Alterações fisiológicas e metabólicas evidenciam a sensibilidade do açaizeiro (Euterpe oleracea Mart.) a altas temperaturas.

Abstract

The açaí palm (Euterpe oleracea Mart.) Is a palm native to the Amazon and of great economic interest in Brazil and in the world. Brazil is the world's largest producer of açaí fruit, the state of Pará being the largest national producer. This production was destined for local consumption, but the conquest of new markets and the increase in exports stimulated the expansion of commercial plantations on land. Increasing greenhouse gas emissions are expected to influence temperature rise and thermal stress leads to a series of physiological and biochemical changes in plants. In this sense the sensitivity of açaiseiro to thermal stress is related to the progressive loss of Rubisco activity as a function of the time of exposure of the plants to stress and its consequences in plant physisology. In addition, the search for materials that are tolerant to this type of work becomes essential to overcome the negative effects caused by it. In this context, the BRSPA variety, which presents greater tolerance to water deficit than unimproved or native materials, also presents greater tolerance to thermal stress. To test these hypotheses, two independent experiments were conducted with the objective of evaluating the magnitude of the physiological changes directly related to the photosynthetic metabolism as a function of the different times of exposure of the plants to thermal stress and to evaluate the physiological and biochemical behavior of two plant materials of açaizeiro (native plant material, Wt; and var BRS-PA) at high temperature. The açaizeiro is extremely sensitive to thermal stress, both in its magnitude and when comparing two plant materials (Wt and BRS-PA) presenting significant damage in its photosynthetic apparatus, in terms of gas exchange and photosystem IIstability, when submitted to a stress of 40 ° C, causing negative oxidative and metabolic alterations, such as reductions in Rubisco activity, increase in the production of reactive oxygen species (lipid peroxidation) and decrease of primary metabolites (starch, glucose and sucrose). However, the BRS-PA variety presented lower damages related to water status, physiological changes and PSIIstability.