Ear Related Traits in Wheat Genotypes under Terminal Heat Stress

Abstract

Growth, development and productivity of wheat are significantly influenced by heat stress. Terminal heat stress (prevalence of heat stress at anthesis and grain-filling stages) leads to reduction in productivity and quality of wheat grains. Being photosynthetically active, ear of wheat plant is beneficial, particularly under terminal heat stress. This study investigated a few ear related morpho-physiological traits across twenty-nine wheat genotypes under terminal heat stress condition. Genotypic variability was quantified for different traits and contrasting genotypes were identified. Intra-ear competition was noticed at morphological level. Ear traits such as; low temperature of ear surface (for better and sustained photosynthesis), more stomatal density on glumes (for keeping ear temperature low via transpiratory cooling), longer awns (for higher surface area of ear, faster grain growth rate and more width of ear due to broader spikelets with more florets) and higher succulency of ear (for more ear length and number of grains in ear) supported for higher grain yield under terminal heat stress. Total projected surface area of ear was calculated from the images of ear and thereby a new image-based method is developed. This study clearly suggested that thermal imaging of ear can be used as a non-destructive and rapid screening/phenotyping technique to evaluate the physiological performance and thermo-tolerance status across the diverse genotypes/populations of wheat under heat stress condition. Lastly, inter-relationships among different ear related traits are summarized along with the suggestions for future lines of work that can help in making wheat more thermo-tolerant.