Remote detection of crop water "stress" and distinguishing it from other stresses
2011
Jones, H.G.
This paper discusses the relationship between both biotic and abiotic stresses and the responses that can be detected remotely (whether using in-field 'proximal' or conventional airborne or satellite remote sensing). All stresses give rise to a range of intermediate or remotely detectable responses (for example drought causes stomatal closure, reduced photosynthesis, leaf yellowing and senescence and leaf wilting), but many of these responses can also be the result of other stresses. The challenge is to find an appropriate suite of remote sensing technologies to derive a system that can be used both for stress diagnosis and for stress monitoring to allow optimal crop management, e.g. for irrigation scheduling. The remote sensing techniques reviewed include: thermal sensing (particularly suitable for studying water use and stomatal closure), spectral reflectance sensing and the use of vegetation indices (useful both for following changes in canopy leaf area index and leaf pigments and for following changes in biochemistry as in the photochemical reflectance index), fluorescence (valuable both for the study of photosynthesis and its control and for oxidative stress-related effects on biochemistry), and multi-angular sensing (particularly useful for studies of canopy structure related to leaf wilting and senescence). The example of remote sensing of crop water stress and its potential application to the development of automated irrigation scheduling approaches will be discussed. In addition, an approach to the development of a "stress catalogue" will be presented.
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