Nutritional contents of young cupuaçu (Theobroma grandiflorum) plants subjected to increasing copper doses.

Abstract

The cupuaçu tree (Theobroma grandiflorum), primarily cultivated in the North and Northeast regions of Brazil, has significant economic importance, especially for small producers. With the increasing demand, research on genetic improvement and agricultural practices has intensified, and cupuaçu cultivation has expanded with the use of modern technologies. The study conducted at Embrapa Amazonia Oriental in Belém-PA evaluated the effects of increasing doses of copper (Cu) on two cupuaçu tree progenies. The experiment was conducted in a greenhouse with five copper doses: 0, 15, 30, 60, and 120 mg/kg of soil, analyzing variables such as vegetative development and dry biomass. Copper is essential for photosynthesis and cellular respiration, but in excess, it can be toxic to plants. Progeny 63 showed an increase in Cu levels up to a critical dose of 15 mg/kg, followed by a decrease, indicating regulatory mechanisms against toxicity. Progeny 61, on the other hand, showed greater stability, with a gradual increase in Cu levels in the leaves and roots at higher doses, suggesting greater efficiency in utilizing and tolerating excess copper. Progeny 63 had difficulties translocating copper to the stem at high doses, while progeny 61 showed a more dynamic physiological response, allowing Cu redistribution throughout the plant parts. These results indicate that progeny 61 is more adaptive and resistant to the stress caused by Cu accumulation, while progeny 63 is more sensitive to toxicity, which may hinder its long-term development. At excessive doses, copper can affect stem lignification, causing damage to growth and plant stability