Guangzhou Liu

Optimizing row spacing can improve canopy structure and productivity in densely planted maize, but variety-specific responses under drip fertigation remain unclear. A field experiment was conducted in Baoding in 2024 and 2025 to evaluate three row spacing configurations (60 + 60, 40 + 80, and 30 + 90 cm) for three maize varieties (DH605, MY73, and JH517) at 90,000 plants ha⁻¹. DH605, MY73, and JH517 achieved their highest yields under 40 + 80, 30 + 90, and 60 + 60 cm, respectively, with values of 15.0, 13.9, and 13.2 t ha⁻¹, indicating clear variety-specific responses. Compared with the other configurations, the optimal row spacings increased leaf area index at maturity, ear-layer light transmittance, net photosynthetic rate, photosynthetic and antioxidant enzyme activities, post-silking dry matter accumulation, and resource use efficiency, while reducing malondialdehyde content. Yield improvement was mainly associated with higher kernel number per ear and thousand-kernel weight. Correlation and random forest analyses showed that grain yield was closely associated with these canopy, physiological, and resource-use traits, with water use efficiency being the strongest predictor. These results suggest that variety-specific row spacing optimization can enhance maize productivity by coordinating canopy architecture, post-silking physiological function, and resource use efficiency under drip fertigation.

On the North China Plain, the winter wheat season is poorly synchronized with precipitation, making the traditional winter wheat–summer maize system heavily dependent on supplemental irrigation and associated carbon inputs. Based on a split-plot field experiment in Shenzhou, Hebei, from October 2022 to October 2025, this study evaluated the trade-off between annual system yield and area-scaled carbon emission among six cropping systems under conventional irrigation (CK) and rainfed management (R). The winter wheat–summer maize system (WM) maintained the highest grain-oriented annual system yield (22.91 t ha⁻¹ yr⁻¹ under CK), but it also showed the highest area-scaled carbon emission (11.97 t CO₂-eq ha⁻¹ yr⁻¹). The winter wheat–summer maize–spring maize system (WMM) reduced area-scaled carbon cost relative to WM (8.97 vs. 11.97 t CO₂-eq ha⁻¹ yr⁻¹ under CK), whereas its product-scaled carbon footprint remained comparable to or slightly higher than that of WM. Under a unified dry-matter basis, the double silage-maize system (FM) showed the lowest dry-matter-scaled carbon footprint (CF_DM; 193.85 and 175.71 kg CO₂-eq t DM⁻¹ under CK and R, respectively). Soil respiration in 2025 varied mainly with observation date and cropping-system configuration, and soil organic carbon (SOC) stock at the 2025 harvest differed among cropping systems, water-management regimes, and soil depths. Overall, WM remained the highest-yielding option under a grain-supply objective, whereas FM, the ryegrass–early-summer maize system (RM), and the forage winter wheat–early-summer maize system (FWM) were relatively more suitable under multifunctional biomass-supply and low-carbon-transition objectives.

In maize (Zea mays L.), rational root structure promotes high grain yield under dense sowing conditions. This study was conducted at Qitai Farm in Xinjiang, China, in 2019 and 2021. A traditional wide and narrow row planting method was adopted, with wide rows of 0.7 m and narrow rows of 0.4 m. The cultivars DH618 and SC704, which have grain yield potentials of 22.5 and 15 Mg ha⁻¹, respectively, were selected for study of the root structure and distribution characteristics under high-yield and high-density planting conditions. The highest yield (20.24 Mg ha⁻¹) was achieved by DH618 under a planting density of 12 × 10⁴ plants ha⁻¹. The root structure of DH618 was well developed at that planting density, and the root dry weight (RDW) was 17.49 g plant⁻¹ and 14.65 g plant⁻¹ at the silking and maturity stages, respectively; these values were 7.56% and 11.86% higher, respectively, than those of SC704. At the silking stage, the proportions of RDW at soil depths of 0–10, 10–20, 20–40, and 40–60 cm were 66.29%, 11.83%, 16.51%, and 5.38%, respectively, for DH618; over the 20–60 cm soil layer, this was an average of 4.04% higher than the RDW of SC704. At maturity, the proportions of RDW at soil depths of 0–10, 10–20, 20–40, and 40–60 cm were 61.40%, 11.19%, 17.19%, and 10.21%, respectively, for DH618, which was an average of 9.59% higher than that of SC704 over the 20–60 cm soil layer. At maturity, DH618 roots were mainly distributed in the narrow rows, accounting for 72.03% of the root structure; this was 9.53% higher than the roots of SC704. At silking and maturity, the root weight densities of DH618 were 471.98 g m⁻³ and 382.98 g m⁻³, respectively (5.18% and 5.97% higher, respectively, than the root weight densities of SC704). The root lengths of DH618 were 239.72 m plant⁻¹ and 199.04 m plant⁻¹ at the silking and maturity stages, respectively; these were 16.45% and 25.39% higher, respectively, than the root lengths of SC704. The root length densities were 0.58 cm cm⁻³ and 0.46 cm cm⁻³ at the silking and maturity stages, respectively, and these were 16.86% and 17.08% higher, respectively, than the root length densities of SC704. This study indicated that the maize hybrid DH618 had a more developed root structure with increased root distribution in the deep soil and narrow rows under high-density planting compared to cultivar SC704, contributing to high grain yield under dense planting.

Solar dimming due to global climate change is becoming increasingly more common in some agricultural areas. Such low-light stress inhibits maize ear number, kernel number per unit area (KN), and kernel weight (KW) as vital yield components. However, which yield component factors are most important for yield formation under low-light stress remains unknown. In this study at Qitai Farm in Xinjiang, China, in 2019 and 2020, we planted three maize (Zea mays L.) cultivars (Denghai 618 (DH618), Xianyu 335 (XY335), and Zhengdan 958 (ZD958)) at two densities (7.5 × 10⁴ (D1) and 12 × 10⁴ (D2) plants ha⁻¹). We used four shading treatments (85% (S1), 70% (S2), and 50% (S3) natural light and no shading (CK)) from the three-leaf stage until maturity to create different light conditions. KN was the key factor that directly affected yield under low-light stress. For every 100 MJ m⁻² decrease in photosynthetically active radiation (PAR), the KN decreased by 803.2 kernels per m² . When the PAR was >674.3 MJ m⁻² , KW tended to stabilize at 36.2 g/hundred kernels and the growth rate was 5.82 g/100 MJ m⁻² per hundred kernels. DH618 and XY335 KNs were more sensitive to lowered solar radiation than ZD958. When density increased, DH618 required fewer light resources than the other cultivars to produce an equivalent amount of photosynthates for kernels. Therefore, in the face of climate change, particularly solar dimming, there is an urgent need to breed maize cultivars, such as DH618, with low-light stress tolerance and high grain yield.

The root system connects the plant with the soil, which is a key factor in determining the utilization of soil resources and plant growth potential. Solar radiation can change maize shoot and root growth and affect grain formation. In this study, the effects of different solar radiation conditions on root morphology of three maize cultivars XY335, ZD958 and DH618 and their quantitative relationships were studied by conducting shading experiments. This study was conducted in maize high yield region of Qitai and Yinchuan, China, in 2018 and 2019. The planting densities were 7.5 × 10⁴ (D1) and 12 × 10⁴ (D2) plants ha⁻¹. The shading levels were natural light (CK), shading 15% (S1), 30% (S2) and 50% (S3). The results showed that maize responded to the decreased solar radiation through the increase in ratio of shoot dry weight (SWR) to whole plant dry weight and the decrease in ratio of root dry weight (RWR) to whole plant dry weight. As the solar radiation decreased, the root length density (RLD), root surface area (RSA), average root diameter (ARD) and root length ratio (RLR) decreased, while the specific root length (SRL) increased. With 100 MJ m⁻² decrease in solar radiation, the RWR, RLD, RSA and RLR each decreased by 1.47%, 0.5 mm cm⁻³,0.4 m m⁻² and 0. 19 m g⁻¹, respectively. Among the cultivars, the changes of DH618 were the fastest followed by XY335 and ZD958 but DH618 maintained the largest root system under any solar radiation condition. After the decrease of solar radiation, RWR, RLD and RLR were significantly positively correlated with the yield. This indicated that large root systems were conducive to the rapid response to decreased solar radiation and important for achieving stable and high yield. Maize cultivars with these type of root systems should be recommended to better adapt low solar radiation induced by regional variation or climate change.

The final leaf number is an important morphological characteristic of maize (Zea mays L.) and is therefore an important input parameter in some maize crop models. In this study, field experiments were conducted from 2013 to 2016 at 23 sites across China, which were located between latitudes of 26°30′ and 46°45′ N, focusing on five modern maize cultivars, in order to determine the amplitude of variation in mean leaf numbers between each cultivar, identify differences between the mean leaf numbers of cultivars under different climatic conditions, and clarify the effects of the differences in final leaf numbers on aboveground dry matter (DM) and grain yield. The results showed that the mean final leaf numbers increased in the order of XY335 < NH101 < ZD909 < ZD958 < DH11 among the five cultivars, with the wide distribution ranges of final leaf numbers being 17.0–23.3 (DH11), 16.7–22.3 (ZD958), 16.7–22.0 (ZD909), 16.7–22.3 (NH101), and 17.0–22.0 (XY335) across all locations. In addition, leaf numbers above and below the primary ear showed the same trends with the mean final leaf numbers for the same cultivars. Many climatic factors were found to significantly affect the final leaf numbers across four maize-growing regions in China, and the result of stepwise regression indicated that the influences of photoperiod and temperature, in particular, were greater than other climatic factors for these cultivars. Finally, there were found to be significant and positive relationships between the final leaf number and (1) the maximum leaf area index (LAImax), (2) DM at both silking and physiological maturity, and (3) grain yield for the same cultivars across all locations. The results of this study are of great importance for guiding future trans-regional maize cultivation and further model calibration.

Increasing planting density is an important practice associated with increases in maize yield, but densely planted maize can suffer from poor light conditions. In our two-year field experiments, two morphologically different cultivars, ZD958 (less compact) and DH618 (more compact), were planted at 120,000 plants ha⁻¹ and 135,000 plants ha⁻¹, respectively. We established different leaf area index (LAI) treatments by removing leaves three days after silking: (1) control, no leaves removed (D0); (2) the two uppermost leaves removed (D1); (3) the four uppermost leaves removed (D2); (4) the leaves below the third leaf below the ear removed (D3); (5) the leaves of D1 and D3 removed (D4); (6) the leaves of D2 and D3 removed (D5). Optimal leaf removal improved light distribution, increased photosynthetic capacity and the post-silking source-sink ratio, and thus the grain yield, with an average LAI of 5.9 (5.6 and 6.2 for ZD958 and DH618, respectively) for the highest yields in each year. Therefore, less-compact cultivars should have smaller or fewer topmost leaves or leaves below the ear that quickly senesce post-silking, so as to decrease leaf area and thus improve light distribution and photosynthetic capacity in the canopy under dense planting conditions. However, for more compact cultivars, leaves below the ear should senesce quickly after silking to reduce leaf respiration and improve the photosynthetic capacity of the remaining top residual leaves. In future maize cultivation, compact cultivars with optimal post-silking LAI should be adopted when planting densely.