Agronomy Journal最新文献

The high protein content in soybean (Glycine max (L.) Merrill) necessitates maximizing the nitrogen (N) absorption capacity and the biological N fixation process. This study aimed to evaluate whether foliar application of molybdenum (Mo) combined with cobalt (Co) enhances the productivity, yield components, N content, and protein and oil contents of soybeans. The experiment consisted of randomized blocks with a split-plot arrangement, with two soybean cultivars (BRS 399 Roundup Ready [RR] and BRS 284) as a main plot and the presence or absence of foliar application of Co + Mo as a subplot, during two seasons and eight replications. Foliar application was performed during the vegetative stages V3 and V5. The results revealed that foliar fertilization with Co + Mo increased the grain yield by 9.8% for BRS 399 RR in the first season and by 15.4% for BRS 284 in the second season. For BRS 399 RR, the N concentration in the leaves, protein yield, and oil content were also positively affected by the Co + Mo application. For BRS 284, only the N concentration in leaves increased in the first season, whereas the protein yield improved in the second season. However, compared with the control, the protein and N concentrations in the grains of both cultivars and seasons were not significantly influenced by Co + Mo application. The foliar application of Co + Mo had both positive and neutral effects on grain yield, protein yield, and leaf N concentration, depending on weather conditions and the soybean cultivar used, thus impacting N use efficiency.

Identifying how maize (Zea mays L.) light interception has historically changed due to breeding and plant density can inform strategies to maximize future crop yields. We measured light interception at the top, middle, and lower canopy and derived the light extinction coefficient in 18 maize hybrids released by Bayer Crop Science between 1983 and 2017 in two environments in the US Corn Belt. Results indicated that at a constant plant density of 8.5 plants m⁻², breeding has decreased light interception at the top canopy by 0.51% year⁻¹, enhanced light capture in the middle canopy without affecting whole-canopy light interception. Newer hybrids at 8.5 plants m⁻² intercepted more light at the bottom canopy than older hybrids at 4.5 plants m⁻². We revealed a trade-off between breeding and plant density on light interception, in which the combination of both factors increased the total light interception by approximately 3%. The light extinction coefficient has decreased with the hybrid year of release by 0.5% year⁻¹ at 8.5 plants m⁻² (p = 0.15). Breeding and planting density had similarly contributed to decreasing light extinction coefficient. Present results enhance our understanding of historical changes in maize light interception as affected by breeding and plant density, which could inform future crop modeling and crop ideotype design studies.

Sulfur (S) is an essential nutrient for optimizing corn (Zea mays L.) growth and yield. While S deficiency has increased in recent years, corn response to S fertilizer application remains challenging to predict owing to complex interactions among soil, crop, and weather conditions. Forty field trials were conducted between 2009 and 2011 over a range of soil types and environments to evaluate corn grain yield response to S fertilizer and assess the ability of soil and leaf S concentration to predict yield response to S fertilizer. Rate trials included two (0 and 34 kg S ha⁻¹) or five rates (0 to 52 kg S ha⁻¹, in 13 kg ha⁻¹ increments), whereas S sources were evaluated at 26 kg S ha⁻¹ (ammonium sulfate [21-0-0-24S], elemental S [0-0-0-90S], gypsum [0-0-0-21Ca-17S], monoammonium phosphate [MAP] MAP-10S [12-40-0-10S], MAP-10S+Zn [12-40-0-10S-1 Zn], and MAP-15S [13-33-0-15S]). Over the 3-year study period, we found minimal yield response to S fertilizer application with an overall response rate of 5% (two of 40 trials). In addition, neither S fertilizer evaluated increased corn grain yield relative to no S at any site; however, elemental S significantly reduced yield in one of 18 sites. While S application generally increased soil and earleaf S concentration, this did not translate into yield increases; hence, the lack of relationship between relative yield and soil and earleaf S. Under the study's conditions, these results indicate that S fertilization is unlikely to increase corn yields, and standard diagnostic tests such as soil S and earleaf S concentration are unreliable in predicting yield response in the upper US Midwest. Future research should incorporate other organic and inorganic soil S fractions to improve understanding and prediction of crop response to S fertilization.

Straw and biochar have shown potential to enhance soil structure, increase nutrient availability, improve crop productivity, and reduce reliance on chemical fertilizers. However, their cumulative effectiveness as partial fertilizer substitutes over extended periods remains unclear. This study evaluated rice (Oryza sativa L.) straw and its biochar as partial fertilizer substitutes on soil pore structure, nutrient supply, pH, root growth, yield, and nitrogen partial factor productivity (PFP_N-chem) in a 7-year field trial in Northeast China. The experiment included five treatments: (1) 100% chemical NPK fertilizer (NPK), (2) low-dose biochar (LB: 1.5 Mg ha⁻¹ year⁻¹), (3) high-dose biochar (HB: 3.0 Mg ha⁻¹ year⁻¹), (4) low-dose straw (LS: 4.5 Mg ha⁻¹ year⁻¹), and (5) high-dose straw (HS: 9.0 Mg ha⁻¹ year⁻¹). Chemical NPK application rates in the straw and biochar treatments were adjusted to maintain equivalent total nutrient level. After 7 years, both LB and LS attained average rice yields (LB: 6.7; LS: 7.6 Mg ha⁻¹) similar to NPK (7.3 Mg ha⁻¹), though initial yields were lower than NPK. This parity resulted from enhanced macroporosity and pore connectivity, which promoted root growth to compensate for reduced nitrogen availability. Specifically, LS exhibited 42.4% greater macroporosity (100–500 µm), 19.3% longer roots, and 54.8% higher root biomass than LB, yielding superior PFP_N-chem (+27.3%) with a 16% chemical N fertilizer reduction. However, high doses (HB/HS) led to average yield declines (22.8% and 13.1% lower than NPK). These findings highlight the potential of low-dose straw and biochar as sustainable strategies for improving soil quality and reducing fertilizer dependency.

The ability of cotton (Gossypium hirsutum L.) to compensate for lower plant densities and 2 × 1 skip row patterns has been evaluated by numerous studies. Studies were conducted to determine if cotton yield can be maintained in a 1 × 1 skip row pattern and across plant densities to increase profit margins. Cotton growth, development, and yield were investigated in an irrigated production system in Starkville, MS, on a Leaper silty clay loam (fine, smectitic, nonacid, and thermic Vertic Epiaquepts) and in Stoneville, MS, on a Beulah very fine sandy loam (coarse-loamy, mixed, active, and thermic Typic Dystrudepts). Row patterns consisted of solid planted and 1 × 1 skip row pattern, and plant density consisted of 37,065, 74,130, 111,195, and 148,260 plants ha⁻¹. Skip row pattern and lower plant density reduced plant height. Total node and nodes above cracked boll were reduced as plant density increased. There was an interaction between location, year, and pattern, as well as year and plant density, with respect to yield. At three of four site years, solid row pattern produced greater yield in comparison to skip row pattern. However, row pattern and plant density had no effect on yield when pooled over location and year. Net returns varied by location and row pattern. Skip row produced a greater net return in Stoneville when compared to solid planting pattern; however, in Starkville, a greater net return was produced with solid planting pattern. Increased plant density did not increase profit margin due to increased seed costs.

Artemisia sphaerocephala, a xerophyte shrub from the Compositae family, has gained significant attention in ecological restoration and various industries. However, limited knowledge of agricultural practices for its seed production hinders the development and use of this species. In a 5-year field experiment, we investigated the effects of four surface drip irrigation treatments (W0, W1, W2, and W3 with 0, 80, 160, and 240 mm, respectively) on seed yield, quality, and water use efficiency (WUE) in A. sphaerocephala. Higher irrigation levels significantly increased seed yield, with annual averages of 37, 85, 140, and 195 kg/ha for W0, W1, W2, and W3, respectively. Additionally, increased irrigation improved germination percentage and reduced median water potential ($�{\psi }_{��50�(�g��)�}$). However, the effect of irrigation on WUE varied from year to year. Therefore, we recommend total irrigation of 240 mm, distributed as 80 mm each during winter, regreening, and full flowering stages, to optimize A. sphaerocephala seed production, particularly in arid regions. A structural equation model identified seeds per flower (SF) as the most significant contributor to seed yield, highlighting SF as a key trait for breeding programs aimed at improving A. sphaerocephala seed yield. Our study provides valuable insights for implementing effective agronomic measures to enhance seed yield in A. sphaerocephala and similar semi-shrubs.

Over-seeded annual grasses and legumes, which can provide forage on dormant perennial warm-season grass pastures, serve as cover crops on fallow cropland. Although erosion control is not a typical need for pastures with perennial grass sod, cover crops functioning as catch crops to reduce cool-season nutrient loss or legumes for N fixation could contribute to reduced-cost warm-season pasture growth. Treatments of over-seeded cool-season species and management evaluating effects of cover crop removal as forage versus mulched as a N source were evaluated at three locations in 3 years. Cool-season legumes produced more biomass N than cool-season grasses, indicating biological N contributions of the legumes. Nitrogen limitation of the less productive, non-fertilized grasses indicates that readily available soil N had been depleted, limiting N leaching. Despite mulching of legume biomass with N amounts of 45–89 kg ha⁻¹, biomass production of bermudagrass [Cynodon dactylon (L) Pers.] in the following growing season was not increased. Lack of benefit of cover crop N contributions to subsequent bermudagrass forage production indicates that the availability of increased soil N was not synchronized with periods of efficient bermudagrass N uptake. These unanticipated results appear to be due to the effect of N mineralization-immobilization processes on N availability combined with variable rates of bermudagrass growth in response to periodic moisture limitations in this warm, humid, but uncertain environment.

Variable weather patterns and extended growing seasons over the last couple of decades have prompted growers to plant soybean [Glycine max (L.) Merr.] earlier than the historical standard. Field experiments were conducted in Michigan over three site-years to evaluate soybean planting date, row width, and herbicide program on weed suppression and soybean yield. Planting date had minimal impact on soybean stand, except at one site-year where soil crusting reduced stand 44%–52% in early (April 12–21) compared with the typical planting date (May 11–23). Weed densities and biomass for the untreated controls were substantially higher in early compared with the typical planting in all site-years. Soybean planted in 19 cm rows (370,500 and 494,000 seeds ha⁻¹) reduced weed biomass 29%–47% compared with 76 cm rows (370,500 seeds ha⁻¹) in two of three site-years when weeds were not controlled; however, the effects of row width were not observed when a PRE herbicide was applied. Similarly, narrow row widths (<76 cm) resulted in quicker canopy closure compared with 76 cm rows in two of three site-years. Regardless of row width, a PRE followed by a POST herbicide program provided the most consistent weed control. Soybean yield was 7% greater for 19 cm rows at 494,000 seeds ha⁻¹ compared with 76 cm rows in two of three site-years. However, planting date did not affect soybean yield when weed control was good in all site-years. Overall, combining narrow row widths with a complete herbicide program is equally beneficial for soybean planted early and at typical planting dates.

Plant diseases pose an important threat to agricultural productivity, affecting both the quality and quantity of crops. Early detection and severity assessment of infections in plant crops are critical for effective disease management and minimizing crop loss. This paper proposes a methodology for detecting wheat crop diseases using hybrid deep learning models that combine graph neural networks (GNNs) with convolutional architectures. By leveraging GNN + convolutional neural network (CNN), GNN + ResNet, and GNN + Visual Geometry Group 16 (VGG16) models, we aim to enhance the ability to detect diseases from images of wheat leaves accurately. The proposed models were trained on a comprehensive dataset of wheat crop images, with extensive preprocessing, model training, and hyperparameter tuning to optimize their performance. Our results indicate that the GNN + CNN model achieved the highest accuracy at 93%, followed by GNN + ResNet at 86% and GNN + VGG16 at 82%. These findings suggest that GNN + CNN is particularly effective for disease detection, providing a high degree of accuracy and robustness. This approach shows promise for automated, precise crop disease management, offering a valuable tool for advancing agricultural productivity and disease control.