Net CO2 Uptake for Agave tequilana in a Warm and a Temperate Environment1

Abstract

The main objective was to evaluate the effects of seasonal variations in air temperature, soil water content, and irradiation on the net rate of CO2 uptake for Agave tequilana growing in a warm subtropical environment (Amatitan, Jalisco, Mexico) and in a temperate subtropical environment (Arandas, Jalisco, Mexico). At Amatitan, the lowest value of positive daily net CO2 uptake (141 mmol/m2/d) occurred at the end of the summer rainy season and the highest values during the winter (578 and 921 mmol/m2/d); at Arandas, the lowest value (188 mmol/m2/d) occurred at midsummer and the highest values at the end of the summer (763 mmol/m2/d) and in late winter (572 mmol/m2/d). The highest values of daily net CO2 uptake in both localities reflected prolonged daily periods of net CO2 uptake that included both daytime and nighttime assimilation accompanied by high rates of nocturnal net CO2 uptake due to moderate nighttime air temperatures. High temperatures in the summer reduced daily net CO2 uptake at both localities but in late summer, the nighttime temperatures at Arandas were moderate, which lead to high daily net CO2 uptake. Leaf succulence allowed substantial daily net CO2 uptake when the soil water content was relatively low during the winter and the spring (January–March). Indeed, appreciable daily net CO2 uptake occurred throughout the year for A. tequilana at both localities, indicating that this CAM plant species can sequester carbon even during prolonged dry periods.