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Air conditions are usually used to control the environmental parameters in plant factories with artificial light. Among them, the air velocity is generally lower than the optimum range of 0.1-1 m/s that is required for plant growth. The occurrence of tipburn behavior is often observed on the inner and newly developed leaves of lettuce plants, especially during the last days of transplanting. It is very necessary to properly design the airflow in the indoor cultivation systems, thus promoting the growth for less occurrence of tipburn in the lettuce plants. The perforated air tubes can be used to improve the airflow. However, this ventilation scheme is required by the installation of pipelines in the plant factory, inevitably leading to an increase in the installation process and the complexity of the project. In this study, a kind of air-conducting cultivation tank was designed to integrate with the cultivation bed (CBT). The airflow disturbance increased inside the crop canopy in the multi-layer cultivation mode of the plant factory, indicating the simple construction of the ventilation pipe. A model of CBT was also constructed using three-dimensional Computational Fluid Dynamic software (CFD). The airflow velocity was simulated and measured inside the plant canopy with the inlet velocity of 5 m/s. The root mean square error was 0.22 m/s between the calculated and measured airflow velocity. There was a consistent distribution of the simulated and measured geometric center section in the cultivation area, indicating the accurate simulation of the airflow velocity. The validated model was used to simulate the effects of different air inlet velocities on the airflow direction and distribution inside the crop canopy. The simulation results showed that the airflow entered the crop canopy area via the holes of the cultivation pipe, thus forming a regular airflow beam profile. There was a larger airflow area of high velocity in the crop canopy with the increase of the inlet airflow velocity. Once the inlet velocity was 6 m/s, the percentage of volumes was 56.3% inside the plant canopy with the air velocity between 0.1 and 1 m/s, and the volume-weighted average air velocity was 0.15 m/s in the canopy interior. Correspondingly, 6 m/s was selected as the entrance speed of CBT, where the mature lettuce was used as the test material. The microenvironment was compared in the inner part of the lettuce canopy under CBT and traditional ventilation control mode (TVC) under the same environmental conditions. A systematic investigation was carried out to test the effect of ventilation and temperature regulation on the air flow velocity. The results showed that the air temperature was 22.4 ℃ inside the canopy under CBT treatment during the light period, which was lower than the TVC treatment of 23.7 ℃. There was a relatively less significant difference in air temperature in the dark period. The average air relative humidity in the light and dark periods inside the canopy under the CBT treatment was 65.8% and 71.6%, respectively, which were 5.6% and 8.7% lower than those under the TVC treatment. As such, the CBT greatly contributed to the regulation and control of various micro-environmental parameters inside the crop canopy, compared with the traditional ventilation mode. The finding can provide the promotion value to reduce the requirements of environmental control for the high efficiency of air conditioning temperature. [ABSTRACT FROM AUTHOR]

An accurate and universal monitoring model of nitrogen nutrition can greatly contribute to the precise management and application of regional rice. In this study, a systematic investigation was carried out to explore the impact of the images on the monitoring models. The consumer-grade multispectral images were captured by unmanned aerial vehicles (UAV) from the different ecological sites and rice varieties. A series of field experiments were conducted at two test sites: Mengzhe Town, Xishuangbanna, Yunnan Province (with trial variety Yunjing 37) and Beibei District, Chongqing City (with trial variety Jiyu 6135) in South China, with the varying nitrogen levels. Four multispectral drones (DJI Phantom) were used to capture the multispectral images of the rice canopy during tillering, jointing, and heading stages. The nitrogen content in rice plant canopies (CNC) was measured to calculate the above-ground nitrogen accumulation (PNA) using the Kjeldahl method. The nitrogen nutrition monitoring models were established using vegetation indices, partial least-squares regression (PLSR), random forest (RF), and backpropagation neural network (BPNN) for the single trial site, single variety, different trial sites, and multiple varieties of rice. The transferability was also explored in the models. The monitoring models were established for the CNC and PNA during each growth stage of rice for the single trial site and single variety with the high accuracy (normalized difference vegetation index NDVI or near-infrared normalized vegetation index NNVI, where the coefficient of determination was 0.68-0.88). However, the inaccurate model was obtained with the vegetation index during the tillering stage (NDVI, the coefficient of determination was 0.53-0.79), indicating the low transferability of all models. It was difficult for the vegetation indices to construct the monitoring models for the canopy nitrogen content throughout the entire growth period of rice. But a monitoring model was established for the above-ground nitrogen accumulation of single-variety rice in the period of the growth using the ratio vegetation index, the high accuracy and the high transferbility of the model. The monitoring models constructed by PLSR, RF, and BPNN were more accurate than those by vegetation indices. Among them, the highest accuracy was achieved in the monitoring model for the canopy nitrogen content and above-ground nitrogen accumulation in the entire growth period of multiple varieties using RF, with the coefficient of determination values were 0.84 and 0.94, respectively, and root-mean-square errors of 0.28% and 10.09 kg/hm², respectively. The finding can provide a theoretical basis and technical support for the application of consumer-grade multispectral images captured by drones in monitoring rice nitrogen nutrition during the entire growth period of different ecological sites and rice varieties. [ABSTRACT FROM AUTHOR]

Erosion and sediment transport can vary greatly with the change of spatial and temporal scales in the continuous system from slope water flow to the river channel. The vegetation can be the main driver of the spatial and temporal evolution in the water flow structure, sediment erosion transport, and landscape patterns, as the landscape gradient decreases. It is worth noting that vegetation morphology and canopy structure are important factors to determine the impacts of vegetation on the fluid structure and sediment transport. In addition, the properties of sediment are also the key to clarifying the turbidity currents transport pattern in the natural environment. However, there is a lack of attention to the above two points in the available studies. In this study, the simulated plants were utilized using Acorus calamus L. and Abutilon theophrasti Medicus to deploy the vegetation patches of different densities in a randomized distribution, in order to configure with the natural sediment in different grain size gradations of turbidity currents. A lock-exchange flume experiment was carried out to clarify the influence of vegetation patches with the natural plant canopy morphological characteristics on the turbidity currents transport pattern and resistance. The feedback mechanism was also studied between the sediment grain size gradation factor and the turbidity currents movement pattern. The plant leaf length-width ratio was proposed as a measure of the change in the canopy morphological characteristics. The influence of canopy morphological characteristics and sediment grain size class on turbidity currents flow was expressed, in terms of the non-dimensional canopy dragforce at the plant stem scale CDaad, the non-dimensional canopy dragforce at each position CDaax, and the non-dimensional depositional flux DF. The results in the test conditions were as follows: 1) The transport and deposition processes of turbidity currents were influenced by the morphology of the plant canopy and the content of coarse-grained suspended material (weakly cohesive particles of 10-100 μm). There was an inverse ratio between vegetation canopy morphology size and non-dimensional depositional flux DF. Furthermore, the sediment was easily deposited in the vegetation patches with large canopy morphology. The coarse-grained suspension content was positively proportional to the non-dimensional depositional flux DF, whereas, there was no deposition of turbidity currents with the high coarse-grained suspension content. The trend of bed sand refinement along the water movement analysis was more significant in the turbidity currents streams with the larger vegetation canopy morphology or high coarse-grained suspended mass content. 2) The vegetation patches with the greater density and canopy morphology produced the greater canopy resistance. There was a greater effect on the water flow structure, the stronger water and sand blocking effect in the random distribution state. There was a low degree of influence of sediment grain size class on the vegetation canopy resistance, compared with the vegetation characteristics. 3) The turbidity currents movement state was zoned using the dynamic mechanism. There was also a strong feedback mechanism between the vegetation canopy morphology and sediment grain size gradation, together with the non-dimensional depositional flux DF in the resistance-dominated zone (CDaax>4.5). Both plant canopy morphology and vegetation density shared the positive feedback mechanisms with the canopy resistance. There were vegetation canopy morphology and sediment grain size on the turbidity currents. The finding can also provide some references to deepen the erosion mechanism in small watersheds. In practice, the transport and deposition processes of turbidity currents in small watersheds often need to consider the dynamic changes in water flow resistance and sediment characteristics that are affected by vegetation characteristics. The transport and deposition of sand-bearing water can be more complex in further research. [ABSTRACT FROM AUTHOR]

Water resource is very deficient in the world. Agricultural water consumption is accounted for a large proportion of the total. Especially, high consumption can be found in the protected cultivation of vegetables, due to the great scale and multiple cropping index. Hence, it is urgent to develop water-saving irrigation for protected cultivation. However, simple and practical technology is still lacking in practical production. In this study, three typical soil textures (loam, clay loam, and sandy loam) were adopted for vegetable cultivation. Cucumber was selected as the experimental material, because of its wide cultivation areas. A field experiment was carried out from 2021-08-02 to 2021-12-24 in the Chinese solar greenhouse in Beijing, China. Cultivation density was set as 2.57 plants per square meter. Three irrigation treatments for each soil texture were performed from the fruiting period in the form of drip irrigation. The accumulated solar radiation reached up to the setting value (15/20/25 MJ/m²), corresponding to the onset of the irrigation system. The data logger was reset and recounted in the control system. There was consistency in the total irrigation amount under the same accumulation of solar radiation for each soil texture. A systematic investigation was made to explore the effects of different irrigation strategies on the growth and quality of autumn-winter cucumber under the above soil textures. The average air temperature varied from 11.5 to 25.6 ℃ during this experiment. There were 35 days below 12 ℃ during nighttime. The daily solar radiation on the plant canopy varied from 0.18 to 11.87 MJ/(m²·d). Meanwhile, the average water vapor deficit during the daytime varied from 0.11 to 3.75 kPa. Results showed that the irrigation strategies with different accumulated solar radiations caused the ‘ high frequency and low irrigation amount’ and ‘ low frequency and high irrigation amount’ . However, there was no influence of different irrigation strategies on the fruit yield and irrigation water use efficiency using the same total irrigation amount under the same soil texture. Greater photosynthetic rate, leaf area, plant height, and number of internodes were obtained, when the accumulated solar radiation of 25 MJ/m² was set as the irrigation starting point, together with each irrigation amount of 3.22, 3.56, and 2.77 mm for the loam, clay loam, sandy loam, respectively. The highest contents of soluble sugar and vitamin C and the lowest nitrate content were all achieved, when the accumulated solar radiation of 20 MJ/m² was set as the irrigation starting point, together with the irrigation amount of 2.59, 2.85, and 2.22 mm for the loam, clay loam, sandy loam, respectively. Meanwhile, there was no significant difference in soil textures on the contents of soluble sugar, soluble protein, and vitamin C. Therefore, controlling accumulated solar radiation can be expected to serve as the irrigation starting point for the feasible irrigation strategy in protected cultivation. Meanwhile, the discrepant parameters of accumulated solar radiation as an irrigation starting point should be considered for the different cultivation goals under various soil textures. [ABSTRACT FROM AUTHOR]

The restoration and reconstruction of mangrove wetland ecosystem is one of the key research fields in ecological restoration in the coastal zone of South China. In order to reveal the physiological and ecological strategies to light conditions of mangrove species, the characteristics of leaf soluble protein contents and activities of antioxidant enzymes in seedlings of eight mangrove species(Sonneratia apetala, Kandelia obovata, Bruguiera gymnorhiza, Aegiceras corniculatum, Acanthus ilicifolius, Acrostichum aureum, Heritiera littoralis and Hibiscus tiliaceus)under different light intensity treatments(100%, 45%, 30%, and 10% of natural light intensity)were studied using shading control experiment. The results were as follows:(1)Low light intensities had little effect on the leaf soluble protein contents of Bruguiera gymnorhiza, Acanthus ilicifolius and Acrostichum aureum, whereas the other five species showed a decreasing trend of leaf soluble protein contents with the decline in light intensity.(2)The activities of superoxide dismutase(SOD)and ascorbate peroxidase(APX)in the leaves of Bruguiera gymnorhiza, Acanthus ilicifolius and Acrostichum aureum under 10% of natural light intensity treatment had no significant differences compared with the control, while the other five mangrove species showed a decreasing trend of all the five antioxidant enzyme activities. In conclusion, the results indicate that Bruguiera gymnorhiza, Acanthus ilicifolius and Acrostichum aureum are suitable to be planted under the forest with high canopy density, while Sonneratia apetala, Kandelia obovata, Aegiceras corniculatum, Heritiera littoralis, Hibiscus tiliaceus are suitable to be planted under the forest with lower canopy density or planted as middle and upper layer tree species in mangrove. The results of this study provide theoretical guidance for the optimal allocation of artificial mangrove communities. [ABSTRACT FROM AUTHOR]

【Objective】The study aimed to investigate the spatial distribution characteristics of fine roots and their effects on the electrical conductivity (EC), pH and water content (SM) of surface soil (0-10 cm) in coastal salt land under different plant configuration patterns. 【Method】The distribution characteristics of fine roots and the horizontal distribution patterns of soil conductivity (EC), pH and water (SM) of three plant configuration modes(tree stand model (TSM), shrub stand model (SSM), tree-shrub stand model (TSSM) and bare soil (CK) in new reclamation salt land were studied by combining root drilling method and geostatistics. 【Result】The horizontal distribution patterns of fine root biomass (FRD) and root length density (FRLD) under the three configuration modes had obvious differences and high coefficient of variation, and the differences in total amount were significant (P < 0.05). The TSSM model had the highest FRD and FRLD values (54.71 g/m² and 5451.66 m/m³), followed by TSM mode (20.62 g/m² and 2204.06 m/m³) and SSM mode (14.29 g/m² and 1717.83 m/m³). The horizontal distribution of soil EC, pH and water under the three configuration modes had obvious spatial heterogeneity, and CK had the highest spatial heterogeneity. After planting, roots changed the distribution patterns of soil EC, pH and SM in TSM, SSM and TSSM communities and made their distribution more homogeneous due to the shading effect of plant canopy to reduce soil surface water evaporation, the competition mechanism between plant underground roots, and the leaching effect of rainfall. Compared with CK, the soil salinity (EC) of TSSM, TSM and SSM decreased significantly (90.48%, 90.32% and 91.12%), and the soil pH reduced obviously (1.03%, 0.69% and 1.72%), while soil moisture (SM) showed significant increasing trend (41.52%, 45.16% and 46.44%).【Conclusion】FRB and FRLD were positively correlated with soil EC and SM under the three configuration modes. After planting, EC and pH of soil were decreased, SM content of soil was increased, and its spatial distribution pattern was changed. Among them, TSSM model had the largest FRB and FRLD owing the best ability to reduce soil salinity and pH and increase soil moisture, so TSSM model should be given priority when choosing plant configuration model. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plant phenotype has been one of the most important indicators to select and breed superior varieties in modern agriculture. The traditional phenotypic analysis of leafy vegetables cannot fully meet the requirement of large-scale production in recent years, such as the slow speed, large error, and limited dimension. Moreover, most morphological measurements have been currently confined to only several plants (such as maize, cotton and sorghum), particularly with the complex procedure and low automation. Taking the Chinese cabbage sprout as the research object, this study aims to extract the key phenotypic parameters of the plant using the high-throughput reconstruction and automatic segmentation of stem and leaf. Firstly, a multi-view geometry was utilized to reconstruct the three-dimensional model of Chinese cabbage sprout from sequence images. A series of pre-processing operations were used to establish the three-dimensional model of pure plants with the actual scale, including scale recovery, background removal, point cloud denoising, and uniform simplification. Secondly, the stem and leaf organs were automatically segmented using the convexity criterion and random sampling consistency. Thirdly, the principal component analysis and directed bounding box were combined to measure the plant height and width for the phenotypic parameters. The number of leaves was counted by the cluster segmentation of leaf clusters. The shortest path searching was selected to accurately calculate the leaf length and width. A greedy projection triangulation was used to calculate the leaf area. An HSV model and mean color histogram were utilized to measure the color characteristics for distinguishing health status of plants. The classification accuracy, recall, and F1-score were 0.922, 0.938, and 0.930, respectively. Finally, the segmentation experiments were carried out on the six varieties of Chinese cabbage sprouts at different growth stages. A comparison was then made with the ground truth. It was found that the parts belonging to stem and leaf were segmented correctly. The average precision, recall, and F1-score of stem and leaf organ segmentation were 0.961, 0.940 and 0.943 respectively, indicating better performance than the smoothing threshold-based and the color-based region growth. In addition, 50 samples were tested to verify the measurement. A regression analysis was performed between the algorithmic and manual measurements of Chinese cabbage sprout plant traits. The experimental results showed that the determination coefficients of plant height, plant width, leaf length, leaf width, leaf area, and leaf number were 0.987, 0.982, 0.984, 0.985, 0.922, and 0.924, respectively. The mean absolute percentage errors were 1.659%, 1.643%, 1.417%, 2.486%, 8.258%, and 6.000%, respectively. Among them, the Root Mean Square Error (RMSE) of plant height, plant width, leaf length, and leaf width were 0.261, 0.313, 0.174, and 0.100 cm, respectively. The RMSE of leaf area and number were 1.608 cm2, and 0.283, respectively. Consequently, the automatic measurement was realized for the seven key phenotypes of Chinese cabbage sprouts, including the plant height, leaf length, and color in lower error. Therefore, the segmentation and measurement can be expected to extract the plant phenotypic parameters with irregular leaf shape, especially in the young leaves of plant canopy, with high efficiency of phenotype extraction. The finding can provide an effective technical means for the efficient and accurate phenotypic analysis of leafy vegetables. [ABSTRACT FROM AUTHOR]

Green roofs have drawn much more attention under the promotion of the Sponge City-Low Impact Development Rainwater System (LID) in modern urban construction and planning. Much more green roofs have been built so far. However, there is a great challenge on the later maintenance in the process of green roofs, such as the difficult irrigation, high cost, and large water consumption. Therefore, automatic irrigation is urgently needed suitable for roof greening. Taking the microfiber capillary as the material, this study aims to propose an automated irrigation technology for the roof green potted test, called the microfiber capillary wicking irrigation (MCWI). Taking the Antirrhinum majus, Murraya paniculata, Podocarpus macrophyllus, Portulaca grandiflora, succulent plant, and Sedum lineare as test plants, a systematic investigation was made to clarify the effects of MCWI treatment on the soil water content and evapotranspiration of green roof. The transpiration rate and evapotranspiration amount were measured for the different plants in different seasons using the specific steaming instrument. A three-temperature model was established to evaluate the MCWI performance on the evaporation of green roofs. The field experiment was carried out in the Zhuhai Campus, Sun Yat-sen University, Guangdong Province, China. The results showed that the average soil water contents of Murraya paniculata, Antirrhinum majus, and bare soil module with MCWI were 27%, 18%, and 47% higher than those without MCWI, respectively. The MCWI increased the soil water content, further reducing the occurrence of water stress. The transpiration rate of Antirrhinum majus with MCWI was significantly higher than that without MCWI (P>0.01) in summer (rainy season). The average daily transpiration rates of Antirrhinum majus were more than 13.8, 39.2, 45.7, and 19.0 J/(m2 ·s) on April 8, May 18, June 29, and July 27, 2021, respectively. Simultaneously, the maximum transpiration rates with MCWI were 22.3, 104.4, 94.0, and 30.8 J/(m2 ·s) higher than those without MCWI, respectively. The largest difference in transpiration rate between MCWI and non-MCWI was at 12:00-14:00, the hottest period of the day. Correspondingly, the higher the temperature was, the greater the temperature difference between plant canopy and air surrounding. By contrast, the bottom temperature of the test module with the MCWI was higher than that without MCWI in winter (dry season), no matter the day and night. The MCWI increased by 0.25 °C for the average temperature of the roof base, indicating a less temperature variation for the better energy storage of the green roof in winter. Evapotranspiration of Sedum line with MCWI at night was 0.14 mm higher than that without MCWI, but the MCWI evapotranspiration in the daytime was 0.57 mm lower than that without MCWI, indicating the overall decrease of 9.3% in the MCWI treatment. The change was attributed to the formation of dew in the process. Consequently, the MCWI can be used to improve the soil water content, the evapotranspiration of vegetation in summer, and to increase the roof evapotranspiration at night in winter. At the same time, it is also necessary to explore the air moisture for the green roof during the day, further to promote the non-precipitation resource. This finding can also provide sound theoretical support to the microfiber capillary wicking irrigation for water-saving green roofs. [ABSTRACT FROM AUTHOR]

A micro-sprinkling hose has been a promising type of equipment for water-saving irrigation, due to the cheap, easy to lay and pack up when working. The performance of the micro-sprinkling hose depends on the kinetic energy in the process of field irrigation. Correspondingly, the intensity of kinetic energy can be determined by the droplet distribution of spraying water in the air, where the irrigation water is sprayed from the thin pipe within regular orifices. There is also a different tolerance of various plant organs to the kinetic energy of droplets sprayed from the micro-sprinkling hose. Particularly, the plant height and the canopy coverage of crops vary greatly in each growth period. In this study, an indoor irrigation experiment was carried out to explore the influence of spraying angle and pressure on the droplet distribution of micro-sprinkling hose. An N44-5 micro-sprinkling hose was used, where “44” was defined as the folding diameter of 44 mm, and “5” was represented a group of five orifices on the pipe wall of the micro-sprinkling hoes. Four working pressures were set, including 20, 24, 28, and 32 kPa, expressed as P20, P24, P28, and P32. Three spraying angles were also set, including 40°, 60°, and two-angle combinations, expressed as A40, A60, and A4060. A total of 12 working conditions was completed in the entire experiment. The measuring points were arranged in the wet area of the micro-sprinkling hose. Then, the irrigation water was sprayed from the single or two holes of the micro-sprinkling hose under different conditions, where the spraying water droplets were passed through the measuring area of the instrument. An LPM instrument was developed to measure the droplet number, diameter, velocity, and irrigation intensity of the spraying water. The results showed that: 1) The irrigation intensity at A40 was relatively stable, with the production of working pressure, where the intensity was 17.9-23.0 mm/h. Meanwhile, the irrigation intensity decreased gradually, with the increase of the working pressure at A60. When the two angles were combined for the irrigation, the irrigation intensity of the micro-sprinkling hose presented an outstanding increase trend, where two peaks of irrigation intensity were generated. 2) The droplet diameter decreased under the same spraying angle, with the increase of working pressure. However, the diameter of single-hole spraying droplets in the micro-sprinkling hose decreased under the same working pressure with the increase of spraying angle. 3) Both spraying angle and working pressure posed great influences on the spatial velocity and droplet diameter distribution of the single hole spraying droplets in the micro-sprinkling hose. The diameter range of the droplet was 0-2.5 mm for the single hole with the micro-sprinkling hose, where the droplet diameter was concentrated in the range of 0.45-1.25 mm. This finding can provide promising theoretical support to design the micro-sprinkling hose. [ABSTRACT FROM AUTHOR]

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Much more cultivation layers and high canopy density have posed great challenges to the even distribution of airflow in plant factories. It is highly required for the optimal design of airflow distribution systems, thereby improving the physiological orders and post-harvest quality for a high commercial value of the products. In this study, a ventilation system was designed with the three parallel lines of perforated air tubes, further to generate a constant airflow inside the plant canopy. The air tube was fabricated in a diameter of 0.02 m with a length of 1.5 m using the layout and size of a cultivation shelf. Each air tube was equipped with two rows of jets. A three-dimensional computational fluid dynamics (CFD) model was developed to analyze the distribution of airflow in the plant’s canopy under different inlet velocities. Furthermore, the lettuce leaves were assumed as the porous medium with the drag coefficient of 0.02, resulting in a viscous resistance factor and the inertial resistance factor of 25 and 1.3, respectively. A LED lamp (Ø0.02 m) was assumed as an aluminum substrate and a glass part. An energy term with a constant heat generation of 297 525 W/m3 was also defined as the heat source lost by the volumetric convection from the LED lamp aluminum substrate part for the heat dissipation. The average error of simulated air velocity was 16%, compared with the measured. Three groups of air velocity (lower than 0.1 m/s, between 0.1 and 1.0 m/s, and higher than 1.0 m/s) were selected to calculate the proportion of the areas of the plant’s canopy surface and the volume proportion inside the plant’s canopy. The results showed that the percentage of air velocity at the lettuce canopy surface between 0.1 and 1 m/s increased from 33.33% to 68.57%, while, the percentage of volumes inside the plant’s canopy increased from 44.84% to 77.08%, respectively, when the air velocity increased from 6 to 9 m/s. By contrast, the percentage of volumes inside the plant’s canopy increased from 0.01% to 0.06%, with the air velocity higher than 1.0 m/s. The maximum distance between the ventilation pipe and high airflow increased from 50 to 70 mm. Therefore, the air velocity was recommended as 8 m/s, further to avoid the air velocity higher than 1 m/s plants canopy. At the inlet air flow velocity, the percentage of volumes inside the plant’s canopy with the air velocity between 0.1 and 1 m/s was 67.58%, the percentage of areas on the plant’s canopy surface with the air velocity between 0.1 and 1.0 m/s was 55.23%, and the volume-weighted air velocity in the canopy was 0.14 m/s. This finding can provide a new solution to improve the canopy environment in a plant factory. Much more cultivation layers and high canopy density have posed great challenges to the even distribution of airflow in plant factories. It is highly required for the optimal design of airflow distribution systems, thereby improving the physiological orders and post-harvest quality for a high commercial value of the products. In this study, a ventilation system was designed with the three parallel lines of perforated air tubes, further to generate a constant airflow inside the plant canopy. The air tube was fabricated in a diameter of 0.02 m with a length of 1.5 m using the layout and size of a cultivation shelf. Each air tube was equipped with two rows of jets. A three-dimensional computational fluid dynamics (CFD) model was developed to analyze the distribution of airflow in the plant’s canopy under different inlet velocities. Furthermore, the lettuce leaves were assumed as the porous medium with the drag coefficient of 0.02, resulting in a viscous resistance factor and the inertial resistance factor of 25 and 1.3, respectively. A LED lamp (Ø0.02 m) was assumed as an aluminum substrate and a glass part. An energy term with a constant heat generation of 297 525 W/m3 was also defined as the heat source lost by the volumetric convection from the LED lamp aluminum substrate part for the heat dissipation. The average error of simulated air velocity was 16%, compared with the measured. Three groups of air velocity (lower than 0.1 m/s, between 0.1 and 1.0 m/s, and higher than 1.0 m/s) were selected to calculate the proportion of the areas of the plant’s canopy surface and the volume proportion inside the plant’s canopy. The results showed that the percentage of air velocity at the lettuce canopy surface between 0.1 and 1 m/s increased from 33.33% to 68.57%, while, the percentage of volumes inside the plant’s canopy increased from 44.84% to 77.08%, respectively, when the air velocity increased from 6 to 9 m/s. By contrast, the percentage of volumes inside the plant’s canopy increased from 0.01% to 0.06%, with the air velocity higher than 1.0 m/s. The maximum distance between the ventilation pipe and high airflow increased from 50 to 70 mm. Therefore, the air velocity was recommended as 8 m/s, further to avoid the air velocity higher than 1 m/s plants canopy. At the inlet air flow velocity, the percentage of volumes inside the plant’s canopy with the air velocity between 0.1 and 1 m/s was 67.58%, the percentage of areas on the plant’s canopy surface with the air velocity between 0.1 and 1.0 m/s was 55.23%, and the volume-weighted air velocity in the canopy was 0.14 m/s. This finding can provide a new solution to improve the canopy environment in a plant factory. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

There are relatively few studies on the spray quality of citrus tree canopy in China. In most cases, the method is that farmers observe the spray quality of citrus tree canopy up close in the orchard, which wastes manpower and material resources. Moreover, the observation effect is not ideal and may cause harm to human safety. Domestic conditions allow some orchards to judge the spray effect by observing the water-sensitive paper. This method does save a lot of manpower, and efficiency is significantly improved compared with the previous ones. However, this method is affected by the external environment, and the naked eyes cannot correctly determine the spray quality, which will cause certain errors. Therefore, this study explored new ways to solve these problems. In recent years, thermal imaging technology had shown great research promise in some emerging research areas, especially in agricultural production. In the field of precision agriculture, for example, high-resolution thermal imaging cameras, with the aid of advanced aerial photography technology, can quickly capture thermal images of the canopy before and after spray, which provides new ideas for precision agriculture spray detection technology. This study combined thermal imaging technology and computer vision technology to identify and classify the spray conditions of the plant canopy and accurately detected the spray quality of the leaves, which avoided the waste of pesticides and reduced the manual re-examination steps. Thereby reducing agricultural production costs and improving the economic benefits of agricultural products. In this study, the canopy of a citrus tree was used as a thermal image acquisition area. Inevitably, there are problems such as high noise, low contrast, and blurred feature information in the thermal image acquisition process. In response to the above problems, this study preprocessed the acquired thermal images and eliminated unreasonable data, and set the original data set to two labels (sprayed and unsprayed), and divided them into the training set and the test set. An improved SPP-Net-Inception-v4 model based on the Inception-v4 model and the SPP-Net target detection algorithm was proposed to achieve multi-feature fusion to enhance the feature extraction effect. The model took the construction of a sparse network structure to generate dense data as the core design idea. By introducing the Inception and Reduction modules, the feature description bottleneck problem was reduced; further, SPP-Net (Spatial Pyramid Pooling Network) was innovatively connected between the convolutional layer and the fully connected layer pooling network), which aimed to extract fixed-length feature vectors through the pyramid space pooling method to achieve the fusion of multi-scale features and extraction enhancement effect. Compared with the two models of Inception-v4 and ResNet-152, the experimental results showed that the accuracy of the improved SPP-Net-Inception-v4 model test set was 95.07%, which was 1.58% higher than the accuracy of the original Inception-v4 model and 3.26% higher than that of ResNet-152. Compared with Inception-v4 and ResNet-152, the SPP-Net-Inception-v4 model reduced the model size by 13% and 24%, respectively. The SPP-Net-Inception-v4 model could be used to detect the spray quality of chemicals in citrus fruit trees quickly as well as could improve the economic benefits of agricultural production, and would provide a reference for the further improvement of pesticide detection technology in precision agriculture. [ABSTRACT FROM AUTHOR]

The usage of aircrafts to perform crop spraying is becoming increasingly prevalent, owing to their high speed and efficiency in operations, compared with the manual crop spraying representing an expensive and time-consuming labor activity in agricultural production. Agriculture drones or unmanned aerial vehicles (UAVs) have attracted increasing attention, due to their small size, easy handling, and without a runway, particularly suitable for small farmlands in Asia. Currently, the agriculture drones have been widely used in modern precision agriculture. The UAVs has produced rapidly in East Asia for their excellent application efficiency and ability to protect densely planted crops, especially in China. A survey that conducted by the National Agricultural Technology Extension Center of Ministry of Agriculture and Rural Affairs showed that there are more than 50 000 plant protection drones, and 311 333.3 hm² cultivated field spraying in 2019. Nowadays, the spray technology applied on UAVs has developed into the main plant protection approaches. However, the key theory associated with the spraying technology of UAVs remains unknown. Three key theories mainly are: 1) The characters of downwash flow structure and its effect on droplet movement during aerial spraying, as well as plant canopy. Unique complex feature in the downwash flow structure of UAVs influences the law of droplet dispersion, the velocity and direction of droplet movement, as well as the canopy structure and morphology of target plant, particularly on the incidence angle, the impact diameter, and impact velocity of droplet, during the interaction process between droplet and plant. There was a significant influence on the droplet deposition and drift. 2) The flight parameters of UAVs, spray parameters in a spray system applied on UAVs, and physical quality have posed an important effect on the droplet deposition and drift. The flight parameters UAVs also influence the downwash flow structure and droplet transport distance. The unreasonable parameters of UAVs flight can cause some deposition, resulting the drift potential of droplet. The formulation and spray parameters in the UAVs can also influence the droplet size, dispersion, and transport velocity, indicating the interaction process between the droplet and downwash flow of UAVs, as well as the law of droplet deposition and drift. 3) The interaction mechanism between the droplet and plant. There was a significant influence on the retention and drift of final droplet, and the biology efficacy of pesticide, indicating a critical part of plant protection. An investigation on the key theories can contribute to improve the performance of spray technology using UAVs. This review covers the current status related to three key theories, presenting an idea to build the downwash flow model of UAVs, a droplet dispersion model, a droplet evaporation model, the interaction model between downwash flow and droplet, between downwash flow and plant canopy, and between droplet and plant canopy, and a spray retention model applied on UAVs basing on these daughter model. The parameters of flight and spray were optimized by the spray retention model, indicating an excellent spray performance. [ABSTRACT FROM AUTHOR]

The real-time, fast, non-destructive and quantitative monitoring of leaf area index (LAI) is critical for precise regulation population quality of double cropping rice production. The objective of this study was to test the accuracy and adaptability of crop growth monitoring and diagnosis apparatus (CGMD) in double cropping rice of different plant types growth index monitoring and application, and to establish the leaf area index (LAI) monitoring model of double cropping rice based on CGMD. Field experiments were conducted in Jiangxi China in 2016 and 2017, including different plant type cultivars and nitrogen application rates. The differential vegetation index (DVI), normalized difference vegetation index (NDVI) and ratio vegetation index (RVI) were measured at tillering stage, jointing stage, booting stage, heading stage and filling stage with two spectrometers, i.e., CGMD (a passive multispectral spectrometer containing 810 and 720 nm wavelengths) and analytical spectral devices (ASD, a passive hyper-spectral spectrometer containing 325 to 1 075 nm wavelengths). Vegetation indexes change characteristics were compared between CGMD and ASD, and their quantitative relationships were analyzed. The LAI monitoring models for compact and loose plant type cultivars of double cropping rice were established based on CGMD from field experimental dataset in 2016 and then validated using field experimental dataset in 2017. The results showed that the LAI, DVI, NDVI and RVI of different plant type cultivars were increased with increasing nitrogen application rate at different growth stages. All of them showed a “low-high-low” trend with double cropping rice development progress. The determination coefficient (R²) of DVI, NDVI and RVI based on CGMD and ASD were 0.959-0.968, 0.961-0.966 and 0.957-0.959, respectively. This indicated that vegetation indexes based on CGMD and ASD was highly consistent, and the CGMD could be used to replace expensive ASD to measure NDVI, DVI and RVI. The prediction effect of LAI monitoring model at single growth stage based on CGMD vegetation indexes was better than that in the whole stage, and the prediction effect of LAI monitoring model in the loose plant type cultivar based on CGMD vegetation indexes was better than that in the compact plant type cultivar. The linear equation based on DVICGMD could be used to estimate LAI with the R² in the range of 0.857-0.903, and the correlation coefficient (r), root mean square error (RMSE) and relation root mean square error (RRMSE) of model validation in the range of 0.950-0.984, 0.18-0.43 and 3.95%-9.40%, respectively. The exponential equation based on NDVICGMD could be used to estimate LAI with the R² in the range of 0.831-0.884, and the r, RMSE and RRMSE of model validation in the range of 0.906-0.967, 0.24-0.38 and 5.73%-9.16%, respectively. The power function equation based on RVICGMD could be used to estimate LAI with the R² in the range of 0.830-0.881, and the r, RMSE and RRMSE of model validation in the range of 0.905-0.954, 0.25-0.56 and 7.37%-9.99%, respectively. Compared with the normal manual sampling method, using the CGMD can real-time and non-destructive monitoring the LAI dynamic change of double cropping rice. The CGMD could be used to replace SunScan (an expensive plant canopy analyzer used to measure LAI) to measure LAI of double cropping rice, which has a potential to be widely applied for precise regulation of LAI and high yield cultivation in double cropping rice production. [ABSTRACT FROM AUTHOR]

Aiming at the problem of the computational complexity and low segmentation precision of the multi-threshold image segmentation method, this paper proposed an ISCA based multi-threshold image segmentation method. Firstly, this method used a chaotic initialization technique to improve the quality of initial population. Secondly, it introduced an adaptive strategy to adjust the parameters according to the fitness values. Finally, it utilized an opposition-based learning strategy, then selected the better particles. The results of the Berkeley image and the plant canopy image segmentation experiments show that this method has a satisfied performance in terms of running time and segmentation accuracy. And it has a strong robustness. [ABSTRACT FROM AUTHOR]

Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The plant factory has been developed for many years, a series of theory and approach of environmental control in such facilities have been established. However, the environmental parameters closed to the plants were significantly affected by the physiological activity of leaves and boundary layer resistance of the canopy, leading to suboptimal microclimate deviated from the set values, poor ventilation uniformity and inefficiency of air conditioning. In this study, a new environmental control technic was proposed to introduce the regulated ambient air into the interlayer between cultivation plates and nutrient solution surface in a deep flow hydroponic system, then flow out upward into the internal canopy through the reserved vent hole units on cultivation plates, which was called root zone ventilation(RV). By adjusting the fan speeds and their running modes, low rotation rate continuous root zone ventilation (LCRV) and high rotation rate intermittent root zone ventilation (HIRV) treatments were proposed. The effects of these treatments on microclimate change of mature butterhead lettuce (Lactuca sativa var. capitata) were examined, and the performances on environmental regulation were evaluated by comparison with conventional environment control (CEC) under identical ambient environment conditions at the same time. RV treatments were carefully isolated by black films to prevent airflow impact from ambient. The CEC cultivation area was in an open state, under the air distribution of the plant factory, air flowed over the canopy from one side to another, formed the traditional side ventilation mode. The results showed that the interlayer air temperature of all treatments were lower than ambient value, while higher in relative humidity (RH). Specifically, LCRV earned the lowest temperature, which was 2.67°C lower than ambient. RH of CEC was the highest, which was 100%. Identical trend was also observed in the internal canopy, where LCRV temperature was 3.47°C lower than ambient, and the RH of CEC was 27.56% higher. The CO2 concentration in such area under the action of LCRV is 139×10-6 higher than CEC. With the increasing of height and canopy occlusion, the influence of RV on the environmental parameters of canopy was gradually weakened. Although LCRV was still the lowest in temperature, the gap from ambient was narrowed down to 0.75°C, while CEC temperature grew from below to 0.84°C above ambient. Reduction was observed in RH differences as well. LCRV, the highest in RH, was only 15.8% higher than ambient. In nutrient solution, its temperature in LCRV was 4.03°C lower than CEC. Meanwhile, HIRV slowed down the dissolved oxygen (DO) depletion to a big extent. At the end of the experiment, DO in HIRV was still maintained at 3.8 mg/L, while the other treatments were only 2.8 mg/L. In conclusion, RV technique overcomes the airflow occlusion and boundary layer resistance of canopy effectively. Benefit from it, uniformity, efficiency of ventilation and environment control were improved. In addition, there were obvious differences between the microclimate around canopy in CEC and plant factory ambient, showed the importance of using microenvironment parameters around the plants as the temperature control targets, instead of the ambient. RV played a positive role in lowering internal canopy temperature. It was feasible to cut down energy consumption by increasing ambient setting temperature while reducing refrigeration capacity and start-up frequency of air condition system. For CEC, further refrigeration capacity and energy consumption were inquired to achieve approximate environmental parameters around canopy as RV did. In addition, RV influenced the rhizosphere parameters positively. The decreasing of nutrient solution temperature and DO descent rate may have great impact on root development and plant growth. In future technological renewal of plant factories, this kind of precise microclimate control technology for each cultivation units will replace existing whole space ventilation mode and applied in medium and large plant factories. [ABSTRACT FROM AUTHOR]

Solar radiation is an important parameter affecting light and thermal environment in solar greenhouse. Accurately obtaining the solar radiation value and variation of the interior wall and ground in the greenhouse can play an important guiding role in greenhouse design, construction, environmental regulation and crop production. On the basis of summarizing the previous models of solar radiation, a relatively perfect solar radiation model of solar greenhouse was established in this paper. Meteorological data, the laws of the earth and the movement of the sun, and the relationship between the sun's rays and the angle of the front roof were all considered in this solar radiation model. Internal radiation change of the greenhouse was analyzed based on the model. The model was verified in typical sunny days. The results showed that there were some differences between the calculated and measured solar radiation values, the MBE(mean bias error) was 63.46 W/m2, the MAE(mean absolute error) was 63.48 W/m2, the RMSE(root mean square error) was 79.18 W/m2 and the coefficient of determination R2 was high, ranged from 0.95 to 0.99. The model can be used to calculate the solar radiation intensity of the wall and the ground of solar greenhouse in any area anytime. Highly accurate analysis of the radiation change and the variation of light transmittance in the greenhouse in different seasons were achieved in this paper. It was found that the light transmittance is more affected by the solar azimuth and the solar elevation angle than by the roof angles at different positions. The solar radiation on the surface of the wall and the ground in greenhouse changes with the seasons. The spring equinox and autumn equinox are the days in which the wall and the ground received the longest solar radiation during the year. At this time, the surface of the wall is roughly equivalent to the solar radiation on the ground. From the spring equinox to the autumn equinox, the ground radiation is higher than the surface radiation, while it is opposite when it comes from the autumnal equinox to the vernal equinox. The daily accumulation of solar radiation on the wall changed little from the winter solstice to the start of spring, decreased from the start of the spring to the summer solstice and rose from the summer solstice to the start of winter. The time from winter to the start of the spring is the main production season in the greenhouse, and the heat accumulation of the wall is also the highest in the whole year. Therefore, it is of great significance to carry out research on the heat storage at this stage. Solar radiation in greenhouses in different regions is mainly affected by latitude. In lower latitudes, the amount of solar radiation in winter is large and the amount of radiation in summer is small. The research results can provide reference and related data for the study of wall heat storage, roof optimization, crop planting and energy balance of envelope in solar greenhouse. In addition, the change rule of solar radiation in greenhouse was analyzed just under clear and cloudless conditions. For the plant canopy shade, radiation under different weather conditions, insulation quilt position, different rear roof incline angles and lengths, azimuth angles, wall inclined angle and other aspects of the solar radiation change inside the greenhouse can be further explored by the method proposed in this paper. [ABSTRACT FROM AUTHOR]

Aiming at the problem that the standard particle swarm algorithm is easy to fall into the local optimum which leads to poor image segmentation effect, a hybrid particle swarm optimization algorithm combined with simulated annealing algorithm is used to optimize the threshold selection process of multi-threshold image segmentation. The variance function between Otsu classes is used as the fitness function of the algorithm and simulated annealing algorithm is used to avoid jumping into local optimum. The experiment results show that the algorithm can effectively deal with the problem of complex plant canopy image segmentation, and can improve the image segmentation accuracy while guaranteeing the operation efficiency. It provides a theoretical basis for improving the reliability of plant growth condition evaluation and the accuracy of leaf information, with a strong engineering practicability. [ABSTRACT FROM AUTHOR]

To investigate the flow field characteristics of large-size plant protection unmanned helicopter hedgehopping，the numerical simulations were conducted,and the full-size physical model of the large-size helicopter was established. The three-dimensional flow field of large-size unmanned helicopter hedgehopping was simulated by SST k-ω turbulent flow model. The results show that the downwash flow field is relatively disorder under the fuselage because of the obstruction of fuselage.The distribution characteristics of downwash are generally consistent at the same nozzle location of different height，however the distribution characteristics of downwash are quite different for the same flight altitude at different nozzle location. The vertical velocity is increased with latter decreasing along the direction of rotor at the spray boom location，and the maximum velocity is obtained near the x/R value of 0.8. The width of plant canopy velocity is increased with the decreasing of flying height，and the better fly height of H is 4 m. The boom of UAV should be installed in the area with z from -1.50 to -2.00 m and x from -0.50 to 0.50 m. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Accurate three-dimensional canopy structure of fruit trees is an important carrier for the study of functional structure model, and the canopy leaf is an important part of the fruit tree canopy structure. The spatial distribution and morphological structure of leaf canopy play an important role in fruit yield and quality. Compared with field crops, fruit trees have high branches, complex branches and luxuriant branches, so the rapid and accurate reconstruction of tree canopy is the focus of current research. With the development of laser measurement technology, 3D (three-dimensional) laser scanner is widely used in 3D reconstruction of plants because of its high precision, wide collection range, high efficiency and non contact. An accurate and automatic canopy leaf reconstruction method of fruit tree is presented based on point cloud. Firstly, using FARO Laser Scanner Focus3D to obtain dense point cloud of fruit tree canopy leaf, and according to global characteristics (the point cloud density distribution meets the ellipsoid layered characteristics) and local characteristics (different organs and organs of different parts have different point cloud density) of the leafy trees point cloud, this paper proposes a point cloud density shrinkage method with ellipsoidal layer to realize the separation of leaf point cloud. The model's parameters (the leaf width and the radius of main branches) are obtained by manual measurement. And experiment shows that point cloud segmentation effect is the best when the relation coefficient is 0.75 between the density threshold and the average density of the point cloud. After the point cloud density calculation, high-density point cloud on each leaf is gathered in the veins, and high-density point cloud of branches is gathered in the intersection of branch and branch bulge so as to realize the segmentation between organs. Then we calculate leaf characteristic parameter by the principal component analysis algorithm of the neighboring point cloud, in which the K mean algorithm is used to simplify the leaf point cloud, and the principal component analysis is used to calculate the normal vector of the leaf point cloud. Then, after removing the leaf point cloud, the branches point cloud is contracted into a connected skeleton by the Laplacian shrinkage algorithm which is a classical point cloud shrinkage algorithm, so as to realize the automatic reconstruction of canopy leaf combined leaf template. Finally, with C++ and Point Cloud Library (PCL), the automatic reconstruction system of point cloud of canopy leaf is developed on the PlantCAD development platform, and the method is validated by different types of fruit trees (Fuji apple tree, Wanglin apple tree, Maogu citrus tree). The results show that the recognition accuracy of leaf is higher than 90%, the correct rate of leaf area index is more than 95%, the number of leaf inclination deviation within 5 degrees is more than 90% of the total leaf, the efficiency is more than 7 times that of the artificial, and there is less artificial participation in the whole process. It gets better effect of visualization, and strong sense of reality and canopy leaf reconstruction precision, which provides effective technical support for the research on the photosynthesis, pruning and training of the tree as well as experimental simulations in the later period. Nevertheless, this method depends on the density of point cloud data, and has poor robustness to non ellipsoidal tree and severe noise point cloud (acquiring under windless weather). In the future, we will study the adjacent relation of the leaf point cloud, and make the algorithm adaptive to different tree structure and sparse canopy leaf point cloud. [ABSTRACT FROM AUTHOR]

To investigate the relationship between canopy structure and understory wild flower, the typical method of plant community was applied to research the effect of canopy structure on wild flower in Nanling mountain forest and provide theoretical reference for the garden application of wild flower. The result showed that there were 104 species/hm2 in investigated area, which belonged to 55 families and 92 genuses, in which Indocalamus tessellates, Fissistigma oldhamii and Sinarnndinaria basihirsnta were dominant species; Kruskal-Wallis analysis and regression analysis indicated that leaf area index (LAI), canopy openness (CO) and transmitted diffused light (Tdif) had larger effects on understory wild flower than other canopy structure parameters; The effects of each canopy parameters on wild flower species density of three hues (cold, warm and neutral) had no significant differences, while the species density of three hues decreased at first and increased later with LAI and transmitted total light changing; Multi-Response Permulation Procedure (MRPP) and Indicator Sp eci es An alysis (ISA) revealed that Morinda officinalis and Barthea barthei were the indicative species of both CO and LAI which had stronger responses to change of canopy structures. [ABSTRACT FROM AUTHOR]