Produtividade e qualidade pós-colheita de cebola adubada com doses crescentes de nitrogênio e potássio

Abstract

A produção mundial de cebola em 2005, foi de 59,5 milhões de toneladas, cultivadas em 3,2 milhões de hectares, o que proporcionou uma produtividade média de 18,6 t ha -1 (FAO, 2007). No Brasil, a cebola ocupa entre as hortaliças o terceiro lugar em importância econômica (Souza & Resende, 2002 Não se constatou efeitos significativos aos 20 dias para perda de massa, evidenciando-se efeitos significativos apenas aos 40 e 60 dias após cura (DAC), e não houve interação entre as doses de nitrogênio e potássio. Palavras-chave:Allium cepa, fertilização, rendimento, conservação pós-colheita. ABSTRACTYield and post-harvest quality of onion fertilized with increasing levels of nitrogen and potassium This study was carried out from March to September 2000, in Petrolina, Pernambuco State, Brazil, to evaluate the influence of nitrogen and potassium levels on yield characteristics and post-harvest quality of onion bulbs (Allium cepa L.). The cultivar Franciscana IPA-10 was used. The experimental design was a randomized complete block in a 4 x 3 factorial scheme, involving four levels of nitrogen (0; 60; 120 and 180 kg ha ) with three replications. The commercial yield showed a linear effect in the absence of potassium fertilization, while the levels of 90 and 180 kg ha -1 of potassium provided maximum yield with the levels of 175.8 and 169.4 kg ha -1 of nitrogen. Increasing the doses of nitrogen resulted in a reduction of the non-commercial yield (culls). In the absence of potassium fertilization, a linear effect was obtained as a result of the levels of nitrogen for fresh mass of the bulb. For the levels of 90 to 180 kg ha -1 of potassium, the highest yield of fresh mass of the bulb was obtained with the level of 153.3 kg ha -1 of nitrogen. The levels of nitrogen influenced the classification of commercial bulbs of onion and the largest percentage of bulbs of the class 3 (85,8%) corresponded the dose of 153,6 kg ha -1 of nitrogen. No significant mass loss occurred after 20 days and only after 40 and 60 days after cure did any significant effects become evident and there was no interaction between the levels of nitrogen and potassium.

Effects of levels of potassium and nitrogen on yields and post-harvest conservation of onions in winter

“…The average fresh mass of bulb (g. bulb -1 ) was determined by dividing the total mass of commercial bulbs, after curing, by the number of bulbs. The classification of commercial bulbs, in percentages, according to the cross-sectional diameter (mm) was made in Class 2: greater than 35 to 50 mm in diameter; Class 3: greater than 50 to 70 mm; Class 4: greater than 70 to 90 mm and Class 5: greater than 90 mm (Resende et al, 2009). Percentage data were transformed into arcsine, for effects of statistical analysis.…”

Rendimento e conservação de cebola alterados pela dose e parcelamento de nitrogênio em cobertura

“…Considerando o preço médio pago ao produtor de cebola em santa Catarina (R$ 0,61 kg -1 de bulbo) nos últimos cinco anos, seriam necessários apenas 4,13 kg de cebola para adquirir 1,0 kg de n usando como fonte o nitrato de amônio (R$ 2,50 kg -1 de n). (Resende et al, 2008). aumentos no peso de bulbos com o aumento na adição de n foram também obtidos por Hassan (1984) a obtenção de bulbos maiores, além de estar diretamente relacionada com o aumento no rendimento, também aumenta a lucratividade, pois bulbos com diâmetro inferior a 50 mm apresentam menor valor de mercado do que bulbos maiores.…”

Soil covering in organic cultivation of onion cultivars

“…Resende and Costa (2006) observed similar behavior for the onion cultivar Texas Grano, being influenced only by storage time. Moreover, the mass loss of the bulbs during storage varies among the cultivars onion and these are less marked when adopts the organic cultivation system (RESENDE et al, 2010). The physiological rot may be related to the curing process that has as an end goal the loss of excess water, drying the external films (husks) and reducing the intensity of rot (SOUZA; RESENDE, 2002).…”

“…According Resende et al (2010) organic cultivation make it possible to achieve superior productivity than that of conventional agriculture using chemical fertilizer, especially when one uses adapted cultivars. It is required to adjust the technologies, mainly with the application of organic waste that provides the necessary nutrients for the growth of the plants, as well as the physical protection of the soil.…”