Márcio Ender

Incremento na densidade de plantas: uma alternativa para aumentar o rendimento de grãos de milho em regiões de curta estação estival de crescimento

The development of earlier hybrids, with shorter plant height, lower leaf number and upright leaves has increased maize potential adaptability to withstand high plant densities. This trend may be emphasized on the high lands of Southern Brazil due to their mild Spring and Summer temperatures and shorter maize growing season. Four trials were carried out, aiming to investigate the viability of using higher than recommended plant populations, as an alternative to improve grain yield. The maize hybrids Cargill 901 and XL 370 were evaluated at several plant populations, ranging from 37000 to 100000pl ha-1, under different management situations. In three out of four experiments, plant populations above 60000pl ha-1 maximized grain yield. The greater competition among individuals verified at high plant populations did not decrease substantially the number of ears per plant, which contributed to improve maize adaptation to high plant densities. Therefore, for regions with a short growing season, the use of early small stature maize hybrids may be accompanied by an increment in plant population up to a value varying between 65000 and 80000pl ha-1. This is conceivable as long as there is adequate soil fertility, water availability and stem lodging resistant genotypes.^lpt^aO surgimento de novos cultivares de milho, de ciclo mais curto, estatura reduzida, menor numero de folhas e folhas mais eretas aumentou o potencial de resposta da cultura a densidade de plantas. Essa tendencia pode ser acentuada nos planaltos do Sul do Brasil, que apresentam temperatura media nos meses mais quentes inferiores a 22°C, o que resulta em menor estacao estival de crescimento. Quatro experimentos foram conduzidos objetivando avaliar a viabilidade de se trabalhar com densidade de plantas maiores do que as atualmente recomendadas para esta regiao, como uma forma de aumentar o rendimento de graos. Nestes experimentos, submeteram-se os hibridos Cargill 901 e XL 370 a uma populacao que variou de 37.000 a 100.000pl ha-1, sob diferentes situacoes de manejo. Em tres dos quatro experimentos realizados, o uso de densidade de plantas superior a 60.000plha-1 maximizou o rendimento de graos. A maior competicao intraespecifica verificada nas densidades mais elevadas nao reduziu drasticamente o numero de espigas por planta, o que contribuiu para a melhor adaptacao da cultura a densidades elevadas. Dessa forma, para locais com estacao estival de crescimento mais curta, o uso de cultivares precoces, de menor porte, pode ser acompanhado pelo incremento na densidade para valores compreendidos entre 65.000 e 80.000pl ha-1. Isso e possivel desde que se tenha bom nivel de fertilidade no solo, boa disponibilidade hidrica e cultivares resistentes ao acamamento.^len^aThe development of earlier hybrids, with shorter plant height, lower leaf number and upright leaves has increased maize potential adaptability to withstand high plant densities. This trend may be emphasized on the high lands of Southern Brazil due to their mild Spring and Summer temperatures and shorter maize growing season. Four trials were carried out, aiming to investigate the viability of using higher than recommended plant populations, as an alternative to improve grain yield. The maize hybrids Cargill 901 and XL 370 were evaluated at several plant populations, ranging from 37000 to 100000pl ha-1, under different management situations. In three out of four experiments, plant populations above 60000pl ha-1 maximized grain yield. The greater competition among individuals verified at high plant populations did not decrease substantially the number of ears per plant, which contributed to improve maize adaptation to high plant densities. Therefore, for regions with a short growing season, the use of early small stature maize hybrids may be accompanied by an increment in plant population up to a value varying between 65000 and 80000pl ha-1. This is conceivable as long as there is adequate soil fertility, water availability and stem lodging resistant genotypes.

A desuniformidade de emergência reduz o rendimento de grãos de milho

High maize grain yields are related to a fast, complete and regular plant emergence. This experiment was carried out in Lages, SC, Brazil, with the objective of evaluating the effects of an uneven plant emergence on maize grain yield at different plant populations. A split plot design was used, with the main plots disposed in randomized complete blocks. Four plant populations, equivalent to 40,000, 60,000, 80,000 and 100,000 pl.ha-1 were tested in the main plots. Different levels of unevenness in plant emergence were analyzed in the split plots by varying the sowing dates of adjacent hills inside each as it follows: 1 - even emergence (0-0-0-0); 2 - unevenness of 12 days (0-12-0-12); 3 - unevenness of 19 days (0-19-0-19); 4 - unevenness of 12 and 19 days (0-12-19-0-12-19). The increase in plant population up to 76,500 pl.ha-1 enhanced grain yield to 12,900kg.ha-1. At this plant population, the difference in yield grain per hectare among treatments with even and uneven emergence was nearly 2,900kg. This indicates that under similar productivity levels replanting maize may be on economically viable option. Besides reducing grain yield, uneven emergence also limited maize response to the increment in plant population.

Incidência e severidade de doenças de quatro híbridos de milho cultivados com diferentes densidades de plantas

Modern maize hybrids have greater yield potential than cultivars used in the past, particularly under stressful conditions such as high plant population and water deficit. It is possible that the yield advantage presented by modern genotypes is partially due to their better ability to resist major maize diseases. This experiment was carried out to evaluate the incidence and severity of maize leaf, stem, and ear diseases on hybrids usually grown in Southern Brazil, under different plant populations. A split plot design was used, with the main plots disposed in randomized complete blocks. Three plant populations, equivalent to 50,000, 75,000 and 100,000pl ha-1, were tested in the main plot. The hybrids Ag 12, Ag 28, Ag 303 and Ag 9012, which were cultivated expressively in the 60s, 70s, 80s and 90s, respectively, were tested in the split plot. The enhancement in plant population promoted increases on the incidence of stem diseases caused by Fusarium moniliforme, Colletotrichum graminicola e Diplodia maydis, especially on Ag 12 and Ag 28, contributing to decrease their stem standability at harvesting. The hybrid Ag 9012 had lower incidence and severity of ear diseases caused by Fusarium moniliforme e Diplodia maydis, regardless of plant population. The hybrid Ag 9012 did not express lower severity levels of leaf diseases in relation to the older hybirds used in the trial.

Análise de trilha dos componentes do rendimento de grãos em genótipos de canola

Grain yield is a variable of complex association which has an economic importance. A trial was conducted in Lages, SC, during the 1996-growing season, in order to determine the association and the direct and indirect effects of some agronomic traits on grain yield of 12 canola genotypes, through the study of the phenotypic correlation and path analysis. A randomized complete block design with four replications per treatment was used. According to the analyses performed on the trial, plant height didn’t show any association with weight of 1,000 grains and grain yield. Path analysis showed that the primary components plant population per area and number of grains per plant have the largest direct impact on grain yield. On the other hand, the number of grains produced per plant is the major responsible for the increase in the weight of 1,000 grains. Path analysis also evidenced that the secondary component number of grains per pod has the highest direct effect on grain yield.

Tillering does not interfere on white oat grain yield response to plant density

Plant density is one of the cropping practices that has the largest impact on individual plant growth. This work was conducted to evaluate the response of white oat (Avena sativa) cultivars with contrasting tillering patterns to variations in plant density. Two field experiments were carried out in Lages, SC, Brazil, during the 1998 and 1999 growing seasons. A split plot experimental design was used. Four oat cultivars were tested in the main plots: UFRGS 14, UFRGS 18, UPF 16 and UPF 17 using five plant densities split plots: 50, 185, 320, 455 and 550 plants m-2. Five plant samples were taken 25, 34, 48, 58 and 70 days after plant emergence to assess the treatment effects on dry matter partition between main stem and tillers. UFRGS 18 promoted dry matter allocation to tillers whereas UPF 17 directed dry mass mostly to the main stem. Differences in dry mass allocation between the main stem and tillers had no impact on grain yield, UPF 16 presenting the highest values for both growing seasons. The lack of interaction between population density and cultivar and the small effect of plant population on grain yield indicates that the oat tillering ability is not fundamental to define its grain yield.

Efeitos do arranjo e da população de plantas sobre o crescimento do feijão em semeadura tardia

The bean crop is often sown after the ideal time in southem Brazil which brings along a decrease in grain yield. This experiment was carrica out in Lages, SC, with the purpose of looking for alternativos in the arrangement and population of plants as a way of compensating the small production of grains in late sowings. A split-split piot design with the main piots arranged in randomized complete blocks was used. Two cultivars, Barriga Verde (indeterminate erect, type II growing habit) and Carioca 80 SH (indeterminate prostate, type III growing habit) were tested in the main piot. Row spacings o f 0.2 5m and 0.50m were used in the split piot and plant populations o f 200, 300 and 400 thousand pl ha-1were observed in the split split piot. The increase in plant population promoted a greater number o f grains per area, specially for the indeterminate erect cultivar at the narrower row spacing, having a concomitant decrease in seed weight. The use of0.2 5m row spacing enhanced Barriga Verdes grain yield and decreased Cariocas grain productivity at high plant populations.

Increasing plant density: a method of improving maize grain yield in regions with short summer growing seasons.

The development of earlier hybrids, with shorter plant height, lower leaf number and upright leaves has increased maize potential adaptability to withstand high plant densities. This trend may be emphasized on the high lands of Southern Brazil due to their mild Spring and Summer temperatures and shorter maize growing season. Four trials were carried out, aiming to investigate the viability of using higher than recommended plant populations, as an alternative to improve grain yield. The maize hybrids Cargill 901 and XL 370 were evaluated at several plant populations, ranging from 37000 to 100000pl ha-1, under different management situations. In three out of four experiments, plant populations above 60000pl ha-1 maximized grain yield. The greater competition among individuals verified at high plant populations did not decrease substantially the number of ears per plant, which contributed to improve maize adaptation to high plant densities. Therefore, for regions with a short growing season, the use of early small stature maize hybrids may be accompanied by an increment in plant population up to a value varying between 65000 and 80000pl ha-1. This is conceivable as long as there is adequate soil fertility, water availability and stem lodging resistant genotypes.^lpt^aO surgimento de novos cultivares de milho, de ciclo mais curto, estatura reduzida, menor numero de folhas e folhas mais eretas aumentou o potencial de resposta da cultura a densidade de plantas. Essa tendencia pode ser acentuada nos planaltos do Sul do Brasil, que apresentam temperatura media nos meses mais quentes inferiores a 22°C, o que resulta em menor estacao estival de crescimento. Quatro experimentos foram conduzidos objetivando avaliar a viabilidade de se trabalhar com densidade de plantas maiores do que as atualmente recomendadas para esta regiao, como uma forma de aumentar o rendimento de graos. Nestes experimentos, submeteram-se os hibridos Cargill 901 e XL 370 a uma populacao que variou de 37.000 a 100.000pl ha-1, sob diferentes situacoes de manejo. Em tres dos quatro experimentos realizados, o uso de densidade de plantas superior a 60.000plha-1 maximizou o rendimento de graos. A maior competicao intraespecifica verificada nas densidades mais elevadas nao reduziu drasticamente o numero de espigas por planta, o que contribuiu para a melhor adaptacao da cultura a densidades elevadas. Dessa forma, para locais com estacao estival de crescimento mais curta, o uso de cultivares precoces, de menor porte, pode ser acompanhado pelo incremento na densidade para valores compreendidos entre 65.000 e 80.000pl ha-1. Isso e possivel desde que se tenha bom nivel de fertilidade no solo, boa disponibilidade hidrica e cultivares resistentes ao acamamento.^len^aThe development of earlier hybrids, with shorter plant height, lower leaf number and upright leaves has increased maize potential adaptability to withstand high plant densities. This trend may be emphasized on the high lands of Southern Brazil due to their mild Spring and Summer temperatures and shorter maize growing season. Four trials were carried out, aiming to investigate the viability of using higher than recommended plant populations, as an alternative to improve grain yield. The maize hybrids Cargill 901 and XL 370 were evaluated at several plant populations, ranging from 37000 to 100000pl ha-1, under different management situations. In three out of four experiments, plant populations above 60000pl ha-1 maximized grain yield. The greater competition among individuals verified at high plant populations did not decrease substantially the number of ears per plant, which contributed to improve maize adaptation to high plant densities. Therefore, for regions with a short growing season, the use of early small stature maize hybrids may be accompanied by an increment in plant population up to a value varying between 65000 and 80000pl ha-1. This is conceivable as long as there is adequate soil fertility, water availability and stem lodging resistant genotypes.

Increment on plant density: an alternative to improve maize grain yield in short growing season regions

The development of earlier hybrids, with shorter plant height, lower leaf number and upright leaves has increased maize potential adaptability to withstand high plant densities. This trend may be emphasized on the high lands of Southern Brazil due to their mild Spring and Summer temperatures and shorter maize growing season. Four trials were carried out, aiming to investigate the viability of using higher than recommended plant populations, as an alternative to improve grain yield. The maize hybrids Cargill 901 and XL 370 were evaluated at several plant populations, ranging from 37000 to 100000pl ha-1, under different management situations. In three out of four experiments, plant populations above 60000pl ha-1 maximized grain yield. The greater competition among individuals verified at high plant populations did not decrease substantially the number of ears per plant, which contributed to improve maize adaptation to high plant densities. Therefore, for regions with a short growing season, the use of early small stature maize hybrids may be accompanied by an increment in plant population up to a value varying between 65000 and 80000pl ha-1. This is conceivable as long as there is adequate soil fertility, water availability and stem lodging resistant genotypes.^lpt^aO surgimento de novos cultivares de milho, de ciclo mais curto, estatura reduzida, menor numero de folhas e folhas mais eretas aumentou o potencial de resposta da cultura a densidade de plantas. Essa tendencia pode ser acentuada nos planaltos do Sul do Brasil, que apresentam temperatura media nos meses mais quentes inferiores a 22°C, o que resulta em menor estacao estival de crescimento. Quatro experimentos foram conduzidos objetivando avaliar a viabilidade de se trabalhar com densidade de plantas maiores do que as atualmente recomendadas para esta regiao, como uma forma de aumentar o rendimento de graos. Nestes experimentos, submeteram-se os hibridos Cargill 901 e XL 370 a uma populacao que variou de 37.000 a 100.000pl ha-1, sob diferentes situacoes de manejo. Em tres dos quatro experimentos realizados, o uso de densidade de plantas superior a 60.000plha-1 maximizou o rendimento de graos. A maior competicao intraespecifica verificada nas densidades mais elevadas nao reduziu drasticamente o numero de espigas por planta, o que contribuiu para a melhor adaptacao da cultura a densidades elevadas. Dessa forma, para locais com estacao estival de crescimento mais curta, o uso de cultivares precoces, de menor porte, pode ser acompanhado pelo incremento na densidade para valores compreendidos entre 65.000 e 80.000pl ha-1. Isso e possivel desde que se tenha bom nivel de fertilidade no solo, boa disponibilidade hidrica e cultivares resistentes ao acamamento.^len^aThe development of earlier hybrids, with shorter plant height, lower leaf number and upright leaves has increased maize potential adaptability to withstand high plant densities. This trend may be emphasized on the high lands of Southern Brazil due to their mild Spring and Summer temperatures and shorter maize growing season. Four trials were carried out, aiming to investigate the viability of using higher than recommended plant populations, as an alternative to improve grain yield. The maize hybrids Cargill 901 and XL 370 were evaluated at several plant populations, ranging from 37000 to 100000pl ha-1, under different management situations. In three out of four experiments, plant populations above 60000pl ha-1 maximized grain yield. The greater competition among individuals verified at high plant populations did not decrease substantially the number of ears per plant, which contributed to improve maize adaptation to high plant densities. Therefore, for regions with a short growing season, the use of early small stature maize hybrids may be accompanied by an increment in plant population up to a value varying between 65000 and 80000pl ha-1. This is conceivable as long as there is adequate soil fertility, water availability and stem lodging resistant genotypes.