Morphoanatomic and Physiological Characterization of Cacao (<i>Theobroma cacao</i> L.) Genotypes in the South of Bahia, Brazil

Abstract

Cocoa tree genotypes (Theobroma cacao L.) were studied and characterized in terms of their morphoanatomical and physiological attributes in a non-stressful environment, as these attributes are of fundamental importance to understanding the plant’s relationship with the environment. Therefore, the objective of this study is to describe morphoanatomical and physiological patterns that can differentiate the seven cocoa genotypes, evaluated under the same conditions of temperature, humidity, and light. The genotypes remained in a greenhouse for 40 days, where sample collection procedures were carried out to analyze gas exchange parameters, such as net photosynthetic rate, stomatal conductance, and transpiration; growth parameters, such as dry weight, height, and leaf area; and the anatomy of leaves and stems via root, stem, and leaf dimensions and histochemistry. The cluster divided the genotypes into six groups. The Ipiranga-01, CCN-10, and PH-16 genotypes were grouped since they presented the highest means of anatomical variables and photosynthetic parameters. The PS-1319 genotype was segregated from the others for having the lowest physiological parameter values. CCN-51 and Cepec-2002 were grouped due to their similarity only in the internal concentration of CO2, while Ipiranga-01, CCN-10, SJ-02, and PH-16 were grouped due to having higher physiological parameters and morphoanatomical variables. The results indicated an intergenotypic variation in physiological and morphoanatomical variables, serving as a basis for the six genotype groups.

Keywords

• inter-clonal comparison
• phytotechnics
• photosynthesis
• growth analysis