Respostas ecofisiológicas de plantas jovens de castanheira do Brasil (Bertholletia excelsa Bonpl.) submetidas à deficiência hídrica.

Abstract

The Brazil nut tree is known as (Bertholletia excelsa Bonpl -. Lecythidaceae) is a large tree that can reach 50m in height. It is important both ecologically as it contributes to the dynamics of the forest and succession, and socially, thousands of families in Brazil, Bolivia and Peru survive from the harvest of the fruit of the Brazil nut tree. The species has a wide distribution in lowland Amazonia and called Guiana Highlands, which occurs naturally in upland forest. Among the arboreal forest species most commonly used in reforestation programs in the Amazon region, the chestnut-the-Brazil (Bertholletia excelsa HB) has proved to be one of the species with the greatest potential, due to its good performance in growth in various soil and climatic conditions. The establishment of forest plantations, either for commercial or restoration purposes, depends on a number of factors, and the quality of seedlings key to initial success. In this light we sought to investigate the growth responses and physiological ecology of the Brazil nut tree seedlings under water stress by associating biometric variables to physiological processes related to water use mechanisms. With the overall goal: to analyze the growth of B. excelsa under the influence of water suspension; and specific: to determine the vegetative growth of the Brazil nut tree, submitted to water stress; determine the physiological and biochemical processes located in the plant leaf under water stress, such as photosynthesis (A); Stomatal conductance (Gs); Internal carbon (C); Photosynthetically active radiation (PAR); Transpiration (E) and concentrations of carbohydrates and amino acids. In which hypotheses were tested: that there may be slowing the growth of plants under induction of water stress due to the power shift to decreased sweating; the photosynthetic performance of young plants of the Brazil nut tree, submitted to water deficit is reduced. The diameter growth and accumulation of total dry matter of B. excelsa were reduced to 9 days of water deficit. The plants tolerate water stress for nine days, attributing this behavior, mainly to stomatal efficient regulation by the plant. Indicators of the gas exchange (A, gs, E and C) and biochemical plants of B. excelsa strongly decreased in 9 days of water deficit.