Canopy temperature: A predictor of sugarcane yield for irrigated and rainfed conditions

Our recent work with a large genetically diverse sugarcane germplasm (131 clones) grown at different commercial production regions over multiple years with varying water supply (a total of 27 crop cycles) has shown that canopy conductance (gc), and a related easy-to-measure trait, canopy temperature (Tc), when integrated with canopy development, have a strong genetic correlation with crop yield irrespective of the growing condition. In order to exploit this result for variety improvement in the Sugar Research Australia breeding program, three different Tc measurement systems were assessed for their accuracy, genetic correlation of measured Tc with cane yield (tonnes cane per hectare, TCH) and trait (Tc) and heritability. The methods include manual ground-level Tc measurements taken at 3-6 month crop age, aerial screening using UAV-assisted infra-red and optical imagery and continuous real-time absolute Tc measurements using ArduCrop infra-red radiometers. Significant genetic variation for Tc among genotypes was detected with all three methods, with aerial screening and ArduCrop being more accurate and useful than manual ground-level measurements. Both UAV-aided and ArduCrop-based Tc measurements showed high heritability and high negative genetic correlation under variable moisture conditions. Results of field experiments suggest that aerial Tc measurements taken under the appropriate conditions will be an effective, rapid screening method for selecting superior, water-efficient and high-yielding clones from large breeding trials.