COLOUR- CODED WHEAT

It’s tough growing wheat in salty soil. In this field trial, drones are helping scientists evaluate which varieties do best.

Vigorously growing foliage reflects infrared light (shorter wavelengths are absorbed by photosynthesis). Here a drone uses a multispectral imager to spot the best-performing plants.

In the top three rows of the image, infrared light is depicted in shades of red. The brightest plots contain the most vigorously growing plants.

In the middle five rows, the researchers used a combination of red and near-infrared wavelengths to measure plant health. On this grey scale, brighter is healthier.

In the bottom four rows, a computer gave each plot an overall colour- coded score of plant performance; bright green is best, followed by yellow, orange and red.