| Facility agriculture is a modern agricultural application field with the goal of low-carbon,circular,efficient and high-yield development and reasonable utilization of limited resources.Tomato is the main agricultural economic crop cultivated in Greenhouse in northern China,and its cultivation area,market sales and economic benefits are the first among vegetables.Greenhouse tomato cultivation is based on the outdoor climate,indoor environment,varieties,matrix or soil nutrient content and plant growth situation,the indoor light,temperature and humidity,CO2 concentration and other environmental parameters are reasonably controlled,so that the tomato is in the best growth climate,to improve the efficiency of photosynthesis and respiration,increase the accumulation of organic matter,shorten the development cycle,prevent diseases and pests The purpose of this study is to reduce the use of chemicals,improve the quality and yield of products,and reduce the input-output ratio.According to the demand of greenhouse tomato cultivation,this project developed a low-cost and high-precision phenotypic group sensor of plant height,fruit diameter and stem diameter,and a wireless multi-sensor network greenhouse crop phenotypic group and environmental monitoring system and platform with the functions of ad hoc network and automatic data acquisition and processing,and automatic control of greenhouse equipment The continuous real-time monitoring and equipment control of group and non-uniform distribution of multiple environmental factors information improve the continuity,scientificity and reliability of the data,and provide an effective and reliable research platform for the analysis of greenhouse crop phenotypic groups,dynamic differences of environmental zoning and the establishment of tomato growth and development model,which has strong practical value.In the aspect of tomato growth and development model,the exponential dynamic model of development cycle,leaf area index and yield was put forward,and the non-linear regression method was used to fit and verify the net photosynthetic rate.The main research results are as follows:(1)According to the physical characteristics of plant and fruit growth,plant height sensor,fruit diameter sensor and stem diameter sensor were developed by using high precision potentiometer,angle sensor and displacement sensor.The results showed that the effective measurement range of plant height sensor was 10-500 cm,and the accuracy was ± 1 cm;the effective measurement range of fruit diameter sensor was 0-15 cm,and the accuracy was ±0.1 cm;the effective measurement range of stem diameter sensor was 0-3 cm,and the accuracy was ± 0.1 mm.Phenotype sensors with the advantages of low cost,low power consumption,high precision and easy operation have considerable practical value for continuous phenotype acquisition in the future market.(2)Based on high-speed ARM3 processor and wireless Lora data transmission technology,a wireless multi-sensor network greenhouse crop phenotype group and environmental monitoring system is developed.According to the external environment,there are 4G network and LAN transmission modes for selection.A star type wireless command and data transmission network with "one network and multiple nodes" is constructed to realize the collection and transmission of greenhouse crop phenotype group and environmental data in wireless ad hoc network RF433 MHZ Ad Hoc network communication protocol is designed by using hierarchical network communication protocol and distributed algorithm.The transmission mode of "broadcast communication,synchronous acquisition(reception)and asynchronous transmission" solves the "congestion" problem in large capacity network communication,and makes the network run stably and reliably.The gateway with ad hoc network function realizes the collection section Based on cloud computing B/S architecture and TCP/IP communication mechanism,the Internet of things management platform is designed to realize remote greenhouse data transmission,storage,processing,graphical display and video monitoring Control,greenhouse equipment control command forwarding and user rights management functions.(3)In the period of 2018-2020,it has the advantages of flexible networking,long transmission distance,low packet loss rate,low power consumption,low cost and convenient operation in the greenhouse(37°49′N and 112°74′E).It is widely used in agriculture and other fields It has a good application prospect in domain environment monitoring.The test results show that: the wireless network constructed by RF433 mhz Ad Hoc network communication protocol can automatically establish and release the communication link between gateway and node,the time for establishing communication is less than 5.5 s,the time for all nodes(10nodes)to transmit data to the platform and complete decoding,storage and display is less than15 s,and the effective transmission distance between gateway and node is up to 1500 m.The packet loss rate is less than 4.5%.(4)In the research of greenhouse tomato development model,inspired by the radiant heat product and "rice clock",the exponential dynamic development model of greenhouse tomato was established by introducing tomato gene coefficient,temperature sensitivity coefficient,sunshine duration coefficient,light sensitivity coefficient and photoperiod correction.From2019 to 2020,four crop experiments were carried out in a small high standard greenhouse(37°25′N and112°34′ E)in the College of agricultural engineering,Shanxi Agricultural University.The tomato development model was fitted and verified,and compared with the accumulated temperature method and radiant heat product method,which are the main research methods of tomato development.The results show that the MAE and RMSE between the predicted value and the observed value are less than 2 days,and the correlation coefficient(R2)is 0.9938.The model established in this paper has high accuracy and small error in predicting the duration of tomato growth and development in each period.By modifying tomato gene coefficient,temperature coefficient,sunshine duration coefficient and light sensitivity coefficient,it can be applied to Tomato Cultivation in greenhouse with different structure,which has good applicability and reliability,and provides scientific basis for digital cultivation management,environmental control and crop arrangement of facility tomato.(5)In the study of greenhouse tomato growth model,the exponential dynamic growth model of greenhouse tomato was established by introducing tomato gene coefficient,temperature sensitivity coefficient,sunshine duration coefficient,light sensitivity coefficient and photoperiod correction.Two crop experiments were carried out in 2020 to fit and verify the tomato growth model.The results showed that: the RMSE between the predicted value and the actual value of Lai dynamic model was 0.7523,and the coefficient of determination(R2)was 0.9975;the fitting degree between the net photosynthetic rate and photosynthetic active radiation,temperature,humidity,carbon dioxide concentration was 0.9291,and the RMSE between the predicted value and the actual value was 1.1076,and the coefficient of determination(R2)was 0.96 The RMSE between the predicted value and the actual value was45.43,and the coefficient of determination(R2)was 0.9943.The growth model established in this study can better reflect the relationship between greenhouse tomato growth process and environment,and provide theoretical and decision-making basis for improving tomato leaf area index,photosynthesis,yield and quality. |
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