Use of GROWSCREEN-Rhizo Boxes Allowed Detection of Useful Differences in Root Response to Water Deficit in Faba Bean (Vicia faba L.)

Improving the drought tolerance of crops will help to sustain the supply of food and feed in the face of increasing temperature and demand for water for non-agricultural purposes. Sources of tolerance are sought in the available germplasm pool and further characterized using phenotyping and genotyping techniques. Reaction to drought is affected by root traits that are difficult to phenotype in ordinary circumstances. Faba bean is an important protein crop that is considered to be relatively susceptible to drought. Hence, we undertook a root phenotyping experiment on faba bean using GROWSCREEN-Rhizo Boxes to allow imaging of root zone. The potting medium was peat-based and 8 accessions of plants were grown to the vegetative growth stage in a split-plot design, under well watered and water limited conditions, with 4 replicates at the Julich Plant Phenotyping Center, Germany. The length of the primary roots was reduced by drought from a minimum of 30% in DS70622 to a maximum of 77% in DS74573, showing a significant genotype by environment interaction. Drought limited the length of lateral roots as well as the formation and length of secondary laterals. Drought-tolerant accessions (DS70622 and DS11320) apparently avoided water deficit by increased uptake of water from the soil by increased tap root length as well as root system depth and breadth. These two accessions can be considered as valuable new sources of potential drought avoidance by water uptake.