Principal And Subordinate Mode Virtual Instrument System Of Measuring Photosynthesis And Transpiration Rate

Principal and subordinate mode virtual instrument system of measuring photosynthesis and transpiration rate is designed in the paper. The system measures photosynthesis rate by using infrared CO2 gas analyze method. It has two work modes: open route and close route. It can measure the leaf photosynthesis rate, transpiration rate, stomata conductance and CO2 thickness in cell clearance etc parameters about plant physiology. The interface is very friendly; people can operate it very easily. People can realize the measure theory, the structure of system and compute the Photosynthesis and transpiration rate. The system can achieve the requirement of experiment and research in university. It can be apply widely to the research of plant physiology, bionomy, agriculture, forestry and molecule biology etc.The system makes use of principal and subordinate mode virtual instrument theory. The system makes up of two parts: subordinate part is the measure instrument, it also is principal part's data collection equipment, it makes use of microcontroller's advantage, it intelligentizes the management and data collection circuit, it has liquid crystal display and 4x4 keyboard, it can work alone on the field, so it is very convenient and ensures the credibility of data sampling; principal part is virtual instrument software on personal computer, the software can be installed in notebook PC and work with subordinate part on the field, it extends the subordinate part's function, the teachers also can use it as demo teaching.The system has been tested and ameliorated times. Its capability is steady and the data is credible by comparing some international congener instruments, it exceeds foreign congener instrument on some targets. The system is opening and extensible. Its foreground is wide.The paper also analyses briefly the errors in measuring photosynthesis rate using infrared CO2 gas analyze method. The errors come from instrument, observation and biology. The paper offers some advice on using the instrument.