Espaçamento, densidade populacional e adubação nitrogenada na cultura do milho

Abstract

RESUMOA distribuição espacial de plantas por área é um recurso para aumentar a produtividade. Para materiais de alta produtividade, são necessárias mais informações quanto à resposta à adubação nitrogenada. Assim, avaliou-se na cultura do milho a influência do espaçamento, da densidade populacional e de doses de nitrogênio no teor de nitrogênio nas folhas, estimativa do teor de clorofila, número de grãos por espiga, massa de 1.000 grãos, produtividade e teor de proteína nos grãos. O trabalho foi instalado no ano agrícola 2000/2001 e constou de tratamentos representados pela combinação de dois espaçamentos entre as linhas (0,80 e 0,60 m) com três densidades populacionais (40, 60 e 80.000 plantas ha -1 ) e quatro doses de nitrogênio em cobertura (0, 50, 100 e 150 kg ha -1 N). O aumento na doses de N em cobertura promoveram acréscimo no teor de N foliar, na estimativa do teor de clorofila, no número de grãos por espiga, na massa de 1.000 grãos, na produtividade e no teor de proteína nos grãos de milho. A maior produtividade de grãos foi obtida de acordo com as doses crescentes de N em cobertura juntamente com o espaçamento entre as linhas de 0,80 m e 80.000 plantas ha -1 . Termos de indexação:Zea mays (L.), clorofila, nitrogênio, produtividade.

Spacing, population density and nitrogen fertilization in corn grown in an Oxisoil

“…For the densities of 60,000 and 80,000 plants ha -1 there was increase in 1000 grain weight with increasing rates of N. The density of 60,000 plants ha -1 had higher 1000 grain weight in both spacings, 0.45 and 0.90 m. This response indicates a greater effect of competition among plants in density of 80,000 plants ha -1 (Figure 2f). The variable 1000 grain weight increased linearly with N rates in both spacings, which was consistent with the results of Amaral Filho et al (2005) and Cancellier et al (2011) who found direct correlation (0.52) between the 1000 grain weight and yield, increasing yield with increasing N rates.…”

“…At the rates 80 and 120 kg N ha -1 , the density of 60,000 plants showed larger number of grains per ear than 80,000 plants (Figure 2e). However, both densities showed a linear increase for number of grains per ear with increasing N rates, which was also reported by Amaral Filho et al (2005). Significant interaction was found for this variable between plant density and spacing, since the population of 60,000 plants ha -1 showed a similar number of grains per ear in both spacings of 0.45 and 0.90 m, while the population of 80,000 plants ha -1 had higher means in the spacing 0.45 m (Table 2).…”

“…The use of reduced row spacing has provided higher productivity in corn due to more equidistant plant distribution (Von Pinho et al, 2008) coupled to the reduction of the number of plants in the row (Amaral Filho, 2005). The increase in corn yield with reduced spacing identified by Kaneko et al (2010) and Modolo et al (2010) facilitates the no-tillage system in crop succession with soybean and corn while maintaining the same spacing for both cultures, without the need to rearrange the seed distribution in seeders.…”

“…This increase is related to the increasing number of ears per area, but excess plant densities lead to competition between plants for water, light and nutrients (Amaral Filho et al, 2005). According to Fancelli and Golden-Neto (2000), well-managed agricultural systems achieve high yields with 55,000 to 72,000 plants ha -1 , using the spacings 0.55 m and 0.80 m between rows.…”

Popping expansion and yield responses of popcorn cultivars under different row spacings and plant populations

“…IAC TC-01 under a row spacing of 0.60 m presented lower grain weight than at 0.40 and 0.80 m. In contrast, IAC 12 and Zelia were not affected by row spacing. To date, no impact of row spacing on grain weight has been reported (Flesh & Vieira, 2004;Amaral Filho et al, 2005;Demétrio et al, 2008).…”