A system for controlling the root and shoot environment for plant growth studies

A growth chamber-based system was developed for controlling an array of shoot and root environmental factors for plant growth studies. A data acquisition and control system continuously monitors and regulates environmental conditions in each chamber as specified by a computer program. Shoot environmental factors which can be independently varied include air temperature, light intensity and photoperiod, relative humidity, and CO₂ and SO₂ gas concentrations. Root environment is controlled by regulating the temperature, pH and nitrate level of the hydroponic nutrient medium. Initial growth experiments have been conducted in which nitrate concentration in the hydroponic solution was held constant at levels from 5 mmol/m³ to 1000 mmol/m³, spanning a wide range of nitrogen limitation. Plants also have been raised either with or without SO₂ (0-0.4 cm³/m³). Results of these studies show the degree of environmental control achieved, indicate the variation in plant growth response, and suggest the potential for experiments with combinations of controlled environmental stresses.