Produção de cebola submetida a diferentes lâminas de água e doses de nitrogênio com adubação molibdica

• Autor(a) principal: Baptestini, Júlio Cezar Machado
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/766
• topic: Cebola; Nitrogênio; Adubação molibdica; Onion; Nitrogen; Molybdenum fertilization; CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA

In Brazil, the onion is considered the third most important vegetable crop in terms of economic value. Production factors, water and nutrients are those that limit crop productivity with greater intensity. Thus, control of irrigation and soil fertility are predominant criteria for successful agriculture. In this project, had the following objectives: ( a) evaluate the influence of different irrigation water and nitrogen on the yield of onion, ( b ) assess the effect of application of molybdenum in the reduction of nitrogen in the culture of onions, using different depths of water and nitrogen, and ( c ) determine the values of crop coefficients in each stage of development, using drainage lysimeters. Three experiments were conducted, and the first two refer to the use of irrigation water and nitrogen, with and without application of molybdenum, while the third was related to the determination of crop coefficient for the onion, using lysimeters drainage. Soil samples were collected for determination of physical and chemical characteristics. In the first two experiments we used a hybrid cultivar, called Aquarius. The planting was done in plots of 15 m long and 1 m wide, with row spacing of 25 cm between plants and 10 cm, being transplanted two plants per hill. We adopted a split-plot, in randomized completely randomized ( CRD) with four replications in plots with five irrigations ( 0, 75, 100, 125 and 150 % of ETc ) and subplots to five doses of nitrogen ( 0 , 120, 180 , 240 , and 300 kg ha - 1 ). In one of the experiments was applied a dose of 100 g ha 1 de Mo, while the other was not performed with molybdenum fertilization. Nitrogen fertilization was performed with the use of urea and 10 % applied at 15 days after transplanting ( DAT ), 40 % at 40 DAT and 50 % at 60 DAT. Irrigation management was done using the Irrigameter. Irrigation was carried out using the method of sprinkling. Plants were harvested when more than 60 % of the plants were clicked. We evaluated the following characteristics: Total yield, marketable yield, dry matter bulbs, assessment of nutritional status using the SPAD onion and determination of Brix. The third experiment was determined crop coefficient of onion ( Kc) was used BRS 367 - Riva, and the planting done by direct sowing in the soil. We used six drainage lysimeters. The irrigations were made daily using the spray method. The blade drains was collected in pails and measured daily using a beaker. The reference evapotranspiration was determined using meteorological data collected by a weather station installed near the experimental area was obtained using the computer program REF - ET , based on the equation of Penman - Monteith FAO 56 . Kc values were obtained by ETc / ETo. With the results, we can conclude that: ( a) The highest total yield of onion bulbs ( 69.6 t ha -1 ) was obtained with application of 141.3 kg ha -1 nitrogen, with 150 % ETc use of molybdenum. Without this micronutrient should apply 226.8 kg ha - 1 nitrogen with the same water depth, ( b ) the application of molybdenum caused a reduction of 61.9 % of the need for nitrogen fertilization onion crop , leading to increased 9.6 % in the commercial onion ; ( c ) the increase of applied water in culture causes decreased dry matter content of onion . However, the 50 % increase in water depth equivalent to 100 % of ETc caused 28.6 % increase in dry matter production, and ( d ) Kc values found for the onion crop, at I, II, III and IV were 1.12 , 1.69 , 2.51 and 1.50, respectively.