Característica ecofisiológicas de clones de bertholletia excelsa H. & B. em plantios de produção na Amazônia

Abstract

To reincorporate to the productive processes up to 700,000 km2 of areas in Amazon region involves the implementation of reforestation programs. However, one of the segments of these programs, the productive plantations requires robust knowledge about the species selected for this purpose. Among the species used, Bertholletia excelsa H. B. has been native forest species most used in plantation to reclamation disturbed area and agroforestry systems in Amazon. Agropecuária Aruanã S. A. Company with 1,257,000 trees (Itacoatiara, AM) is the highest example of commercial plantation of this species. The plantations are composed of five clones (Aruanã - ARU, 609, 606, Manuel Pedro - MP and Santa Fé - SF) propagated by grafting. However, physiological potential of these clones and the interaction with their site characteristics in productive plantation were not studied yet. In order to investigate the physiological performance of the five clones and responses their regard to the temporal (high and low precipitation) and spatial (leaf crown growth environment – sun and shade) factors, photosynthesis and irradiance capture efficiency and use, carbon isotopic composition, leaf water potential, specific leaf area, leaf nutrient concentration and photosynthetic nutrient use efficiency were studied. The clones showed different responses for the most variable analyzed. ARU clone exhibited the best performance to carbon assimilation (12 – 14.9 μmol m-2 s- 1) and nutrient use efficiency. This clone showed photosynthesis average about 28% higher than SF (8.4 – 11.6 μmol m-2 s-1) clone and was the most efficient, specially, in the macronutrient use N (93 – 118 mmol mol-1 s-1), P (4157 – 4761 mmol mol-1 s-1) and K (1030 – 1612 mmol mol-1 s-1). 609 clone exhibited the highest Ca (5.0 – 12.2 g kg-1) and Mg (1.7 – 2.7 mg kg-1) leaf concentrations, P and K use efficiency, and the best irradiance capture efficiency and use by PIABS (1.3 – 2.5) and PItotal (0.7 – 1.4) performance indexes. 606 clone showed the highest K (2.9 – 8.1 g kg-1) leaf concentrations and high N use efficiency (84 – 115 mmol mol-1 s-1). MP clone showed the highest Mg (2.1 – 3.1 g kg-1) leaf concentrations, though, together with SF clone, exhibited the lowest photosynthetic nutrient use efficiency. SF clone showed the highest performance indexes (PIABS and PItotal) and carbon isotope composition (-30.1 - - 28.7‰), however the lowest values of stomatal conductance and photosynthesis. The clones showed the highest photosynthesis per unit leaf area, dark respiration, stomatal conductance, transpiration rate, compensation and saturation irradiance, carbon isotopic composition, Mn leaf concentration, PItotal and IP phase (expresses relative abundance of PSI as compared with PSII) in sun leaves. The highest values of specific leaf area, P and K concentrations and PIABS index were observed in shade leaves. Altogether, there was higher Mn leaf concentration, Fv/Fm, PIABS and PItotal indexes during high precipitation period. On the other hand, the highest values of photosynthesis per unit leaf mass, specific leaf area, P and K leaf concentrations were observed during low precipitation period. Thus, it was conclude that B. excelsa clones have different physiological performance when used in productive plantation and exhibit different structural and functional responses to the spatial and temporal factors.