A passive two-band sensor of sunlight-excited plant fluorescence

摘要: We have designed and built a passive remote sensor of sunlight-excited chlorophyll fluorescence (U.S. Patent No. 5,567,947, Oct. 22, 1996) which provides for the real-time, in situ sensing photosynthetic activity plants. This sensor, operates as Fraunhofer line discriminator,detects light at cores lines comprising atmospheric oxygen A B bands, centered 762 688 nm, respectively. These bands also correspond to wavelengths far-red red bands. The is based on an induced approach; collected from fluorescing plants passed through low-pressure cell containing oxygen, absorbs energy subsequently reemits photons are then detected by photomultiplier tube. Since same that been strongly absorbed atmosphere, response incident sunlight minimal. mode measurement limited target sufficiently close range plants’ not itself appreciably (∼200 m). In vivo measurements 760 690 nm vegetation full presented. Measurements plant single-plant canopy level were obtained greenhouse-grown bean subjected nitrogen treatments. ratio two showed statistically significant variation with respect