A New Method of Measurement and Analysis of the Stem Extension Growth Rate to Demonstrate Complete Synchronisation of Chenopodium rubrum Plants by Environmental Conditions

Abstract

Summary Linear voltage differential transformers (LVDTs) are among the most appropriate devices for measuring plant organ growth. They are characterized by high resolution, low cost, and easy handling. As a novum we have developed a computerized LVDT based measuring system that permits numerical and graphical analysis of stem elongation while the corresponding measurement process itself (i.e. data acquisition) concurrently takes place in the background. Using these methods an adequate interpretation of the growth behavior of the plants under investigation is already possible during the course of the experiment. This is usually referred to as on-line analysis. Since data sets of up to six different experiments can be handled in the main memory of the computer at the same time, even the comparison of the running experiment with earlier ones is feasible. Ten individual plants as well as environmental variables like light fluence rate and temperature can be measured simultaneously. The precision of the growth measurement amounts to ± 0.002 mm. Longterm measurement is possible by a software controlled self adjusting circuit that constantly maintains the LVDTs within their measuring range. Moreover, our software provides an easy-to-use menu oriented user interface to facilitate handling the system. The presented measuring system visualizes the ongoing plant growth process, thereby allowing one to apply chemical or physical treatments to the individual plants of a perfectly synchronized experimental population at specific, well-defined developmental stages. In this article we give detailed information about the set-up of the measuring system, the employed soft- and hardware and the checks needed to ensure their proper functioning, and demonstrate the perfect synchronization of the stem extension rate of a population of plants.