Radiation Characteristic And Simulation Model For Tomato Canopy Photosynthesis In Solar-greenhouse Long-season Cultivation

The simulation model of tomato photosynthesis was established by sorting and analyzing the test data which was based on large numbers of test data in solar greenhouse. It also can predict the effects of environment factors affecting tomato and provide the optimal strategies and managements for environment control and tomato production in solar greenhouse. This research observed the distribution of photosynthetic active radiation (PAR) in solar greenhouse, established leaf photosynthesis model and analyzed the effect of the environment on the photosynthesis at the same time. The photosynthesis model of tomato canopy was established on the base of these, simulated group photosynthesis production, and provided theoretical basis for the environmental condition management in tomato production of greenhouse. The major findings are as follows:1. According to the height of tomato canopy in the solar greenhouse, it was divided into 4 layers. The PAR, leaf area index (LAI), net photosynthetic rate (Pn) and transmittance of PAR at different canopies were measured. The regulation of PAR in tomato group was explored. The horizontal and vertical distribution of PAR was reached and the correlation analysis between cumulate LAI and PAR, canopy height, Pn of tomato in solar greenhouse was done. The results showed that it was significantly positive correlation between PAR and canopy height and negative correlation between PAR and cumulative LAI. It was significantly positive correlation between Pn and canopy height, PAR. The correlation coefficient was more than 0.94.2. The model of photosynthesis which adapted tomato leaf in solar greenhouse of northern China was established. The formula was The daily variation of Pn was simulated in sunny day. The fitting degree was more than 0.94 and the relative error was less than 10%, so the simulation results were good.3. The dynamics of canopy LAI and the effect of environment on photosynthesis of tomato were analyzed by measuring canopy LAI, greenhouse environment (light, temperature and CO2, et al). The results showed that the trend of canopy LAI was "slow-fast-slow"; Pn increased rapidly with the increasing of light intensity and CO2 concentration. Pn no longer increased when the light intensity and CO2 concentration reached a certain value which was the CO2 saturation point. The appropriate photosynthesis temperature of 24 to 34℃was determined, and 26 to 32℃was the most appropriate. It provided theoretical foundation for environmental control photosynthesis production of solar greenhouse.4. The extinction coefficient of 0.89 was determined in greenhouse long-season cultivation tomato. The accuracy of model was improved in greenhouse long-season cultivation tomato. The simulation method of the daily total amount of canopy photosynthesis was proposed. The daily total amount of canopy photosynthesis could be calculated with this model in greenhouse long-season cultivation tomato at different areas and dates. Gaussian integral method simplified the calculated process of canopy photosynthesis while ensuring the calculable accuracy.The greenhouse tomato photosynthesis simulation model brought forward in this paper has higher accuracy, mechanism nature and practicability, which established the foundation for completing the greenhouse tomato planting simulation optimizing system. The production of greenhouse tomato can be arranged, the sowing time of tomato can be determined, the photosynthesis production can be forecasted reasonably with this model, at the same time, the model also provided theoretical foundation for environmental control in tomato growth.