Yongjun Wang

In response to the growing issue of maize lodging caused by typhoons shifting northward into Northeast China, the rational application of plant growth regu

Low-temperature stress is a major environmental constraint on rice yield stability, considerable variation remains in the reported direction and magnitude of these effects. In this study, we conducted a systematic meta-analysis combined with dose–response analysis to evaluate the effects of low-temperature stress on rice yield formation, photosynthetic capacity, and physiological responses. The results showed that low-temperature stress significantly reduced yield-related traits in rice, with yield per plant and pollen viability decreasing by 10.58% and 21.75%, respectively. Photosynthetic performance was also markedly affected, as net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs) decreased by 26.67%, 10.93%, and 31.00%, respectively, while intercellular CO ₂ concentration (Ci) increased by 5.75%. Low-temperature stress also significantly induced the accumulation of osmotic regulatory substances and aggravated oxidative damage. Subgroup analysis and meta-regression indicated that the effects of low-temperature stress were jointly regulated by growth stage, stress temperature, and stress duration. Specifically, yield responses were more sensitive at the booting stage and heading–flowering stage, while Pn showed more pronounced responses to severe low temperature and prolonged stress. Dose–response analysis showed that most traits exhibited response turning points around 24 °C. Overall, this study quantitatively revealed the associations among yield reduction, photosynthetic inhibition, and physiological homeostasis imbalance in rice under low-temperature stress, providing comprehensive evidence for understanding the response patterns of rice to low temperature.

Nitrogen application rate (N rate) is a key factor affecting maize yield, but the physiological mechanisms by which it improves yield through the coordination of the source-sink relationship remain unclear. In this study, field experiments were conducted in the black soil region of Northeast China for three consecutive years (2022–2024). Five N rates were tested: 0 kg ha⁻¹ (N0), 90 kg ha⁻¹ (N90), 135 kg ha⁻¹ (N135), 180 kg ha⁻¹ (N180), and 225 kg ha⁻¹ (N225). The results showed that the N180 treatment achieved the highest yield across the three growing seasons, with yields 7.23–51.40% higher than those of the other treatments. This was mainly attributable to the synergistic improvement in grain number per ear and 100-grain weight. After anthesis, the N180 and N225 treatments significantly increased chlorophyll content (SPAD), PSII photochemical efficiency-related parameters (F_v/F_m, Φ_PSII, and qP), and the activities of carbon assimilation-related enzymes (RuBPCase and PEPCase) in the ear leaf, indicating improved photosynthesis-related physiological status. Meanwhile, N180 significantly promoted the translocation of stored dry matter from pre-anthesis vegetative organs to the grains, resulting in a 5.21–51.41% increase in the proportion of dry matter allocated to the grains at maturity compared with the other treatments. Logistic equation fitting showed that an increased grain-filling rate and an extended grain-filling period were the main reasons for the higher grain weight under N180. Although N225 maintained high post-anthesis dry matter accumulation, more assimilates were retained in vegetative organs, which limited further improvement in grain-filling and grain weight. These findings provide a theoretical basis and practical guidance for the rational application of nitrogen fertilizer in this region.

Rotational cover cropping is a key practice in conservation agriculture. To investigate the effects of maize-crop rotation with cover crops combined with nitrogen management on maize yield, nitrogen use efficiency (NUE), and related traits, a field experiment was conducted from 2023 to 2025. The experiment employed a split-plot design. The main plots consisted of three cropping systems: continuous maize (Fumin 985’) monoculture (CK), maize rotated with rapeseed (CC-Ra), and maize rotated with rye (CC-Ry). The subplots comprised five nitrogen (N) fertilizer application rates (0, 75, 150, 225, and 300 kg ha⁻¹) respectively. Compared to CK, CC-Ra and CC-Ry increased average maize grain yield by 5.93% and 12.89%, and NUE by 8.09% and 2.89%, respectively. At the silking stage, these treatments increased average DM by 6.45% and 16.55%, respectively, and by 5.75% and 15.01% at the maturity stage. The maximum LAI was enhanced by an average of 16.24% and 26.82%, while the net photosynthetic rate (Pn) of the ear leaf increased by 12.29% and 26.32%, respectively. In contrast, the leaf net assimilation rate (NAR) decreased by an average of 19.98% and 18.01%. While higher N application boosted yield, it sharply reduced NUE. Notably, yields under rotations at 225 kg N ha⁻¹ matched the yield of continuous maize at 300 kg N ha⁻¹. This suggests that the inclusion of cover crops can substitute for a portion of nitrogen fertilizer input while maintaining stable maize yield. Principal component analysis fundamentally clarified that maize rotational cover cropping combined with nitrogen fertilizer management significantly promotes yield. While cover crops increase maize yield, they also facilitate nitrogen accumulation and enhance NUE, albeit at the expense of leaf net assimilation rate. Therefore, balancing the source–sink characteristics of the maize population is necessary to avoid the loss of advantages conferred by rotational cover cropping. This study holds significant implications for incorporating cover crops into maize production systems.

Aims Extracellular enzyme stoichiometry is a key indicator for assessing resource limitations faced by soil microorganisms. Yet the characteristics of microbial resource limitation in rhizosphere soil under the combined agricultural practices of intercropping and straw retention remain unclear. Methods Here, we conducted a field experiment in the black soil region of Northeast China, to quantify the effects of intercropping and straw retention on soil nutrients, microbial biomass, extracellular enzyme activities, and their C:N:P stoichiometry in the rhizosphere of maize and peanut crops. Results Our results revealed an average vector length (VL) of 1.68 and 1.57 for extracellular enzymes in the rhizosphere soil of maize and peanut, with a vector angle (VA) of 37.80° and 34.67°, respectively. This indicated that soil microorganisms in the rhizosphere of both crops were co-limited by C and N, and the N limitation was more significant in the peanut rhizosphere. Notably, the combined treatment of intercropping and full straw retention increased the VA by 5°, effectively alleviating N limitation in the rhizosphere soil. The extracellular enzyme C:N:P stoichiometry in the rhizosphere soil of maize and peanut was 1.33:1.29:1.00 and 0.89:1.29:1.00, respectively. Microbial biomass nitrogen (MBN) was the primary factor affecting microbial nutrient limitation. Conclusions The extracellular enzyme stoichiometric characteristics of rhizosphere soil differed significantly between the two crops. Intercropping had a stronger impact on rhizosphere microbial nutrient limitation than straw retention, and their synergistic effect could significantly alleviate rhizosphere microbial N limitation by enhancing extracellular enzyme activity.

Waterlogging stress severely limits crop photosynthesis and energy supplies, resulting in significant yield reductions. However, the critical duration of waterlogging stress during the maize jointing stage remains unclear, and the physiological and molecular mechanisms underlying its effects on photosynthetic efficiency and energy synthesis in maize require further investigation. In this study, we systematically analyzed the responses of physiological traits, transcriptomic profiles, and the yield formation in maize (Zea mays L.) to varying waterlogging durations imposed during the jointing stage, including 0 days (CK), 2 days (F2), 4 days (F4), 6 days (F6), 8 days (F8), and 10 days (F10). Our results indicate that the (1) grain weight (GW) showed no significant difference between F2 and CK. However, the GW in F4, F6, F8, and F10 decreased significantly by 17.49%, 26.45%, 60.24%, and 100.00%, respectively, compared to the CK. (2) Compared with the CK, the malondialdehyde content progressively increased from F4 to F10, while antioxidant enzyme activity gradually decreased. The chlorophyll content declined by 29.93% to 57.38%, and net photosynthetic efficiency decreased by 13.82% to 38.93%. Although the leaf sucrose content in from F4 to F10 gradually decreased, the leaf starch content remained stable in F4 and F6. In contrast, the starch content in F8 and F10 leaves was significantly reduced by 37.55% and 47.60%, respectively, compared with CK. (3) A transcriptomic analysis revealed that during from F2 to F4, genes encoding photosystem I subunit protein, such as PSAD, and the cytochrome b6f complex proteingene PETC were downregulated. At F6, these key genes encoding photosynthetic proteins were upregulated. However, at F8 and F10, their expression was significantly downregulated. Concurrently, genes related to ATP synthesis (e.g., ATPD) as well as starch and sucrose metabolism (e.g., SPP2, SS1) were also downregulated. In summary, when waterlogging stress persists for no longer than 6 days, plants can maintain their starch content to supply energy for growth, thereby ensuring basic developmental needs. When waterlogging persists for more than 6 days, energy synthesis is impaired, and the nutrient transport to the grains is significantly inhibited, ultimately resulting in a substantial reduction in yield. Therefore, 6 days of waterlogging can be considered the critical threshold for significant yield loss in maize during the jointing stage.

This study investigates the effects of different tillage practices on soil quality and maize yield in black soil farmland. Based on an eight-year continuous field plot experiment initiated in 2017, we examined the impacts of five tillage methods: conventional tillage (CT), no-tillage with straw mulching (NTS), subsoiling tillage with straw mulching (STS), harrow tillage with straw mulching and incorporation (HTS), and moldboard plowing tillage with straw incorporation (MPS). The focus was on soil structure, hydrothermal characteristics, organic matter, and nutrient content within the 0–40 cm soil layer, as well as maize dry matter accumulation and grain yield. The results indicate that, in 2023, compared to CT, STS significantly improved the soil structure and hydrothermal characteristic quality index (SHQI) in the 0–40 cm soil layer. Additionally, NTS, STS, HTS, and MPS significantly enhanced the soil organic matter and nutrient quality index (ONQI) in the 0–40 cm soil layer. NTS and STS increased the soil quality index (SQI) by 9.0% to 16.6% compared to the other treatments. Additionally, NTS, STS, HTS, and MPS significantly enhanced the soil organic matter and nutrient quality index (ONQI) in the 0–40 cm soil layer. In 2024, NTS and STS increased the soil quality index (SQI) by 9.0% to 16.6% compared to the other treatments. Furthermore, NTS and MPS significantly improved the SHQI in the 0–40 cm soil layer compared to CT. NTS and STS also significantly enhanced the ONQI in the 0–40 cm soil layer, while NTS, STS, and MPS increased the SQI by 7.3% to 22.6% compared to the other treatments. STS and MPS treatments significantly increased both hundred-kernel weight and grain yield compared to CT and NTS. Correlation and redundancy analyses revealed that SHQI in the 10–40 cm soil layer is a crucial factor affecting dry matter accumulation, yield, and its components in maize. In summary, in the semi-humid region of Northeast China, STS and MPS are cultivation techniques that optimize black soil quality and enhance maize grain yield.

Topsoil degradation poses a significant threat to agricultural production worldwide. However, whether degraded topsoil is a net nitrogen source or sink depends on crop uptake and nutrient loss, and how it affects the sustainability of agricultural production remains unclear. To fill this gap in understanding, we conducted a three-year experiment with five topsoil depth treatments: 10 cm (D10), 20 cm (D20), 30 cm (D30), 40 cm (D40), and 50 cm (D50). Increasing topsoil depth significantly increased grain yield by a maximum of 49.4% (between D10 and D50). With increasing topsoil depth, the NFUE rises from 14.2% to 64.9% (between D10 and D50 treatments), while the G-NFUE climbs from 9.0% to 36.2% (between D10 and D40 treatments). Increasing topsoil depth reduced topsoil N depletion and the percentage of change in soil N stocks. In addition, N fertilizers applied during the season were generally enriched in soil at a depth of 30–40 cm. Therefore, increasing the depth of topsoil can effectively increase the source of nutrients absorbed by a crop by increasing access to additional resources stored in deeper soils, which ultimately increases maize grain yield and N fertilizer use efficiency. In this study, the threshold for maize to achieve high yields and efficiency was a topsoil depth of 30 cm. This study elucidated the differences in maize grain yield and resource utilization at different topsoil depths and established a link with soil N characteristics, and thus, it will provide a theoretical basis for the sustainable management of topsoil.

Soil degradation limits maize grain yield, but the mechanisms by which leaf functions respond to topsoil depth and their contributions to yield are unclear. We quantified the response mechanisms of leaf functions to topsoil depth with topsoil depths of 10 cm (S₁), 20 cm (S₂), 30 cm (S₃), 40 cm (S₄), and 50 cm (S₅) and planting densities of 15,000 plants ha⁻¹ (D₁, the plant spacing was 111.1 cm and there was no mutual influence between individuals) and 75,000 plants ha⁻¹ (D₂). The grain yield in S₁ was significantly lower than that in S₂, S₃, S₄, and S₅, and the maximum reductions in yield were 39.7% in D₁ and 39.1% in D₂. The coefficients of variation for yield in S₁ and S₂ were significantly higher than those in S₃, S₄, and S₅ at both densities and in both years. The net assimilation rate and production efficiency of leaf area, as well as leaf nitrogen and carbon accumulation, all decreased with decreasing topsoil depth. The decreasing topsoil depth significantly reduced the maize leaf net photosynthetic rate, activities of key nitrogen metabolism enzymes, and photosynthesis. Therefore, eliminating intraspecific competition did not reduce the yield loss caused by a reduction in topsoil because leaf nitrogen metabolism and photosynthetic processes were severely limited by the decrease in topsoil depth.