Phenotyping maize and sorghum at an early development stage in controlled environments

In the frame of Work Package 1 of the project, taking place in the department of Crop Production and Biostimulation Laboratory at ULB in Brussels (Belgium), the first task consisted in a morphological evaluation of root traits at an early development stage in controlled environments – hydropony under two abiotic stress conditions: nitrogen and hydric deficiency.

Test on leaves measuring physiological parameteres in a chamber under controlled conditions.

C4FUTURE is focused on nitrogen (N) and water (H2O) since those soil resources are considered as the most important limitations to yield stability. On one hand, mineral N fertilization is used to increase crop yield, but excessive concentrations of nitrate are detrimental to the environment and the human health. On the other hand, the impact of climate change on crop yield is a reality in Europe and drought is the main driver of losses for cereal crops.

Optimizing root system architecture could enhance the crop capacity for soil exploration and, thus, nutrient and water acquisition. A current challenge for plant breeding is the limited ability to phenotype the root organ, a lack of methods for non-invasively imaging root organs has restricted the understanding of the genetic basis of root system architecture.

The plant material utilized was two panels of 279 genotypes of maize and 179 genotypes of sorghum (figure 1):

Two different kinds of tests were performed on the two collections, one for evaluating the roots and another for evaluating the aerial part of the plant.

For the root test, a ‘pouch & wick’ hydroponic system, consisting of a “sandwich” of two rigid plates and a blue germination paper covering the seedling (figure 2) captured the 2D root morphology of the maize and sorghum diversity panels under controlled conditions, what means ideal conditions (temperature, humidity, photoperiod, nutrients) for the two species growth.

After 4 days in a hydroponic solution, roots were scanned and then analysed with the program RootNav. Different parameters of the architecture of the root were measured: