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Li D.,Hunan Academy of Agricultural science | Li D.,Hunan University of Technology | Li D.,CAS Institute of Subtropical Agriculture | Tang N.,Hunan Academy of Agricultural science | And 8 more authors.
Nanoscience and Nanotechnology Letters | Year: 2016

Plastid transformation has been successfully employed in several dicotyledonous plants for genetic modification, but it is difficult to be achieved in monocotyledonous cereal crops and remains still a demanding technique in the engineering agriculture field. One of major obstacles applying plastid transformation in crop plants is the limited availability of suitable selective markers. Hygromycin B is an aminoglycoside antibiotic which has the ability to inhibit prokaryotic protein synthesis, but to our best knowledge, it has never been reported in the research of plastid transformation yet. In this study, we aimed to use the hygromycin phosphotransferase gene (hpt) as a selective marker gene for tracking plastid transformation in rice. A site-specific transformation vector of rice plastid, pCTE04, was constructed for dicistronic expression of the hygromycin phosphotransferase (hpt) and enhanced green fluorescent protein genes (EGFP). The results showed that transplastomic rice plants successfully grew up after a gradual selection of hygromycin resistance. Integration of the dicistronic expression cassette into the intergenic region trnI-trnA of plastid genome was verified by Southern blotting analysis. Transplastomic expression of the hpt and EGFP genes was identified by RT-PCR. The stable expression of dicistronic cassette in the rice was confirmed by confocal microscopy. Although the plastid transformants in rice presented a heteroplastomic status, this study may facilitate the development of new selective markers and further improvement of plastid transformation efficiency in cereal crops. Copyright © 2016 American Scientific Publishers All rights reserved.


Niu K.,China Agricultural University | Niu K.,Chinese Academy of Agricultural Sciences | Zhou L.,Chinese Academy of Agricultural Sciences | Yuan Y.,Chinese Academy of Agricultural Sciences | And 3 more authors.
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2016

Spoon-chain metering is the most widely used metering device in small and medium-sized potato planter at present because of its high reliability, low cost and adjustable plant spacing. Its performance is closely related with the planting quality. However, spoon-chain metering still encounters loss sowing problem, which can be reduced by optimizing structure and parameters of metering device. Nevertheless, the rate of loss sowing is still around 7%. Artificial assistance metering can resolve these problems effectively but with increased labor intensity and hidden danger. In order to solve this problem, a loss sowing detection method based on capacitance value precision measurement technology was proposed in this paper, and an automatic re-seeding system was designed which was mainly composed of control system, capacitance sensor and reseed-metering device. In order to test performance of the automatic compensation system, a performance test was carried out using self-made device. Spoon-chain was driven by a servo motor and its speed was adjusted by servo driver. Reseeding-chain was driven by a servo motor and its speed was controlled by PLC controller. Micro potatoes, with diameter of 25~30 mm, were used in main metering system and re-seeding system. The metering speed was set as 0.3, 0.4, 0.5, 0.6, 0.7 m/s, and the number of theoretical seed metering was 600 at different speeds. By mounting a laser sensor on seed discharge hole, the number of normal seeding and re-seeding were recorded by PLC automatically. Total seeding, loss sowing, normal seeding, theoretical seeding, re-seeding rate, original rate and final rate of loss sowing can be calculated. The tests showed that, with the metering speed increasing from 0.3 m/s to 0.7 m/s, the original rate of loss sowing, the final rate of loss sowing, the metering row spacing error and the reseeding row spacing error were increased from 7% to 11.3%, 1.1% to 1.75%, 3.3% to 9.1% and 7.6% to 16.9%; with the increasing of chain speed, changes of reseeding rate were relatively small, and the final rate of loss sowing was less than 1.75%, and rate of reseeding was around 84.6%. The performance of the designed compensation system is stable, and the loss sowing problem of potato spoon-chain metering device can be solved well. © 2016, Chinese Society of Agricultural Machinery. All right reserved.


Zhao Z.,South China Agricultural University | Zhao Z.,Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China | Shi L.,South China Agricultural University | Liu X.,South China Agricultural University | And 3 more authors.
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2015

Kinematics model of mechanical hydraulic system usually involves the speed, acceleration and geometric constraint, which will contain one or two and even higher order differential equations. The number of differential-algebraic equations (DAEs) increases with the increase of system complexity. In order to find a suitable control arithmetic, it is needed to figure out the relationship of different state variables. However, it's always impossible to get analytical solution. Thus it is needed to find the numerical solution of DAEs system, especially when it has too many state variables. Solving this problem with computer software is a common way; there are several helpful softwares, such as Matlab, Maple, Simulink and Mathematica. The mathematical function provided by the Matlab ode45 was used to solve the kinematics model of leveling system of paddy field leveler with sinusoidal input current. Firstly, the real paddy field leveler was simplified to kinematics model and showed in DAEs form based on theoretical mechanics and hydraulic theory. Secondly, the DAEs were changed into ODEs (ordinary differential equations). Finally, the ode45 was used to get numerical solution and show the relationship of state variables. The input current and output state variables were showed in figure. The method can help to get accurate numerical solution for DAEs system, and it also can display the relationship between the random input with known equations and other state variables. It will help to forecast the state variables at the next moment and design an efficient control algorithm for paddy field leveler. © 2015, Chinese Society for Agricultural Machinery. All right reserved.


Ma X.,South China Agricultural University | Ma X.,Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China | Tan Y.,South China Agricultural University | Qi L.,South China Agricultural University | And 4 more authors.
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2016

At present, most of the work that taking trays out from the rice nursery seedling planter is completed one by one manually, which is labor-intensive and inefficient. There are some tray stackers can realize the function of automatic stacking, but the existing devices are only suitable for hard trays. Aiming at above problems, the automatic tray stacking device of rice precision seeding for nursing seedlings pipeline, suitable for both hard and soft trays, was developed to improve productivity and reduce labor intensity. According to the characteristics of common hard tray, the pallet of soft tray was developed for stacking. Besides, the transportation mechanism was designed through analyzing the conveying model. Based on the programmable logic controller (PLC), the trays were detected by a proximity switch of the control system, and the tray stacking mechanism was controlled to lift and drop the trays to achieved the tray stacking automatically(2~4 trays per stack is available). In addition, the cover plate of the soil anti-falling mechanism was controlled to lift after stacking and finally the device can effectively prevent the soil falling out of the tray in the process of stacking that lead to seeds exposed. For detecting the performance of automatic tray stacking device, the orthogonal experiment was carried out which regarded stacking success rate and seeds exposed rate as indexes and regarded the lifting speed of tray stacking mechanism, cover plate installation conditions and productivity as factors. Orthogonal experiment results showed that the lifting speed had more influence on success rate while the lifting speed and cover plate installation conditions had more influence on seeds exposed rate. When the lifting speed was 0.15 m/s, the cover plate installing with pneumatic cylinder and the productivity was 600~800 trays per hour, the stacking success rate of hard tray and soft tray was 100% and 99%~100% respectively while the seeds exposed rate was 0.28% and 0.60% respectively. The automatic tray stacking device can effectively raise productivity and reduce labor intensity, and the experimental indexes meet the using requirements of rice precision seedling. © 2016, Chinese Society of Agricultural Machinery. All right reserved.


Zhao R.,South China Agricultural University | Hu L.,South China Agricultural University | Hu L.,Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China | Luo X.,South China Agricultural University | And 4 more authors.
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2016

Aiming at reducing the influence caused by uneven fields to the working quality of precision agricultural equipment, lots of agricultural machinery were designed with special mechanisms to profile the farm surface, while the working efficiency is still limited to the response rate of servo and control system. For above reasons, a kind of ARMA (Auto-regressive and moving average) algorithm was put forward and then be applied to predict vehicle attitudes so as to realize compensation control for tractor implement. The theory and applicability of ARMA were analyzed in detail before modelling using roll angle data collected from a working rice transplanter by the Inertia and GNSS measurement system. Finally, a 90 s-length data set was acquired of which the first 60 s data was used to model, while the last 30 s data was designed to make comparison with predicted values. In order to reduce the amount of calculation, the 100 Hz raw data at frequency of 2 Hz, 5 Hz and 10 Hz was output and then predicted the future roll angle of the three sets of data in 1~2 s respectively. First of all, the different method was deployed to make angle series stationary; secondly, a combining method of box order-search solution and the MLE (Maximum likelihood estimation) was adopted to build models; at last, with the aid of AIC (Akaike information criterion), the final best model was identified after confirming the AIC. For better following of the dynamic trend of rice transplanter attitude and eliminating the negative influence brought by the increasing amount of sample data, the on-line modelling method that older sample data was substituted constantly by new observational values in the modeling process was needed. By using three groups of sample data, prediction of rice transplanter attitude in future 1~2 s was conducted utilizing Matlab, meanwhile, the whole predicting time was 30 s. The results showed that: the validity of ARMA model in predicting attitude trend of farm vehicles was proven; for all the three sets of angle samples, 2 s predicting error shows larger than 1 s predicting error; the 5 Hz roll angle series showed the best predicting effect, with 1 s RMSE (root mean square error) and std (Standard deviation) of 0.6567°and 0.6565°, and 2 s RMSE and std of 0.6712° and 0.6769° respectively. © 2016, Chinese Society of Agricultural Machinery. All right reserved.


Yuan Q.,South China Agricultural University | Hu L.,South China Agricultural University | Hu L.,Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China | Luo X.,South China Agricultural University | And 4 more authors.
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2016

The widely-used online mixing system has a small range of mixture ratio and a detection problem at small flow ratio of pesticide. This paper developed an online-mixing system, which mixed pesticide into carrier directly. A spiral porous mixer, which included left-hand type and right-hand type of the spiral plates, was designed and assembled alternatively. A disk-shaped mixer was proposed to promote the uniformity of the concentration from the spiral porous mixer. This system consisted of a precise plunger pump to deliver the pesticide, an embedded controller based on STM32 to detect the water level in the tank, a disk-shaped mixer, and an electro-magnetic switch valve to provide a certain outflow of water. The water and pesticide were mixed in the spiral porous mixer, then flowed into the disc-shaped mixer, and sprayed on the crops by the spray pump. The pressure sensor was calibrated with the water level in the water tank, the flowmeter was calibrated with the pressure sensor, and used to test the error. The pulse frequency driving the plunger pump was calibrated with the rotate speed, and used to test the outflow error of pesticide. In the range of the work flow, the flow of the water and the flow of the pesticide were measured at the same time. Using chlorpyrifos as the target pesticide, the sampling points of the mixture concentration were measured by a liquid mass spectra. The actual density of the sampling points was obtained, and a comparison experiment with the artificial full mixing of the pesticide and the water was carried out. The experiment results showed that working at the mixture ratio of 150:1~1000:1, the average flow error of water was 1.35%, the maximum error was 7.15%; the average flow error of pesticide was 2%; the maximum error was 3%; the maximum error of the mixture ratio was 6.75%. After a test of mixing using chlorpyrifos, the average error of the mixture concentrations was 11.7%. © 2016, Chinese Society of Agricultural Machinery. All right reserved.


Zhou H.,South China Agricultural University | Hu L.,South China Agricultural University | Hu L.,Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China | Luo X.,South China Agricultural University | And 3 more authors.
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2016

Rotary tiller is a land preparing implement with great practicability, which is widely used to reduce the farming time and labor spend. The left and right wheels of tractor don't work in the same horizontal plane in practical due to the uneven farmland. Rotary tiller and tractor are connected by the three-point hitch, which means the rotary tiller has the same gesture as the tractor during the rotary tillage. Rotary tilling in lateral inclination gesture will not only destroy the untilled bottom of the farmland, but also affect the tillage flatness, tillage depth etc. All of this will ultimately lead to the poor rotary tilling quality and low working efficiency. To decrease the influence of rotary tiller working in lateral inclination gesture, a rotary tiller auto leveling system was designed which mainly including rotary tiller, leveling rack, hydraulic control system and the auto leveling control system. The front of leveling rack was connected to the tractor three-point hitch while rotary tiller was hanged in the lower back of the leveling rack with two pin rolls. One end of the leveling cylinder was hinged with leveling rack while the other was hinged with the rotary tiller. Therotary tiller rotated relatively to the telescopic movement of the leveling cylinder. Auto leveling control system controlled the solenoid directional valve according to roll angle of the tractor detected by angle sensor, and drove leveling cylinder stretching out and drawing back to adjust the angle between the rotary tiller and leveling rack (namely the angle between the rotary tiller and tractor). An auto leveling close-cycle control was designed to keep rotary tiller working in a desired angle by the means of combining the leveling cylinder elongation detected by the linear displacement sensor and the geometrical relationship between rotary tiller and leveling rack. Experiment was taken in ridge vegetable lands between auto leveling rotary tiller and the non-leveling rotary tiller. The data of the surface flatness of the field before and after plowing was collected by the level gauge, while the tractor roll angle and rotary tiller leaning angle were collected respectively by two attitude sensors at the same time. The tillage flatness and tillage depth of two kinds of rotary tillers and the performance of auto leveling system were analyzed. Experimental results show that the surface flatness by the auto leveling rotary tiller was improved significantly comparing to the non-leveling rotary tiller, the maximum height difference of the auto leveling rotary tiller in lateral direction was 1.9 cm, while the non-leveling rotary tiller was 9.8 cm; the tillage depth of auto leveling rotary tiller in lateral direction was more stable, the maximum height difference in lateral direction of the tillage depth was 1.8 cm, while the non-leveling rotary tiller was 9.7 cm. © 2016, Chinese Society of Agricultural Machinery. All right reserved.


Li P.,Hunan Agricultural University | Li P.,Chinese Academy of Agricultural Sciences | Li P.,Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China | Li F.,Chinese Academy of Agricultural Sciences | And 8 more authors.
PLoS ONE | Year: 2016

Plant viruses are mostly transmitted by sucking insects via their piercing behaviors, which may differ due to host plant species and their developmental stages. We characterized the transmission of a fijivirus, southern rice black-streaked dwarf virus (SRBSDV), by the planthopper vector Sogatella furcifera Horvâth (Hemiptera: Delphacidae), between rice and corn plants of varying developmental stages. SRBSDV was transmitted from infected rice to uninfected corn plants as efficiently as its transmission between rice plants, while was acquired by S. furcifera nymphs at a much lower rate from infected corn plants than from infected rice plants. We also recorded a high mortality of S. furcifera nymphs on corn plants. It is evident that young stages of both the virus donor and recipient plants added to the transmission efficiency of SRBSDV from rice to corn plants. Feeding behaviors of the vector recorded by electrical penetration graph showed that phloem sap ingestion, the behavioral event that is linked with plant virus acquisition, was impaired on corn plants, which accounts for the high mortality of and low virus acquisition by S. furcifera nymphs on corn plants. Our results reveal an asymmetric spread of SRBSDV between its two host plants and the underlying behavioral mechanism, which is of significance for assessing SRBSDV transmission risks and field epidemiology, and for developing integrated management approaches for SRBSDV disease. © 2016 Li et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Luo X.,South China Agricultural University | Luo X.,Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China | Liao J.,South China Agricultural University | Hu L.,South China Agricultural University | And 5 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2016

Although great development has taken place in agricultural mechanization since reform and opening up, China still faces the big challenge in improving agricultural resource utilization as well as promoting the sustainable development of agriculture at present. As we all know, it is mainly the 5 factors, i.e. water, soil, fertilizer, pesticide and seed that affect sustainable development in the construction of China's agricultural modernization. The overall development of agriculture in China will be impeded if the resource utilization stays low. There exist some phenomena: 1) the irrigation water use is 360 billion m3 each year, while canal-system water use efficiency is only 0.4~0.6; 2) high-quality cultivated land is lacking; 3) nitrogen use efficiency is about 30%~35%, which is 20% less than developed country; 4) pesticide utilization is merely about 30%, while leads to severe environmental pollution; 5) the demand of seeding quantity is high while there are shortage of high-quality seeds and serious waste of seeds. Accordingly, several technologies and machines in PA (precision agriculture) were put forward in this article so as to meet the requirement of agricultural sustainable development: precision irrigation, precision plow, precision fertilization, precision spraying, and precision sowing. By reviewing the researches at home and abroad, the current situation of PA was analyzed and thus the methods to achieve the 5 mentioned key technologies were presented. Meanwhile, some other suggestions were proposed to push the agricultural mechanization to play a greater and more important role on the utilization of agricultural resource and agricultural sustainable development: 1) further strengthen the combination of agricultural machinery and agronomy as well as the basic study of related theory; 2) carry out in-depth studies on key technologies of maximum utilization of agricultural resource, especially in precision irrigation, precision plow, precision fertilization, precision spraying, and precision sowing; 3) enhance the capacity of independent innovation, namely, the capability of equipment design and manufacture related to PA; 4) accelerate extensive application of precision agricultural machine and equipment. Above all, this paper has provided a scientific guide and policy direction for improving utilization of agricultural resource, promoting agricultural mechanization and agricultural sustainable development. © 2016, Chinese Society of Agricultural Engineering. All right reserved.


Zhang M.,South China Agricultural University | Zhang M.,Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China | Luo X.,South China Agricultural University | Luo X.,Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China | And 8 more authors.
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2016

Due to the differences of soil, climate, varieties in different regions and different planting habits, the rice planting agronomic requirements are different. In order to meet the seeding requirement of conventional rice and hybrid rice simultaneously and to adjust the seeding rate quickly, a combined hole-type metering device was designed based on a simple hole-type metering device which was developed by South China Agricultural University. The device included hole-type shell, hole-type roller and adjusting mechanism. A complete hole-type was comprised by the label through holes which were uniformly distributed on the hole-type shell and the small/big hole-type which were uniformly distributed on hole-type roller. The shape, size and style of the hole-type and the adjusting mechanism were designed and optimized. The reliability experiments of the adjusting mechanism were carried out and the result showed that its structure was reasonable and the seeding rate adjusting process could be completed in 5 s. According to the existed model and theory, the outline dimensions of the hole-type were calculated and the results confirmed that the number of the hole-type was 8, the big radius was 5 mm, the small radius was 4.5 mm and the length was 11 mm. To further study on the main impact factors of the seeding performance of the metering device, the length and the chamfering angle of the guiding groove and the type of the hole-type were selected as the factors of the performance experiment while the conventional rice pre-germinated seed Yuxiangyouzhan was selected as the experimental material. The results indicated that the optimal combination parameters were the length of the guiding groove of 6.5 mm, the chamfering angle of 60°, the big hole-type on the hole-type roller with 6.5 mm cylindrical hole and the small hole-type with 4 mm spoon-shaped hole. The test results with rotational speed of 50 r/min showed that the qualified rate of the seed number per hole of the small hole-type was 87%, the seeding qualified rate of the big hole-type was 87.67%, and the seeding variable coefficients of these towed hole-type were 22.60% and 20.46% which could meet the rice seeding requirement. The correlation analysis showed that the main effect on the qualified rate was the type of the hole-type, and the length and the chamfering angle of the guiding groove had effects on the seeding variable coefficients as well. Furthermore, the adaptability experiment was designed by 4 varieties pre-germinated rice seeds and 4 rotational speeds (30 r/min, 40 r/min, 50 r/min and 60 r/min). The results showed that the combined hole-type metering device had good adaptability of seeding conventional rice seeds such as Xiushui 134 and Yuxiangyouzhan, and hybrid rice seeds such as Huayou 14 and Peizataifeng. © 2016, Chinese Society of Agricultural Machinery. All right reserved.

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