O subsolo, normalmente utilizado para a produção de mudas de espécies frutíferas, apresenta baixa concentração de potássio e, assim, existe grande probabilidade de resposta à aplicação deste nutriente. Desse modo, objetivou-se avaliar a aplicação de potássio ao substrato de produção de mudas de maracujazeiro-amarelo (Passiflora edulis) e os seus efeitos no desenvolvimento, na produção de matéria seca e no estado nutricional das plantas. O delineamento experimental foi o de blocos ao acaso, com cinco tratamentos e quatro repetições. As doses de potássio (cloreto de potássio) foram: 0; 75; 150; 225 e 300 mg de K dm-3. As mudas receberam doses de N, P, B e Zn de 300; 450; 0,5 e 5 mg dm-3, respectivamente. O experimento foi conduzido em casa de vegetação, em vasos com 2 dm³ de solo (Latossolo Vermelho distrófico), durante 60 dias. A aplicação de potássio afetou de forma quadrática o desenvolvimento e a nutrição de mudas do maracujazeiro. A maior produção de massa seca das plantas ocorreu na faixa entre 200-220 mg de K dm-3, e concentração de 3 mmol c de K dm-3 no solo.

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Este trabalho objetivou avaliar os efeitos da adubação com N e K no desenvolvimento de mudas de maracujazeiro-amarelo (Passiflora edulis) cultivadas em Latossolo Vermelho distrófico. O delineamento experimental foi o inteiramente casualizado, com três repetições, num esquema fatorial 4 x 4, com 4 doses de N (zero, 150, 300 e 600mg de N dm-3) e quatro de K (zero, 75, 150 e 300mg de K dm-3), parceladas em quatro vezes. A unidade experimental foi constituída por vasos de 3,3L. Após 84 dias da germinação, foram avaliados: altura da planta, o diâmetro do caule, o número de folhas e a área foliar. O melhor desenvolvimento das mudas de maracujazeiro ocorreu com as doses de 150mg de N dm-3 e de 300mg de K dm-3.

Tropical soils are usually highly acidic and this may hamper mango trees nutrition and production. The objective of this work was to evaluate the effects of lime doses applied to the soil surface on the plant nutritional status, the production, and the technological quality of mango fruits. The study was carried out at Selviria, in the state of Mato Grosso, Brazil, in a Typic Haplustox. Thirteen year old producing mango plants of the "Heden" variety, grafted on rootstock of the "Coquinho" variety, were used in this experiment. Lime doses of 0, 1.55, 3.10, 4.655, and 6.20 t·ha -1 were applied to the soil. Each treatment was replicated 4 times and the experimental units distributed according to a randomized complete block design. Lime (CaO: 390 g·kg ) was superficially applied to the soil and then incorporated at depths between 0 and 5 cm in the total area of the orchard. The soil chemical characteristics pH, Ca, Mg, K, sum of bases, and bases saturation, in the 0 -20 cm layer, were evaluated 16 and 28 months after soil liming. Plant nutritional status was evaluated 12 months after soil liming. Fruit production and technological quality were evaluated during the cropping years of 2006 and 2007. Soil liming had a positive effect on the evaluated soil chemical characteristics and this improved plant nutritional status and fruit technological quality as well as increased fruit production. These beneficial effects though were observed only in the second year after soil liming. The highest fruit production was verified when soil bases saturation was of 72% and the contents of Ca and Mg were of 32 and 8 g·kg -1 , respectively.

The tropical soil acidity is one of the main limiting factors for crop productivity. This study aimed to evaluate the effects of application of limestone dose to soil fertility, nutritional status of the crop, and productivity and quality of the fruits of mango, cultivar Keitt. The study was carried out at Selvíria, state of Mato Grosso Sul, Brazil, in a Typic Haplustox (pH in CaCl 2 = 4.7), cultivated with mango cultivar Keitt grafted on Coquinho pattern in the production phase (13 years old). Treatments were composed of limestone doses (0, 1.55, 3.10, 4.65, and 6.20 t ha −1 ), arranged in blocks at random with three repetitions. The limestone was applied and incorporated in the surface layer of 0 to 5 cm deep in the total area. We evaluated the chemical attributes of the soil [pH, hydrogen (H+) aluminum (Al), calcium (Ca), magnesium (Mg), potassium (K), and sum of bases and base saturation] at 16 and 28 months after liming (layer 0 to 20 cm deep), the nutrition of plants at 12 months after liming, and quality of the fruit in two crop years. Liming promoted improvements in soil chemical attributes, reflected in the nutritional status, productivity, and quality of mango fruit. Also, there was a linear effect with the application of lime dose on the productivity of the fruit, but after the second year of evaluation.