Nitrogen compounds and enzyme activity in young muruçi (Byrsonima crassifólia L.) plant subjected to water stress.

The objective of this study was to verify the nitrogen compounds and enzyme activity in muruci plants subjected to water stress. The experiment was conducted in a greenhouse on 4-month-old seedlings. The experimental design was completely randomized with two water conditions (control and water stress), with 14 repetitions, totaling 28 experimental units. The parameters analyzed were relative water content, nitrate concentrations, ammonia, total soluble amino acids, total soluble proteins, proline and glycine betaine and the activities of the enzymes nitrate reductase (ARN) and glutamine synthetase (GS). The suspension of irrigation (water stress) for 25 days provided significant changes in all parameters. The suspension was sufficient to alter the metabolic and enzymatic pathways of young muru i plants, reducing the relative water content, nitrate concentration and total soluble protein, nitrate reductase and glutamine synthetase activity. However, the suspension raised the free ammonium, total soluble amino acids, proline and glycine betaine concentrations in the plant parts. Therefore, these changes indicate that this species is susceptible and can change its metabolic pathways. However, some important enzymes in nitrogen metabolism cannot be activated, compromising the entire process of assimilation of this element in soils with low water availability, contributing to the knowledge about abiotic stresses in murucizeiro plants.