Crescimento e produtividade do algodoeiro em função da aplicação de nitrogênio e níquel
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Data
2016-08-23
Autores
Silva, Igor Cabreira da [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Para atingir altas produtividades, o algodoeiro exige grandes quantidades de nitrogênio (N) em relação à demanda por outros nutrientes. O níquel (Ni) participa na constituição da metaloenzima urease, que catalisa a degradação da ureia em dióxido de carbono e amônia, permitindo o uso da ureia gerada externa ou internamente como fonte de nitrogênio. Dessa maneira, desperta-se o interesse em elucidar a relação do Ni com o metabolismo do nitrogênio nas plantas. O objetivo do presente trabalho foi verificar os efeitos da aplicação de fontes e doses de nitrogênio, e a possível interação com doses de níquel sobre o crescimento, produtividade e características bioquímicas do algodoeiro em condições de campo. Os experimentos foram conduzidos durante dois anos agrícolas, no período de dezembro de 2013 a maio de 2014 e dezembro de 2014 a maio de 2015. O delineamento experimental foi o de blocos ao acaso em um esquema fatorial 4x4x2, com 3 repetições, perfazendo 32 tratamentos: quatro doses de níquel (0, 2, 4 e 6 kg ha-1 ), quatro doses de nitrogênio (0, 40, 80 e 120 kg ha-1 ) em duas fontes (ureia e nitrato de amônio), aplicados na cultivar de algodoeiro FM 975WS®. Aplicaram-se as doses de níquel e nitrogênio via solo no momento recomendado para a adubação de cobertura de maneira parcelada, aos 30 e 45 dias após emergência (d.a.e.) do algodoeiro. Constatou-se que a altura de plantas, número de estruturas reprodutivas, número de capulhos e a produtividade de algodão em caroço aumentaram de acordo com o incremento das doses de N até 120 kg ha-1 em cobertura. A aplicação de níquel aumentou os seus teores na camada superficial do solo, bem como seus teores foliares no algodoeiro. O aumento de doses de fertilizantes nitrogenados em cobertura no algodoeiro reduziu os valores de pH, Ca e da SB em superfície do solo, assim como aumentou os teores de Al+ trocável. Em anos com veranicos ou com má distribuição de chuvas, o uso de nitrato de amônio aumentou a altura de plantas, número de estruturas reprodutivas, teor foliar de N, número de capulhos e produtividade de algodão em caroço quando comparado com a ureia.
The cotton crop requires relatively large amounts of nitrogen (N) when compared to the demand for other elements, for higher yield. Nickel (Ni) participates in the formation of urease metaloenzyme, which catalyses the breakdown of urea into carbon dioxide and ammonia, allowing the use of urea generated externally or internally as a nitrogen source. Thus, spark interest in elucidating the Ni ratio with nitrogen metabolism in plants. The aim of this study was to determine the effects of application of nitrogen sources and doses, and possible interaction with nickel doses on growth, yield and biochemical characteristics of cotton plants under field conditions. The experiments were conducted during two crop years, from December 2013 to May 2014 and December 2014 to May 2015. The experimental design was a randomized block in a factorial 4x4x2, with three repetitions, totaling 32 treatments, with four nickel doses (0, 2, 4 and 6 kg ha-1 ), four nitrogen rates (0, 40, 80 and 120 kg ha-1 ) in two sources (urea and ammonium nitrate), applied in farming cotton FM 975WS®. Apply the nickel doses and nitrogen in the soil at the time recommended for topdressing in installments way, 30 and 45 days after emergence (d.a.e.) of cotton plant. It was found that plant height, number of reproductive structures, boll number and seed cotton yield increased with increasing N doses up to 120 kg ha-1 in coverage. The nickel application increases its content in the topsoil and its leaf content in cotton plant. Increasing doses of nitrogenous fertilizers in cotton plant reduced pH, Ca and the SB (sum of bases) in the soil surface, as well as increased levels of exchangeable Al+ . In years with dry spells or poor distribution of rainfall, the use of ammonium nitrate increased the plant height, number of reproductive structures, leaf N content, number of bolls and cotton yield in core compared to urea.
The cotton crop requires relatively large amounts of nitrogen (N) when compared to the demand for other elements, for higher yield. Nickel (Ni) participates in the formation of urease metaloenzyme, which catalyses the breakdown of urea into carbon dioxide and ammonia, allowing the use of urea generated externally or internally as a nitrogen source. Thus, spark interest in elucidating the Ni ratio with nitrogen metabolism in plants. The aim of this study was to determine the effects of application of nitrogen sources and doses, and possible interaction with nickel doses on growth, yield and biochemical characteristics of cotton plants under field conditions. The experiments were conducted during two crop years, from December 2013 to May 2014 and December 2014 to May 2015. The experimental design was a randomized block in a factorial 4x4x2, with three repetitions, totaling 32 treatments, with four nickel doses (0, 2, 4 and 6 kg ha-1 ), four nitrogen rates (0, 40, 80 and 120 kg ha-1 ) in two sources (urea and ammonium nitrate), applied in farming cotton FM 975WS®. Apply the nickel doses and nitrogen in the soil at the time recommended for topdressing in installments way, 30 and 45 days after emergence (d.a.e.) of cotton plant. It was found that plant height, number of reproductive structures, boll number and seed cotton yield increased with increasing N doses up to 120 kg ha-1 in coverage. The nickel application increases its content in the topsoil and its leaf content in cotton plant. Increasing doses of nitrogenous fertilizers in cotton plant reduced pH, Ca and the SB (sum of bases) in the soil surface, as well as increased levels of exchangeable Al+ . In years with dry spells or poor distribution of rainfall, the use of ammonium nitrate increased the plant height, number of reproductive structures, leaf N content, number of bolls and cotton yield in core compared to urea.
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Palavras-chave
Gossypium hirsutum L., Adubação nitrogenada, Metaloenzima urease, Nitrogen fertilization, Metaloenzyme urease