Calibration, validation and testing of a rotational displacement transducer for measuring wheat leaf elongation rates

Abstract

Flag leaf growth has been emphasized in the literature as an important secondary trait for wheat breeding under drought stress. To measure leaf elongation rate (LER) in monocotyledons such as wheat, the rotational displacement transducer (RDT) has already been used in several studies, mostly on maize. Still, a comprehensive calibration and measurement protocol of the sensor is lacking. To fill this gap, several experiments were performed: (i) to calibrate the sensor and test its resilience to physical disturbances and changes in environmental conditions, (ii) to validate the calibration on growing plants, and (iii) to compare growth rate in flag leaves of well-watered and drought-treated wheat (Triticum aestivum L.) plants. The study showed that calibration of RDT sensors with a height gauge resulted in very accurate and robust measurements of growth rate and drought stress dynamics in monocotyledons, such as wheat. To correctly interpret the sensor measurements and derive the underlying mechanism, it is however important to consider the complex architecture of the plant, as the RDT not merely measures leaf growth, but also any potential growth of supporting parts.