The genetic improvement of field crops through plant breeding and genetic modification is highly dependent on understanding, measuring, selecting, and manipulating phenotypes. Most phenotypes result from the complex interaction of a crop's genetics with the environment and management practices in which that crop is grown. Linking gene to phenotype in field environments to create superior crop varieties can therefore be challenging, particularly for genetically complex traits that are difficult to measure. This chapter is designed to help readers overcome these difficulties by describing tools and techniques used in successful crop improvement programs. It provides methodologies that can be broadly applied across numerous situations irrespective of field crop, environment, modest financial resources, or other factors. The chapter's focus is primarily on small- and large-scale, replicated, research plot-based screening trials since these trials are crucial, ubiquitous, and costly for both public- and private-sector crop improvement programs. To ease the understanding of the protocols discussed, this chapter's materials and methods section is composed of ten subsections, with each subsection covering a critical portion of the field crop phenotyping process: regulatory, environmental, and safety considerations; trait identification and prioritization; environment characterization; field site selection; experimental design; field design, preparation, and management; crop and soil measurements; environmental monitoring; in-field data recording; and data management and analysis.
Keywords: Environment characterization; Experimental design; Field crop; Field selection; Phenotyping; Remote sensing; Research plot; Secondary trait; Unmanned aerial vehicle.