An experimental method for varying root temperature independently of shoot temperature

Abstract

In the field, roots and shoots of plants are seldom exposed to the same temperature. Methods for varying root temperature independently of shoot temperature have relied upon hydroponic systems or field‐based studies, and both approaches have limitations for investigating the physiological affects of temperature on nutrient uptake. A low‐cost method for varying root and shoot temperature independently using a solid root medium was developed, and its utility demonstrated in an experiment with white clover. The “temperature gradient trough” enabled the effects of a range of root temperatures from 6 to 24°C on nitrogen (N) uptake and distribution to be evaluated. Results showed that at an 8°C shoot temperature, an increase in root temperature resulted in an increase in ¹⁵N distribution to the laminae. At a 24°C shoot temperature, and root temperatures greater than 10°C, plants had significantly more ¹⁵N in laminae and petioles than at shoot temperatures of 8°C. The temperature gradient trough enabled independent varying of root and shoot temperatures in a controlled environment, allowing rapid exploration of the effects of temperature on N distribution in white clover.

Key words:

• nitrogen
• root temperature
• temperature gradient
• white clover