Ecophysiological responses of Cupuassu tree ecotypes ( Theobroma grandiflorum) in an agroforestry system designed with rubber trees in Colombian Amazon

Cupuassu [Theobroma grandiflorum (Willd. ex Spreng.) K. Schum] is a promising Amazonian fruit tree of great interest for implementation in sustainable agroforestry enrichment alternative models for the Colombian Amazon. The purpose of this study was to assess the diurnal and seasonality eco-physiological behavior of two distinctive ecotypes (i.e., Eco11 and Eco4) and a control ecotype (EcoCaq) in association with rubber plantations (clone FX 4098) in growth phase in two agro-climatic zones of Caqueta in the Colombian Amazon. Cupuassu was established in a completely random design with distances of 3.0x4.0 m in double rubber corridors, and the latter in turn with distances of 4.0x2.8x10.0 m. Linear models were used to analyze the daily courses of gas exchange and water potential of the plant, micro- climatic parameters and soil water potential. A biplot genotype x environment analysis was used to analyze the adaptability and stability of the three eco-types. The highest photosynthetic rates occurred between 9:00 and 12:00 h and in times of greater precipitation (wet and transition to dry season). The plants water potential was the eco-physiological parameter that best correlated with photosynthesis, and with climatic factors, positively with relative humidity and negatively with PAR (photosynthetically active radiation), temperature and VPD (vapor pressure deficit). Eco11 presented the highest photosynthetic performance therefore representing the best option for implementation of agroforestry enrichment arrangements with rubber plantations with potential for the Colombian Amazon