Development in China

This paper summarized comprehensively the history, current development of the green house industry and its researches. The historic significance, problems, and prospects were also analyzed. The summary was expected to provide references for determining the historic position and future developmental direction of green house industry.

Effect of Lodging Resistance on Yield and Its Relationship with Stalk Physical Characteristics

Stalk physical characteristics and tilt angle of matured plant of eighteen populations from six cultivars wereinvestigated under three conditions. The relationships between lodging resistance and yielding were also studied. TheresultS indicated that: the intensity of lodging of rice population could be grouped into three categories-lodging, slantand erect types according to the tilt angle of matured plant. Lodging resistance is significantly negatively correlatedwith the length of the first internode, and significantly positively correlated with the area of the basal stalk and withthe thickness of the hasal stalk. Difference among varieties and lodging resiStance was also found. Nitrogenapplication also had an obvious effect upon population lodging of rice. But if only yielding was considered, the highyield populations were given usually in the medium fertilization treatment. Therefore, rice resistance to the lodgingcould be improved by means of shortening length between the first and the second internode, strongtheningthe hardnes of the basal stalk, lowering the position of panicle, and elonging panicle or the neck-panicle internode.So the contradiction between lodging resiStance and plant height could be settled at a level of higher yielding.

Comparison of A New Model of Light Response of Photosynthesis with Traditional Models

Photosynthetic rates increase gradually with light intensity in the traditional models of light response curve of photosynthesis,i.e.rectangular hyperbolic model and nonrectangular hyperbolic model.So the maximum net photosynthetic rates calculated by nonrectangular hyperbolic model and rectangular hyperbolic model were far more than the measured data,and the saturation light point was not obtained.A new model of light-response of leaf net photosynthesis was proposed in this paper.Some properties of the new model of light-response of leaf net photosynthesis were discussed in detail.Results showed that the data of light-response of leaf photosynthesis of winter wheat under different environmental conditions were modeled by three models.The results fitted by nonrectangular hyperbolic model,rectangular hyperbolic model and the new model were compared.In addition,the measured data of light response of photosynthesis under different temperatures and CO2 concentrations could be dealt with,and the main parameters of photosynthesis,i.e.the maximum photosynthetic rates,saturation light point,light compensation point and the rate of dark expiration could be calculated without any hypotheses.The response data of leaf photosynthetic rate to irradiance under low irradiance and photo inhibition could be fitted by the new model.The measured data of light response of photosynthesis under different temperatures,CO2 concentrations and light intensity,including at low photon fluxes and photo inhibition could be dealt with.The fitted results were tallied with very well the measured data.So the new model has generality.

Current Situation of Remediating Techniques of Petroleum Contaminated Soil and Its Prospects

Current situations and damage of petroleum contaminated soils were summarized. Several main methods and techniques of remediating petroleum contaminated soil, application as well as advantages and disadvantages of the techniques were introduced in the paper. It points that traditional methods and techniques should combined with the bioremediation in the process cleaning the pollution, which will play the advantages of respective techniques. In the same time, the economic benefit, social benefit and environmental benefit should be considered together in treating petroleum contaminated soils.

A COMPARISON OF METHODS OF MEASUREMENT OF CHLOROPHYL IN PLANTS

Current Situation and Prospects of Green House Industry Development in China

This paper summarized comprehensively the history, current development of the green house industry and its researches. The historic significance, problems, and prospects were also analyzed. The summary was expected to provide references for determining the historic position and future developmental direction of green house industry.

Status and Developing Prospects of Biopesticide Research and Application

Biopesticides have many advantages over the traditional chemical pesticides,being safe to human,livestock and nontarget organisms,having wonderful environmental compatibility,stable controlling effects and benefit to protect the biodiversity,and having many resources etc.Status of research and application of biopesticides were reviewed in this paper.The authors pointed out the major problems in the research and application of biopesticides.The developing prospects of biopesticides were discussed and some advices were given for biopesticide development in future.

Determination of Blueberry Anthocyanins through pH Differential Method

For determinieg the contents of blueberry anthocyanins more exactly,the blueberry pigments were extracted by acidic alcohol and were identified anthocyanins by UV-VIS spectra and chemical methods.The blueberry anthocyanins were quantitatively analyzed through pH differential method.The results indicated that the content of blueberry anthocyanins was 313.24mg.100g-1 and the relative standard deviation was 1.39%.The influence on measuring results by impurity in the solution was eliminated by pH differential method.

Current Situation of Remediating Techniques of Petroleum Contaminated Soil and Its Prospects

Current situations and damage of petroleum contaminated soils were summarized. Several main methods and techniques of remediating petroleum contaminated soil, application as well as advantages and disadvantages of the techniques were introduced in the paper. It points that traditional methods and techniques should combined with the bioremediation in the process cleaning the pollution, which will play the advantages of respective techniques. In the same time, the economic benefit, social benefit and environmental benefit should be considered together in treating petroleum contaminated soils.