Tropentag, September 10 - 12, 2025, Bonn "Reconciling land system changes with planetary health"

Remote sensing-based assessment of heat stress tolerance in tropical bread wheat using spectral reflectance indices

¹University of Hohenheim, Inst. of Agric. Sci. in the Tropics (Hans-Ruthenberg-Institute), Germany
²University of Hohenheim, Inst. of Agric. Sci. in the Tropics (Hans-Ruthenberg-Institute), Germany
³University of Hohenheim, Inst. of Agric. Sci. in the Tropics (Hans-Ruthenberg-Institute), Germany
⁴Wageningen University and Research, Centre for Crop Systems and Analysis, The Netherlands
⁵International Maize and Wheat Improvement Center (CIMMYT), Physiology and Remote Sensing, Mexico
⁶University of Hohenheim, Inst. of Agric. Sci. in the Tropics (Hans-Ruthenberg-Institute), Germany

Abstract

Heat stress poses a critical challenge to wheat production in tropical regions, particularly under the growing impact of climate change. Conventional phenotyping methods for evaluating heat tolerance are often labour intensive, time-consuming, and subjective. Using spectral reflectance data in remote sensing has become an effective method in crop breeding, facilitating the evaluation of physiological traits and crop responses to environmental stress. The development of efficient, non-destructive phenotyping methods is essential in tropical wheat breeding, particularly considering the growing influence of heat stress on crop productivity. This research investigates the use of Spectral Reflectance Indices (SRIs) to assess heat stress tolerance in tropical bread wheat, focusing on 380 diverse genotypes from CIMMYT’s Candidates for Selection (CANPBY) panel. Genotypes were sown in late February 2023 in the field at the CIMMYT experiment station at Ciudad Obregón Mexico, to ensure exposure to average temperatures exceeding 35 °C during the grain filling period. Spectral reflectance was measured at the canopy level using a handheld Spectroradiometer. Data was collected from late tillering through to physiological maturity to evaluate the predictive capability of various SRIs, including NDVI, PRI, TCARI, OSAVI, SIPI, ARI, NWI4, EVI, MTCI1, and RARSc, concerning the important agronomic traits mainly grain yield. The correlation analysis demonstrated a strong association between various spectral indices, such as NDVI, EVI, OSAVI, with grain yield and yield components, underscoring their potential utility as non-destructive proxies for assessing heat tolerance. The boxplot analyses provided additional insights into the variability and distribution of these traits among genotypes, highlighting significant genetic diversity in both agronomic performance and spectral responses when subjected to heat stress. The combination of spectral reflectance data with traditional phenotyping facilitates a more effective identification of heat-tolerant genotypes, thereby enhancing breeding programmes focused on increasing wheat resilience in a heat-stress environment. This approach highlights the potential of remote sensing in advancing genetic improvement for heat tolerance, although genotypic variation in phenological development may confound trait expression. Further evaluation of spectral reflectance dynamics across growth stages is needed to assess genotypic variation in phenology and heat stress responses.

Keywords: Climate change, heat Tolerance, remote sensing, wheat (Triticum aestivum L.)

Contact Address: Deena Thankachan , University of Hohenheim, Inst. of Agric. Sci. in the Tropics (Hans-Ruthenberg-Institute), garbenstr. 13, 70599 Stuttgart, Germany, e-mail: deena.thankachanuni-hohenheim.de