Efficiency of the photosynthetic rate and water use was evaluated in cassava cultivars (Coimbra, Platina, IAC-12, Coqueiro, and Cacau-UFV), sprayed with five mesotrione rates (0, 72, 108, 144, and 216 g ha-1). CO2 consumed, internal carbon, photosynthetic rate, water vapor stomatal conductance, transpiration rate, leaf temperature, and water use efficiency were assessed 45 days after application of the herbicide. Platina cultivar was found to be less affected by mesotrione. Only in this cultivar, the applied rates of 144 and 216 g ha-1 did not alter the photosynthetic rate of the plants. The leaf temperature of the cassava cultivars was not affected by the herbicide, either; however, reduced water use efficiency was observed in the Coqueiro cultivar.
water use efficiency; Manihot esculenta; photosynthetic rate
