RESPONSE OF ADAXIAL AND ABAXIAL STOMATA TO LIGHT

Abstract

The response to light by adaxial and abaxial stomata was measured with an aspirated diffusion porometer in normal and inverted leaves of sorghum (Sorghum bicolor (L.) Moench) and tobacco (Nicotiana tabacum L.). The adaxial stomata, normally exposed to bright light, closed at 2000 ft‐candles in both sorghum and tobacco whereas the abaxial stomata, normally in dim light, closed at approximately 1000 ft‐candles in sorghum and 200 ft‐candles in tobacco. The greater sensitivity of the abaxial stomata to light in both the monocotyledon, sorghum and the dicotyledon, tobacco, indicates that the phenomenon is widely distributed and occurs irrespective of differences in stomatal density. Further, the narrowing of the adaxial stomata which occurred upon leaf inversion suggests that the level of carbon dioxide within the intercellular spaces of the leaf does not control stomatal apertures. Copyright © 1970, Wiley Blackwell. All rights reserved