Search Results (113)

Climate change is reshaping yield formation and water use in cold-region rice production through rising air temperatures, altered precipitation patterns, and increasing atmospheric CO₂ concentrations. However, the responses of yield, crop evapotranspiration (ET_c), and water use efficiency (WUE) to climate forcing and elevated CO₂ remain insufficiently quantified for cold-region rice systems in Northeast China. This study simulated changes in rice yield, ET_c and WUE during the 2030s–2090s relative to the 2000–2020 baseline period under the SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios at 10 agro-meteorological stations in Heilongjiang Province. Simulations were conducted using the AquaCrop model driven by CMIP6 multi-model climate data, and the contribution of elevated CO₂ was quantified by comparing the rising-CO₂ and fixed-CO₂ treatments. The results showed that under SSP5-8.5, the maximum air temperature in the 2090s is projected to increase by 5~6 °C relative to the baseline period, while precipitation is projected to range from −10% to 20%. Compared with the fixed-CO₂ treatment, rice yield under the rising-CO₂ treatment is projected to increase by 18.70%. Although ET_c showed an overall increasing trend, rising CO₂ attenuated its increase. Under SSP5-8.5 in the 2090s, ET_c increased by only 2.70% under rising-CO₂ treatment, compared with 11.61% fixed CO₂. As a result of increased yield and ET_c, the WUE improved by 15.42% and 14.28% under SSP2-4.5 and SSP5-8.5, respectively, in the 2090s, whereas it remained below the baseline level under the scenarios without CO₂ effects. These findings indicate that rising CO₂ may enhance yield and moderate ET_c increases, thereby providing useful information for regional grain-yield assessment, agricultural water-resource evaluation, and climate-change adaptation planning. Full article

Maize (Zea mays L.), a typical thermophilic crop originating from tropical regions, exhibits an inherent sensitivity to low-temperature stress. Cold stress severely restricts maize seed germination, seedling growth, the physiological metabolism, and the final grain yield, which greatly limits its geographical cultivation range and sustainable industrial development. Elucidating the molecular regulatory mechanisms underlying maize cold tolerance and excavating cold-resistant functional genes are essential for the molecular breeding of cold-tolerant maize varieties and expanding maize planting areas in high-latitude and low-temperature-prone regions. In this study, using the strongly cold-tolerant maize inbred line B144 as the experimental material, we cloned the ZmMAPKKKA gene (NCBI accession: LOC103651289) and systematically screened and verified its cold-stress-specific interacting proteins via multiple molecular biological assays. The full-length coding sequence (CDS) of ZmMAPKKKA is 1134 bp, encoding a 377-amino-acid protein with a predicted molecular weight of 40.37 kDa. The quantitative real-time PCR (qRT-PCR) results demonstrated that the ZmMAPKKKA expression was significantly upregulated by 16.56-fold in maize roots after 12 h of low-temperature treatment, indicating a tissue-specific and robust cold response in root tissues. A total of 25 interacting proteins were identified through yeast two-hybrid screening, among which three stress-responsive proteins, including a protein kinase (LOC100286253), a protein phosphatase 2C (PP2C) (LOC542176), and a NAC transcription factor (LOC118474710), were selected for subsequent verification. The Pull-Down, Co-immunoprecipitation (Co-IP), and bimolecular fluorescence complementation (BiFC) assays consistently confirmed that ZmMAPKKKA specifically interacts with these three proteins both in vitro and in vivo under cold stress conditions. This study is the first to construct a ZmMAPKKKA-centered protein interaction module in the maize mitogen-activated protein kinase (MAPK) cascade under cold stress, establishing a novel kinase–phosphatase–transcription factor regulatory cascade that improves the current understanding of cold signal transduction mechanisms in maize. Homologous genes of ZmMAPKKKA in gramineous crops including rice (Oryza sativa) and sorghum (Sorghum bicolor) have been proven to participate in diverse abiotic stress responses, suggesting the conserved functional roles of MAPKKK family genes across gramineous species. Collectively, our findings provide comprehensive insights into the molecular mechanism of the maize MAPK signaling pathway mediating cold stress adaptation and supply valuable functional gene resources for cold-tolerant maize germplasm innovation and molecular breeding. Full article

To investigate the effects of water-saving irrigation and different straw retention methods on soil CH₄ and N₂O emissions from paddy fields in cold regions and their potential underlying mechanisms, a field experiment was conducted in Qing’an City, Heilongjiang Province. Two water management regimes were set, combined with four straw retention treatments. The static chamber-gas chromatography method was used to monitor CH₄ and N₂O emission fluxes during the entire rice growth period. Meanwhile, soil pH, oxidation–reduction potential (Eh), dissolved oxygen (DO), and dynamic changes in carbon and nitrogen substrates were measured, and the global warming potential (GWP) and greenhouse gas emission intensity (GHGI) were comprehensively evaluated. The results showed that controlled irrigation significantly increased soil dissolved oxygen content and oxidation–reduction potential. Compared with conventional flooding irrigation, total CH₄ emission decreased by more than 50%, while N₂O emission increased by 1.5–2.5 times, exhibiting an obvious divergent correlation with the two gas emission fluxes. Among different straw retention methods, organic fertilizer returning and direct straw returning significantly promoted CH₄ emission by supplying easily decomposable organic carbon. In contrast, biochar, due to its stable carbon structure and favorable pore properties, inhibited CH₄ emission without significantly stimulating N₂O emission. The treatment of controlled irrigation combined with biochar returning (CB) achieved the lowest global warming potential and greenhouse gas emission intensity at 7230.82 kg CO₂-eq/hm² and 0.8054 kg CO₂-eq/kg, respectively, while maintaining high rice yield. Path analysis based on soil physicochemical properties and emission fluxes further revealed that Eh and DO were significantly negatively correlated with CH₄ emission but positively correlated with N₂O emission. Path inference from flux and substrate data indicated that carbon and nitrogen availability were the key factors limiting the denitrification process. In conclusion, the combined application of controlled irrigation and biochar returning can realize the synergistic effect of stable yield and emission reduction in cold-region paddy fields by improving soil aeration and regulating the transformation of carbon and nitrogen substrates, providing a scientific basis for establishing a green and low-carbon rice production technology system for black soil in cold regions. Full article

Ridge tillage (RC) has been proposed as a water-saving irrigation technique to mitigate greenhouse gas (GHG) emissions from paddy fields. To evaluate its effectiveness under cold-region climatic conditions, a two-year field experiment (2023–2024) was conducted in Northeast China. The study assessed the effects of RC on rice yield, methane (CH₄), nitrous oxide (N₂O), and total GHG emissions (expressed as CO₂e). A no-puddling treatment (NP) was additionally included in 2024. The results showed that compared to conventional cultivation (CK), RC significantly increased the number of effective panicles in 2023 (p < 0.05) but did not significantly affect yield in either year. CH₄ emissions exhibited a double-peak pattern, with peaks at the heading and grain-filling stages; the heading stage contributed the largest part (53.1–69.0%). N₂O emissions showed no distinct seasonal pattern, although N fertilization events stimulated N₂O peak. RC consistently reduced CH₄ emissions, with reductions of 50.8% in 2023 and 71.0% in 2024. NP in 2024 reduced CH₄ emissions by 27.0%. N₂O emissions showed no significant differences among treatments; however, their contribution from fertilization events varied with treatment and year. Total GHG was dominated by CH₄ (>99%). RC significantly lowered GHG and GHGI by 50.7–70.1% and 57.9–73.2% compared to CK, respectively. In conclusion, ridge tillage is an effective practice to reduce CH₄ and GHG emissions while maintaining rice yield in cold-region paddy fields. The large inter-annual variability strongly affects baseline emissions and underscores the needs for multi-year assessments. Full article

Non-flooding irrigation is widely promoted as a carbon–water co-benefit strategy in paddy rice, but field-scale trials overlook return flow compensation within irrigation districts and therefore overstate water-saving potential. To reconcile this scale mismatch, we developed a semi-distributed multi-scale water balance model coupled with a carbon footprint and full-component blue–green–grey water footprint framework and applied it across field, district, and provincial scales in Heilongjiang Province—a leading cold-region japonica rice region in Northeast China—using the Qinglongshan Irrigation District on the Sanjiang Plain as the focal case, supported by two growing seasons of field observations and 35 years of provincial records. Under alternate wetting and drying, apparent field-level water savings of 50–60% converge to 33% after return flow correction, implying that field-based indicators overestimate savings by 40–50%. Carbon mitigation is decoupled from water volume: CH₄ suppression dominates total abatement and is governed by drying frequency rather than water saved. At the provincial scale, the water footprint has shifted from grey- to blue-water dominance, suggesting that blue-water efficiency now represents a principal remaining lever for further cold-region carbon–water co-benefits. Two-season coverage and fixed parameter assumptions affect magnitudes but not directions. Water-saving irrigation in cold-region paddy systems should therefore be evaluated at the district scale where data permit, rather than relying solely on field-scale indicators. Full article

Osmotic stress limits rice productivity, yet the crosstalk between hydrogen sulfide signaling and redox regulation remains incompletely understood. We previously showed that redox-dependent oligomerization of the basic (region) leucine zippers transcription factor bZIP68 at Cys245 confers osmotic tolerance. However, the role of an adjacent cysteine, Cys171, was undefined. Here, we demonstrate that osmotic stress induces persulfidation of bZIP68 specifically at Cys171. This modification facilitates Cys245-mediated oxidation-dependent oligomerization, thereby enhancing bZIP68 transcriptional activity toward COLD-REGULATED413-THYLAKOID MEMBRANE1 (COR413-TM1). Transgenic complementation and physiological assays confirmed that Cys171 persulfidation is essential for full bZIP68 function in osmotic adaptation. Transcriptomic analysis further revealed that Cys171 is required for bZIP68-driven transcriptional reprogramming under stress. Our findings establish a hierarchical redox cascade wherein persulfidation primes bZIP68 for oxidative activation, highlighting a regulatory crosstalk between distinct post-translational modifications. These mechanistic insights expand our understanding of H₂S signaling and identify the bZIP68 cysteine network as a potential target for improving crop stress resilience. Full article

Low temperature during grain filling is a major constraint affecting rice quality in cold regions. This study investigated how low temperature influences rice quality and starch characteristics at different periods of the grain-filling stage using two Japonica rice cultivars, Kenjing 7 (KJ7, moderate stress tolerance) and Kenjing 8 (KJ8, strong stress tolerance). Low-temperature treatments (17/13 °C, day/night) were applied during the early (5–11 days after anthesis), middle (12–18 days), and late (19–25 days) grain-filling stages and milling, appearance, nutritional, eating and cooking qualities as well as starch physicochemical properties were evaluated. Responses differed markedly between cultivars and treatment periods. Under low-temperature conditions, brown rice and milled rice rates of KJ8 increased during the early and middle grain-filling stages, whereas those of KJ7 declined during the late stage. Low-temperature stress increased protein, total starch, and amylose contents, while reducing gel consistency and the taste value of KJ7. Grain chalkiness increased significantly during the late stage, whereas during the early and middle stages, grain chalkiness, peak viscosity, and breakdown decreased and setback increased. Low temperature increased starch granule size and the proportions of short and intermediate chains of amylopectin, reduced medium-long and long chain and relative crystallinity, without altering starch crystalline type, and produced uneven starch particle surfaces with small pores. These effects were most pronounced during the late grain-filling stage. Overall, low temperature altered starch content and structure, thereby modifying pasting properties and ultimately leading to differences in rice quality. Full article

Optimizing nitrogen (N) fertilizer application within conventional rice production systems remains essential for improving grain quality while avoiding inefficient resource use. This study examined how different N application levels influence rice quality, starch structure, and physicochemical properties in two japonica rice types cultivated under cold-region conditions in Northeast China. Using two cultivars, common japonica rice ‘Putian 1498’ and glutinous japonica rice ‘Longjing 57’, four nitrogen levels were established under machine-transplanting conditions: N0 (0 kg/hm²), N1 (80 kg/hm²), N2 (135 kg/hm²), and N3 (190 kg/hm²). The results indicate that increasing nitrogen application differentially affected the milling quality of the two rice types: it reached its maximum at the N1 level for common japonica rice and at the N3 level for glutinous japonica rice. However, the taste value decreased and chalkiness increased in both types. Regarding starch properties, increased nitrogen application led to rougher starch granule surfaces, a decrease in large granules, and an increase in medium and small granules. Starch content decreased, and the amylose-to-amylopectin ratio declined. Relative crystallinity increased, while the FTIR ratio of 1045/1022 cm⁻¹ decreased. Solubility showed an increasing trend, whereas swelling power exhibited the opposite trend. The gelatinization enthalpy and pasting temperatures were positively correlated with nitrogen rate, whereas retrogradation degree showed a negative correlation. These results demonstrate that nitrogen application regulates rice quality through changes in starch structure and physicochemical properties, with distinct responses between common and glutinous japonica rice. Moderate nitrogen input improves milling quality, but excessive application reduces eating quality, indicating a trade-off between processing performance and consumer-oriented quality. This study provides mechanistic evidence to support more precise nitrogen management in conventional rice systems, contributing to improved resource-use efficiency without overstating broader sustainability claims. In conclusion, moderate nitrogen application optimizes rice quality by balancing milling performance and eating quality through its effects on starch structure, whereas excessive nitrogen input leads to quality deterioration and inefficient resource use. Full article

Heilongjiang Province is China’s largest commercial grain-producing base, meaning that understanding the stability and climatic sensitivity of its major crops are essential for national food security. Using statistical and meteorological data from 2004 to 2023, this study systematically examines the impacts of climate change on cropping structure, yield dynamics, and production stability. The results show that over two decades the total grain crops-sown area and the yield per unit area increased by 79.4% and 38.4%, respectively. The cropping pattern shifted from a diversified structure to a maize-soybean-rice dominated pattern, while the wheat area declined by 92.2%. Additionally, mean and extreme yield fluctuations decreased by 52.3% and 42%, respectively. Rice exhibited the highest yield stability, whereas maize and soybeans experienced marked reductions in interannual variability. Spatial analysis identified Harbin and Daqing as hotspots for yield stability risk, characterized by higher yield standard deviations relative to other cities in the province. Climate elasticity analysis revealed that soybeans and rice were sensitive to warming, while wheat responded positively to increased rainfall. Overall, Heilongjiang’s grain production system has expanded and become more stable at the provincial scale, but it remains vulnerable to emerging climatic risks. Strengthening climate adaptation through crop-specific management, varietal improvement, and field water regulation is vital for enhancing system resilience and sustaining food production in cold-region agroecosystems. Full article

Climate change poses significant challenges to global agricultural systems, exerting profound impacts on crop yields and water resource management, which are particularly pronounced in cold-region rice-growing systems. This study employed the AquaCrop model to assess the spatiotemporal distribution characteristics of rice yield, crop water requirement (ET_c), irrigation water requirement (Ir), and water use efficiency (WUE) in Heilongjiang Province under the RCP4.5 and RCP8.5 scenarios from 2021 to 2080. The results indicate that the average rice yield in Heilongjiang Province will increase by approximately 2% to 5%, with more significant gains observed in the western and southern regions. However, climate warming will cause ET_c to increase by 3–7%, leading to a rise in Ir of about 5–12%, which is particularly pronounced under the RCP8.5 scenario. Compared to RCP4.5, the yield under RCP8.5 will increase by 1–2%, but the increase in Ir will be more significant. Despite these changes, WUE remains within a relatively constrained range (approximately 1.55~1.75 kg·m⁻³), as yield increases are largely offset by corresponding rises in ET_c. Overall, the findings reveal a pronounced yield–water trade-off in cold-region rice systems under future climate scenarios, indicating that yield gains may be accompanied by heightened Ir. Full article

Two-line hybrid rice breeding relies on photoperiod-/thermosensitive genic male sterile (P/TGMS) lines with reliable fertility transition across different environments. The fertility of japonica P/TGMS lines is intricately regulated by photoperiod and temperature, making it more challenging to breed japonica sterile lines with stable sterility than indica sterile lines. This complexity is one of the primary reasons the breeding and promotion of two-line japonica hybrid rice has lagged behind that of indica hybrid rice. Here, we report on Yun1032S, a novel japonica P/TGMS line bred in the low-latitude plateau. It was bred by crossing Peiai 64S, the famous P/TGMS line with the largest application area in China, with Yungengyou 1, a plateau japonica variety noted for its excellent cold tolerance and disease resistance. Yun1032S exhibited stable sterility and female-parent traits favorable for two-line seed production. The elite combination YLY7706 (Yunliangyou7706), derived from a cross between Yun1032S and Yungenghui7501, showed a stable and competitive yield and strong disease resistance in the 2022–2023 Yunnan provincial regional trials. To analyze the genetic basis of phenotypes, we performed whole-genome resequencing and functional loci analysis of the parents and found that they carry a great number of superior alleles, which account for their yield and disease-resistant performance. To assess the breeding value of Yun1032S, we analyzed heterosis of a new batch of combinations derived from Yun1032S and identified a new combination, Jian3, with greater yield potential than YLY7706. These findings not only enhance the breeding of japonica P/TGMS lines but also provide direction for future pairing of two-line hybrid combination breeding. The study presents innovative concepts that further integrate genomics with traditional breeding techniques. Ultimately, Yun1032S marks a significant milestone in japonica P/TGMS line breeding technology, opening new avenues for the development of the two-line system. Full article

Precise timing of rice harvesting is critical for ensuring grain yield and quality. Traditional manual evaluation methods are highly subjective and time-consuming, highlighting the critical demand for rapid, non-destructive approaches to estimate rice maturity. This study focused on cold-region japonica rice grown in Heilongjiang Province, aiming to develop and validate dual-scale (pot and field) maturity estimation models. For model development, canopy spectral data were collected using two complementary acquisition tools: a ground-based active sensor (CGMD402) and UAV-borne multispectral imagery. Four modeling algorithms—Linear Regression (LR), Decision Tree (DT), Random Forest (RF), and Support Vector Machine (SVM)—were utilized, with input variables comprising single spectral indices (Normalized Difference Vegetation Index, NDVI; Ratio Vegetation Index, RVI) and composite spectral indices (Normalized Difference Maturity Ratio Vegetation Index, NDMRVI; Normalized Difference Pigment Ratio Vegetation Index, NDPRVI). At the pot scale, composite spectral indices showed stronger correlations with rice maturity than single indices. Among the four algorithms, the DT model with combined NDVI + RVI input yielded the optimal comprehensive performance, with a coefficient of determination (R²) of 0.957, a root mean square error (RMSE) of 0.064, and a relative error (RE) of 4.8% in the test set. At the field scale, NDVI and RVI both exhibited strong negative correlations with maturity (Spearman’s correlation coefficients of −0.76 and −0.79, respectively). While the RF model performed best in the training set (R² = 0.752), it was prone to overfitting; in contrast, Multiple Linear Regression (MLR, Ridge Regression) with NDVI + RVI combination demonstrated greater stability in the test set (R² = 0.515, RMSE = 0.116). Notably, composite spectral indices consistently outperformed single indices across all modeling algorithms, but their accuracy was comparable to the optimal single index combination model. To tackle the challenge of scaling models from pot to field conditions, this research developed a “modeling–validation–evaluation–scaling” framework and a four-indicator combined judgment criterion (ΔR²–ΔRMSE–ΔRE–SF). Quantitative analysis showed that the optimal pot-scale model suffered significant accuracy loss during cross-scale transfer: ΔR² = 0.447, ΔRMSE = 0.120, ΔRE = 22.84%, and Scale Transfer Factor (SF) = 2.875. A “regional calibration + residual correction” scheme was proposed, which is expected to reduce the transferred RMSE to below 0.12 and SF to 1.8–2.0. Overall, this research offers a reliable technical method for large-scale, non-destructive monitoring of rice maturity, which can facilitate data-driven precision harvesting decisions. Full article

Isopentenyltransferase (IPT) is the rate-limiting enzyme in cytokinin biosynthesis and plays a critical role in plant acclimation to abiotic stress. To explore soybean IPT genes, we performed genome-wide identification, bioinformatics analysis, and molecular experimental validation to systematically characterize the features and functions of the soybean IPT (GmIPT) gene family. We identified 15 GmIPT genes in the soybean genome, which are unevenly distributed across 12 chromosomes; their evolutionary expansion is primarily driven by whole-genome duplication events. Phylogenetic analysis of soybean IPT proteins with those from Arabidopsis, rice and maize clustered them into four groups, exhibiting lineage-specific functional specialization. GmIPT genes exhibit significant variations in conserved motifs, gene structure, and cis-acting elements; their promoter regions are enriched in light-responsive, abiotic stress-responsive, and hormone-responsive elements, indicating their involvement in complex transcriptional regulatory networks. Tissue expression profiling revealed that GmIPT7 and GmIPT10 are highly expressed in various tissues, whereas GmIPT14 shows specific expression in flowers and the shoot apical meristem. Transcriptomic analysis and qRT-PCR validation demonstrated that GmIPT7, GmIPT10 and GmIPT15 respond differentially to drought, salt and low-temperature stress, with GmIPT15 exhibiting a transient upregulation at 3 h (p < 0.01) followed by a gradual decline to levels close to the pre-treatment control at 6–12 h under low-temperature stress. We further performed haplotype analysis of GmIPT15 and identified a putative elite haplotype (hap1) associated with cold tolerance based on low-temperature germination index assessment. This study provides useful insights for the future functional characterization of plant IPT genes and offers potential genetic resources and molecular markers that may support molecular-assisted breeding for soybean abiotic stress tolerance. Full article

Cold stress poses a major threat to rice productivity and grain quality. WRKY transcription factors, one of the largest plant-specific gene families, play crucial roles in plant responses to abiotic stress. However, their functions in cold responses and the evolutionary mechanisms underlying cold adaptation during the long-term domestication of cultivated rice remain poorly understood. Here, we identified OsWRKY26 as an important regulator of cold adaptation in japonica subspecies through transcriptome sequencing (RNA-seq). Subcellular localization analysis showed that the OsWRKY26 protein is localized to the nucleus under both normal and cold-stress conditions. Expression analysis indicated that OsWRKY26 is significantly upregulated at low temperature. Moreover, transgenic validation and measurements of multiple physiological traits demonstrated that OsWRKY26 positively regulates seedling cold tolerance in rice. Evolutionary analyses of OsWRKY26 and OsMYB2, a previously reported positive regulator of rice cold tolerance, suggested that these two genes diverged in wild rice and subsequently experienced directional selection in temperate japonica cultivated in high-altitude and high-latitude regions. Together, these findings provide a theoretical foundation for dissecting cold-tolerance mechanisms in rice, as well as promising genetic resources for molecular breeding in low-temperature environments. Full article

Large quantities of agricultural waste, particularly rice husk ash (RHA), are generated worldwide each year, and the lack of rational, value-added disposal pathways poses both environmental and resource-utilization challenges. To address this practical problem while improving the freeze–thaw (F–T) durability of cement-based materials in cold regions, this study investigates the effects of replacing silica fume (SF) with finely milled RHA on the hydration behavior, mechanical performance, and durability of cement mortar. From a scientific perspective, the freeze–thaw behavior of RHA-modified cementitious materials and the underlying relationships among hydration kinetics, microstructural evolution, and durability remain insufficiently understood. Mortars with different RHA–SF blending ratios were prepared at a constant water-to-binder ratio. Compressive strength was measured before and after F–T cycling, and the underlying mechanisms were investigated using isothermal calorimetry, water absorption tests, and scanning electron microscopy. Results show that SF significantly enhances pre-F–T compressive strength, with the SF-only mixture reaching 56.8 MPa at 28 d, approximately 28.7% higher than the control. With increasing RHA replacement, pre-F–T strength decreased with a non-monotonic variation (40.1–51.5 MPa). F–T cycling caused severe degradation in the reference mortar, with a strength loss rate of 31.75%, whereas RHA- or SF-modified mortars exhibited substantially lower loss rates (6.30–21.54%). Notably, high-RHA mixtures retained residual strengths of 36.0–38.3 MPa after F–T cycling. Although RHA delayed early hydration and increased water absorption, freeze–thaw resistance was not proportionally reduced. These results demonstrate that freeze–thaw durability is governed primarily by long-term microstructural stability rather than early-age strength, and they provide mechanistic evidence supporting the rational utilization of finely milled RHA as a low-carbon supplementary cementitious material for cold-region applications. Full article