Everton Leonardo Forsthofer

Resposta de híbridos simples de milho à redução do espaçamento entre linhas

The objective of this work was to determine the effects of using narrow row spacing on grain yield, grain components and on other agronomic traits of maize single-cross hybrids. Two experiments were conducted in the state of Rio Grande do Sul, Brazil. In the 1997/98 growing season, treatments were composed by two singlecross hybrids (Cargill901 and BraskalbXL212) and four row spacings (40, 60, 80 and 100 cm). In the 1998/99growing season, two single-cross hybrids were tested at two plant densities (50,000 and 65,000pl./ha) and four row spacings (40, 60, 80 and 100 cm). Maize grain yield was influenced by hybrid and plant density. The reduction in row spacing promoted a high grain yield specially for hybrids with a low plant height sown at the density of 50,000pl./ha.

Rendimento de grãos de milho cultivado após aveia-preta em resposta a adubação nitrogenada e regime hídrico

O rendimento de graos de milho e influenciado pela disponibilidade de nitrogenioxa0(N) no solo durante o ciclo de desenvolvimento da planta. Oxa0objetivo deste trabalho foi avaliar os efeitos da adubacao nitrogenada em pre-semeadura e do regime hidrico no rendimento de graos e nos componentes de rendimento em cultivo de milho sob semeadura direta apos aveia-preta. Oxa0experimento foi conduzido em Eldorado do Sul, RS, no ano agricola de 1998/99. Osxa0tratamentos constaram da aplicacao de um nivel de irrigacao adequado as exigencias da cultura, e outro, com excesso hidrico; e de sete sistemas de aplicacao de N em milho: 0-30-150, 150-30-0, 75-30-75, 0-30-60, 60-30-0, 30-30-30 e 0-30-0, correspondendo, respectivamente, as quantidades de Nxa0(kgxa0ha-1) aplicadas em pre-semeadura (no momento de dessecacao da aveia-preta), na semeadura e em cobertura do milho. Com a antecipacao da aplicacao de N da cobertura para a epoca de pre-semeadura, o rendimento de graos de milho foi menor em relacao ao obtido com a aplicacao na epoca convencional, principalmente sob alta disponibilidade hidrica e com elevada dose de adubacao nitrogenada. Oxa0componente mais associado ao rendimento de graos de milho foi o numero de graos porxa0espiga.

Desenvolvimento fenológico e agrônomico de três híbridos de milho em três épocas de semeadura

Variations in environmental conditions determined by different sowing dates have a great influence on maize ontogeny. This experiment was carried out to evaluate the phenological development of three maize hybrids, at three sowing dates. The experiment was carried out at the Depressao Central region of the state of Rio Grande do Sul-Brazil during 2000/2001 grows season. The single-cross very early hybrid Pioneer 32R21, the single-cross early hybrid Dekalb 214, and the double-cross normal hybrid Agroceres 1051 were evaluated at 08/22/2000 (early), 10/31/2000 (intermediate) and at 01/25/2001 (delayed) sowing dates, with no supplemental irrigation. All hybrids presented shorter developmental subperiods when sowing was delayed. Tassel and ear differentiation occurred, respectively, in the stages of 6 to 7 and 10 to 11 completely expanded leaves, regardless of hybrid cycle and sowing date. The highest leaf emission rate occurred when very early hybrid was sown in October. Delaying sowing resulted in a reduction of leaf area per plant mainly in early hybrids. Number of spikelets per ear, grain yield and grain weight were generally higher in October than in the other two sowing dates.