**7. Conclusions**

Traditional methods, such as measuring the soil moisture, have drawbacks in terms of their sensor costs and installations, and difficulty in obtaining estimates. Plant-based estimates are more dependable and accurate. There are significant relationships between the PRI and NDVI, and attributes such as the LWP, stomatal conductance, crop efficiency, and stem water potential. A crop water stress evaluation is a technical and intricate process in and of itself. Our study suggests new techniques that bring together farmers, researchers, and tech developers. Narrow-band optical indices could be used to plan the irrigation for high-value vegetable crops in water-stressed countries. Conventional irrigation scheduling methods use measurements of the soil moisture and weather, and physiological assessments of the plant response. These methods are ineffective because it is difficult to obtain these measurements, especially for varied soil and crop canopies. This assessment makes recommendations for remote sensing systems and sets the path for creating new facilities that assess a system's effectiveness in diverse environmental scenarios, such as multispectral/hyperspectral and thermal sensing systems that are based on remote sensing features.

**Author Contributions:** Conceptualization, M.S.; Comparison of Crop Water Stress Detection Methods, M.S. and M.A.S.; Satellite-Based Crop Water Stress Detection, A.S.; Crop Water Stress Detection Using Spectral Indices, F.R.; Crop Water Stress Detection Using Multispectral Sensing Systems, M.D.M., M.A.S., and R.M.S.; Future Directions & Conclusions, writing—original draft preparation, M.S.; writing a review and editing, M.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Free sources of satellite data are available for the study, but for better accuracy unavailability of data due to non-free availability.

**Conflicts of Interest:** The authors declare no conflict of interest.
