Size, chlorophyll retention and protein and oil contents of grains from soybean plants grown in different spatial arrangements

Abstract

The spatial arrangement of soybean plants, determined by row spacing and seeding rate, affects the intraspecific competition for water, light, and nutrients, as well as plant architecture and grain development, quality, and chemical composition. The aims of this study were to evaluate the effect of row spacing and seeding rate on the grain size produced, and the influence of these three factors on chlorophyll retention and protein and oil content in grain. Two experiments were conducted in the 2013/14 and 2014/15 growing seasons, using a 4 × 3 factorial randomized block design with three replications. Four different row spacings [20 cm (narrow row), 50 cm (conventional), 20/80 cm (twin rows) and crossed lines (50 cm)] and three seeding rates (150, 300, and 450 thousand viable seeds ha -1 ) were evaluated. The grains were classified by size using oblong sieves and then the effects of spatial arrangements and size of grain on the percentage of green grains and protein and oil contents were evaluated. Higher plant densities were associated with larger grain size, whereas the effects of spacing between the rows on the grain size varied between growing seasons. The arrangement in cross-rows and high plant density produced a higher percentage of green grains under weather conditions favorable to the development of this attribute. The effects of plant spatial arrangements on the contents of protein and oil in grains were variable, and it was not possible to determine whether the spatial arrangement of plants had an effect on the levels of protein and oil in grains. Larger grains had higher protein content, but oil contents were not affected by grain size. Key words: Glycine max L. Grain quality. Green grains. Row spacing. Seeding rate. ResumoO arranjo espacial de plantas de soja, determinado pelo espaçamento entre as fileiras e pela densidade de semeadura, afeta a competição intraespecífica por água, luz e nutrientes, bem como a arquitetura da planta, podendo influenciar na formação, qualidade e composição química dos grãos produzidos. Os objetivos do trabalho foram avaliar o efeito do espaçamento entre fileiras e da densidade de semeadura no tamanho dos grãos produzidos e qual a influência desses três fatores na retenção de clorofila e nos teores de proteína e óleo nos grãos. Dois experimentos foram conduzidos nas safras 2013/14 e 2014/15, com delineamento de blocos casualizados, em esquema fatorial 4x3, com três repetições. Foram avaliados quatro espaçamentos entre fileiras: 20 cm (reduzido), 50 cm (convencional), 20/80 cm (fileira dupla) e 50 cm cruzado e três densidades de semeadura (150, 300 e 450 mil sementes viáveis ha -1 ). Os grãos produzidos foram classificados em peneiras de crivos oblongos. Após, avaliaram-se os efeitos do arranjo espacial e do tamanho dos grãos sobre a porcentagem de grãos verdes e os teores de proteína e óleo. As maiores densidades de plantas possibilitam a formação de grãos com maior tamanho, enquanto os efeitos de espaçamentos entre as fileiras sobre o tamanho dos grãos são vari...

Minimum optimal seeding rate for indeterminate soybean cultivars grown in the tropics

“…Theoretically, the lower intraspecific competition occurring at reduced plant densities should result in a higher TSW. However, the present study confirms that planting soybean at very low densities leads to smaller seeds with lower weight, as reported by recent surveys (Werner et al., 2017). Other studies did not find an effect of SR varying from 185 to 556 thousand seeds ha −1 on the TSW (Cox & Cherney, 2011; Cox, Cherney, & Shields, 2010; De Bruin & Pedersen, 2008).…”

“…(2014) found a decrease in protein content by reducing the SR from 520 to 250 thousand viable seeds ha −1 . On the other hand, in some cases, plant density had no influence on this characteristic (Werner et al., 2017), which may be related to variations in genotype and cropping environment.…”

The Influence of Agricultural Practices, the Environment, and Cultivar Differences on Soybean Seed Protein, Oil, Sugars, and Amino Acids

“…Soybean is a major crop in the world due to its seed nutritional value as a food for human consumption and feed for livestock. Soybean seeds contain on a dry weight basis approximately 40% to 45% protein, 18% to 24% oil, 9% to 13% palmitic, 3% to 5% stearic, and 18% to 26% oleic acids, sugars, amino acids, isoflavones, and minerals (seed composition) [1][2][3][4][5]. Although seed composition is genetically controlled, it has been reported to be influenced by agricultural practices, including seeding rate, row spacing, irrigation, growing conditions, geographic location, and fertilizers.…”

“…Although seed composition is genetically controlled, it has been reported to be influenced by agricultural practices, including seeding rate, row spacing, irrigation, growing conditions, geographic location, and fertilizers. Research on the effects of agricultural practices on seed composition is limited [3,4] and results obtained are still conflicting [6,7]. Therefore, further investigation is needed before recommendations are made.…”

“…In spite of the conflicting results, the effects of seeding rate, row spacing, and fertilizers have been previously reported [3,4,[8][9][10][11][12]. For example, research on the effects of row spacing on yield showed that narrower row spacing increased the soybean yield, especially at late planting dates in the southeastern USA [12,13].…”