Agave tequilana is an important crop in the central west part of Mexico. Basic studies on functional aspects of this CAM plant are scarce, particularly the effects of the environment on the photosynthesis. The effect of the seasonal variation on irradiance, air temperature and relative humidity and plant water status in the photosynthesis were studied in both young (2 years old) and in mature plants (6 years-old) growing in a warm subtropical environment.

Results/Conclusions

For mature and young plants, net CO₂ uptake occurred during both dry and wet months of the year, and the higher values of daily net CO₂ uptake coincided with cool daytime/nighttime air temperature and the highest values of irradiance. Daily net CO₂ uptake in the 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. The succulence of the photosynthetic tissue, and both the night and the day net CO₂ uptake were determinant to maintain carbon gain in both young and mature plants of A. tequilana throughout the year, particularly during the dry season.