RHIZOTRONS - THEIR DEVELOPMENT AND USE IN AGRICULTURAL-RESEARCH

Rhizotrons are tools for making nondestructive, repeated observations and measurements of root systems. Primary objectives of this review are to report features of several rhizotrons and to describe the types of research that have been and will be performed in them. Rhizotrons are permanent installations, geneally with transparent viewing surfaces for measurement of plant roots. Typically, these facilities have control of drainage and are well instrumented for macroscopic and microscopic observations of roots. They are excellent for getting descriptive and semi-quantitative data on simulataneous changes in root and shoot systems of different cultivars or species over seasons or in response to treatments. Rhizotrons can also be designed to allow measurement of mass balances of water and nutrients within the rooting volume of a crop. Future uses of rhizotrons will include research on the root-zone behavior of soil nutrients such as NO3, detailed measurement of processes such as diffusion and mass flow of liquids and gases in soils, and development of better information on the role of soil biota in nutrient cycling and uptake. This new information will permit better definition of the role of root systems in plant growth and development.