Construction and Performance of a Temperature-Gradient Bar and Chamber.

An inexpensive temperature-gradient bar and chamber for use in studies of seed germination and root growth is described. Aluminum troughs and a bar, surrounded by insulation and heated and cooled at their ends by water baths, form the floor of a chamber. A plexiglass top permits illumination by overhead light banks. The temperature gradient may be adjusted to any range within the limits of 10° and 50°C. The linearity and stability of the bar gradient, and the presence of temperature and humidity gradients in the chamber air above the bar, are discussed.