Association Between Water Reflectance Index and Yield in Bread Wheat Under Stressed Field Growing Conditions

Spectral reflectance (SR) indices were measured on bread wheat (Triticum aestivum L.) genotypes to determine their relationship with yield under irrigated, drought and high temperature conditions. Bread wheat lines from three international nurseries from the International Maize and Wheat Improvement Centre (CIMMYT) were used for this study: ESWYT (elite spring wheat yield trial), SAWYT (semi-arid wheat yield trail), and HTWYT (high temperature wheat yield trial). These genotypes were grown during the 2006 and 2007 growing seasons in field plots in a temperate, high radiation environment in Sonora, NW Mexico. Spectral reflectance indices were determined with a spectroradiometer during booting, anthesis, and grain-filling stages. The WI (water index) had the strongest relationship with grain yield in all environments, and it had the highest relationship with genotype yield in the SAWYT and HTWYT under drought and high temperature conditions. The WI was also associated with canopy temperature under adverse growing conditions. The potential of the water index to identify higher-yielding genotypes under dry, irrigated, or high temperature conditions was established in the present study.