Banca de DEFESA: EDEVALDO DE CASTRO MONTEIRO
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.DISCENTE : EDEVALDO DE CASTRO MONTEIRO
DATA : 27/02/2019
HORA: 13:00
LOCAL: Instituto de Agronomia, Sala 24
TÍTULO:
Adjustment Methodology for Quantification of Nitrogen Biological Fixation in Sugarcane by the 15N Natural Abundance Technique
PALAVRAS-CHAVES:
Mass spectrometry. BNF. Sugarcane productivity. Labeled fertilizer. Isotopes. Poaceae. Diazotrophic with Bacteria Inoculation
PÁGINAS: 110
GRANDE ÁREA: Ciências Agrárias
ÁREA: Agronomia
SUBÁREA: Ciência do Solo
ESPECIALIDADE: Fertilidade do Solo e Adubação
RESUMO:
One of the factors responsible for the low levels of sugarcane productivity in Brazil is the inadequate supply of N. In this context, studies about BNF in this crop have scientific relevance. The objectives of the current research were: (i) to evaluate the interactive effect of Nitrogen fertilization and diazotrophic bacteria in the accumulation of N and the yield in two commercial varieties, (ii) to evaluate non-fixing plants and the strategy of sampling in different parts of sugarcane plants to estimate BNF using the 15N natural abundance technique
In sugarcane plant inoculated or not with diazotrophic bacteria; (iii) to determine the 15N enrichment in different parts of sugarcane plant to estimate the efficiency of N use (EUN) because of inoculant application. The experiment was carried out in field conditions with sugarcane from pre-sprouted seedlings sugarcane in pots containing 100 kg of derived from 0 -40 cm layer of an Ultisol soil. In the first part of this work, the interactive effect of inoculation (with and without) and nitrogen fertilization (0 and 45 kg N ha‑1, ammonium sulphate with 2% excess of 15N atoms) in the accumulation of N and in the yield of two sugarcane varieties (RB867515 e RB92579) harvested at 90, 180, 270 and 360 days after transplanting (DAT). In the second part of this work, the δ15 values were determined in roots, leaves, straw and in three stalk fractions (bottom, medium and upper) in the last sugarcane harvesting (360 DAT) in pots without Nitrogen fertilization. In the third and last part of this work the excess % of 15N atoms was determined in the same sugarcane parts and harvesting, although only in the pots fertilized with Nitrogen. Sporadically, the addition of N-fertilizer inhibited, or even caused, an antagonistic effect of inoculation on some growth variables (stalk diameter, leaf dry matter, straw dry matter, N content and accumulation in leaf), but with no significant effect on stalk yield. The BNF contributes, on average, 53% of the N accumulated in the variety RB92579 and 49% in the variety RB867515. There was no significant variation in the 15N natural abundance of available N in the soil (7.8 δ15N ‰) estimated by different non-fixing plants. On the other hand, there was a significant variation in the values of δ 15N in different parts of sugarcane plant, indicating that the sampling strategy for BNF quantification by 15N natural abundance technique should consider the whole plant. However, when there was enrichment of the plant with 15N from the fertilizer to study the EUN, no significant variation in the values of excess 15N atoms in the different parts of the plants was observed. This indicates that, in fertilizer 15N recovery studies, only specific parts of the plant can be sampled, representing a significant reduction in the time and cost of sampling and analysis. The EUN was 60% for both varieties, without inoculation influence. Studies with other varieties and in different soil and climate conditions should be done to define scenarios with greater possibility of diazotrophic bacteria inoculation in sugarcane
MEMBROS DA BANCA:
Presidente - 058.898.198-28 - SEGUNDO SACRAMENTO URQUIAGA CABALLERO - USP
Interno - 631.052.847-53 - VERONICA MASSENA REIS - UFRRJ
Externo ao Programa - 2136627 - NIVALDO SCHULTZ
Externo à Instituição - MARCIO DOS REIS MARTINS - EMBRAPA
Externo à Instituição - CLAUDIA POZZI JANTALIA - EMBRAPA