A simple method for reducing moisture condensation on Petri dish lids

Condensation on the lids of Petri dishes, used to culture plant tissues, can often obscure the view of the contents of the dish and interfere with data collection. Under the high humidity conditions that exist in the culture container, a small temperature drop causes water to condense on the inside lid and sides of the container. Mild condensation causes "fogging" while continual or repeated rounds of condensation result in the formation of water droplets. To control condensation in the standard plant tissue culture Petri dish, a simple method was developed whereby the lid of the culture dish was modified, to buffer the lid from temperature fluctuations. Polymer discs, which were the same diameter as the Petri dish lid, were either placed on the top of the lids of existing dishes or surface-sterilized and used in place of the lid. Polymer discs of varying thicknesses and type, and possessing different thermal conductivities, were evaluated for their abilities to reduce the rate of condensation formation. Petri dishes with modified lids were placed under reduced temperature conditions. Condensation, forming on the lids of the dishes was quantified over time using image analysis. Gray value determinations indicated that the thicker polymer discs with the lowest thermal conductivities provided the best protection against condensation. Placement of polymer discs on the top of Petri dishes is a relatively simple method that can be used to buffer the lid from small temperature changes and minimize condensation problems.