Application areas and calculation methods of photosynthetically active radiation

Application areas and calculation methods of photosynthetically active radiation

Photosynthetically active radiation (PAR) is a kind of climatic resource and it is used as an important scientific basis in the study of crop photosynthetic potential and potential yield. PAR (band is generally 400-700 nm) plays an important role in the process of photosynthesis in plants, and is a key factor affecting the photosynthetic process. PAR is also a major factor in the emission of volatile organic compounds (VOCs) from plants, and VOCs are important precursors of ozone in the tropospheric photochemical processes. Therefore, PAR plays an important role in agronomy, forestry, ecology, and atmospheric chemistry. The measurement of photosynthetically active radiation can be performed using photosynthetic active radiometers, photosynthetic active radiation recorders, and photo quantum meters.

Currently widely used PAR metrology methods are: irradiance (W・m-2), mainly used in radiation, weather, climate and other fields; quantum flux density (μmol・m-2・s-1), mainly used In agronomy, ecology and atmospheric chemistry and other fields. A large number of researches on PAR experiments and algorithms at home and abroad are mostly focused on climatology, including the estimation of total PAR daily and monthly totals[1,5-13]. However, the demand for PAR hourly values ​​is increasingly urgent in practical applications. .

The measurement of PAR hourly value directly uses an optical quantum meter to operate. There are three operation methods in its operation model, two of which are the time setting mode, and the PAP is calculated by setting the time interval. Powerful data storage function and analysis function, photosynthetic effective radiation recorder can store up to 30,000 data, you can view the data on the host, you can also import the computer. The instrument itself carries a calculation software, which has powerful data processing functions, can form the curve of the collected data and display it visually. The collected data can also be stored as an EXCEL spreadsheet file, allowing users to save and process data, or use specialized software for data processing, drawing bars, pies, and prints.

Through the picture to understand the changes in PAP, more accurate analysis can be performed.