Laser-induced chlorophyll fluorescence sensing to determine biomass and nitrogen uptake of winter wheat under controlled environment and field conditions

The relationship between laser-induced chlorophyll fluorescence intensity (690 nm and 730 nm), ratio F690/F730 and nitrogen supply in winter wheat was characterized using two different sensors (growth chamber and field sensor). In the field, chlorophyll fluorescence was measured at a distance of approximately 3.3 m from the canopy and the sensed area was approximately 6-7 m(2). The fluorescence ratio F690/F730 was inversely correlated with N content and uptake and dry shoot biomass. Shoot dry biomass could be determined by means of biomass index measurements independent of leaf chlorophyll content. The results indicated that nitrogen uptake and biomass can be reliably detected through chlorophyll fluorescence measurements under field and controlled growing conditions.