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Soybean [Glycine max (L.) Merr.] yield and profitability can be affected by plant‐to‐plant spatial uniformity and sowing rate. This study aimed to evaluate the agronomic and economic performance of soybean in relation to the spatial distribution of seeds in rows and seeding rates. A field experiment was conducted during the 2018–2019 and 2019–2020 growing seasons in Londrina, Paraná state, Brazil. We evaluated three coefficients of variation of seed distribution in rows (coefficient of variation of seeds distribution (VDS): 0%, 50%, and 100%) and four seeding rates (350,000, 262,500, 175,000, and 87,500 seeds ha−1), which corresponded to 100%, 75%, 50%, and 25% of the recommended seeding rate of the cultivar BRS 1003 IPRO, respectively. Sowing was performed manually to ensure that seed distribution accurately adhered to the experimental setup. Soybean yield components, yield, and profitability were then evaluated. The lower VDS improved the yield by 374 kg ha−1 compared to the higher VDS and increased the profitability by $334.7 ha−1 in 2019–2020. A seeding rate of 262,500 seeds ha−1 yielded the highest grain yield. The highest soybean profitability was achieved at a seeding rate 6.5% lower than that which produced the highest yield. Branching is essential in compensating for lower seeding rates and plants with uneven spatial distributions. The present study shows that equidistant distribution of seeds in rows optimizes grain yield. Core Ideas: Plant‐to‐plant spatial uniformity increases soybean yield and profitability.Reduced soybean seeding rate increases profitability.Branching is the most important phenotypically plastic mechanism in soybean. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista de Ciencias Agroveterinarias is the property of Revista de Ciencias Agroveterinarias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Soybean tolerance to defoliation may be affected by population density, as the plant population interferes with the crop leaf area index . This study aimed to evaluate the effect of defoliation at the beginning of pod formation on the agronomic performance of soybean at different plant densities. The experiment was conducted under field conditions in Campos Novos, SC, Brazil, during 2016/2017 and 2017/2018 growing season. The experimental design was a randomized block in a split-plot arrangement. The main plot consisted of three densities (100,000, 300,000, and 500,000 plants ha-1), whereas the subplots consisted of the cultivar NA 5909 RG submitted to five defoliation levels (0, 16.6, 33.3, 50, and 66.6%). Grain yield ranged from 4,219 to 5,356 kg ha-1 in the 2016/2017 growing season and 3,732 to 5,186 kg ha-1 in the 2017/2018 growing season. Plant density did not interfere with the grain yield response to defoliation performed at the beginning of pod formation. The 16.6% defoliation increase grain yield by 7.5 and 5.6% relative to the control in 2016/ 2017 and 2017/2018 growing seasons, respectively. The soybean tolerate defoliation of up to 33.3% at R3 with no significant decrease in grain yield, regardless of the plant density. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Agricultural Sciences / Revista Brasileira de Ciências Agrárias is the property of Universidade Federal Rural de Pernambuco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sowing date and nitrogen (N) fertilisation modify the morpho-physiological characteristics of maize (Zea mays L.) plants, which can alter the yield. The aim of this study was to analyse the effects of sowing date and N rate on the growth-pattern characteristics of maize hybrids with contrasting cycles, and the subsequent relationship with grain yield. Two experiments were set up in Santa Catarina State, southern Brazil. Two maize hybrids (AG9025, super-early cycle; P30F53, early cycle), two sowing periods (early spring and late spring), and four rates of topdressed N (0, 150, 300 and 450 kg N ha−1) were tested. Plant height, leaf area index (LAI), and relative chlorophyll content (RCC) were evaluated. The increment in N rate increased plant height at the silking stage for early spring sowing, and had no effect for late spring sowing. Higher N rates increased plant height of P30F53 and did not affect plant height of AG9025. Increasing the N rate enhanced LAI and RCC at silking more sharply when maize was sown in early spring. Higher N rates resulted in increased RCC during grain-filling, as well as maintenance of LAI, factors that were strongly associated with grain yield, especially for early spring sowing with hybrid P30F53. This research shows that the use of increasing N rates is an adequate management strategy to increase maize grain yield when the crop is sown in early spring. When applied at this sowing time, N has greater effect on the elevation of LAI and RCC and their maintenance during grain filling. Sowing date affects the environmental conditions experienced during maize development, which modifies maize response to nitrogen (N) fertilisation, depending on the hybrid cycle. The use of increasing rates of topdressed N enhances maize capacity to intercept solar radiation and to convert it into grain production. The use of high rates of N is an adequate management strategy to increase the yield when the crop is sown at the beginning of spring. [ABSTRACT FROM AUTHOR]

Copyright of Agronomía Colombiana is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Caatinga is the property of Revista Caatinga and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An uneven distribution of maize plants at the sowing row can decrease grain yield. This work was carried out to evaluate the effect of an increasing nitrogen rate on maize agronomic performance under different variation coefficients of plant spatial distributions at the sowing row. The experiment was conducted in Lages, Santa Catarina State, South Brazil. Three variation coefficients (VC) of plant spatial distribution (0, 50, and 100%) were tested. At the 0 level, seeds were evenly distributed 17 cm from each other. In the other treatments with uneven spatial distributions, the distances between two neighbouring seeds ranged from 2 to 54 cm. Four nitrogen side-dress rates (0, 125, 250, and 375 kg N ha-1) were evaluated. The increase in VC of plant spatial distribution decreased the leaf area and the relative chlorophyll content of the index leaf at silking, regardless of the nitrogen rate. When the variation coefficient of seed placement was enhanced from 0 to 100%, such behaviour contributed to a decrease in the number of kernels per ear and the grain yield. Therefore, increasing the amount of N was not an efficient strategy for preventing yield losses caused by irregular plant spatial distribution at the sowing row. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Natural infection of Gibberella ear rot (GER) of maize, caused by Fusarium graminearum, is not consistent from year to year in southern Brazil, thus an effective approach to identifying resistance to GER is to use artificial inoculation methods to test germplasm, however not widely implemented in Brazil where no maize hybrids are known with resistance to GER. A GER index, Fusarium-damaged kernels (FDK), and Fusarium-infected kernels (FIK) were used to evaluate the inoculation methods and hybrids resistance. Four different inoculation methods were tested on four hybrids in three environments during the 2011/12 growing season. Silk-channel, silk-channel-spray, pin and collar-deposition method were tested. For all hybrids, the pin method consistently showed the highest GER index values followed by the silk-channel method. Collar-deposition method was also able to infect the ears, suggesting attention to this point of infection. These two best methods were used to screen the 20 hybrids for GER in two environments during the 2012/13. The pin method showed 2-fold more GER index, FDK, and FIK ( P < 0.05) than the silk-channel method. Silk-channel and pin method showed a significant positive GER index correlation ( r = 0.646; P = 0.001). The hybrids appeared to have a form of silk resistance rather than kernel resistance, since the majority (95 %) of hybrids tested were either moderately susceptible (MS) or susceptible (S) to F. graminearum when pin method was used. However, 65 % of the hybrids were classified as MS or S in the silk-channel method. [ABSTRACT FROM AUTHOR]

Nitrogen fertilizer broadcast application over maize (Zea mays L.) is becoming more common as narrow row spacing is adopted and larger fields are cultivated. The contact of N fertilizers with plant leaves can partially damage leaf tissues and consequently affect crop yield. This study was conducted to evaluate the effect of source, method, and time of application of N fertilizer on maize leaf area and grain yield. A field trial was conducted in Brazil during two growing seasons. Urea (UR) and ammonium nitrate (AN) were applied at V5 and V10 maize growth stages broadcasted over the canopy or banded on the soil at a rate of 200 kg N ha-1. Solid fertilizers were broadcasted over dry and wet leaves whereas for applications to the soil solid fertilizers or solutions were used. In the first season, broadcasting AN reduced the leaf area at silking by 15.7% compared to soil application regardless of leaf moisture. In the following year, broadcasting AN reduced by 7.5% the leaf area at silking compared with UR. In the first growing season, the grain yield with UR was 10.1% greater than that with AN when both fertilizers were broadcasted. In the second season for the same application method, the grain yield from crops fertilized with UR was 32% higher than those where AN was used. In addition, the yield was 18% greater when fertilizers were applied to the soil than when they were broadcasted. Broadcasting N fertilizers causes leaf phytotoxicity and may decrease grain yield, especially when AN is used. [ABSTRACT FROM AUTHOR]