Scales of development for wheat and barley specific to either single culms or a population of culms

Accurate assessment of plant development is essential for agronomic management and scientific research, and crop development scales with repeatable and reproducible protocols are required to achieve this. Development scales currently in use are ambiguous, subjective and qualitative, they do not describe all stages in a crop’s lifecycle, they do not explicitly distinguish between culm-level and crop-level development, and they are incompatible with modern analytical and computational technologies. Here we propose two new scales of wheat and barley development: the Single Culm Development Scale (SCDS) to define progression through the lifecycle of an individual culm, and the Population of Culms Development Scale (PCDS) to identify the timing of stages and duration of phases within a crop canopy. These development scales merge and fill gaps within existing scales currently in use, describe development in terms that are unambiguous, objective and quantitative, and better interface with crop simulation models, automated image analysis and other computational tools and analytical methods. The SCDS and PCDS are paired with definitive protocols to measure each stage that were developed and tested using different operators in controlled environment and field experiments. •Crop development scales are essential tools for agronomic management and scientific research.•Scales should measure development using unambiguous, objective and quantitative protocols.•Two new scales for wheat and barley development have been designed, tested and validated.•Results are reproducible and repeatable