A system for the study of roots 3D kinematics in hydroponic culture.

Recent studies support the hypothesis that the root apex exhibits computational features related to sensory integration. To date, it is difficult to test this idea from a behavioural perspective given that available technologies for root imaging focus mostly on static characterizations, lacking time- and 3D spatial information. Investigating roots’ growth as a mean of their interaction with the environment might be of key importance to unveil how sensorial processing serves the roots to code for elements in the environment and behave accordingly. We developed a system enabling effective dynamic 3D imaging of the maize root tip in hydroponic culture. The system is based on infrared stereo-cameras acquiring time-lapse images of the roots for 3D reconstruction compensating for water distortion. The acquisition protocol guarantees the root growth in complete dark while the upper part of the plant grows in normal light conditions. The system extracts the 3D trajectory of the root tip and a set of descriptive kinematic features. The system was tested individually on several maize seedlings during the first 7 days of growth. The system shows good intra-operator reliability and good measurement accuracy. Values obtained are in line with expected values when considering maize growing in hydroponic culture. The system and protocol proposed enables accurate 3D analysis of root growth. The approach is fairly easy to adopt and has the potential to become a standard for dynamic root imaging. The system is now in use to investigate roots interaction with the environment in the presence of different stimuli/obstacles.