NO3-/NH4+ ratios affect nutritional homeostasis and production of Tanzania guinea grass under Cu toxicity

Autor(es)

de Souza Junior, Joao Cardoso ; Nogueirol, Roberta Correa ; Monteiro, Francisco Antonio

• Tipo de documento: Artigo Científico
• Fonte: Environmental Science and Pollution Research; v. 25, n. 14, p. 14-pg., 2018-05-01.

Resumo

Nitrogen (N) can alleviate metal toxicity. However, as of yet, there have been no studies showing the efficacy of NO3-/NH4+ mitigating Cu toxicity. The objective of this study was to evaluate the Cu toxicity on the nutritional and productive attributes of Panicum maximum cv. Tanzania as well as the role of NO3- and NH4+ ratios in nutritional homeostasis. The experiment was conducted using 3 x 4 factorial treatments arranged in a randomized complete block design with three replicates. The treatments were three NO3-/NH4+ ratios (100/0, 70/30, and 50/50) and four Cu rates (0.3, 250, 500, and 1000 mu mol L-1) in nutrient solution. Copper concentrations in the diagnostic leaves (DL) were highest in plants grown under 70/30 NO3-/NH4+ ratios and a Cu rate of 1000 mu mol L-1. In this combination, it was observed that DL had higher concentrations of NH4+, greater glutamine synthetase activity, lower chlorophyll concentration (SPAD value), and lower shoot dry mass, suggesting high disorders of nutritional homeostasis. Plants receiving N in the form of NO3- and 1000 Cu mu mol L-1 showed that DL had lower concentrations of Cu, higher concentration of chlorophyll, higher NO3- concentration, higher nitrate reductase activity, and higher NO3- accumulation in the roots, suggesting a reduction in disorders of nutritional homeostasis. The disorders on mineral uptake, N assimilation, and biomass production caused by Cu toxicity are shown to be affected by NO3-/NH4+ ratios, and N supply via NO3- allowed for better homeostasis of the forage grass. (AU)

• Processo FAPESP: 15/20624-4 - Nutrição mineral de plantas e a tolerância do capim tanzânia ao estresse causado por metais
• Beneficiário: Francisco Antonio Monteiro
• Modalidade de apoio: Auxílio à Pesquisa - Regular