Photochemical Efficiency and Leaf Carbohydrates of Theobroma cacao L. Genotypes Under Different Light Regimes and Cultivation Systems

The cacao tree is naturally adapted to shade; however, cultivation in full-sun systems is becoming increasingly common. However, high light intensity can damage the photosynthetic apparatus, making the choice of genotype fundamental to the success of the crop. Thus, in the north of the state of Espírito Santo, municipality of Linhares, the physiological and biochemical responses of the cacao genotypes PS1319, CEPEC 2002, and PH16 were evaluated in agroforestry, cabruca, and full sun cultivation systems during the months of April to October. To this end, chlorophyll a fluorescence, photosynthetic pigments, and carbohydrates were evaluated using a completely randomized split-plot experimental design. Across agroforestry, cabruca (a traditional Brazilian shaded system), and full-sun systems, the cacao genotypes PH16, PS1319, and CEPEC 2002 did not show limitations in photosynthetic performance, as evidenced by the stable values of PI abs and PI total throughout the evaluation period. The highest quantity of photosynthetic pigments was found in the genotypes CEPEC 2002, PH16, and PS1319 in full sun cultivation, in the genotypes PH16 and PS1319 in the agroforestry system, and in the genotype CEPEC 2002 in the cabruca system. The genotypes PH16 and PS1319 obtained higher levels of glucose, sucrose, and fructose, both in shaded environments (agroforestry and cabruca systems) and in full sun. Therefore, due to their greater stability and adaptability, we recommend the PH16 and PS1319 genotypes for cultivation in agroforestry and full-sun systems, and the CEPEC 2002, PH16, and PS1319 genotypes for the cabruca cultivation system.