Morpho-physiological Effects of Drought on Medicinal Plants and the Potential Use of Remote Sensing - A Review.

This review addresses the growth and development of medicinal plants under arid land conditions and the potential use of remote sensing technologies to map their distribution, as well as morphological and physiological responses in Arid lands. Plant morpho-physiological variables including, chlorophyll content, and gas exchange (photosynthesis, transpiration, vapor pressure, and stomatal conductance) are linked to plant water status. Multispectral and hyperspectral remote sensing techniques are promising for detecting morphological physiological changes. Vegetation indices derived from hyperspectral and multispectral imagery makes it possible to assess medicinal plants' health through successful detection of the ground plant physiological variables and canopy cover including chlorophyll, canopy density, gas exchange (red, 600-700 nm, nearinfrared spectrum, 700-1100 nm) as well as water status (shortwave infrared, 1300-2500 nm). Surface reflectance data within the shortwave infrared bands (water bands) revealed significant differences between well-watered and drought-stressed plants. However, the moderate spatial resolution (Sentinel-2: 20 m, Landsat: 30 m) for the space-born free sensors and the need for a cloud-free sky could be limitations. Overall, vegetation indices derived from remotely sensed data are a useful approach for estimating the physiology of plants (medicinal plants) especially those under drought stress. [ABSTRACT FROM AUTHOR]