| The crop growth information perception and acquisition is an important process in precision agriculture, which is also an important basis of variable fertilization and precision irrigation. This study used wireless sensor network technology and advanced sensor technology to develop crop leaf surface micro environmental parameters detection system, furthermore the analysis of temporal and spatial distribution of the maize leaf surface micro environmental parameters in plant population and single plant were conducted; multispectral technology and advanced sensor technology were used to design crop canopy spectral reflectance detection system, and the relationship between the winter wheat canopy spectral reflectance with tiller number and dry matter accumulation at different growing stage were analyzed and used to establish prediction model. In addition, the variation of tiller number and dry matter accumulation of winter wheat at different growing stage and different nitrogen levels were analyzed. The author used the opportunity to visit and learn in the United States to conduct thorough investigation of problems existed in the current mechanized orchard harvest, and finished the design and manufacture of the vibration harvesting platforms for mechanized apple harvest, and used the platform to investigate factors causing apple collision damage. The main research contents were as follows:[1] Development and experiment of micro environmental parameter measurement system of crop leaves.Research and development of the crop leaf surface micro environmental parameters detection system, including contact leaf surface temperature measurement node, leaf surface wetness measurement nodes, non-contact vane surface temperature measurement node, PDA handheld client. All measurement nodes and PDA handheld client use ZigBee wireless communication, which can realize the distributed online measurement of micro environmental parameters of crop leaf surface in large field. System hardware design mainly includes the design of communication module and control circuit, contact type temperature measurement design and corresponding sensor selection, non-contact type temperature measurement design and corresponding sensor selection, selection of humidity sensor, light sensor selection and mixed sensor signal conditioning circuit, a power supply and multi-level power conversion circuit, PDA handheld terminal circuit transformation. The software design includes the communication network flow, data acquisition and serial communication procedures, data packege format and the sensor output data smoothing algorithm, given the relevant software interface. The whole system has also carried on the calibration experiment and the communication reliability test and so on other performance tests, and has given each measurement node linearity, the precision, the precision and the stability index. Tests were conducted in Shaanxi, Shandong and other places, which proved that the detection system is reliable.[2]Study on spatial and temporal distribution of micro environmental parameters on corn leaf surface.In this part, the temporal and spatial distribution of micro environmental parameters of maize leaf surface was studied by using the micro environmental monitoring system and the infrared thermal imaging instrument. At single plant case, corn leaf temperature changes with the environmental temperature, which presents single peak curve that increased firstly and then decrease, temperature of single piece of leaf vein leaves were 0.5℃ lower than the temperature of leaf surface. In space, the temperature of maize per plant showed vertical stratification, that is, the temperature of the top leaf was lower than that of the middle leaf. When the water supply is adequate, the surface humidity of maize leaves appears to be "decreasing-increasing-decreasing-increasing", while the "basin" is formed in water stress, which is related to the physiological regulation of the crop. The changes of leaf air temperature difference and leaf air humidity difference were almost same in each layer ". Environmental group maize leaf surface temperature, humidity, leaf air temperature difference, leaf air humidity difference are still present in the vertical stratification and similar distribution rule and corn plant, but in part time node (such as noon) showed the inflection point. In the field of spatial scales, corn leaf temperature showing a rise gradually from outside to inside and the trend, the humidity in corn leaves in the morning session has gradually increased from the outside and inside, showing a decreased gradually from outside to inside and the trend in the afternoon, this and leaf transpiration and other physiological effects. In the end of this study, the relationship between the electrical conductivity and the micro environmental parameters and the relative water content of the leaves was studied, and it was proved that the micro environmental parameters could indicate whether the crop was affected by water stress.[3] Research of the number of winter wheat tillers and dry matter accumulation based on crop spectral reflectance characteristicsThis part mainly studies the different applying nitrogen level under winter wheat tiller number and dry matter accumulation amount of variation, that too high or too low nitrogen will cause the number of tillers decreased and the dry matter accumulation amount decreased; studied the relationship between 9 index on the planting of winter wheat at different growth stages of tillering number change differences and tiller number and, which osavi (650 to 850) of greenup tiller number is most sensitive, Evi2 (650 to 850) to up the number of tillering stage is most sensitive. To establish the related to tiller number prediction model, greenup tiller number calibration model decision coefficient RC2 was 0.85, model validation coefficient Rv2 was 0.79; up tillering number calibration model decision coefficient RC2 was 0.84, model validation coefficient Rv2 was 0.75; to study the rates of change of the amount of dry matter accumulation of Winter Wheat in different growth stage, that accumulated quantity of dry matter accumulate slowly in the prophase, up stage to flowering stage cumulative maximum speed, flowering to maturity stage, the accumulative rate of decline. Studied at different growth stages of winter wheat dry matter accumulation amount and 9 planting is the relationship between index and the osavi (650 to 850) of reviving stage dry matter accumulation was the most sensitive, Evi2 (650 to 850) the rising amount of dry matter accumulation was the most sensitive. Dry matter accumulation prediction model is established, reviving stage, dry matter accumulation amount of calibration model decision coefficient RC2 was 0.6117, model validation decided coefficient Rv2 is all; erecting stage dry matter accumulation calibration model decision coefficient RC2 was 0.84 and model validation decision coefficient Rv2 of 0.75.[4] Development and experiment of crop canopy spectral reflectance detection system.This part introduces the passive crop canopy spectral reflectance detection system architecture, optical channel design, selection and design of the sensor, software design and application system in the presence of problem, then leads to active crop canopy spectral reflectance detection system development and design. The design method based on the laser active crop canopy spectral reflectance detection system, system architecture, selection of laser diode, a level amplifying circuit, pulse and expanding circuit, CPU circuit, system power supply circuit, and gives the flow chart of software design are introduced in detail. At last, the test system performance test is given, and it is concluded that the stability of the system is better than that of the detection system based on the comparison of Matsu Hikarugi, ASD, SPAD chlorophyll meter and other instruments.[5] Study on the apple vibration harvest platform and the factors of apple bruise.According to the Washington State Apple mechanization harvest status, an apple vibration harvesting platform was proposed, it proposed a "slow+ separation" design, through a combination of deceleration rod and sponge curtain the initial realization of the goal of reducing the apple damage rate; This research also studied the influence of different inclination angle of platform on apple damage rate and damage area percentage changes, receiving platform in 0-40 degree, apple injury rate showed a "trough" trend of decreased first and then increased,25 degrees for a better solution, the angle of the apple damage index were the lowest. Through the harvest field experiments:Gala, honeycrisp, GrannySmith three apples,the platform was proved with high receiving efficiency. Through control the inclination angle of platform and different combinations of deceleration rod and sponge curtain can significantly reduce apple’s damage rate and damage area percentage. At the same time, there are significant differences in the damage of different kinds of apples with the harvest platform, which may be related to the physical and chemical properties of apple. |
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