Comparative Scrutiny of Okra Lines for Water Stress by Plant Leaf Temperature Using Thermal Imaging

Canopy temperature is widely utilized as a proxy for evaluating plant water stress. Recent technological innovations have advanced agricultural practices, transitioning from leaf-mounted sensors to short-range remote sensing techniques, such as infrared thermometry and thermal imaging. Although thermal imaging is well-documented for assessing crop water stress, comparative research on lines of intra-species under water deficit is scarce. This study aimed to evaluate the feasibility of usingtermal imaging to compare water deficit responses among different okra lines based on plant leaf temperature. To achieve this, leaf temperatures of 10 different okra lines were assessed across four different irrigation regimes: full irrigation, and mild, moderate and severe water deficits. The results show that pre-irrigation thermal image data reflect water deficits and line-specific differences more accurately than post-irrigation measurements. Across almost all lines, the highest leaf temperatures occurred under severe water deficit, while the lowest were recorded under full irrigation. Notably, lines, MGL-4-SH-2, MGL-5-SH-2, MGL-7-SH-2 and MGL-8-SH-2 demonstrated greater resistance to water deficit, consistently exhibiting the lowest leaf temperatures. In conclusion, thermal cameras effectively measure water stress in okra and successfully differentiate line-specific responses to deficit water conditions.