Abstract:【Objective】 Excessive application of pesticide has adverse impact on the quality and safety of agricultural products and ecological environment in China. It has become critical to optimize the pesticide spraying approach and improve the pesticide utilization and spraying effect. 【Method】 Droplet size detection technology development and the relationship between droplet size and control effect were introduced based on the investigation on present testing methods of pesticide droplet size. The theory of optimum spraying droplet size was discussed. Method to determine optimum spraying droplet size and current research status were analyzed. Existing problems of optimum pesticide spraying droplet size were summarized. Suggestions were proposed for future research of spraying droplet size in agricultural aviation. 【Result】The optimum droplet size achieved from artificial surface is inconsistent with actual optimum size in real spraying operation. Artificial surfaces tend to collect only large droplets. Massive drift does not inevitably occur to small droplets. The optimum particle size of the spray is changing in different stages of the same target. A large number of experimental data have showed that small droplets were more easily adsorbed on the surface of target to kill pests by penetrating inside the plant canopy. 【Conclusion】 The best spraying particle size varies very much for different pesticides, targets or liquid concentrations, even in different growth periods of pests. In the future, theoretical study on optimum pesticide droplet size should be strengthened from multi-angle macroscopic and microscopic analysis. In addition, precision controllable nozzles with variable diameter must be developed for agricultural aviation applications.

Abstract:【Objective】Obstacle avoidance is a crucial issue in unmanned aerial vehicle(UAV) operation. Ultrasonic transducers are critical components in UAV obstacles avoidance system. The vibration characteristics of UAV are important to increase UAV obstacles avoidance capability. Research was conducted to understand the vibration characteristics of small-size UAV(SUAV) and impacts of vibration on ultrasonic sensors. 【Method】Spatial distributions of SUAV vibration strength and the distributions in frequency domain were derived by acquiring SUAV vibration data at multiple test points with different throttles. The impact of SUAV vibration characteristic on ultrasonic transducer performance was detected through the spatial distribution of vibration strength. 【Result】With the distance away from the center and along the arms of SUAV, the increase and decrease of vibration strength occurred alternatively. Equipped with propellers, the ultrasonic transducer had a max error of 0.69 m in horizontal direction while the maximum error only reached 0.20 m in vertical direction. 【Conclusion】With the distance away from center and throttles increasing, the amplitude of vibration is strengthened. To avoid the effect of vibration, it is necessary to adjust the vibrational frequency of sensor. Findings reported in this paper may provide guidance for applications of ultrasonic transducer in agricultural SUAVs.

Abstract:【Objective】The feasibility of agricultural information extraction and analysis based on low cost agricultural visible band platforms with low altitude remote sensing was investigated to provide a technical support for precision spraying and monitoring with unmanned aerial vehicles (UAVs).【Method】A series of tests were conducted to study the visible light remote sensing images that contained only red, blue and green bands. First, Zhang correction method was used to get the distortion matrix of camera and to correct images. Then, the visible vegetation indices were extracted from corrected images. Finally, by analyzing the spectral characteristics of low altitude farmland visible images of vegetation and non-vegetation, the vegetation information was extracted from visible band based on low altitude remote sensing images. 【Result】Vegetation was separated from non-vegetation area with farmland vegetation index extraction.【Conclusion】 Agricultural information acquisition system based on visible light low altitude remote sensing is applicable and can provide a reference for the development of low cost visible band monitoring system with low altitude remote sensing.

Abstract:【Objective】In order to improve the efficiency and utilization of conventional unmanned aerial vehicle (UAV) spraying in fertilizer and pesticide applications, an variable rate UAV spraying system was developed based on image recognition.【Method】Median filter was applied to the images for denoising. K_means clustering algorithm was then used to segment the UAV images to extract 22 texture features and the color of non-crop region. Support vector machine (SVM) classifier was designed for classification. According to the 17 selected characteristic parameters, the non-crop region was recognized through the SVM classifier with Radial basis function (RBF) as the kernel function. Finally, precision spraying was achieved with controllable nozzles based on the recognition results.【Result】The recognition accuracy reached up to 76.56%. In undisturbed wind farm, the reduction rate reached 32.7% with the threshold P of 10%.【Conclusion】This research can serve as reference guides for application of precise spraying control technology in agricultural aviation.

Abstract:【Objective】Fuzzy PI closed loop control algorithm was studied for constant speed demand in agricultural unmanned aerial vehicle (UAV) operations.【Method】The principle and structure of the UAV electrical control system was analyzed in this paper. According to the requirement of electrical control system for brushless direct current motor (BLDCM) speed adjustment, the simulation model of BLDCM control system was established in Matlab/Simulink software environment. Double closed loop control of speed and current was applied with fuzzy PI speed control and current hysteresis control. Simulation analysis was conducted with defined systematic parameters. The ARM circuit simulation board was built to verify the effectiveness of the algorithm.【Result】Simulation results proved that the BLDCM control system had improved response speed, reduced overshoot, and higher anti-disturbance capacity with fuzzy PI control. In addition, the dynamic behavior and robustness ability of the system were improved as well.【Conclusion】This study proves effectiveness of the fuzzy PI closed loop contriol algorithm and provides theoretical reference for real UAV control system design and debugging.

Abstract:【Objective】To provide communication services for agricultural aviation plant protection service providers and terminal farmers, accelerate the establishment of agricultural aviation standards, promote the transformation of achievements in scientific research institutions, implement the national plant protection UAV tracking and monitoring, promote the normalization of agricultural aviation market, popularize agricultural aviation applications in precision agriculture, and help achieve zero growth in pesticides and fertilizers application. 【Method】Based on the thoughts and methods of the “Internet +”, combined with the characteristics of agricultural aviation and the services development in China, an “Internet +” agricultural aviation services platform was designed. New generation of information technologies, such as big data, cloud computing, mobile applications and HTML5 were applied for the technical design in developing the fundamental platform architecture design of agricultural aviation services, the service work-flow design, UI interface design, and database design.【Result】The advanced and integrated agricultural aviation services platform was established, including plant protection services management, operation effectiveness evaluation, UAV detection, plant protection UAV regulation, and big data application.The platform had good properties of plaform, user and big data, and excellent expansibility.【Conclusion】The architecture design of the platform can meet the requirements of agricultural aviation users and service providers to simplify the plant protection operation, and achieve the purpose of government to effectively manage information as well. At last, through data analysis based on multi-mining techniques, this design provides various value-added services, and ultimately realizes a virtuous circle of agricultural aviation services ecosystem effectively with better services for agricultural modernization in China.

Abstract:【Objective】 To assess the carcass and meat quality traits of American Duroc×(Landrace×Yorkshire) three-way cross hybrid (ADLY) pigs and Taiwan Duroc×(Landrace×Yorkshire) three-way cross hybrid (TDLY) pigs, and to analyze the effects of breed and gender on these traits. 【Method】A total of 203 pigs including 118 ADLY pigs (50 barrows, 68 sows) and 85 TDLY pigs (57 barrows, 28 sows) with similar body mass (110±5) kg were slaughtered in the same abattoir, and were measured for carcass traits such as live mass, carcass mass, loin eye area, backfat thickness and loin eye depth, and meat quality traits such as meat color, marbling, PSE (Pale, soft, exudative) value and electrical conductivity. The measurements were statistically analyzed. 【Result】All carcass traits of TDLY pigs were better than those of ADLY pigs except for lean meat percentage (P<0.01), and the meat color, electrical conductivity and a^* value of TDLY pigs were better than those of ADLY pigs (P<0.05), while ADLY pigs had higher PSE value and shear force compared with TDLY pigs (P<0.05). Compared to sows, castrated boars had thicker backfat (P<0.01) and lower lean meat percentage (P<0.05). The sows of TDLY pigs had higher electrical conductivity and L^* value compared to boars (P<0.05), while the boars of ADLY pigs had much better marbling and smaller loin eye area compared to sows (P<0.05). 【Conclusion】 In general the carcass traits of TDLY pigs were better compared to ADLY pigs, while the meat quality traits were better for the latter. The carcass traits of sows were better than those of castrated boars for both ADLY and TDLY pigs.

Abstract:【Objective】 To study the expression of germ-cell special gene Sohlh1 in different tissues of young and adult pigs, analyze the features of molecular genetic evolution of Sohlh1 gene, and determine the core region and specific regulatory region of the promoter. 【Method】The expressions of Sohlh1 gene in different pig tissues and different time were verified by RT-PCR. The features of molecular genetic evolution of Sohlh1　gene was analyzed using biology software, the promoter was constructed and confirmed by a verification vector, and the core region and specific regulatory region of the promoter were analyzed by dual luciferase assay.【Result】Sohlh1 gene was expressed in testis of piglet and adult pig and ovary of piglet, and was not expressed in ovary of adult pig. Sohlh1 gene had evolved along with the evolution of lower to higher vertebrates based on phylogenetic analysis of SOHLH1 proteins in multiple species. The core region of the promoter of pig Sohlh1 gene was near 78 bp, and the specific regulatory region was between 771 and 2 981 bp based on dual luciferase assay of the promoter verification vector. 【Conclusion】Pig could be a superior animal model compared with rodent based on Sohlh1 gene evolution analysis. The tissue specific expression of Sohlh1 gene may be mainly controlled by the specific regulatory region of its promoter.

Abstract:【Objective】 To investigate the predatory effect of red-eared slider turtle, Trachemys scripta elegans on golden apple snail,Pomacea canaliculata so as to provide an effective way for resource utilization of P. canaliculata, and to explore its indirect interference effect on P. canaliculata.【Method】T. scripta elegans and P. canaliculata were put in a set of specially-designed plastic aquarium together, control effects of the turtles on various sizes of snails were determined through regular surveys of the survival and damage of P. canaliculata. Meanwhile, the change of feeding, growth and survival of another group snails outside the cage net under indirect interference effect of T. scripta elegans were investigated, which means that the snails were exposed to the caged predators which had no opportunities to attack them but can respond to alarm signals from conspecific snails predated by turtles.【Result】The snails under the predation of T. scripta elegans for 14 days, only one third of individuals were still alive, among which, the survival rate of small snails (5-15 mm shell height) and medium snails (15-25 mm shell height) decreased to 0 and 40 percent respectively. Two thirds of large snails (25-35 mm shell height) survived but the injured individuals accounted for 45 percent of the survival. The food intake of the other snails (medium) significantly decreased and growth was restricted under the indirect interference of the turtles, although this treatment exhibited less impact on its survival.【Conclusion】T. scripta elegans has strong predatory effect on the invasive P. canaliculata, that also depresses the feeding and growth of surrounding conspecific snails which can perceive the predation risk. These findings would provide new ideas for control of P. canaliculata in its invaded habitat and origin area of turtle (United States), and provide reference values for invasion mechanism and population dynamics research of P. canaliculata.

Abstract:【Objective】To isolate nematophagous fungus Arthrobotrys musiformis from substances associated with cattle and sheep, and observe the process of the fungus predating third-stage larvae of Haemonchus contortus and free-living nematode Caenorhabditis elegans. 【Method】A. musiformis was isolated using baited plate technique, and the dynamic processes of A. musiformis predating H. contortus and C. elegans were observed under scanning electron microscopy (SEM). A. musiformis isolate NPS045 was inoculated onto 20 g·L^-1 water agar plate covered with cellulose membrane on agar surface, incubated for four days, and then the nematodes were added to the plates. The samples containing nematodes and fungi were collected and observed at different time points after the two nematode species were captured. 【Result】SEM analysis showed that 5 hours after the two nematode species were added, A. musiformis produced predating structures and started to capture the nematodes. The third-stage larvae of H. contortus were penetrated by A. musiformis 22 hours after being caught, invasive hyphae grew out of the larval body after 56 hours, and the larvae were completely digested by 68 hours. C. elegans were penetrated by A. musiformis and clearly shrunk 14 h after being caught, seriously collapsed after 19 hours, and were completely digested by the 24th hour. 【Conclusion】Seventeen A. musiformis strains were isolated from 1 502 samples associated with cattle and sheep, and the prevalence of A. musiformis in total samples was 1.13%.

Abstract:【Objective】 To study the effects of hormone, salt, fungi and artificial wounding induction on resistance ability of Aquilaria sinensis trees, and discover the mechanism of agarwood formation in A. sinensis trees.【Method】We conducted the experiment in Huidong county, Guangdong province, and used a random block design with three single tree repeats per treatment. Six months after stimulation, stress-resistance related substances and enzyme activities were analyzed for A. sinensis tree samples.【Result】Among the different treatments of hormone, salt, fungi and artificial wounding, the optimal treatments were treatment 2 (MeJA and Et), treatment 8 ［NaHSO₃(w=1‰), NaCl(w=20‰) and FeCl₂(w=10‰)］, treatment 10(Trichoderma atroviride) and treatment 16 (burning-chisel-drilling). For these four treatments, the contents of essential oil were 8.48%, 9.86%, 12.46% and 6.21% respectively, approaching or reaching agarwood quality standard (10%). Polyphenol, soluble sugar content, and CAT, POD, SOD, NOS, PAL activities were higher compared to other treatments of the same treatment type, while MDA and starch contents were relatively lower. Based on principal component analysis, the scores of resistance ability of A. sinensis trees with treatment 2, 8, 10 and 16 were 1.83,2.31,2.10 and -1.51, respectively, all highest among the same treatment type. 【Conclusion】 MeJA and Et, NaHSO₃(w=1 ‰), NaCl(w=20‰) and FeCl₂(w=10‰), Trichoderma atroviride and burning-chisel-drilling could induce strong resistance, and could promote agarwood formation of A. sinensis trees.

Abstract:【Objective】 To demonstrate the morphological and physiological response of Cunninghamia lanceolate roots, and the variation of nutrient and microorganism contents in potting soil under phosphorus (P) deficiency.【Method】Three treatments including P deficiency (P0), normal concentration P (P1) and high concentration P (P2) were applied to potted C. lanceolate seedlings. The temporal dynamics of root phenotype and physiology, as well as the nutrient and number of microbes of the potting soil were measured.【Result】 After 30 days treatment, P0 had the least accumulations of shoot and whole plant dry mass, and the highest accumulation of root dry mass and root/shoot ratio, which were 2.07 and 5.37 times of those of P1, respectively. Starting from day 15, the root P uptake rate of P0 had been the lowest while P utilization rate had been the highest. At day 30, the root P uptake and utilization rates for P0 were 43.18% and 231.59% of those for P1, respectively. Root surface area and root tip number increased with the increase of treatment time, and were 3.46 cm² and 56 respectively for P0 at day 30, significantly higher compared to P1 and P2. During the entire treatment process, acid phosphatase, SOD activities and MDA content of P0 were significantly higher compared to P1 and P2. Compared with P1 and P2 treatments, P0 had obviously higher content of soil alkali hydrolysable nitrogen, serious shortage in available P, minor differences in pH, available K and cation exchange capacity, significant increase in acid phosphatase activity, and decrease in the number of fungi.【Conclusion】P deficiency(P0) treatment led to increase in root dry mass accumulation and root/shoot ratio, increase in root surface area and root tip number with the increase of stress time, decrease in P uptake rate but increase in P utilization rate, and significant increase in root acid phosphatase, SOD activities and MDA content. In addition, acid phosphatase activity of the potting soil significantly increased, alkali solution nitrogen content obviously increased, available P content was in serious shortage and fungi content was the least for P0 compared to other treatments. Therefore, P deficiency has significant effect on root growth, as well as nutrient and number of microbes of potting soil.

Abstract:【Objective】 In order to study the diurnal variations in fluxes of greenhouse gases including CO₂, CH₄ and N₂O from Acacia mangium plantation soil, and determine the optimal observation time. 【Method】The emission fluxes of CO₂, CH₄ and N₂O from A. mangium plantation soil in southern China were continually observed using static-chamber and gas chromatograph. 【Result】The fluxes of CO₂, CH₄ and N₂O from A. mangium plantation soil had clear diurnal variations. The A. mangium plantation soil was a source of CO₂ and N₂O and a sink of CH₄. The daily fluxes of CO₂, N₂O and CH₄ ranged from 401.33 to 555.59 mg·m^-2·h^-1, 24.50 to 34.72 μg·m^-2·h^-1 and -10.96 to -41.88 μg·m^-2·h^-1 respectively. The fluxes of CO₂ or CH₄ from soil surface had highly significant (P<0.01) or significant (P<0.05) positive correlations with soil temperature at 5 cm depth, while CH₄ flux from soil surface was not significantly correlated with soil temperature.【Conclusion】Based on the analysis of the correction coefficients of three greenhouse gases and manipulability of sampling, the optimal time for collection and observation of these three greenhouse gases from A. mangium plantation in southern China during rainy seasons is around 09:00．

Abstract:【Objective】 To investigate the physiological mechanisms of drought adaptation and protective enzyme system of Saposhnikovia divaricata under drought stress. 【Method】 Three levels of water supply including full irrigation (CK), light drought stress（LD） and severe drought stress (SD) treatments were set up for annual S. divaricata. Effects of drought stress on leaf protective enzyme activities, contents of osmoregulation substances and total content of two chromones (prim-O-glucosylcimifugin and 5-O-methylvisammioside) of S. divaricata were studied. 【Result】The activities of superoxyde dismutase (SOD), peroxidase (POD), catalase (CAT), and proline content under different water treatments increased during early test stage，reached peak during middle stage and then decreased. Malondialdehyde (MDA) content under different water treatments increased throughout the entire test period. The total contents of two chromones under different water treatments all increased at early stage, reached peak during middle stage and then decreased for LD and SD treatments, while slowly increased during both middle and late stage for CK treatment. Changes in the activities of SOD, POD and CAT, the contents of osmoregulation substances, and the total contents of two chromones for LD and SD treatments were higher compared to CK, and the peak values of these measurements for LD and SD treatments were also higher compared to CK. There were significant correlations between CAT activity, the total content of two chromones and SOD activity under different water treatments.【Conclusion】Appropriately imposing drought stress in the cultivation of S. divaricata can increase protective enzyme activities and the contents of osmoregulation substances of S. divaricata leaves, which is beneficial for S. divaricata growth and can increase the total content of two chromones.

Abstract:【Objective】To explore effect of lipid content on major qualities of japonica rice grains and to provide a theoretical basis for breeding high quality rice in the future. 【Method】Twelve japonica rice cultivars were selected as the materials. Their lipid contents, protein contents, cooking and eating qualities and processing qualities were measured respectively, and the relationships were analyzed to find out the effect of lipid content on major qualities of japonica rice grains. 【Result】The lipid contents and breakdown values of D79 and Koshihikari were significantly higher than those of other 10 cultivars (P<0.05), but setback values of both cultivars were evidently lower than those of other cultivars (P<0.05). Koshihikari showed the highest taste value (84.2), and then followed by D79 and W140, which were significantly higher than those of other nine cultivars (P<0.05). No significant correlation was found between lipid content and processing quality or protein content (P>0.05). Lipid content exhibited the significant negative relationship with amylose content (P<0.01), and the positive relationship with taste value or breakdown value (P<0.05). 【Conclusion】Enriching lipid content and reducing amylose content could be beneficial to improve the cooking and eating qualities of japonica rice grains.

Abstract:【Objective】To optimize the chromosome preparation procedure and investigate the karyotype of malabar spinach (Basella alba) and to provide a theoretical basis for studying genetic and phylogenetic relationships of different types of malabar spinach.【Method】The cultivar ‘large leaf malabar spinach’ was used as plant material. Factors that affected chromosome preparation including organ selection, pretreatment and dissociation durations were investigated. With the optimized protocol, the karyotypic characteristics were analyzed.【Result】The proportions of mitotic cells and metaphase cells of the main root tip samples were the highest compared to other sampled organs. Six-hour pretreatment using 0.002 mol·L^-1 8-hydroxyquinoline resulted in the highest degree of chromosome contraction, the best shape and evenly spreading of chromosomes. Eight-minute dissociation at 60 ℃ using 1 mol·L^-1 HCl resulted in the highest contrast with clear chromosome staining and transparent cytoplasm. The karyotype formula of malabar spinach is 2n=2x=44=38m (2SAT)+6sm. The constitution of relative length is 20 M2+22 M1+2 S, and the ratio of chromosome length to width is 1.93. The relative length ranges from 3.13% to 6.06%, the centromeric index ranges from 3519% to 47.86%, and the arm ratio ranges from 1.09 to 1.84. The 10^th, 16^th and 17^th pairs of chromosomes belong to submetacentric chromosomes and the rest are metacentric chromosomes. Two satellites were observed at the 13^th pair of chromosomes. The karyotype asymmetry index is 57.89%, and malabar spinach has the 1A karyotype according to Stebbins’ classification criteria.【Conclusion】This study established an optimal chromosome preparation procedure for malabar spinach，and revealed its karyotypic characteristics from the cytogenetic aspects.

Abstract:【Objective】 To overcome the defects of 418-type heat interchanger in bulk curing barn, such as being susceptible to corrosion and having short service life, and to optimize the structure and performance of heating equipment in bulk curing barn.【Method】 A nonmetallic refractory material with high conductivity was choosen to make the heat interchanger. The heat interchanger was structured with three layers of circular horizontal dual pipelines and three heating interchange pipelines in the same vertical plane were connected by an S-shape connector. The heat interchanger was equipped with a squared and vaulted stove (with a cast iron cover)feeding disposable coal. Using bulk curing barn with metal heating equipments as the control, the performances and baking effects of the nonmetallic refractory heating equipment in bulk curing barn were studied.【Result】The heating rate of bulk curing barn installed with the nonmetallic refractory heating equipment(5.36 ℃·h^-1) was significantly lower than the control(21.73 ℃·h^-1) without loading tobacco, while its cooling rate was slower than the control. The results showed that bulk curing barn installed with nonmetallic refractory heating equipment showed great temperature stability and the trends at three key point temperatures（38,42,55 ℃）were the same. Its plane and vertical temperature difference was less than the control during curing. Compared with the control, the heat efficiencies of baking the middle and upper tobacco leaves increased by 12.42% and 6.74%, the coal consumption rates reduced by 22.50% and 15.13%, the average prices of the dried tobacco leaves after curing increased by 0.84 and 0.20 yuan per kilogram respectively, the proportion of medium-high grade tobacco leaves increased, and the effects of energy saving and quality improving was obvious in the bulk curing barn with nonmetallic refractory heating equipment.【Conclusion】The heating equipment made of nonmetallic refractory material with high conductivity has excellent baking performence and high corrosion resistant, and can be applied for heating equipment update in bulk curing barn.