Unoccupied aerial systems temporal phenotyping and phenomic selection for maize breeding and genetics

Emerging tools in plant phenomics and high throughput field phenotyping are redefining possibilities for objective decision support in plant breeding and agronomy as well as discoveries in plant biology and the plant sciences. Unoccupied aerial systems (UAS, i.e. drones) have allowed inexpensive and rapid remote sensing for many genotypes throughout time in relevant field settings. UAS phenomics approaches have iterated rapidly, mimicking genomics progression over the last 30 years; the progression of UAS equipment parallels that of DNA-markers; while UAS analytics parallels progression from single marker linkage mapping to genomic selection. The TAMU maize breeding program first focused on using UAS to automate routine traits (plant height, plant population, etc.) comparing these to ground reference measurements. Finding success, we next focused on developing novel measurements impractical or impossible with manual collection such as plant growth and vegetation index curves. UAS plant growth curves measured in a genetic mapping populations has allowed discovery of temporal variation in quantitative trait loci (QTL). Now, phenomic selection approaches are being tested using temporal UAS, as first described using near infrared reflectance spectroscopy (NIRS) of grain. Phenomic selection is similar to genomic selection but uses a multitude of plant phenotypic measurements to identify relatedness and predict germplasm performance. Phenotypic measurements are thus treated as random markers with the underlying genetic or physiological cause remaining unknown. Using multiple extracted image features from multiple time points, genotype rankings have been successfully predicted for grain yield. Among the most exciting aspects have been identifying novel segregating physiological phenotypes important in prediction, which occur in growth stages earlier than previously evaluated. Similarly, UAS have allowed investigating plant responses to biotic and abiotic stress over time. UAS findings and approaches permit new fundamental plant biology and physiology research, which is catalyzing a new era in the plant sciences