Alterações biométricas, nutricionais e metabólicas em plantas jovens de Zeyheria tuberculosa (Vell.) Bureau ex Verl submetidas a diferentes níveis e proporções de nitrato e amônio e toxicidade por alumínio

Abstract

Brazil has 58% of its territory occupied by latosol and argisol, characterized by being deep soils, with high weathering, high acidity, low availability of nutrients, and, often, high aluminum saturation. Despite being well adapted to low nutrient availability, native vegetation of this type of soil is capable of responding positively to fertilization, showing higher growth rates and biomass accumulation. Studies have demonstrated that some of these species have adaptations to deal with the high availability of aluminum in the soil, with tolerance strategies to this metal, with some options being aluminum hyperaccumulators. Therefore, it is plausible to consider the importance of studying the physiological and growth modulations of native species under different nutritional conditions, as is the case with nitrition, as well as the ability of these species to tolerate high concentrations of aluminum. Thus, this work aimed to evaluate the responses of young plants of Zeyheria tuberculosa, a species native to the Cerrado and with high potential for use in the recovery of degraded areas, cultivated in different doses and sources of nitrogen fertilizer (nitric and/or ammonia) and under different levels of aluminum. To this end, two experiments were carried out with the objective of: evaluating the best level of nitrogen, supplied exclusively with nitrate, for the development of Z. tuberculosa seedlings and; analyze the interaction of different proportions of aluminum on nitrogen metabolism in young Z. tuberculosa plants. The experiments were set up in a greenhouse and seedlings around 90 days old were subjected, for another 60 days, to different treatments as shown below: Experiment 1: different concentrations of nitric nitrogen (2; 4; 8; 12 and 16mM of NO3-); Experiment 2: different proportions of NO3 -/NH4+(100/0; 75/25; 50/50; 25/75; 0/100) and aluminum concentrations (0; 600 and 1200 μM). In all experiments, biometric and biochemical analyzes were carried out on leaves and roots of the seedlings. The experiments were carried out in a randomized block design (DBC) and the data were subjected to regression and analysis of variance, with means compared by Scott-Knott’s test at 5% probability level, using the R® software through the RStudio platform. The results obtained here demonstrate that nitrogen levels above 10mM constitute luxury consumption for Z. tuberculosa and that nitrogen, carbon and antioxidant metabolism are altered under low nitrogen availability. The highest growth values of Z. tuberculosa were observed when this species was fertilized with mixed sources of nitrogen, with greater performance in a 50/50 ratio. Mixed sources of nitrogen were also developed so that the species under study could maintain the functioning of carbon, nitrogen metabolism and redox homeostasis under the presence of aluminum. The results obtained in this work are important for fundamental strategies for the production of Z. tuberculosa seedlings and their introduction into natural environments using adequate nitrogen fertilization with different sources of nitrogen, which can also mitigate the effects of aluminum on the growth of these plants.