Efeito da fonte de nitrog?nio na libera??o de OH-/H+ na rizosfera e a intera??o com toxidez de alum?nio, estresse de salinidade e associa??o com Trichoderma sp.

• Autor(a) principal: Silva, Aldir Carlos
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFRRJ
• Texto Completo: https://tede.ufrrj.br/jspui/handle/jspui/1633
• topic: nitrogen source; aluminum; salinity; Trichoderma; fontes de nitrog?nio, ,; alum?nio; salinidade; Trichoderma; Ci?ncias Agr?rias

The present study was conducted to evaluate if changes in rhizosphere pH of the growth media, controlled by the use of nitrogen sources could alleviate aluminum toxicity or effects caused by salinization. It is well documented that if a plant is absorbing and assimilating nitrate as a nitrogen source, it releases 0H - for growth substrate. If she is absorbing, assimilating, ammonia source releases H+. This occurs because the cells need to balance its electrochemical charge balance due to differential uptake of cations and anions. Despite being a general rule, scientific research directly use the nitrogen source in the growth medium, few have used other methods to add these sources, such as foliar application of nitrogen and its implications on load balancing. In this work, several alternative management of nitrogen application and its interactions with the toxicity caused by aluminum, excess salts and Trichoderma were studied. Sunflower (Helianthus annuus L.), Passionflower (Passiflora edulis f flavicarpa L.), Pineapple (Ananas comosus Merril), Coffee (Coffea arabica L), Almond (Terminalia catapa Linn) and Sombrero (Clitoria fairchildiana Howard). To conduct studies with plants Sunflower was initially performed a selection of more tolerant to acidity and salinity plants. The experiments were conducted on various substrates, soil and sand, simple and complete nutrient solution. The interaction between Trichoderma x nitrogen source for plants was conducted with Passion fruit and Sunflower. Were selected as moderately tolerant to aluminum to grow Sunflower Helium 360 , the other cultivars to toxicity occurred in contraction equal to or superior 160?M aluminum . Was selected as tolerant to salinity the H?lio 251 > 250 > 253, cultivars, with concentrations above 25 mM NaCl (1.90 dS.m?) plants were stop grown. After this step prior experiments cultivars tolerant or sensitive were used in accordance with the experimental needs. The experiments were divided into the following steps: In the first step, we evaluated the release of OH - / H + with application of nitrogen sources directly in the growth medium, and found that the nitrogen sources were unable to minimize the toxic effects of aluminum and salinity. In the second experiment, the effects of the release OH- /H+ with application of nitrogen sources in the association of the fungus Trichoderma sp. This fungus grown in petri dishes only at pH values above 5.0. The release of OH- / H+ did not influence the association of the fungus with the roots of plants of sunflower and Passion fruit. In the third step, we assessed whether foliar application of nitrogen sources could produce the same effects on efflux of loads in the rhizosphere. It was found that the nitrogen sources applied foliar increased the pH of the solution was applied when 10 % of nitrate and reduced the pH when applied 5 % and 10 % ammonium sulfate in plants of Coffee and 10 % of nitrate in Sunflower . The foliar application of nitrogen sources did not alter the toxicity of aluminum and not the salt effect on plants and Sunflower Coffee.