Crescimento e metabolismo bioquímico em mudas de dendê Elaeis guineensis Jacq. na variedade Deli x Lamé acometidas à diferentes concentrações de alumínio.

Abstract

Studies have shown that Al+3 impairs the growth and development of sensitive plants, as well as the presence of resistant and / or tolerant plants. Excess aluminum, in addition to inhibiting normal root formation, interferes with enzymatic reactions, absorption, transport and nutrient use by plants. In view of the above, the present work aimed to evaluate the effects of the application of aluminum doses on the growth and metabolism of palm seedlings Elaeis guineensis Jacq. The experiment was conducted in a greenhouse of the Institute of Agrarian Sciences of the Federal Rural University of the Amazon, in Belém, Pará, from August 2015 to January 2016, and the biochemical and physiological analyzes were carried out at the Laboratory of Biodiversity Studies in Plants (EBPS), established in the same place. The oil palm seedlings in the variety Deli x Lamé with five months old, were provided by the company ADM (Archer Daniels Midland), Located in the municipality of Concórdia / PA, originated from Embrapa Amazônia Occidental-AM. The experimental design was in DIC-Fully Informed Design, with 5 replicates, one plant being an experimental unit, where the aluminum dosages of 0 mg L-1 , 10 mg L-1 , 20 mg L-1 , 30 mg L-1 and 40 mg L-1 of Al+3, This cation being added in the form of aluminum chloride 95% hexahydrate (AlCl3 .6H2O). Making a total of 25 plants analyzed. Morphological characteristics and biochemical responses were analyzed at the end of the experiment. Most of the growth characteristics of the oil palm Elaeis guineensis Jacq. Were negatively influenced by the increase in AlCl3 dosages. A decrease was observed in most of the biometric characteristics analyzed, with the maximum dosage applied. Observing the lowest averages of Height, Number of leaves, Number of differentiated leaves, DMAP-Dry Matter of Aerial Part, TDM-Total Dry Matter, DMAP / DRM- Dry Matter of Aerial Part / Dry Root Matter, in the plants that received the dosage of 40 mg L-1 of Al+3. Regarding the biochemical parameters analyzed, it was verified that the increase of the AlCl3 dosages, promoted a higher EL-Electrolyte Leakage. Al3+ is expected to affect membrane fluidity by altering the chemical environment of membrane lipids, probably by forming bonds between the polar regions of the phospholipids. The increase in NO3 - and of NH4 + in roots, maybe related to Al+3 interference in the metabolism of some enzymes, including Nitrate RN-Reductase. Who presented a reduction in their activity in the treatment that received the highest dose of 40 mg L-1 of Al+3. The increase in amino acid, protein and carbohydrate concentrations in leaves and roots may be related to the great competition of Al+3 by plasma membrane binding components. The decrease in chlorophyll content causes a disturbance in cellular redox homeostasis, since this molecule plays the role of electron acceptor, thus increasing the production of ROS. Several studies have shown that Al+3 ions increase the production of reactive oxygen species (ROS) and increase membrane lipid peroxidation.