What is plant phenotyping?

Although the concepts were expressed by Mendel decades earlier, the terms “gene”, “genotype” and “phenotype” were introduced by botanist Wilhelm Johannsen in 1909:

• A gene is a section of DNA that encodes a trait;
• A trait is a specific characteristic e.g. plant height, leaf shape, grain yield;
• A genotype is the genetic make-up of the plant i.e. the complete set of genes. In crop science, terms genotypes, lines, varieties and cultivars are interchangeable.

Phenotype can be defined as an observable characteristic/trait that is produced by an interaction of both the genes and the environment (light, temperature, nutrients, stress)

Plant phenotyping can thus be described as the science of the characterisation of crops, which is important for decision support in agriculture and for plant breeders when selecting the best genotypes that will become future cultivars.

Thus, plant phenotyping helps to better understand the functioning of crops in different environments, and this type of information can then be used to calibrate crop models.

In the past, conventional methods used for phenotyping were tedious, time-consuming and labour intensive as it required scientists to score plant samples, record plant characteristics manually (e.g. plant height with a ruler) and carry out destructive plant sampling in order to carry out tests in labs. Nowadays, non-destructive high-throughput methods are often used to characterise plant traits, allowing us to record in a couple of hours what used to take weeks or months to collect.

Modern plant phenotyping measures complex traits related to growth, yield, and adaptation to stress, with an improved accuracy and precision at different scales of organization, from individual cells to entire canopies. Hence, it is at the forefront of future plant breeding.

Selected reading:

• Pieruschka, R and Schurr, U (2019) Plant phenotyping: Past, Present and Future, Plant Phenomics.
• Li, L.; Zhang, Q.; Huang, D. A Review of Imaging Techniques for Plant Phenotyping Sensors 2014, 14, 20078-20111.
• Omari, M.K. et al. Digital image-based plant phenotyping: a review Korean Journal of Agricultural Science, Volume 47 Issue 1, Pages 119-130, 2020.