Development and evaluation of a field-based high-throughput phenotyping platform

Physiological and developmental traits that vary over time are difficult to phenotype under relevant growing conditions. In this light, we developed a novel system for phenotyping dynamic traits in the field. System performance was evaluatedon25Pimacotton(GossypiumbarbadenseL.)cultivarsgrownin2011atMaricopa,Arizona.Field-grownplants wereirrigatedunderwellwateredandwater-limitedconditions,withmeasurementstakenatdifferenttimeson3daysinJuly andAugust.Thesystemcarriedfoursetsofsensorstomeasurecanopyheight,reflectanceandtemperaturesimultaneouslyon four adjacent rows, enabling the collection of phenotypic data at a rate of 0.84ha h -1 . Measurements of canopy height, normalised difference vegetation index and temperature all showed large differences among cultivars and expected interactions of cultivars with water regime and time of day. Broad-sense heritabilities (H 2 )were highest for canopy height (H 2 =0.86-0.96), followed by the more environmentally sensitive normalised difference vegetation index (H 2 =0.28-0.90) and temperature (H 2 =0.01-0.90) traits. We also found a strong agreement (r 2 =0.35-0.82) between values obtained by the system, and values from aerial imagery and manual phenotyping approaches. Taken together, these results confirmed the ability of the phenotyping system to measure multiple traits rapidly and accurately.