Abstract

The objective of this work was to evaluate the variability of photosynthetic pigment content and daily stomatal conductance was evaluated in relation to environmental variables in Copoazú (Theobroma grandi orum) ecotypes. The ecotypes used were part of the germoplasm bank of the University of the Amazon (Colombia). The study was carried out during the year 2015. Four leaves of the average stratum of four plants were collected for each ecotype, to extract and read at different levels of absorbance and determine the content of photosynthetic pigments. During the hours of 04:00 a.m. to 6:00 p.m., the stomatal conductance (gs) was monitored for environmental variables (relative humidity, air temperature, radiation and vapor pressure de cit (VPD). An analysis of variance was made using the Tukey test, correlations and regressions were made between gs and environmental variables. The contents of chlorophyll a, b, total and carotenoids among ecotypes were different (P<0.0001), the ecotype UA-31 presented the highest values, contrasting with the ecotype UA-37. Concerning gs, the interaction ecotype*hour showed significant differences (P<0.0001) .The ecotypes that presented the highest values of gs were UA-67 and UA-039, (P<0.0001), radiation (-0.91, P<0.0001) and DPV (-0.94; P<0.0001) 0.0001).The results suggest that ecotypes UA-039 and UA-31 were the most suitable in terms of gaseous exchange and content of photosynthetic pigments. 

 

Keywords: phenotypic diversity, physiological response, environmental conditions.