Enraizamento de mudas pré-brotadas de cana-de-açúcar após transplantio em função de adubação com nitrogênio e fósforo
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Data
2018-07-10
Autores
Mello, Tayene Franco [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Nas áreas de cultivo de cana-de-açúcar em que se empregam mudas pré-brotadas, o transplantio é um momento crítico, e há necessidade de adoção de práticas de manejo que levem ao enraizamento rápido, de modo que irrigações suplementares possam ser reduzidas ou dispensadas. A adubação, sobretudo o uso de fósforo e de nitrogênio, pode ser um fator de aceleração do enraizamento. Deste modo, objetivou-se, com o presente estudo, avaliar o enraizamento de mudas pré-brotadas de cana-de-açúcar em função do fornecimento de nitrogênio e fósforo, buscando a redução de tempo para o início da emissão radicular após o transplantio. O experimento foi conduzido em casa de vegetação, utilizando amostra da camada superficial (0-20 cm) de solo de textura média, com baixo teor de fósforo. Os tratamentos foram arranjados em esquema fatorial com três fatores (doses de nitrogênio, doses de fósforo e tempos de crescimento), em delineamento inteiramente ao caso com cinco repetições. As doses de nitrogênio e fósforo foram equivalentes a 0 e 100 mg dm-3, e os tempos de crescimento foram 7, 14, 21 e 28 dias. O experimento foi conduzido empregando mudas do cultivar RB97 5201, produzidas em condições comerciais. Em cada data de avaliação foram determinados comprimento, área, diâmetro médio e densidade de raízes, matéria seca de raízes e da parte aérea e concentrações e acúmulos de nitrogênio e de fósforo na parte aérea. O aumento da concentração de nitrogênio no solo promoveu diminuição no diâmetro das raízes de mudas de cana-de-açúcar, cultivar RB97 5201, aos 28 dias após o transplantio. O aumento da concentração de fósforo no solo diminuiu a área, o diâmetro, o comprimento e a densidade de raízes de mudas de cana-de-açúcar após o transplantio, aumentou a produção de matéria seca da parte aérea e a relação matéria seca de parte aérea/raízes, o que pode tornar as plantas mais suscetíveis a estresses hídricos.
In sugarcane cultivation areas where pre-sprout seedlings are used, transplanting is a critical moment and there is a need to adopt methods that lead to fast rooting, so that additional irrigations can be minimized or dispensed. Fertilization, especially the use of phosphorus and nitrogen, can be a factor of rooting acceleration. Thus, the objective of the present study was to evaluate the rooting of pre-sprouted sugarcane seedlings due the supply of nitrogen and phosphorus, aiming to reduce the time to start root emission after transplanting. The experiment was carried out in a greenhouse, using a sample of sandy loam topsoil layer (0-20 cm) with low phosphorus content. The treatments were arranged in a factorial scheme with three factors (nitrogen doses, phosphorus doses and growth times), in a full design with five replicates. The nitrogen and phosphorus doses were equivalent to 0 and 100 mg dm-3 N or P, and growth times were 7, 14, 21 and 28 days. The experiment was conducted using seedlings of cultivar RB97 5201, produced under commercial conditions. At each evaluation date, length, area, root average diameter, root density, dry matter in roots and shoot, and concentration and accumulation of nitrogen and phosphorus in shoot were determined. The increase in concentration of nitrogen in the soil promoted the reduction of root diameter in the sugarcane seedlings at 28 days after transplantation. The increase in concentration of phosphorus in the soil decreased the area, diameter, length and root density of sugarcane seedlings after transplantation, and increased the shoot dry matter and the relation of shoot/roots dry matter, which may make the plants more susceptible to water stresses.
In sugarcane cultivation areas where pre-sprout seedlings are used, transplanting is a critical moment and there is a need to adopt methods that lead to fast rooting, so that additional irrigations can be minimized or dispensed. Fertilization, especially the use of phosphorus and nitrogen, can be a factor of rooting acceleration. Thus, the objective of the present study was to evaluate the rooting of pre-sprouted sugarcane seedlings due the supply of nitrogen and phosphorus, aiming to reduce the time to start root emission after transplanting. The experiment was carried out in a greenhouse, using a sample of sandy loam topsoil layer (0-20 cm) with low phosphorus content. The treatments were arranged in a factorial scheme with three factors (nitrogen doses, phosphorus doses and growth times), in a full design with five replicates. The nitrogen and phosphorus doses were equivalent to 0 and 100 mg dm-3 N or P, and growth times were 7, 14, 21 and 28 days. The experiment was conducted using seedlings of cultivar RB97 5201, produced under commercial conditions. At each evaluation date, length, area, root average diameter, root density, dry matter in roots and shoot, and concentration and accumulation of nitrogen and phosphorus in shoot were determined. The increase in concentration of nitrogen in the soil promoted the reduction of root diameter in the sugarcane seedlings at 28 days after transplantation. The increase in concentration of phosphorus in the soil decreased the area, diameter, length and root density of sugarcane seedlings after transplantation, and increased the shoot dry matter and the relation of shoot/roots dry matter, which may make the plants more susceptible to water stresses.
Descrição
Palavras-chave
Saccharum spp., Adubação nitrogenada, Adubação fosfatada, Muda pré-brotada, Cana-de-açúcar, Nitrogen fertilization, Phosphate fertilization, Pre-budded seedling