Uso do clorofilômetro como ferramenta de manejo da adubação nitrogenada da cultura da batata

• Ano de defesa: 2011
• Autor(a) principal: Coelho, Fabrício Silva
• Orientador(a): Fontes, Paulo Cezar Rezende
• Banca de defesa: Souza, Rovilson José de , Sediyama, Maria Aparecida Nogueira , Pádua, Joaquim Gonçalves de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Fitotecnia
• Departamento: Plantas daninhas, Alelopatia, Herbicidas e Resíduos; Fisiologia de culturas; Manejo pós-colheita de
• País: BR
• Palavras-chave em Português: Solanum tuberosum; Clorofila; Nitrogênio
• Palavras-chave em Inglês: Solanum tuberosum; Chlorophyll; Nitrogen
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA
• Link de acesso: http://locus.ufv.br/handle/123456789/1153

The objectives of the thesis were: a) to determine the optimum economical nitrogen (N) level for potato tuber yield and to estimate the critical value of leaf N indices; b) to utilize the chlorophyll meter reading as an indicator of the sidedress N fertilizer needs and to evaluate the influence of this N management on tuber yield, profitability and N use efficiency by the potato plants; c) to estimate the correct diagnosis percentage obtained by the Cate-Nelson graphical procedure in determining the plant N index threshold values. It also aimed to propose index threshold values estimated by Cate-Nelson graphical and mathematical procedures. Experiments were set in the “winter” and “rain” seasons with Ágata cultivar. The experiments were set in randomized blocks design with four replications. The treatments consist of five N rates (0; 50; 100; 200 e 300 kg ha-1 of N), as urea applied in the furrow at planting. At 21 days after plant emergence (DAE), the chlorophyll meter SPAD-502 was used as an indicator of the sidedress N fertilizer needs, after measuring the fourth leaf from the plant apex and calculating the N sufficiency index (NSI). This index served as the basis to calculate the N dose to be sidedressing complementing the initial 0, 50, 100, 200 and 300 kg ha-1 treatments. The calculated sidedress N rate was applied in the half of the plot, to assess the number of true and false diagnosis. Without sidedress N, the highest economic potato yield was 41.1 t ha-1 with 252 kg ha-1 of N in the “winter season” and 27.6 t ha-1 with 279 kg ha-1 of N in the “rain season”. The combination of 200 kg ha-1 of N at pre-planting and 60 kg ha-1 sidedressed provided the highest profitability. There were 70 and 85 % of correct decisions in the "winter" and "rain" seasons, respectively, when the ISN criterion was combined with the SPAD index to estimate the N rate, being more efficient to recognize plants growing at low N supply (0, 50 and 100 kg ha-1 N treatments). There were some discrepancies in critical values estimated by Cate-Nelson and mathematical procedures.