SUPERFOSFATO SIMPLES E ADUBOS NITROGENADOS NA FORMAÇÃO DO PORTA-ENXERTO DE MARMELEIRO ‘JAPONÊS’

EnglishThe objective of the present work went to verify the action of the nitrogen fertilizations for covering and for the slow liberation, associate simple super phosphate and potassium chloride in the production of ‘Japones’ quince tree rootstock. Seedlings of the ‘Japones’ quince tree standardized with 10 cm of length, was transplanted for plastic sacks, with dimensions of 3 L (dimensions of 18 x 30 cm), filled with composed substrate by soil, composting and sands (1:1:1 v/v), enriched with different dosagens of simple super phosphate (0, 2.5, 5 and 7.5 kg m-3 of substrate, soluble 180 g of P2O5, in water), different doses of the fertilizer of slow liberation Nitrocot (44% N): 0,2, 4, 6 and 8 Kg m-3 of substrate and fertilizations was accomplished by covering with nitrogen in the urea form (45% of N), through irrigation water: 0, 800, 1600, 2400 and 3200 mg N dm-3. After 60 days of the transplantation, the mortality percentage of the rootstock were evaluated, repeated the evaluations to the 180 days of the transplantation and the medium length and diameter of the rootstock (15 cm above the substrate), the mass dries average of the rootses, aerial part and total of rootstock. It was ended that 5 Kg m-3 of simple super phosphate should be used, associated to 800 mg N dm-3, in the production of ‘Japones’ quince tree rootstock. portuguesO objetivo do presente trabalho foi quantificar a acao da adubacao nitrogenada por cobertura e por liberacao lenta, associada a adubacao com superfosfato simples, na producao do porta-enxerto para marmeleiros ‘Japones’. Plântulas do marmeleiro ‘Japones’, obtidas a partir de sementes, padronizadas com 10 cm de comprimento, foram transplantadas para sacos plasticos com capacidade de 3 dm3 (18 x 30 cm), preenchidos com substrato composto por solo de barranco, compostagem e areia (1:1:1 v/v), enriquecidos com diferentes doses de superfostato simples (0; 2,5; 5 e 7,5 kg m-3 de substrato, 180 g de P2O5, soluvel em agua), diferentes doses do adubo de liberacao lenta Nitrocot (44% N) (0, 2, 4, 6 e 8 Kg m-3 de substrato) e adubacoes por cobertura com nitrogenio na forma de ureia (45% de N), via agua de irrigacao (0, 800, 1600, 2400 e 3200 mg N dm-3 ). Passados 60 dias foi mensurada a porcentagem de mortalidade dos porta-enxertos, repetidas as avaliacoes aos 180 dias do transplantio e ainda sendo mensurado o comprimento e diâmetro medio dos porta-enxertos (15 cm acima do colo da planta), a massa seca media das raizes, da parte aerea e total dos porta-enxertos. Concluiu-se que se deve utilizar 5 Kg m-3 de superfostato simples, associado a 800 mg N dm-3 , na producao do porta-enxerto ‘Japones’.