Assessing the interception of photosynthetically active radiation in winter wheat

Abstract

Some current growth and yield models for wheat require methodology to estimate the daily quantity of photosynthetically active radiation ( PAR) captured by the canopy. The interception of PAR was examined throughout the growing season in two varieties of winter wheat ( Triticum aestivum L.) planted at three densities. Daily values of percent of incident PAR intercepted were influenced by cloud cover, when leaf area index ( LAI) values were small. At high values of LAI, the percent interception values were large and independent of the quality of incident PAR. A relationship was determined between daily percent of incident PAR intercepted and LAI, which is valid up to the time of rapid leaf senescence. A mathematical function was developed to quantify the relationship.