Coffee leaf temperatures in a tropical environment

Measurements of leaf temperature, air temperature, stomatal resistance and the net radiation of leaves are presented for coffee leaves exposed to the sun and shaded. Sunlit leaves were generally between 10°C and 15°C above air temperature (which was approximately 29°C) and shaded leaves were 1 °C or 2°C below air temperature. Leaf temperatures are analysed in terms of the leaf energy balance equation and transpiration rates are calculated. Stomatal resistance of sunlit leaves was often higher than that of shaded leaves in continuous sunshine, however on days following substantial rain the stomata of sunlit leaves remained open. The affect of leaf temperatures on the dry matter production of coffee is briefly discussed.