A HIGH-RESOLUTION PLANT GROWTH-MEASURING APPARATUS TO STUDY STEM GROWTH-KINETICS

A custom-designed high-resolution plant growth-measuring apparatus, co ntrolled by a microcomputer is described, Plants are attached with a l igature thread to a measuring arm, which is part of the displacement d etection device (floating zero), The floating zero is mounted on a sle dge fastened to a precision spindle and follows growth with a constant upward tension. A time interval (of is or more) is set at which the f loating zero is adjusted and growth is registered via an incremental e ncoder with a resolution of 1 mu m. The measuring devices are mounted on a vibration-free table and have their own climate-control system wi th photosynthetic lighting from above. The growth of a plant can be fo llowed over a period of several days. Data from individual plants are saved, mean growth rate calculated and smoothed. Results using tomato (Lycopersicon esculentum Mill.) plants are presented. They demonstrate that the growth of a tomato plant has a characteristic pattern during the daily light-dark cycle. The capability to accurately measure grow th is discussed in relationship to environmental factors, such as ligh t quality, temperature and pollution. (C) 1997 Published by Elsevier S cience B.V.