Stomatic dynamics and CO2 capture of napolea cochenillifera salm-dyck varieties at different times and times of evaluation

This study aimed to evaluate the gas exchanges in genotypes of Nopalea cochenillifera Salm-Dyck in different seasons and times of the day. The experiment was conducted with the varieties Miúda and Baiana at the Experimental Station to National Semi-Arid Institute (INSA), in the municipality of Campina Grande, state of Paraíba, Brazil. The treatments were distributed in a 24 x 2 factorial arrangement, corresponding to gas exchange evaluations performed every hour for 24 hours in the rainy season (June) and in the drought season (December). Analyzed were stomatal conductance, and CO2 uptake.In both drought and rainy seasons, variety Baiana presented highergas exchange intensity than the variety Miúda. In the rainy season, gas exchanges are potentialized in both varieties evaluated. In this period, the peak of CO2 uptake occurs from 1:00 a.m. to 3:00 a.m. for the variety Baiana, and from 11:00 p.m. to 2:00 a.m.for the variety Miúda, whereas, in the drought season, it occurs from 11:00 p.m. to 2:00 a.m. for both varieties, with these constituting the ideal intervals for measuring gas exchanges in the field.