【Objective】 To optimize the soybean-maize intercropping system in the Huang-Huai-Hai region, this study aimed to evaluate the effects of different row ratio configurations on crop agronomic traits, canopy structure of the population, yield components, edge effects, and overall economic benefits. The goal was to identify suitable row ratio configurations, thereby improving land resource use efficiency and economic returns. 【Method】 Three row ratio configurations were implemented: 4 rows of soybean intercropped with 2 rows of maize (4:2), 6 rows of soybean intercropped with 4 rows of maize (6:4), and 4 rows of soybean intercropped with 4 rows of maize (4:4), using monoculture soybean (SCK) and monoculture maize (MCK) as controls. Crop dry matter accumulation, leaf area index (LAI), relative chlorophyll content (SPAD), canopy light transmittance, and yield components were measured. The inner and outer row sampling approach was adopted to evaluate edge effects and overall economic benefits. 【Result】 Compared with monoculture, intercropping significantly decreased per-plant dry matter accumulation in maize during the filling, milking, and maturity stages, and in soybean during the full flowering, full pod, grain filling, and full maturity stages. Among the row ratio configurations, maize exhibited maximum per-plant dry matter accumulation under the 4:4 pattern, whereas soybean achieved its highest accumulation under the 6:4 pattern. Row ratio configurations significantly influenced inter-row variations in dry matter accumulation and yield for both crops. Maize yield followed the order 4:4 pattern>4:2 pattern>6:4 pattern, representing reductions of 15.22%, 18.02%, and 12.62% relative to MCK, respectively; soybean yield followed the order 6:4 pattern>4:4 pattern>4:2 pattern, corresponding to reductions of 55.99%, 50.43%, and 56.00% compared with SCK, respectively. Intercropped maize exhibited pronounced edge advantage, with border row maize yields significantly exceeding those of inner rows. Within the intercropping system, both maize and soybean demonstrated lower canopy light transmittance, LAI, and SPAD values compared with their monoculture counterparts. Maize canopy light transmittance, LAI, and SPAD values followed the consistent ranking: 4:4 pattern>4:2 pattern>6:4 pattern; soybean canopy light transmittance followed 4:4 pattern>6:4 pattern>4:2 pattern, while its LAI and SPAD values mirrored the ranking pattern observed in maize. Maize LAI was significantly influenced by row ratio configuration, whereas no significant inter-row variations were detected for maize SPAD values or for soybean LAI and SPAD values. In evaluations of economic returns and intercropping advantages, the 4:4 pattern configuration demonstrated superior performance, achieving the highest values for land equivalent ratio (LER), relative crowding coefficient (K), and economic benefits. Maize in intercropping exhibited higher LER and K values relative to soybean, with the maize competition ratio (CRm) being significantly greater than that of soybean (CRs) (CRm>1, CRs<1), demonstrating maize's competitive dominance in interspecific competition. 【Conclusion】 Although intercropping reduced per-plant dry matter accumulation, LAI, and SPAD values for both crops compared with monoculture, it significantly increased the land equivalent ratio (LER) and overall economic benefits. Under the experimental conditions, the 4:4 pattern exhibited more optimal canopy architecture, with maize demonstrating pronounced edge advantage. This system maintained maize yield while generating additional soybean income, thereby achieving the synergistic enhancement of total productivity and economic returns.
【Objective】 This study aimed to investigate the effects of different row ratio configurations on canopy light distribution, layer-specific photosynthesis, and crop yield formation in a maize-soybean strip intercropping system, thereby providing a theoretical basis for high-yield and high-light-efficiency cultivation. 【Method】 A field experiment was conducted under field conditions during the 2023-2024 growing seasons, with monoculture maize (SM) and monoculture soybean (SS) serving as controls. Four maize-soybean strip intercropping configurations were established: four rows of maize with six rows of soybean (4M6S), four rows of maize with four rows of soybean (4M4S), three rows of maize with four rows of soybean (3M4S), and two rows of maize with four rows of soybean (2M4S). The planting density of maize was consistently maintained at 67 500 plants/hm2 across all intercropping treatments. The soybean planting densities under SS, 4M6S, 4M4S, 3M4S, and 2M4S treatments were 160 000, 153 144, 128 351, 151 068, and 183 556 plants/hm2, respectively, and the effects of different row ratios on the light distribution, photosynthetic performance and yield in the canopy of the composite population were analyzed. 【Result】 The 4M4S treatment resulted in a higher leaf area index (LAI) and greater light transmittance in the middle canopy layer in maize. The LAI under 4M4S was 4.07%, 4.41%, 4.71%, and 5.46% higher than that under 4M6S, 3M4S, 2M4S, and SM, respectively. At the R1 stage, the light transmittance at the ear leaf of maize under 4M4S was 9.76%, 21.11%, 46.83%, and 48.16% higher than that under SM, 2M4S, 4M6S, and 3M4S, respectively. Concurrently, the 4M4S treatment enhanced the net photosynthetic rate of the lower leaves in maize, which was 10.45% and 8.58% higher than that under 3M4S and 4M6S, respectively. The overall radiation use efficiency (RUE) under 4M4S was 1.38%, 6.69%, and 8.01% higher than that under 4M6S, 3M4S, and 2M4S, respectively, demonstrating a stronger photosynthetic capacity under this treatment. The 4M4S treatment achieved the highest yields for both maize and soybean. The two-year average maize yields for 4M6S, 4M4S, 3M4S, and 2M4S were 8.88, 9.22, 8.44, and 8.86 t·hm-2, respectively, while the corresponding soybean yields were 1.44, 1.44, 1.37, and 1.29 t·hm-2, respectively. The land equivalent ratio (LER) for all intercropping patterns exceeded 1.27. Row ratio configuration significantly influenced interspecific relationships between maize and soybean. The aggressivity of maize relative to soybean under 3M4S, 4M6S, and 2M4S treatment was 3.91, 4.41, and 11.32 times that under 4M4S treatment, respectively. In 2023, the relative crowding coefficient was the smallest under 3M4S, followed by 4M4S; in 2024, the value for 4M4S was 3.19%, 10.58%, and 21.82% lower than that under 3M4S, 4M6S, and 2M4S, respectively. Thus, the 4M4S treatment effectively ensured maize yield while simultaneously increasing soybean production. 【Conclusion】 The 4M4S treatment enhanced maize light interception, thereby improving light transmittance within the middle and lower canopy layers of the maize population. This configuration enabled leaves across different canopy positions—both inner and outer rows—to maintain high photosynthetic capacity, while also preserving the photosynthetic performance of soybean plants. Consequently, the system's radiation use efficiency was significantly improved, and both crop yield and land equivalent ratio were markedly increased. Furthermore, this treatment resulted in the smallest values for interspecific competitiveness, relative crowding coefficient, and net effect among all configurations. Therefore, the 4M4S treatment was identified as the most suitable row ratio configuration under the experimental conditions.
【Objective】 The 4:6 maize-soybean intercropping model, widely promoted in the Huang-Huai-Hai region, has issues such as poor ventilation and light penetration, and poor grain setting in the middle rows of intercropping maize. Therefore, this study explored optimizing row spacing configurations to improve the canopy structure of intercropping maize populations and enhance the yield of intercropping systems, for providing a theoretical basis for the promotion and application of maize-soybean strip intercropping in the Huang-Huai-Hai region. 【Method】 From 2023 to 2024, soybean variety HeDou 22 and maize variety Liyuan 296 were used as test materials. Under the maize-soybean 4:6 planting pattern, five row spacing configurations were set: equal row spacing of 60 cm (ER) and narrow-wide row spacing of 40 cm+70 cm+40 cm (WNR1), 40 cm+80 cm+40 cm (WNR2), 40 cm+90 cm+40 cm (WNR3), and 40 cm+100 cm+40 cm (WNR4) to study the impacts of row spacing configurations on the yield, accumulation of dry matter, plant traits, and canopy characteristics of intercropping maize. 【Result】 Under the maize-soybean 4:6 intercropping pattern, the wide-narrow row planting of intercropping maize significantly increased its yield. The WNR3 treatment showed an average yield increase of 6.68% compared with ER over two years, with a 10.49% increase in post-anthesis dry matter accumulation. The yield improvement primarily stemmed from increased kernel number per ear (8.24%-9.95%) and 1 000-grain weight (2.66%-3.04%) in the middle rows. Compared with ER treatment, the wide-narrow row planting alleviated the "shade avoidance response" in the middle rows. Under the WNR3 treatment, the height difference between middle-row and border-row maize plants narrowed by 2.3%, stem diameter increased by 5.7%, leaf senescence was delayed, and the SPAD value of ear-leaf at the silking stage improved by 1.95%-14.95%. As the row spacing of middle rows increased, canopy light transmittance and single-plant leaf area exhibited an upward trend. The WNR3 treatment improved bottom-layer light transmittance by 29.11% and ear-layer light transmittance by 25.44% in the middle rows. However, no significant difference was observed between WNR3 and WNR4 treatments. Although the WNR4 treatment further enhanced canopy ventilation and light conditions, the light interception rate of the intercropping maize population significantly decreased, leading to reduced post-anthesis photosynthetic product accumulation and grain yield. 【Conclusion】 Under the intercropping mode of maize and soybean 4:6, the configuration of 40 cm+90 cm+40 cm wide and narrow rows could significantly improve the crown structure of maize, enhance photosynthetic performance, increase post-flower dry matter accumulation and grain yield, which was an effective way to optimize the yield of intercropping system in Huanghuaihai region.
【Objective】 This study aimed to explore the regulatory effects of different plant height combinations of maize varieties on the light distribution and light resource utilization of the population canopy under the soybean and maize strip intercropping pattern. 【Method】 From 2023 to 2024, four maize varieties with different plant heights were used as experimental materials, including the short-stemmed varieties of MY73 and Denghai 605 (DH605), and the tall varieties of Jingke 968 (JK968) and Xianyu 1466 (XY1466), as well as the soybean variety Qihuang 34. The row configuration of maize and soybean was both 4:4. Different intercropping patterns were set, including intercropping of the same maize variety in all four rows as the control (S-MY, S-DH, S-JK, and S-XY), with 6.75×104 plants/hm2 for each of the four rows and intercropping of tall and short varieties (middle row tall variety JK968, edge row short variety MY73: MY-JK-1, MY-JK-2; middle row tall variety XY1466, edge row short variety DH605: DH-XY-1, DH-XY-2), and two types of planting densities were set, with 6.75×104 plants/hm2 for each of the four rows (MY-JK-1, DH-XY-1), 6.75×104 plants/hm2 for the middle rows, and 8.25×104 plants/hm2 for the edge rows (MY-JK-2, DH-XY-2). The plant spacing of soybean in each treatment was the same. The focus was on analyzing the effects of different intercropping patterns on the canopy structure of the population, light distribution, photosynthetic characteristics of maize and crop yield. 【Result】 The combined planting of maize varieties with different plant height optimized the canopy structure, significantly improved the light transmittance of the spike layer in the maize population, increased the leaf area index and photosynthetic characteristics, and ultimately promoted the increase in total system yield. During the silk production stage, the light transmittance of the spike layer in MY-JK-1 and MY-JK-2 increased by 18.55%-88.22% compared with S-MY and S-JK, and that in DH-XY-1 and DH-XY-2 increased by 39.26%-55.77% compared with S-DH and S-XY. The net photosynthetic rate (Pn) of the four varieties (except MY73) in the tall and short plant combination pattern was all increased. Among them, the Pn of DH605 in the DH-XY-2 pattern is 6.88% higher than that of S-DH, and the Pn of XY1466 in the DH-XY-2 pattern is 10.31% higher than that of S-XY. At the same time, the maximum photochemical efficiency (Fv/Fm) and potential activity (Fv/Fo) of the spike leaf also increased. The yield of maize under the MY-JK-2 pattern increased by an average of 19.44%, 9.58% and 1.66% over two years compared with the S-MY, S-JK and MY-JK-1 patterns, respectively. The average increase of DH-XY-2 over two years was 30.20%, 14.94% and 9.21% compared with the S-DH, S-XY and DH-XY-1 patterns, respectively. The maize yield (12 536.58 kg·hm-2) and total system yield (14 001.29 kg·hm-2) under the DH-XY-2 pattern were the highest in both years. 【Conclusion】 Compared with the intercropping pattern of single maize varieties, the combined planting of maize varieties with different plant heights could optimize the canopy structure of the population, improve the light distribution of the population canopy, and increase the light transmittance of the maize ear position layer and the photosynthetically active radiation at the top of soybean. At the same time, it improved the leaf area index and photosynthetic characteristics of maize, promoted the accumulation of photosynthetic products, and ultimately increased the total system yield. With the increase of edge row density, the maize yield was further enhanced. Under the conditions of this experiment, in the eastern part of the Huang-Huai-Hai region, it was recommended to use the combined planting of short-stemmed DH605 and tall XY1466, with a middle row density of 6.75×104 plants/hm2 and an edge row density of 8.25×104 plants/hm2.
【Objective】 This study aimed to clarify how varying nitrogen application rates and amounts of drip irrigation after sowing influence productivity and resource efficiency in a maize-soybean strip intercropping system, offering a theoretical framework for improving water-nitrogen management in the Huang-Huai-Hai area. 【Method】 From 2023 to 2024, a three-factor orthogonal experimental design was conducted, featuring three cultivation methods: maize alone (M), soybean alone (S), and maize-soybean strip intercropping (MS). The nitrogen levels tested were 120 kg·hm-2 (N1), 180 kg·hm-2 (N2), and 240 kg·hm-2 (N3), while post-sowing irrigation was applied at 0 mm (I1), 30 mm (I2), and 60 mm (I3). This study systematically analyzed the impacts of these planting patterns on leaf area dynamics, yield, water use characteristics, and economic benefits of water and nitrogen regulation. 【Result】 The leaf area index (LAI) for both maize and soybean reached its maximum around 90 days after sowing, following a sine function trend (goodness-of-fit R2>0.967). The MS method notably enhanced maize LAI but reduced soybean LAI. Soybean was particularly responsive to water availability; the lack of post-sowing irrigation (I1) led to a significant decrease in LAI for both S and MS soybean by 13.25%-25.00% and 17.73%-24.48%, respectively, at 30 days after sowing. The most effective intercropping treatment (MSN1I2: low nitrogen at 120 kg·hm-2+30 mm irrigation) yielded 9 063-9 088 kg·hm-2. Although this yield was 3.48%-4.11% less than the highest yield from maize monoculture (MN2I3: 180 kg·hm-2 N+60 mm irrigation), its land equivalent ratio (LER) remained above 1 (1.02-1.26), highlighting the benefits of intensified land use. In comparison to maize monoculture, the strip intercropping system enhanced soil water retention in the 0-40 cm plough layer by 1.20%-8.64%. On average, the trip intercropping system improved economic returns by 4.11%-8.04% and 49.62%-63.28% compared with maize and soybean monocultures, respectively, with the MSN1I2 treatment yielding the highest benefit of 23 638 yuan·hm-2. This treatment (MSN1I2) showed a synergistic improvement in water and nitrogen efficiency, with an irrigation water productivity of 3.06 kg·m-3. 【Conclusion】 In the maize-soybean strip intercropping system, lowering nitrogen application to 120 kg·hm-2 along with 30 mm of post-sowing drip irrigation (MSN1I2) could optimize canopy structure, maintain high and stable yields, enhance economic returns, and improve water and nitrogen efficiency. This approach offered the valuable technical guidance for regional initiatives aimed at reducing nitrogen and enhancing efficiency.
【Objective】 This study clarified the physiological basis of the effects of growth regulators on the stem characteristics and yield of summer maize under maize-soybean strip intercropping, with the aim of providing the technical support and theoretical basis for improving the lodging resistance of summer maize and ensuring stable and high yield in the intercropping system. 【Method】 In 2023-2024, using maize variety of Denghai 605, soybean varieties of Heidou 22 and Andou 203 as test materials, under the strip intercropping pattern of 4 rows of maize and 6 rows of soybeans, six treatments were designed (CK, treatment with water; T1, 300 mg·L-1 ethepene+0.03 mg·L-12, 4-epibrassinolide; T2, 300 mg·L-1 ethepene+0.03 mg·L-1 aminosterol; T3, 300 mg·L-1 ethylene glycol+0.03 mg·L-1 2, 4-epibrassinolide+0.03 mg·L-1 aminosterol; T4, 300 mg·L-1 ethylene glycol+2 g·L-1 chlorpyritin+ 0.03 mg·L-1 2, 4-epibrassinolide; T5, 300 mg·L-1 ethoxylenol+2 g·L-1 chlorpyritin+0.03 mg·L-1 2, 4-epibrassinolide +0.03 mg·L-1 aminosterol) at the V7 (7-leaf) stage. The maize plants were sprayed with either water or different combinations of these growth regulators. The effects of various combination treatments on the morphology of intercropped maize plants, lignin, hemicellulose, and cellulose content in the third internode from the base, as well as on yield, were investigated. 【Result】 Compared with CK, the application of growth regulators increased the stem diameter, lignin, cellulose, and hemicellulose content in the maize third internode from the base, while reducing maize plant height and length of the third internode, thus improving the lodging resistance of intercropped maize. In addition, the growth regulators increased the leaf area index (LAI), number of ears per hectare, and ear tip length of maize, while reducing its plant height, ear length, number of kernels per ear, 1000-grain weight, and grain yield in the maize-soybean strip intercropping system. The decrease in yield was primarily due to the reduction in the number of kernels per ear and thousand kernel weight caused by the growth regulators. The T3 and T5 treatments had higher leaf area index, stem diameter, and lignin content in the third internode, with a yield reduction of 0.38%-1.53% (T3) and 1.40%-3.03% (T5), indicating that the combination treatments of ethephon, 2,4-epibrassinolide, and aminocyclopropane carboxylic acid (T3 and T5) were beneficial to maize yield formation in the intercropping system. 【Conclusion】 After the application of growth regulators, the stem diameter and lignin content of intercropped maize in the maize-soybean strip intercropping system increased, resulting in enhanced lodging resistance. Under the experimental conditions, the combination of ethephon (300 mg·L-1), 2,4-epibrassinolide (0.03 mg·L-1), and aminocyclopropane carboxylic acid (0.03 mg·L-1) was found to be the most effective growth regulator formulation for improving the lodging resistance of maize stalks in the maize-soybean strip intercropping system while conducive to the stable yield of intercropping maize.
【Objective】 Based on of “High-Yield and High-Efficiency Maize-Soybean Intercropping Technology R&D and Integrated Demonstration” project of National Key Research and Development Program in the 14th Five-Year Plan seven demonstration sites were established across Shandong, Henan, Anhui, and Jiangsu Provinces. Key technology research and integrated demonstrations were conducted. To comprehensively evaluate the yield performance, economic benefits, and ecological effects of the project demonstration sites, this study conducted a systematic assessment using neighboring farmers as a control, so as to provide a scientific basis for optimizing maize-soybean intercropping in the region. 【Method】 A comprehensive evaluation index system was established, covering three dimensions: yield, economy, and ecology. Through field surveys in seven demonstration sites and their neighboring farms, the differences in overall benefits of maize-soybean intercropping between the demonstration fields and local farmers were assessed. 【Result】 For yield, the intercropping in the demonstration fields was about 10% to 19% higher compared with neighboring farmers. In terms of economic benefits, the net output value per unit area in the demonstration sites was 5% to 21% higher on average. However, input costs increased by 7% to 15%, resulting in a net benefit per unit area only 2% to 18% higher. From an ecological perspective, the carbon footprint of the demonstration areas was approximately 9% to 34% higher than that of surrounding farmers, and the nitrogen footprint was 5% to 45% higher. This was mainly due to the increased use of fertilizers and diesel to ensure high yields. Based on the differences in yield, economic, and ecological dimensions between surrounding farmers and the demonstration areas, the CVI (comprehensive variation index) levels of all seven demonstration areas were at a moderate difference level (corresponding value of level 3). Among them, the ECI (economic convergence index) performed well (levels 3 to 4), especially with the smallest land output rate differences (the North Shandong, North Anhui, and North Jiangsu regions reaching the optimal level 5). This further proved that although surrounding farmers had lower yields and land output, the high inputs in the demonstration areas reduced the unit output efficiency, objectively narrowing the net profit gap with surrounding farmers and supporting the higher ECI value. The main limitation for the improvement of the comprehensive index in all regions was the relatively low yield, as the YCI (yield convergence index) of all regions concentrated at the poor level of 1 to 2. 【Conclusion】 The technological innovation and application of the project had a positive effect on promoting the yield and economic benefits of maize and soybean intercropping in the Huang-Huai region. But its sustainable promotion still faces challenges, such as rising costs and increasing ecological pressure. Finding ways to reduce costs and improve efficiency was therefore a key focus for the next stage of technological innovation.
