Reduced Row Spacing Research Articles

Corn agronomic characteristics according to crop year, spacing and plant population densities

The present study aimed to evaluate the influence of row spacing, plant density, crop year and yield in crop agronomic parameters in a ‘Cerrado’ area in Brazil. The experiments were conducted during the 2010/2011 and 2011/2012 crop years, at an experimental Farm of the IF Goiás Campus Ceres, located in the city of Ceres, Goiás, Brazil. The experiment was conducted in a complete randomized block design in a 2x3x2 factorial (two crop years: 2010/2011 and 2011/2012, three population densities: 60,000, 70,000 and 80,000 plants ha-1 and two spacing: 0.50 and 0.80 m) with four repetitions, totaling 48 plots. The observed values for plant height and cob height were higher for the 2011/2012 season with values of 2.56 and 1.26 m, respectively. The cob diameter was higher for the 2011/2012 crop year with a value of 51.92 mm. The yield was higher for the 2010/2011 harvest. Increasing plant population and reducing row spacing can lead to an increase on the grain yield due to better spatial distribution of plants per area, fact observed mainly during the 2010/2011 crop year. Corn maintains high productivity with spacing of 0.50 and 0.80m. Increases in plant density can lead to increase on yield. Increasing plant population reduced the corn stem diameter.

Weed management using crop competition in the United States: A review

Exploiting the competitive ability of crops is essential to develop cost-effective and sustainable weed management practices. Reduced row spacing, increased seeding rates, and selection of competitive cultivars can potentially manage crop–weed competition in cotton, soybean, wheat, and corn. These cultural weed management practices facilitate a more rapid development of crop canopy that adversely affect the emergence, density, growth, biomass, and subsequently the seed production of weeds during a growing season. These cultural practices can also favour the weed suppressive ability of the crop by influencing the canopy architecture traits (plant height, canopy density, leaf area index, rate of leaf area development, and leaf distribution). These crop-competition attributes can potentially reduce the risk of crop yield losses due to interference from weed cohorts that escape an early- or a late-season post-emergence herbicide application. Furthermore, reduced row spacing, increased seeding rates, and weed-competitive cultivars are effective in reducing reliance on a single site-of-action herbicides, thereby reducing the selection pressure for development of herbicide-resistant weed populations in a cropping system.

Effects of plant height and row spacing on kenaf forage potential with multiple harvests

Kenaf (Hibiscus cannabinus L.) forage potential can be enhanced through its regrowth capacity and higher production in narrow rows. A field experiment was conducted in Matamoros, Coahuila, Mexico, during 2 growing seasons (2004 and 2005) to study the effects of plant height and row spacing on kenaf forage potential with multiple harvests. This study evaluated the effects of (1) 2 plant heights at cutting (1.0-1.2 m and 1.8-2.0 m) and (2) 4 inter row spacings (0.19, 0.38, 0.57 and 0.76 m) using a 2 x 4 factorial arrangement of treatments in a completely randomized block design with 4 replications. Dry matter (DM) and crude protein (CP) yields, DM partitioning, neutral detergent fiber (NDF) and CP concentrations were determined. Heights at cutting × row spacing interactions were not significant for the monitored variables (p>0.05). Kenaf response to treatments was only relevant for main effects (p≤0.05). Row spacing and plant height affected DM and CP yields (p≤0.05), whereas only plant height affected chemical composition and DM partitioning (p≤0.05). Dry matter (17.0%-26.0%), and CP (12.4%-15.6%) yields were higher (p≤0.05) when plant heights had reached 1.8 to 2.0 m. Row spacing reduction from 0.76 m to 0.38 and 0.19 m increased DM yield (20.4-33.4%) and CP yield (24.2-38.5%) (p≤0.05). Kenaf forage potential increases when planted in narrow rows and harvested 2 or 3 times during the growing season.

Estado nutricional e produtividade de algodoeiro em função de diferentes espaçamentos e aplicação de regulador de crescimento

Strategies of cotton growth as row spacing and use of growth regulator are efficient when the knowledge of crop production potential as well as the amounts of nutrients content. The objective of this study was to evaluate the nutritional status of cotton DeltaOpal cultivar through leaf analysis of macronutrient, chlorophyll index and yield in relation to plant arrangement and managements of the growth regulator. The treatments consisted of plant arrangement: arrangement 1: 88,900 plant ha-1 and row spacing at 0.9m, arrangement 2: 114,300 plant ha-1 and row spacing at 0.7m, arrangement 3: 178,000 plant ha-1 and row spacing at 0.45m; management of growth regulator (mepiquat chloride) at 1.0 L ha-1 dose, concentration was50g L-1: a- no regulator application; b- single application at 70 days after emergency (d.a.e.); c- split application into four stages (35, 45, 55, and 65 d.a.e.). The reading reviews SPAD chlorophyll, leaf analysis of macronutrients and cotton yield were conducted in three agricultural years 2006/07, 2007/08 and 2008/09, under the experimental design of completely randomized blocks, in a 3x3 factorial scheme totaling up nine treatments with four replications. The reduction of row spacing and increasing plant density gives less absorption of potassium and sulfur by cotton crop. A single application of mepiquat chloride increase calcium leaf content. The split application of mepiquat chloride provides increased SPAD reading index, higher foliar magnesium concentration and highest seed cotton yield.

Corn plant arrangement and its effect on silage quality

This experiment was carried out to evaluate the effects of the row spacing between corn plants on silage quality. Different spacing between corn rows (40, 60, and 80 cm) was used, but the population of plants was maintained around 65,000/ha in all treatments. Analysis of variance was carried out and means were compared by Tukey's test at 5% of probability. A reduction in row spacing provided better spatial distribution of plants, but did not alter morphological composition or dry matter production. The corn with most equidistant spatial distribution (lowest row spacing) showed an increase in lignin concentration, neutral detergent fiber, and total carbohydrates, and showed a decrease in total digestible nutrients when compared with 80 cm row spacing. However, the organic digestibility matter was not affected by the treatments. The content and quality of protein were higher for 80 cm row spacing compared with the other levels; also, protein content was reduced as the spacing between rows became smaller. The only mineral affected was calcium, which had the lowest value at higher levels of spacing. Although differences were detected for many variables, the most appropriate spacing between rows should also take into account economic and practical aspects when choosing the best plant arrangement.

Morphophysiology and Yield of Late Season Maize Intercropped With Urochloa in Reduced Row Spacing

Morphophysiology and Yield of Late Season Maize Intercropped With Urochloa in Reduced Row Spacing

Maize response to the variation of sowing density and reduction of spacing between rows in the Cerrado

The management of spatial arrangement in the maize crop by alteration in the spacing between rows and sowing density has been appointed as one of the most important agronomic practices to maximize the grains yield. The objective of this study was to evaluate the behavior of maize in relation to the reduction of row spacing and the different sowing densities during the off season in the Cerrado region. The experimental design was randomized blocks in factorial scheme 2 x 5 with four replications. The treatments consisted of two spacing between rows (0.45 m and 0.90 m) and five sowing densities (40,000, 55,000, 70,000, 85,000 and 100,000 plants ha-1). It was not found significant response for the reduction of row spacing for the assessed characteristics in maize crop. The increase of sowing density resulted in plant height, number of grains per row and number of grains per ears reduction in the maize crop; however, there was an increase in yield until the density of 100,000 plants ha-1.

Yield components, light interception and radiation use efficiency of lucerne (Medicago sativa L.) in response to row spacing

Lucerne sowing is characterized by a rectangular spatial arrangement, i.e. greater distance between sowing rows than between plants in the row. Therefore, the reduction of row spacing generates more square spatial arrangements that can influence intraspecific competition and resource utilization, especially radiation, and thus biomass. The experiment included different row spacings (10–15–17.5–20 and 30cm) at the same plant density in a pure lucerne crop during the first production year. Total aerial dry matter (ADM) was increased by narrow spacing (more square arrangements) up to an optimal distance (around 13cm) (R2=0.60). ADM ranged from 2292 to 1670gDMm−2 for 15 and 30cm row spacing, respectively. Plant density was the forage yield component most affected by row spacing and it increased with narrow spacing (0.15≥R2≤0.5). ADM responses to reduced row spacing were positive as revealed by both a linear increase in radiation interception (PARia) (R2=0.76) and an optimal pattern in radiation use efficiency (RUE) (R2=0.45). PARia in the first year showed an increase of 8MJcm−1 of spacing reduction. RUE values ranged from 2.0 to 1.6gDMMJ−1 for 15 and 30cm row spacing, respectively. The leaf area index (LAI) was also affected by row spacing. Additionally, seasonal variation was found for the main variables but did not interact with row spacing. In conclusion, reducing row spacing to an optimal distance is a practice that allows for more favourable spatial arrangements of a lucerne crop and has a positive impact on forage production.

Maize Evapotranspiration and Water‐Use Efficiency in Response to Row Spacing

Reduced row spacing has shown to increase maize (Zea mays L.) yield; however there are conflicting results on whether narrow rows increases maize crop evapotranspiration and/or water use efficiency. This work analyzes the response of maize yield, crop evapotranspiration (ET) and water use efficiency to reduced row spacing under different water and N regimes. Maize crops were grown at Balcarce, Argentina, during two seasons. Treatments included two water regimes (rain‐fed and irrigated), two rows spacing (35 and 70 cm) and two rates of N (i.e., 180 kg N ha−1 or nonfertilized). Soil water content was measured through the growing seasons using a neutron probe, grain yield and shoot dry matter were determined at physiological maturity. Grain yield response to narrow rows ranged from 0 to 23%; it was higher for water limited (i.e., rain‐fed crops) and/or N deficient crops (i.e., nonfertilized crops) and lower for crops with high N fertilization and irrigation. Narrow rows consistently increased (8%) crop ET during the initial stages of crop growth; and N fertilization did not influence ET response to reduced row spacing during this period. Initial differences in ET between row spacing treatments were diluted as the season progressed, and seasonal crop ET was not influenced by row spacing. Reduced row spacing increased water use efficiency for grain production up to 17%; increments were larger in N deficient crops and/or with water limitations but were negligible in N fertilized and irrigated crops.

Espaçamento e densidade de semeadura para cultivares de sorgo granífero no semiárido

Como existem poucas informações sobre o manejo cultural do sorgo em regiões do semiárido, neste trabalho foram instalados dois experimentos, avaliando-se três densidades de plantas e três espaçamentos de cultivares de sorgo granífero, em dois anos agrícolas, na Região Norte do Estado de Minas Gerais. Em cada ano foram instalados experimentos em áreas contíguas, adotando-se, respectivamente, os espaçamentos entre linhas de 50 cm, 70 cm e 90 cm e no outro experimento foram avaliadas três densidades de semeadura, 100 mil, 140 mil e 180 mil plantas ha-1. Também, em ambos os experimentos, foram avaliadas quatro cultivares de sorgo: SHS400, 1G220, BRS310 e 0992045, em delineamento experimental de blocos casualizados no esquema fatorial 3 x 4, com três repetições. Com a redução dos espaçamentos entre fileiras promoveram-se incrementos na produtividade de grãos e panículas do sorgo granífero, independentemente da população de plantas e cultivar avaliado. A viabilidade do aumento da densidade de semeadura é dependente da cultivar, do espaçamento e das condições climáticas prevalecentes no ano agrícola considerado. As cultivares BRS 310 e 1G220 de sorgo granífero são promissoras para produção de grãos no semiárido da Região Norte de Minas Gerais.

Reduced dosages of atrazine and narrow rows can provide adequate weed control in smallholder irrigated maize (Zea mays L.) production in South Africa

An on-farm experiment was conducted in Zanyokwe irrigation scheme to investigate the effects of row spacing (45 and 90 cm) and atrazine dosage (33, 67 and 100% of the label recommended dosage) on weed density and biomass and on maize yield. Overall percent kill of weeds increased with increase in atrazine dosage and with reduction in row spacing. Percent kill varied according to weed species with a 100% kill of broad leaf weeds such as Amaranthus hybridus, Nicandra physaloides and Bidens pilosa regardless of herbicide dosage while Digitaria sanguinalis, Cyperus esculentus, Cynodon dactylon and Oxalis latifolia could not be controlled even at the LRD. Weed density at maize physiological maturity decreased by 11% when row spacing was decreased from 90 to 45 cm. Atrazine dosage and row spacing did not have significant interactive effects and their main effects did not significantly affect weight of green cobs, cob length or grain yield. The study demonstrated the possibility of incorporation of reduced herbicide dosages and narrow rows to achieve adequate weed control and optimise on yields in smallholder farming systems. Key words : Row spacing, reduced atrazine dosages, weed density, weed biomass, maize yield.

Desempenho de híbridos de milho na Região Sudoeste do Paraná sob diferentes espaçamentos entre linhas

A manipulação do arranjo de plantas de milho, através de alterações na densidade de plantas, de espaçamento entre linhas, de distribuição de plantas na linha e na variabilidade entre plantas, é uma das práticas de manejo mais importantes para maximizar a interceptação da radiação solar, otimizar o seu uso e potencializar o rendimento de grãos. Dessa forma, objetivou-se com este trabalho estudar os efeitos da combinação entre diferentes híbridos de milho e espaçamentos entre linhas no desenvolvimento da cultura em sistema de plantio direto na Região Sudoeste do Paraná. O experimento foi realizado na Área Experimental do Curso de Agronomia da UTFPR, no município de Pato Branco - Pr, com delineamento estatístico aleatorizado em blocos em esquema fatorial (3 x 3), com quatro repetições. Os tratamentos foram compostos pela combinação entre três híbridos (DKB 240, PIONEER 30R50 e SG 6010) e três espaçamentos entre linhas (0,45; 0,70 e 0,90 m). Após a semeadura, foram avaliados: a altura de plantas, o diâmetro do colmo, o rendimento de grãos e seus componentes. Os resultados mostraram que em nenhuma das avaliações houve interações entre híbridos e espaçamentos e que a redução no espaçamento entre linhas promoveu aumento no número de espigas por planta e o incremento na produtividade de grãos na cultura do milho.

Plant and row spacing effects on soil water and yield of rainfed summer soybean in the northern China

Productivity and water resource-use efficiency are crucial issues in sustainable agriculture, especially in high-demand water resource crops such as soybean [Glycine max (L.) Merr.]. The aims of this research were to compare planting pattern in soybean, evaluating soil moisture content (SMC), yield and water use efficiency (WUE). A 2-year field experiment (2006–2007) was carried out in the north of China. The summer soybean (cv. Ludou 4) experiment consisted of 5 planting patterns under the same plant population density (3.09 × 105 plant/ha), and row spacing (cm) × plant spacing (cm) was 18 × 18 cm (A), 27 × 12 cm (B), 36 × 9 cm (C), 45 × 7.2 cm (D), 54 × 6 cm (E). The results showed that SMC and soil storage water (SSW) decreased with evapotranspiration (ETa) increments after reproductive growth stage, and there were remarkable differences between treatments with decreasing rainfall. SMC curve characteristics in the 0–0 cm soil profile were related to rain; the scope changes of shallow SMC were higher than those of deep SMC. The study revealed that yield and WUE had a negative correlation with row spacing, and they were statistically greater in narrow rows, which approximated equidistant plant spacings, compared to wider rows (P < 0.05). The study also indicates that enhanced productivity and WUE of rainfed summer soybean can be achieved via row spacing reduction and plant spacing widening under uniform planting density.

Manejo integrado de plantas daninhas na cultura do milho

Estratégia de manejo de plantas daninhas pode ser realizada de forma integrada com o método químico na redução da utilização de herbicidas na cultura do milho. O objetivo deste trabalho é avaliar o efeito do manejo integrado do espaçamento entre linhas, ou de híbridos de milho com características morfológicas distintas e redução dos níveis de herbicidas, para controlar plantas daninhas na cultura do milho. O experimento foi instalado em delineamento de blocos ao acaso, com quatro repetições, arranjado em um fatorial 2 x 2 x 5, em que: o primeiro fator foram os híbridos Penta (superprecoce, com folhas mais planas) e Flash (superprecoce com folhas mais eretas); o segundo fator foram os espaçamentos entre linhas de milho (0,45 e 0,9 m) e o terceiro fator os níveis de manejo de plantas daninhas (capinado, sem capina e atrazine + foramsulfurom + iodosulfuron nas doses de 3000+45+3, 2250+33,8+2,3 e 1500+22,5+1,5 g ha-1 i.a.). Foram avaliados a altura e o ângulo foliar vertical das plantas, o número de plantas daninhas e a matéria seca de plantas daninhas por área. O ângulo foliar de plantas de milho torna-se mais planófilo com a adoção de espaçamentos reduzidos entre linhas, mas outras características de plantas de milho estão envolvidas no desempenho dos espaçamentos. O uso do espaçamento de 0,45 m entre linhas não contribui para a redução dos níveis de herbicidas para a cultura, mas sua adoção beneficia o manejo de plantas daninhas e o rendimento de grãos do híbrido Flash, embora não seja vantajosa para o híbrido Penta.

Sugarcane response to row spacing-induced competition for light

Information about crop response to row spacing (RS) in sugarcane is often contradictory and there is a lack of understanding of competition for light. This study aimed to gain a better understanding of how competition for light affects leaf and tiller development, radiation capture and conversion to biomass, and its partitioning between leaves and stalks. A first ratoon crop of cultivar NCo376 was started on 29 August 2003 (when the plant crop was cut back) at Mount Edgecombe, South Africa (29°42′18.4″S, 31°02′48.5″E, 105 m). A wagon wheel design was used with RS ranging from 0.36 m to 2.66 m and the crop received adequate water and nutrients. Radiation interception was measured within cane rows (FI INTRA) and across cane rows (FI INTER). FI INTRA was not affected by RS and maximum FI INTRA (defined as the first value above 0.9) was reached simultaneously for all RS. The progression of FI INTER differed substantially between the different RS. Maximum green leaf number was attained when FI INTRA reached 90% and coincided with the occurrence of peak tiller density. Thereafter there was a gradual decline in green leaf number caused by intra-row competition for light. As soon as FI INTER exceeded a value of 90%, there was a drastic reduction in green leaf number due to a sharp acceleration in leaf senescence rate induced by inter-row competition for light. Inter-row competition had an effect on aboveground biomass accumulation of RS of less than 1.37 m from before the first sampling at 730 °Cd (base temperature of 16 °C). For RS of 1.73 m the competition effect commenced sometime between the first and second sampling (at 948 °Cd). There appeared to be no inter-row competition effect for RS of 2.15 m and more. Radiation use efficiency seemed unaffected by RS (average value of 1.50 g MJ −1), although the increase in biomass yield (22% per metre reduction in RS) could not be fully explained by a concurrent increase in intercepted radiation (source size—18% per metre reduction in RS). Sink size (stalk density) responded more to a decrease in RS than source size (intercepted radiation) and the latter became insufficient to fill the sink to capacity when row spacing was less than 1.37 m. Conversely, sink size appeared to be the limiting factor for wider RS as evidenced by a similar mass per stalk for different RS. The stalk partition fraction of biomass increments was unaffected by row spacing, although the start of stalk growth was delayed with decreasing RS in terms of the threshold biomass required for stalk partitioning to commence. This resulted in lower final stalk fractions for narrower RS. The information obtained in this study enabled important new insights into underlying mechanisms of row spacing-induced competition effects on sugarcane growth and development. It should be useful for improving crop models’ ability to predict crop response to row spacing more accurately and in a more functional manner. The improved understanding could highlight avenues for effective crop improvement (e.g. ideal canopy development sub-traits) and crop management (e.g. weed and water management).

Desempenho de híbridos de milho submetidos a diferentes espaçamentos e densidades populacionais

O objetivo deste trabalho foi avaliar a influência de espaçamentos entre linhas e densidades populacionais, nos componentes de produção e na produtividade de grãos, em dois híbridos de milho (Zea mays). O experimento foi conduzido na safra 2006/2007, em Latossolo Vermelho eutrófico típico, textura argilosa, em Jaboticabal, SP. O delineamento experimental de blocos ao acaso foi composto por 24 tratamentos com parcelas subsubdivididas. As parcelas principais foram constituídas por três espaçamentos entre linhas (0,40, 0,60 e 0,80 m), as subparcelas, por dois híbridos e as subsubparcelas, por quatro densidades populacionais (30 mil, 50 mil, 70 mil e 90 mil plantas por hectare). Foram avaliadas as variáveis: altura de planta e altura da inserção da primeira espiga, diâmetro de colmo, número de grãos por espiga, massa de 1.000 grãos, produtividade de grãos e índice de colheita. A produtividade do milho aumentou com a redução do espaçamento entrelinhas para os híbridos avaliados. O incremento na densidade populacional de milho resultou em aumentos na altura das plantas e na altura da inserção da primeira espiga e em redução do número de grãos por espiga. O melhor arranjo de plantas para os híbridos avaliados é de 0,40 m de espaçamento entre linhas e de 75 mil e 80 mil plantas por hectare de densidade populacional.

Arranjo espacial de plantas de milho em sistema plantio direto

Práticas de manejo que aumentem a população de plantas e reduzam o espaçamento através de arrajamento espacial podem, desde que bem planejadas, podem ser uma excelente oportunidade para que o produtor aumente a sua rentabilidade. Neste trabalho, o objetivo primordial foi avaliar os efeitos da variação da distribuição espacial de plantas em dois híbridos de milho cultivados em Sistema Plantio Direto (SPD) sobre os componentes de produção. O estudo foi desenvolvido no CECA/UFAL. Os tratamentos consistiram no cultivo dos híbridos de milho FORT e AGN 30A00, nos espaçamentos 0,80 e 0,40 m e submetidos às populações de 60.000 e 70.000 plantas ha-1. O delineamento estatístico foi o de blocos casualisados em esquema fatorial (2 x 2 x 2), com três repetições. A partir dos resultados obtidos foi possível concluir que nem a redução do espaçamento nem o aumento da densidade de plantas, como práticas isoladas, proporcionaram incremento no rendimento de grãos, para as cultivares testadas; entretanto, a combinação da redução no espaçamento com o aumento na população de plantas resultou em significativo incremento na produtividade de grãos do híbrido FORT.

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.

Manejo químico de plantas daninhas na cultura do milho em função de características morfofisiológicas e redução de espaçamento da cultura

Objetivou-se com este trabalho avaliar o efeito da integração de redução de espaçamento entre linhas sobre características morfofisiológicas de híbridos e estratégias de manejo químico de plantas daninhas em milho. O experimento foi realizado a campo, em delineamento de blocos casualizados, com quatro repetições, em um fatorial 2 x 2 x 5, em que o primeiro fator representou os híbridos de milho (Sprint, ciclo superprecoce e folhas mais eretas, e Penta, ciclo precoce e folhas mais planas); o segundo, espaçamentos entre linhas de milho (0,45 e 0,90 m); e o terceiro, tratamentos para controle de plantas daninhas: 1. atrazine + simazine (1.500 + 1.500 g i.a. ha-1) em pós-precoce; 2. atrazine + simazine (1.500 + 1.500 g i.a. ha-1), em pós-precoce, complementada por nicosulfuron + atrazine (20 + 750 g i.a. ha-1 ), em pós-tardia; 3. atrazine + simazine (750 + 750 g i.a. ha-1 ), em pós-precoce; 4. testemunha capinada; e 5. apenas nicosulfuron+atrazine (20 + 750 g i.a. ha-1 ), em pós -ardia. O espaçamento de 45 cm favoreceu a infestação de plantas daninhas na linha do milho, enquanto no espaçamento de 90 cm as maiores infestações foram observadas nas entrelinhas da cultura. As aplicações complementares de atrazine+nicosulfuron em pós-tardia foram importantes para controlar plantas daninhas no híbrido Sprint em espaçamento convencional, mas não necessárias para o híbrido Penta, nos espaçamentos utilizados. Observou-se no híbrido Penta que a redução do espaçamento afetou o rendimento de grãos, enquanto para Sprint não foi verificada redução de produtividade.

Espaçamento e adubação nitrogenada e potássica em cobertura na cultura do milho

This work had the objective of evaluate the effect of row spacing reduction and nitrogen and potassium fertilization in covering, in the efficiency of absorption of nutrients, in the grain yield and components of the production and other agronomic traits of maize single-cross hybrid. The experiment was installed in Cascavel, State of Parana, in the agricultural year of 2004/05. It was studied three row spacings (0.45; 0.67 and 0.90m), with a population of 55000 plants ha -1 . The experiment design used was that of randomized blocks with four repetitions, in a split plot scheme. It was used 13 combinations of seven nitrogen doses (8; 20; 40; 80; 120; 140 e 152 kg ha -1 of N) with seven potassium doses (3; 7.5; 15; 30; 45; 52.5 e 57 kg ha -1 of K 2 O), adding 39 treatments. The reduction of interlineations spacing of 0.90 m to 0.45 m maintaining the same population in each area caused the increase of whole dry biomass production, more efficiency in the nitrogen and potassium absorption and also more efficiency in using N and K in the grain. The grain productivity was statistically the same in the three spacings studied. It was verified a linear increase in the productivity and of the dry biomass production in the aerial part until the doses of 152 kg ha -1 of N in covering. The fertilization with potassium proportioned an increase of dry biomass production in the aerial part, but does not influenced in the productivity. Over 80 kg ha -1 doses of N and 30 kg ha -1 of K 2 O resulted in a smaller efficiency in using nitrogen and potassium fertilization.