| Since the first generation of energy-saving solar greenhouses and their vegetable production technology systems were developed in the 1980s,the second and third generations of energy-saving solar greenhouses and their corresponding vegetable production technology systems have also been developed successively,which has achieved significant economic,social and ecological benefits.However,there are various types of energy-saving solar greenhouses with different shapes and structures.The front cover has various types of shapes e.g.,parabolic shape,circle,double circle,single slope,digging type,etc.The elevation angle and length of the north roof are various;Which kind of shape structure can let the greenhouse make full use of solar energy and obtain the best environmental effect still requires in-depth research and discussion.On the other hand,how to configure the crop canopy structure in the solar greenhouse can maximize the utilization of light energy in the canopy,is also an important theoretical problem to be solved in the production process of solar greenhouse.Therefore,in this study,the second-generation energy-saving solar greenhouse and tomato were used as the experimental greenhouse and crop types.The simulation approach was used to optimize the shape and structure of the energy-saving solar greenhouse,and to analyze the canopy configuration of the optimal light energy utilization efficiency of tomato in the solar greenhouse structure,the specific results are as follows:1.A virtual simulation method for simulating the light environment of energy-saving solar greenhouse and tomato canopy is proposed.Using the Gro IMP open source software,an external virtual sunlight model,a 3D virtual model of an energy-saving solar greenhouse,and a virtual simulation model of tomato FSPM were established.Compared with ordinary mathematical modelling and simulation approach,the FSPM model can simulate the complex light environment of greenhouses and plant canopies more intuitively and visually.2.Based on the virtual simulation model of the light environment,the optimal structure screening modelling method of the energy-saving solar greenhouse was created.The 3D greenhouse structure function model was mainly established by Gro IMP,and then the external greenhouse energy balance module was built to calculate the temperature.Various structural parameters of the greenhouse were simulated and analyzed,and the field data were used to verify the reliability and accuracy of the method.Then,121 greenhouse front portion shape scenarios and 121 back portion shape scenarios in a total of 14,641 scenarios were simulated.Thirdly,the optimal building structure configuration which suitable for energy-saving solar greenhouses in the 41.5°N latitude of our country was explored.Finally,principal component analysis was performed to explore the quantitative relationship between various structural variables and the most important architectural parameters that affect the greenhouse lighting and thermal insulation.The results showed that the ridge height of the greenhouse has a significant positive effect on the solar radiation capture of the greenhouse,while the curvature of the front roof has a strong negative effect on the ground radiation.This study further simulates the optimal structure of an energy-efficient solar greenhouse in the 41.5°N latitude region（8 m span,5.2 m ridge height,1.2 m north roof projection and 5 m north wall height）and compares it with the widely used original Liaoshen type solar greenhouse design;the new simulated optimal greenhouse structure can increase the minimum indoor temperature on the winter solstice day by 2°C,and increases the daytime light interception performance of the greenhouse by 22%,which converts into a 53 kg reduction in coal consumption.Studies have shown that a 2°C increase in room temperature can increase tomato yield by 5%.3.A light-thermal coupling model suitable for the microenvironment simulation of tomato canopy leaves in an energy-saving solar greenhouse was established using the method of extended energy balance equation module that considering greenhouse microclimate.High-precision radiation and temperature simulations on the surfaces of the greenhouse and tomato leaves were then performed.The results demonstrated the accuracy and reliability of using the latest ray tracing techniques and plant functional structure modelling methods combined with externally extended energy balance equations.This model integrates the energy balance equations that comprehensively considered the different structural layers of the greenhouse（ie,the north wall,roof,and soil）.The accuracy of the model and the simulation results were verified by actual field data.The simulation results revealed the dynamic light and thermal microclimate of the second-generation Liaoshen solar greenhouse in one day.The analysis results show that,compared with the empty greenhouse,the ground radiation of the shaded part of the canopy decreases by about 200 W m-2,and the radiation intensity of the shaded part of the north wall also decreases by about 50-100 W m-2 compared with the empty greenhouse at noon.The results also show that the light radiation received by the leaves with leaf grade≤5accounts for only a small part of the total absorbed radiation,so the lower leaves of the canopy can be removed during the actual production process.4.A functional structure plant modelling method was established to simulate the dynamic thermal microclimate and photosynthetic physiology of tomato canopy in the greenhouse,including the use of the light module based on ray tracing technology,the extended greenhouse energy balance equation module,and the extended K&L photosynthetic module（this in turn simulates dynamic leaf temperature,stomatal conductance,and photosynthesis）.The model quantifies the photosynthetic rate at the leaflet level of tomato while simultaneously considering the greenhouse structure,planting pattern,leaf temperature,age,and stomatal conductance.The reliability and accuracy of the method were verified by simulating both sunny and cloudy weather conditions.The model was then used to calculate and prove that ignoring the effect of leaf temperature（the approach of leaf temperature set to a constant value of 25°C）will produce considerable errors in predicting the photosynthesis of greenhouse leaves（7.6%on sunny days and 8.3%on cloudy days）.The photosynthetic limitation of canopy leaves was further simulated and calculated,and the main limiting factors of leaflet photosynthetic rate at each leaf level in sunny and cloudy days were analyzed.Leaf temperature was determined to be the main limiting factor leading to the increment of photosynthetic biochemical limitation（BL）on cloudy days.5.Using the above established simulation model to calculate the effects of 128 kinds of planting strategies（2 row orientations,4 planting patterns,16 planting densities）and 8 types of tomato plant architectures on leaf light interception,temperature and carbon assimilation and the quantitative relationship between them,and finally determine the ideal canopy configuration and tomato ideal architecture which suitable for mechanized planting.The quantitative relationship between planting pattern and plant configuration under the microclimate condition of energy-saving solar greenhouse was numerically analyzed by partial least squares path modelling method（PLS-PM）.The conclusion drawn from this chapter is that,compared with changes in plant structure,changing planting strategies has a more significant overall effect on light radiation,temperature,photosynthesis and dry matter of tomatoes,among which the effect of changing plant spacing is the most obvious.The planting pattern surprisingly does not have a huge effect on the light interception of the canopy,but can have a large effect on the uniformity of the canopy light distribution.The findings also showed that increasing the ratio of leaf number/area in tomato plants would have a considerable effect on dry matter compared to other plant structure treatments.Increasing internode length,leaf length,leaf length/width ratio and leaf elevation angle also positively affected plant dry matter.In this paper,an ideal tomato plant architecture was further designed to provide useful screening information of tomato plant phenotypic traits for the breeding process.According to the results,compared with the reference plant architecture,the canopy cumulative light interception of the ideal tomato plant architecture can increase by 20.2%. |
PDF Full Text Request