Paulo César Endrigo

Crop management systems and maize grain yield under narrow row spacing

Reduction in row spacing provides a more uniform distribution among plants that can increase grain yield. The benefits of narrow row spacing can depend on the plant architecture and on the kind of crop management system. The objective of this study was to assess the effects of narrow row spacing on the grain yield of maize hybrids growing under different management systems. Six experiments were carried out in Eldorado do Sul, State of Rio Grande do Sul, Brazil, during the 2003/04 and 2004/05 growing seasons. Each experiment corresponded to a crop management system. Treatments consisted of two row spacings (0.8 and 0.4 m), two hybrids (Penta and Flash) and two plant densities, which varied with the crop management system and growing season. Besides plant density, the crop management systems differed in the quantities of fertilizers applied at sowing, side-dress and use of irrigation. A complete randomized block design was used in each experiment, in a 2 × 2 × 2 treatment factorial scheme with four replications. The increases in grain yield with narrow row spacing were small, ranging from zero to 14%. They depended on the growing season and were manifested only with yields higher than 10 t ha -1 , regardless of the hybrid. The number of grains per area was the component that best explained the response of grain to narrow row spacing, regardless of plant density, hybrid and crop management system. Narrow row spacing is a worth management strategy to enhance maize grain yield when high input cropping systems are used.

A resposta do milho irrigado ao espaçamento entrelinhas depende do híbrido e da densidade de plantas

The amount of solar radiation intercepted by the canopy has influence on maize grain yield and it can be enhanced by reducing row spacing and/or increasing plant density. This research was carried out aiming to evaluate the response of four irrigated maize hybrids to variations in row spacing and plant density, under high management level. Two experiments were performed in Eldorado do Sul, RS, Brazil. In 2001/02, treatments had composed by two maize hybrids (Flash and Attack), four plant densities (5.0, 6.25, 7.5 and 8.75 plants m-2) and four row spacings (40, 60, 80 and 100cm). In 2002/03, treatments were set as two maize hybrids (Garra and Penta), four plant densities (4.5, 6.0, 7.5 and 9.0 plants m-2) and four row spacings (40, 60, 80 and 100cm). The reduction in row spacing from 100 to 40cm and the increase in plant population from 4.5-5.0 to 8.75-9.0 plants m-2 has more pronounced effects on grain yield for the erect leaf hybrids Flash and Garra. Conversely, grain yield of decumbent leaf hybrids Penta and Attack was not altered by variations in plant density and row spacing. The effects of narrow row spacing on the agronomic characteristics were lesser magnitude that the obtained ones with variations in plant density.

Produtividade do milho irrigado em sucessão a espécies invernais para produção de palha e grãos

The objective of this work was to evaluate the productivity of irrigated maize, grown using several rates of nitrogen sidedress, in succession to different winter crops. The experiment was carried out in Eldorado do Sul, RS, Southern Brazil, during the 2003/2004, 2004/2005 and 2005/2006 growing seasons. Maize was sown in succession to five winter crops: black oat, common vetch, wild radish (straw production), white oat and wheat (grain and straw production), and to a control treatment, where the spontaneous vegetation was controlled by successive desiccant application. Maize grain yield was higher than 8 Mg ha-1 and was not affected by the specie of preceding winter crop, when nitrogen sidedress was applied. Maize grain yield was higher, when it succeeded wild radish and in the treatment without N in side-dressing. White oat and wheat added more than 3 Mg ha-1 of straw and produced more than 1.5 Mg ha-1 of grain. With supplementary irrigation and side-dress nitrogen application, it is possible to obtain high grain yield, when corn is cultivated as a sequential crop, independently of winter cover species.

Características de dossel e rendimento de milho em diferentes espaçamentos e sistemas de manejo

O objetivo deste trabalho foi avaliar o efeito da reducao do espacamento no indice de area foliar, na senescencia foliar, na radiacao fotossinteticamente ativa interceptada e no rendimento de graos de dois hibridos de milho em tres sistemas de manejo. Tres experimentos em delineamento em blocos ao acaso, em fatorial 2x2x2 foram conduzidos em campo em Eldorado do Sul, RS. Em cada experimento, os tratamentos constaram de espacamentos de 0,4 e 0,8 m; hibrido de folha ereta e de folha decumbente; e duas densidades (5 e 6,6 plantas m-2, 6,2 e 8,3 plantas m-2 e 6,5 e 8 plantas m-2, respectivamente, nos sistemas de manejo medio, alto e muito alto). Niveis de adubacao e disponibilidade hidrica variaram com o sistema de manejo. O indice de area foliar e a radiacao fotossinteticamente ativa interceptada variam com o espacamento, mas dependem de estadio fenologico, densidade e arquitetura foliar e sistema de manejo. A senescencia foliar nao variou de acordo com o espacamento, independentemente de sistema de manejo, densidade e hibrido. Menores espacamentos aumentaram o rendimento apenas no sistema de manejo muito alto. As caracteristicas de dossel nao seguiram o comportamento do rendimento de graos.

Desempenho agronômico e econômico do milho irrigado em sucessão a espécies invernais de cobertura de solo e/ou para produção de grãos

As especies de cobertura de solo no inverno melhoram as caracteristicas de solo, podendo apresentar tambem vantagens economicas. Assim, e importante introduzir especies de inverno que, alem de palha, possam produzir graos para aumentar a rentabilidade e a sustentabilidade da atividade agricola. O objetivo desta pesquisa foi avaliar, em tres estacoes de crescimento, os desempenhos agronomico e economico do milho irrigado em sucessao a especies invernais para cobertura de solo e/ou para producao de graos, cultivado sob dois niveis de nitrogenio (N) em cobertura. A pesquisa foi conduzida nas estacoes de crescimento 2003/04, 2004/05 e 2005/06, no municipio de Eldorado do Sul, RS. Nos tres anos, os tratamentos constaram do cultivo do milho irrigado em sucessao a cinco especies de inverno e ao pousio, como testemunha. O custo de producao do milho em sucessao a ervilhaca comum e menor do que o da aveia preta e do nabo forrageiro. Das especies invernais de cobertura de solo e de producao de graos, a margem bruta obtida com o trigo e maior que a com a aveia branca. As vantagens economicas do uso do nabo forrageiro e da ervilhaca comum como culturas antecessoras ao milho irrigado em relacao as especies poaceas apenas ocorrem sob baixos niveis de N aplicados em cobertura no milho.