Current Issue

10 November 2025, Volume 39 Issue 6 Previous Issue   
---
Reviews and Special Topics
Research Papers


For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

Reviews and Special Topics

Select

Plant Prime Editing: A New Direction in Crop Breeding SONG Anqi, WU Songquan, MA Qiuyue, BAN Wanning, LIU Xiangguo, JIN Yongmei 2025, 39(6): 711-730.  DOI: 10.16819/j.1001-7216.2025.241005 Abstract ( )   HTML ( )   PDF (2292KB) ( )   Plant Prime Editing (PPE) provides a novel approach for precise genome modification in plants, overcoming the limitations of conventional gene editing methods that rely on double-strand breaks and exogenous donor DNA. It enables not only arbitrary base substitutions, but also precise insertions and deletions of small to large DNA fragments, with reduced off-target effects. This review systematically summarizes the latest research advances in PPE technology globally, including its development history and working mechanism, applications in crop breeding and trait improvement, and representative cases. It also discusses the expansion of prime editing into large-scale genome editing and multiplex gene editing. To address the bottlenecks faced by PPE systems in plant genetic transformation, several potential solutions are proposed. Finally, the broad application prospects of PPE technology in plant genetic improvement and its potential integration with artificial intelligence (AI) in future research are outlined.

Select

Flowering Habits of Rice and Its Application in Breeding japonica Cytoplasmic Male Sterile Lines CHEN Ling, LIN Wenying, LIANG Limei, OUYANG Younan, YE Shenghai, JI Zhijuan 2025, 39(6): 731-743.  DOI: 10.16819/j.1001-7216.2025.241120 Abstract ( )   HTML ( )   PDF (1296KB) ( )   The utilization of heterosis has significantly increased the yield of rice. Hybridization between indica and japonica subspecies exhibits stronger heterosis due to their distant genetic relationships. Consequently, indica-japonica hybrid rice has greater yield potential. Inter-subspecies hybridization between indica and japonica is an important way to enhance rice yields. Currently, indica-japonica hybrid rice mainly refers to the combinations derived from crossing a japonica cytoplasmic male sterility (CMS) line with an indica restorer line. These combinations have received widespread attention in production because of their vigorous growth, ideal plant architecture, resistance to premature senescence, and super high yield advantages. However, the japonica CMS line is characterized by its flowering habits, such as low stigma exsertion rate and late flowering time. These habits lead to asynchronous flowering time between the indica and japonica parental lines and low outcrossing rates in the seed production process. Thus, the yield of seed production is low and unstable, which limits further application of indica-japonica hybrid rice. In this work, we review the influencing factors and genetic mechanisms of rice flowering habits. We also summarize and analyze the application research on these mechanisms in japonica CMS lines. This review provides a reference for promoting the breeding, production, and application of indica-japonica hybrid rice and the sustainable development of hybrid rice.

Select

Research Progress on Biological Functions of Ubiquitin-conjugating Enzymes in Rice WANG Juan, WU Lijuan, HONG Haibo, YAO Zhiwen, WANG Lei, E Zhiguo 2025, 39(6): 744-750.  DOI: 10.16819/j.1001-7216.2025.250316 Abstract ( )   HTML ( )   PDF (794KB) ( )   Ubiquitination is a critical post-translational modification, accounting for 80%-85% of protein degradation in eukaryotes. It regulates protein activity, localization, and function, thereby playing extensive roles in modulating diverse biological processes. The ubiquitin-conjugating enzyme E2, the second key enzyme in the ubiquitination cascade, acts not only as a ubiquitin carrier but also determines the type of ubiquitin linkages and the length of ubiquitin chains. A total of 48 E2 genes have been identified in rice, all encoding proteins that contain a highly conserved UBC (ubiquitin-conjugating) domain. This domain binds to ubiquitin via a thioester bond and forms a specific interaction interface with ubiquitin ligase E3, ensuring the precision of ubiquitin transfer. Studies have shown that E2 enzymes are widely involved in regulating rice growth and development, as well as responses to biotic stresses such as pathogen infection and abiotic stresses including drought and cold.

Research Papers

Select

Cloning of Cold6 Conferring Cold Tolerance in Rice TAO Shibo, XU Na, XU Zhengjin, LIU Chang, XU Quan 2025, 39(6): 751-759.  DOI: 10.16819/j.1001-7216.2025.240709 Abstract ( )   HTML ( )   PDF (1726KB) ( )   【Objective】 Exploring cold-tolerant germplasm and identifying cold-tolerant genes are essential strategies to mitigate cold stress in rice. 【Method】 We treated the japonica rice variety Sasanishiki with ethyl methanesulfonate (EMS) to select mutants exhibiting enhanced cold tolerance at the seed germination stage. Candidate genes underwent cloning and functional analysis using fine mapping, CRISPR/Cas9 gene editing, expression profiling, and haplotype analysis. 【Result】 We identified the mutant M34, which displayed markedly improved cold tolerance at the seed germination stage. Genetic analysis suggested that a single recessive gene governs this trait. Fine mapping pinpointed Cold6 as the target gene. CRISPR/Cas9-mediated knockout of Cold6 confirmed its role in regulating cold tolerance during germination. Cold6 expression was observed in all rice organs, peaking in the panicles, and it encodes a protein containing several functional domains, including SNF2. Evolutionary analysis indicated differentiation of Cold6 between indica and japonica varieties, with haplotype analysis revealing 10 distinct Cold6 haplotypes. The predominant haplotypes are I-III; haplotype I is prevalent in japonica rice, whereas II and III are common in indica rice. 【Conclusion】 This study identified Cold6 as a novel regulator of cold tolerance in rice at the seed germination stage, encoding an SNF2 protein. Investigating the molecular mechanism of Cold6 enhances our understanding of the SNF2 gene family's role in rice, offering a theoretical foundation and germplasm resources for breeding cold-tolerant, high-yield northern japonica rice.

Select

Modifying Heading Date of Nanjing 46 via CRISPR/Cas9-mediated Genome Editing CHEN Wei, YE Yuanmei, ZHAO Jianhua, FENG Zhiming, CHEN Zongxiang, HU Keming, ZUO Shimin 2025, 39(6): 760-770.  DOI: 10.16819/j.1001-7216.2025.240707 Abstract ( )   HTML ( )   PDF (2072KB) ( )   【Objective】 Heading date is a key agronomic trait determining the regional and ecological adaptation of rice cultivars. We edited the heading date genes of the medium-maturing late japonica rice variety Nanjing 46 (NJ46) with excellent tasting to shorten its heading date thereby potentially expanding its planting area.【Method】 Using CRISPR/Cas9 technology, the editing constructs, pCAMBIA1305-Actin:Cas9-sgRNADTH8 and pCAMBIA1305-Actin:Cas9-sgRNAGhd2 targeting DTH8 and Ghd2, respectively, were developed and transformed into NJ46 via Agrobacterium-mediated transformation. Homozygous editing lines without exogenous components were screened and evaluated on heading date, agronomic traits and quality-related traits. 【Result】 Three homozygous mutant lines were obtained. The NJ46-dth8 lines (NJ46-dth8-1 to -3) presented 22-36 days earlier than NJ46 on heading date, while the NJ46-ghd2 lines (NJ46-ghd2-1 to -3) showed 14-15 days earlier. The heading date, major agronomic traits, and quality related components of the homozygous mutant lines were evaluated in different areas of central and northern regions of Jiangsu Province, and compared with the widely cultivated varieties Nanjing 9108 and Nanjing 518 in their respectively ecological zones. NJ46-ghd2-1 exhibited a significantly higher yield per plant than Nanjing 9108, while showing comparable heading date and quality traits, and performed better than the other two knockout lines. NJ46-dth8-1 showed no significant differences from Nanjing 518 in yield per plant and major quality traits, and performed better than the other two knockout lines.【Conclusion】 Knockout of DTH8 and Ghd2 genes in NJ46 yielded new germplasms suitable for planting in the northern and central region of Jiangsu Province, respectively, which will help expand the planting area of this excellent-tasting rice variety.

Select

Regulation of Amylose Content in Rice by Editing Wx Using CBE Base Editor CHEN Yuye, JIAO Xiaozhen, WANG Jian, WANG Kejian, CHEN Feng, ZHU Keming, LIU Chaolei 2025, 39(6): 771-778.  DOI: 10.16819/j.1001-7216.2025.240705 Abstract ( )   HTML ( )   PDF (1143KB) ( )   【Objective】 The Wx gene, a key regulator of amylose synthesis in rice, encodes a granule-bound starch synthase and plays a crucial role in determining the amylose content, thereby directly influencing the quality traits of rice. 【Method】 We used the CBE base editor to introduce base substitutions within the first exon of the Wx gene in Shendao18 variety, resulting in two distinct mutation types: GCCCCC→GCCCTT and GCCCCC→GCTCTC. Both mutations led to the substitution of proline with leucine at position 94 of the Wx protein, designated as WxP94L-1 and WxP94L-2 respectively. 【Result】 Field experiments demonstrated that compared to the wild type, both WxP94L-1 and WxP94L-2 plants exhibited no significant differences in plant height, tiller number per plant, panicle length, grain morphology or 1000-grain weight. Rice quality analysis revealed that the amylose content decreased from 14.9% (wild type) to 12.5% (WxP94L-1) and 12.1% (WxP94L-2), while traits such as viscosity, alkali spreading value and protein content showed no significant change compared to the wild type. 【Conclusion】 Our study successfully generated a novel allele of the Wx gene named WxP94L using CBE base editor which resulted in a slight reduction in amylose content; thus providing a way for enhancing rice quality.

Select

Preliminary Analysis of Function and Mechanism of OsRDR5 Gene in Rice HOU Guihua, ZHOU Liguo, LEI Jianguo, CHEN Hong, NIE Yuanyuan 2025, 39(6): 779-788.  DOI: 10.16819/j.1001-7216.2025.250208 Abstract ( )   HTML ( )   PDF (1906KB) ( )   【Objective】 Drought is a major constraint on rice production, and drought avoidance is the most important mechanism for drought resistance of crops. Understanding the mechanism of OsRDR5, a candidate gene of drought tolerance in rice, can provide a theoretical basis for the improvement of drought tolerance in rice.【Method】 The nucleotide sequence, protein domain and phylogenetic relationship of RDR5 were analyzed using the NCBI database. The tissue expression pattern was analyzed by qRT-PCR. An OsRDR5 gene knockout mutant was constructed by the CRISPR/Cas9 system. The effect of OsRDR5 on rice deep root ratio was evaluated by the "basket method".【Result】OsRDR5 has a Coa3_cc domain, belonging to the cytochrome c oxidase assembly factor 3 gene family. OsRDR5 is located in the endoplasmic reticulum and is expressed in roots, stems and leaves of rice. Phenotypic identification of deep root ratio showed that the wild type had a deep root ratio of 53.7%, while the mutant lines had a deep root ratio of 63.3% and 64.9%, respectively. The deep root ratio of the mutant was significantly increased. A total of 1434 differentially expressed genes were identified by root transcriptomic analysis. GO enrichment analysis revealed significant enrichment of these genes in pathways related to drought stress, including response to water deprivation, abscisic acid and reactive oxygen species, among which several NAC genes(OsNAC016, OsNAC45, etc.) related to drought stress were up-regulated in the water deprivation pathway.【Conclusion】OsRDR5 knockout affects the deep root ratio of rice and plays an important role in drought avoidance of rice.

Select

Identification of QTLs for Seed Storability in Dongxiang Wild Rice by Integrating BSA-Seq and QTL Analysis WANG Shilin, WU Ting, ZHOU Shiqi, SONG Siming, HU Biaolin 2025, 39(6): 789-800.  DOI: 10.16819/j.1001-7216.2025.240807 Abstract ( )   HTML ( )   PDF (1690KB) ( )   【Objective】 The storage of rice seeds is crucial for ensuring food security and supporting sustainable agricultural production. Mining more genetic resources associated with seed storability is conducive to laying a genetic foundation for developing new storage-tolerant varieties.【Method】 Using Dongxiang wild rice accession Dongye 80 as the donor and cultivated rice R974 as the recurrent parent, two sets of BC₃F₇ populations—backcross recombinant inbred lines (BILs) consisting of 364 lines and single-segment substitution lines (SSSLs) consisting of 84 lines—were constructed. Germination rates were recorded after artificial aging treatment. QTL mapping and BSA-seq analysis were integrated to identify QTLs for seed storability from Dongxiang wild rice. Candidate genes were further predicted using gene annotation, GO enrichment analysis, and gene sequencing.【Result】 A total of nine QTLs for seed storability were detected on chromosomes 1, 2, 3, 6, 7, 9, and 11 using SSSLs, designated qSS1.1, qSS1.2, qSS2.1, qSS2.2, qSS3, qSS6, qSS7, qSS9.1, and qSS11, with phenotypic variation explained (PVE) ranging from 1.60% to 17.82%. Seven of these QTLs carried favorable alleles from Dongye 80, among which qSS7 and qSS11 were novel. Meanwhile, BSA-seq analysis using BILs identified 37 genomic regions associated with seed storability on chromosomes 2, 4, 5, 6, 7, 8, 9, and 11. The qSS7 interval was consistently detected by both methods and was narrowed down to a 480.1 kb overlapping region. In addition, qSS4 and qSS9.2 were delimited to overlapping regions of 199.7 kb and 177.8 kb, respectively. By integrating annotation information, GO enrichment, and gene sequencing, LOC_Os04g31040 and LOC_Os04g31070, LOC_Os07g07930, and LOC_Os09g15800 and LOC_Os09g15835 were proposed as candidate genes for qSS4, qSS7, and qSS9.2, respectively.【Conclusion】 In this study, nine and 37 QTLs for seed storability were identified by QTL mapping and BSA-seq analysis, respectively. Candidate genes for qSS4, qSS7, and qSS9.2 were further inferred. Notably, the favorable alleles of qSS4 and qSS9.2 from Dongye 80 significantly enhanced seed storability. Analysis of the candidate genes for qSS4 and qSS9.2 provides a foundation for cloning seed storability genes from Dongxiang wild rice and utilizing them in genetic improvement of cultivated rice.

Select

Assembly, Codon Usage Bias, and Phylogenetic Analysis of Chloroplast Genome of Oryza meyeriana LI Rongxin, WANG Bo, XIAO Suqin, YIN Fuyou, ZHANG Jianhong, ZHONG Qiaofang, CHEN Ling, LI Jinlu, YANG Hesheng, CHENG Zaiquan, LIU Li 2025, 39(6): 801-812.  DOI: 10.16819/j.1001-7216.2025.240612 Abstract ( )   HTML ( )   PDF (2031KB) ( )   【Objective】 Oryza meyeriana, which is shade-tolerant and retains many primitive traits, is the only xerophytic type of wild rice in the genus Oryza. This study aims to enrich the genetic foundation of O. meyeriana and provide reference for vector construction of its superior genes. 【Methods】 The chloroplast genome of Yunnan O. meyeriana was sequenced using second-generation sequencing technology, followed by assembly and annotation. Codon usage bias and phylogenetic relationships were analyzed with RStudio and MEGA. 【Results】 The results showed that the total length of the chloroplast genome was 135,937 bp, with a GC content of 39.0%. The average effective number of codons(ENC) value was 48.09, indicating weak codon usage bias. ENC-plot, PR2-plot, and neutral plot analyses revealed that selection pressure plays a major role in shaping the chloroplast codon usage bias in Oryza meyeriana, and that this bias mainly regulates genes involved in self-replication and the photosynthetic system. A total of 16 optimal codons were identified, among which 14 ended with A/U and 2 ended with G/C. Phylogenetic analysis based on the chloroplast genome showed that Oryza meyeriana is closely related to O. brachyantha.【Conclusion】 This study enriches our understanding of the genomic composition and genetic information of Oryza meyeriana. The findings provide a basis for mining favorable genes related to photosynthesis and for investigating the evolution of wild rice species.

Select

Identification and Gene Cloning of a Long Sterile Lemma and Small Grain Mutant lsg8 in Rice (Oryza sativa L.) LU Shuai, TAO Tao, LIU Ran, ZHOU Wenyu, CAO Lei, YANG Qingqing, ZHANG Mingqiu, REN Xinzhe, YANG Zhidi, XU Fuxiang, HUAN Haidong, GONG Yuanhang, ZHANG Haocheng, JIN Sukui, CAI Xiuling, GAO Jiping, LENG Yujia 2025, 39(6): 813-824.  DOI: 10.16819/j.1001-7216.2025.241003 Abstract ( )   HTML ( )   PDF (1444KB) ( )   【Objective】 The aim of this study was to identify and clone a gene responsible for long sterile lemma and small grain size in rice, and to explore the genetic basis and molecular mechanism controlling these traits. 【Method】 A stably inherited mutant displaying long sterile lemmata and small grains was obtained from the japonica rice WYJ27 through ethyl methanesulfonate (EMS) mutagenesis. This mutant was named as lsg8 (long sterile lemma and small grain on chromosome 8). The agronomic traits of both the wild-type and the mutant were observed and recorded. The epidermal cells of the glume were observed using scanning electron microscopy (SEM). An F2 segregating population was generated by crossing lsg8 with the indica rice variety IR36, and used for genetic analysis and gene mapping. Candidate genes were further identified through gene sequencing and expression analysis. RT-qPCR was performed to analyze the relative expression levels of genes regulating cell expansion and floral development. 【Result】 Compared with the wild type, the mutant lsg8 exhibited a significantly longer sterile lemma, significantly decreased grain width and grain thickness, and consequently a reduced 1000-grain weight. In addition, the plant height, panicle length, the length of the first, second, and fourth internodes from the top, the number of primary branches, the number of secondary branches, the number of grains per panicle, and the seed setting rate of lsg8 were significantly lower than those of the wild type WYJ27. SEM observation of the outer epidermis of the glume showed that the cell length and width of the mutant lsg8 were significantly shorter and narrower than those of the wild type. Genetic analysis suggested that the mutant phenotype is controlled by a single recessive nuclear gene. Through map-based cloning, the LSG8 gene was mapped to a region between markers M5 and M6 on chromosome 8. The physical distance between these two markers is approximately 276 kb, containing 42 open reading frames (ORFs). Sequencing analysis revealed a single nucleotide difference in ORF18 (LOC_Os08g06480) between the wild type and the lsg8 mutant, indicating that ORF18 is likely the candidate gene controlling the long sterile lemma and small grain phenotype. RT-qPCR analysis revealed that LSG8 is expressed in various tissues at different developmental stages, with the highest expression in panicles at the mature stage and the lowest in leaf sheaths at the mature stage. Furthermore, significant alterations were observed in the relative expression levels of genes related to cell expansion, sterile lemma development, and floral organ identity in the lsg8 mutant. 【Conclusion】 The lsg8 mutant is a new allele of the previously reported ASP1 gene. The mutation in OsLSG8 results in a long sterile lemma and small grain phenotype, playing an important role in maintaining the morphogenesis of rice sterile lemma and grain morphology.

Select

Mapping Analysis of a New Bacterial Blight Resistance Gene Xa49(t) in Rice DENG Huan, LIU Yapei, WANG Chunlian, GUO Wei, CHEN Xifeng, JI Zhiyuan 2025, 39(6): 825-831.  DOI: 10.16819/j.1001-7216.2025.240302 Abstract ( )   HTML ( )   PDF (1308KB) ( )   【Objective】 Bacterial blight (BB) is one of the most serious diseases in rice. Breeding and planting resistant varieties is the most efficient strategy for disease control, and exploring resistance (R) genes is key to developing BB-resistant varieties. 【Method】 Wild rice provides valuable genetic resources for rice breeding. In this study, an introgression line, W6023, derived from a cross between Oryza rufipogon and Oryza sativa (IR24), was used. Genetic and resistance spectrum analyses revealed that W6023 carries a novel dominant BB R gene, tentatively named Xa49(t). An F₂ segregating population from IR24 × W6023 was constructed, and bulk segregant analysis (BSA) combined with newly designed InDel and SNP markers was applied for preliminary mapping of the target gene Xa49(t). 【Result】 Thirteen molecular markers linked to Xa49(t) were identified on chromosome 11, and the gene was ultimately delimited to a region between markers D11-111 and D11-241. 【Conclusion】 The novel broad-spectrum BB R gene Xa49(t) was preliminarily mapped to an approximately 968 kb region on rice chromosome 11.

Select

Quality Traits Affecting Eating Quality in indica Rice Under Different Nitrogen Application Levels in Early and Late Seasons in South China ZHANG Lanlan, LIU Dilin, MA Xiaozhi, HUO Xing, KONG Le, LI Jinhua, FU Chongyun, LIAO Yilong, ZHU Manshan, ZENG Xueqin, LIU Wuge, WANG Feng 2025, 39(6): 832-746.  DOI: 10.16819/j.1001-7216.2025.240203 Abstract ( )   HTML ( )   PDF (2179KB) ( )   【Objective】 The taste of cooked rice is the most critical factor determining grain quality, which is influenced not only by the genetic background of variety but also by environmental factors such as fertilizer application rate and growing season. Systematically investigating the relationship between rice taste and other quality traits—including appearance, processing, cooking, and nutritional properties—under different nitrogen application levels and planting seasons can provide an important scientific reference for breeding new rice varieties with good taste under various production conditions. 【Method】 In 2021, 17 types of rice varieties (lines) from South China were used as test materials. Four nitrogen application treatments were applied: 0 kg/hm² (N0), 90 kg/hm² (N1), 135 kg/hm² (N2), and 180 kg/hm² (N3), in a field in both early and late seasons in Guangzhou City, Guangdong Province. Three-way ANOVA, stepwise multiple regression analysis, and path analysis were used to explore the relationship between rice taste and other major quality traits related to appearance, processing, cooking, and nutrition. 【Result】 The results showed that: (1) Chalky grain rate (CGR), chalkiness degree (CD), gel consistency (GC), and protein content (PC) were simultaneously influenced by seven factors: season, nitrogen application rate, variety, the interaction between growing season and nitrogen level, the interaction between season and variety, and the three-way interaction among growing season, nitrogen level and variety. These are the most unstable traits. In contrast, alkali spreading value (ASV) was significantly influenced only by growing season and variety, making it the most stable trait. The other six traits—brown rice rate (BRR), milled rice rate (MRR), length-to-width ratio (LWR), transparency (TR), and amylose content (AC)—exhibited moderate instability. (2) A total of 11 quality traits significantly affecting the taste value (TV) of cooked rice were identified across different nitrogen treatments in both early and late seasons. Among them, AC and PC were consistently detected in both seasons and in the comprehensive combined analysis, both exerting negative effects on TV. MRR, CGR, CD, TR and GC were repeatedly detected in the late season and in the combined analysis. BRR, head rice recovery (HRR), and ASV were only detected under the N0 treatment in the late season and in the combined analysis, respectively, while LWR was only identified in the combined analysis. (3) Among the 11 traits significantly influencing TV, only GC and LWR showed positive direct path coefficients and overall effects, indicating a positive regulatory role on TV. Although ASV and BRR exhibited positive direct path coefficients toward TV, their overall effects were negative, implying a net negative regulatory role. The other seven traits all functioned as negative regulators of TV. 【Conclusion】 Based on the magnitude and direction of the effects of these quality traits on TV, the target profile for developing new high-taste indica rice varieties should include: LWR ≥ 3.5, HRR ≥ 58%, TR = Grade 1, CGR ≤ 10%, CD ≤ 1%, AC = 13%-17%, ASV ≥ Grade 6.0, GC ≥ 60 mm, and PC of polished rice ≤ 6.4%

Select

Effect of Application Methods of Mixed Controlled-release Nitrogen Fertilizer on Yield and Nitrogen Utilization of Good Taste Quality japonica Rice Under Different Mechanical Transplanting Methods in the Huaibei Region BIAN Jinlong, REN Gaolei, QIU Shi, XU Fangfu, HU Zhonglei, ZHANG Hongcheng, WEI Haiyan 2025, 39(6): 847-862.  DOI: 10.16819/j.1001-7216.2025.250811 Abstract ( )   HTML ( )   PDF (2521KB) ( )   【Objective】 This experiment was conducted to clarify the effects of application methods of mixed controlled-release nitrogen fertilizer on the yield and nitrogen utilization of good-eating quality japonica rice under different mechanical transplanting methods in Huaibei region, aiming to screen the optimal mixed controlled-release nitrogen fertilizer treatment that matches the nutrient absorption of good-eating quality japonica rice, and to provide a scientific basis for its high-yield, high-quality and simplified cultivation.【Method】 In this experiment, two good-eating quality japonica rice varieties, Xudao 9 and Nanjing 5718, were used as materials to study the effects on yield, population quality indices and characteristics of nitrogen absorption and utilization under different treatments. Controlled-release fertilizer and quick-acting nitrogen fertilizer were mixed at a ratio of 5:5. The controlled-release fertilizer was blended from fertilizers with four different release periods (40, 60, 80, and 100 d) at a ratio of 1:4 to form three mixing modes, designated as N1 (40+60), N2 (40+80), and N3 (40+100). Conventional urea split application (CK) was used as a control. 【Result】 (1) Under different mechanical transplanting methods, the N2 treatment achieved the highest yield. The increase in yield was mainly attributed to the significant increase in effective panicle number and total spikelet number. Under the wide-narrow row pot seedling mechanical transplanting method, the average yields of the N2 treatment over two years reached 11.29 t hm⁻² and 11.79 t hm⁻², showing significant increases of 6.01% and 6.89% compared with CK, respectively. Under the equal-row spacing blanket seedling mechanical transplanting method, the average yields of the N2 treatment over two years reached 10.71 t hm⁻² and 11.12 t hm⁻², showing significant increases of 5.05% and 5.30% compared with CK, respectively. (2) Under different mechanical transplanting methods, the average tiller number at maturity in the N2 treatment was significantly increased by 7.30%−10.44% compared with CK, which effectively promoted the formation of high-yield populations. Meanwhile, under the N2 treatment, the leaf area index and leaf photosynthetic potential during the heading-maturity stage were significantly increased by 3.47%−13.25% and 6.53%−7.77% compared with CK, respectively, effectively promoting the formation of high-photosynthetic-efficiency populations. (3) Under different transplanting methods, the partial factor productivity of applied nitrogen and the agronomic nitrogen use efficiency showed the order of N2 > N3 > CK > N1, while the nitrogen uptake efficiency and the nitrogen uptake per 100 kilograms of grain showed the order of N3 > N2 > CK > N1. In the N2 treatment, the partial factor productivity of applied nitrogen, agronomic nitrogen use efficiency, nitrogen uptake efficiency and nitrogen uptake per 100 kilograms of grain were 5.13%−6.44%, 12.74%-16.14%, 15.14%-16.62% and 2.35%-2.87% higher than those in CK, respectively. The higher nitrogen utilization rate led to greater dry matter accumulation in the population under the N2 treatment. Under the wide-narrow row pot seedling mechanical transplanting method, the average dry matter accumulation during the jointing-heading stage and the heading-maturity stage in the N2 treatment was higher than that in CK by 3.11% and 3.23%, and 6.85% and 11.62%, respectively, over the two years; under the equal-row spacing blanket seedling mechanical transplanting method, the average dry matter accumulation during the jointing-heading stage and the heading-maturity stage in the N2 treatment was higher than that in CK by 2.80% and 2.45%, and 5.61% and 9.23%, respectively, over the two years. 【Conclusion】 Under both wide-narrow row pot seedling mechanical transplanting and equal-row spacing blanket seedling mechanical transplanting methods, the one-time basal application of the N2 mixed controlled-release fertilizer best matched the nutrient absorption of good-eating quality japonica rice in the Huaibei region. It promoted the formation of high-yield and high-efficiency populations, and thus can be regarded as an effective measure for achieving increased yield and efficiency through simplified cultivation of good-eating quality japonica rice in the Huaibei region.

Select

Yield Formation and Photosynthetic Characteristics of Machine-transplanted Late-season Rice with Short Growth Duration LI Xing, ZHANG Ruichun, CHEN Ge, XIE Jiaxin, XIAO Zhengwu, CAO Fangbo, CHEN Jiana, HUANG Min 2025, 39(6): 863-872.  DOI: 10.16819/j.1001-7216.2025.250106 Abstract ( )   HTML ( )   PDF (1399KB) ( )   【Objective】 This study aimed to investigate the high-yield formation and photosynthetic properties of early-season rice varieties used as short growth duration late-season rice under machine-transplanted conditions. The findings are expected to lay a theoretical basis for breeding short growth duration late-season rice varieties and promoting their large-area, high-yield cultivation. 【Method】 Field experiments were conducted from 2021 to 2023 in Yong'an Town, Liuyang City, Hunan Province. Two early-season varieties, Zhongjiazao 17 and Zhongzao 39, which show significant yield differences, were used as experimental materials. Their yield, yield components, dry matter accumulation, leaf photosynthetic characteristics, and canopy structure were measured when grown as short growth duration late-season rice under machine-transplanted conditions. 【Result】 Averaged over the three years, the yield of Zhongzao 39 was 19.76% higher than that of Zhongjiazao 17. In terms of yield components, the 1000-grain weight of Zhongzao 39 was significantly higher (by 7.60%) than that of Zhongjiazao 17. Regarding dry matter production, Zhongzao 39 accumulated 12.24% more of total dry matter than Zhongjiazao 17, mainly due to its stronger pre-heading dry matter production capacity. Zhongzao 39 exhibited stronger early vigor, superior leaf photosynthetic performance at heading, and a better canopy structure during the vegetative growth stage. Specifically, at the heading stage, its net photosynthetic rate, chlorophyll a and b contents, total chlorophyll content, leaf nitrogen content, and specific leaf weight were 10.38% to 29.04% higher than those of Zhongjiazao 17. Furthermore, canopy structure indicators—including pre-heading crop growth rate, leaf area duration, radiation use efficiency, and leaf area index at heading—were 17.80% to 25.95% higher in Zhongzao 39 than those in Zhongjiazao 17. 【Conclusion】 Under machine-transplanted conditions, short growth duration late-season rice varieties characterized by high 1000-grain weight, strong early vigor, and enhanced photosynthetic capacity at the heading stage demonstrate greater yield potential.

Select

Characteristics of Spatiotemporal Evolution of Thermal Resources in Ratoon Rice at Heading and Grain-filling Stages in Sichuan Basin in 1981−2022 LUO Zizi, ZHANG Dejun, CHEN Dongdong, BI Miao, ZHU Yuhan, HAN Xu, WU Qiang, LI Yuechen 2025, 39(6): 873-886.  DOI: 10.16819/j.1001-7216.2025.240614 Abstract ( )   HTML ( )   PDF (3170KB) ( )   【Objective】 This study investigates the dynamic changes of thermal resources during the heading and grain-filling stages of ratoon rice in the Sichuan Basin under climate change, aiming to provide a scientific reference for ensuring the safe production of ratoon rice in the region. 【Method】 Using daily mean temperature data from meteorological stations and observational data on the maturity stage of main-crop rice from agrometeorological stations within the ratoon rice planting area of the Sichuan Basin from 1981 to 2022, we analyzed the spatiotemporal evolution characteristics of thermal resources, the safe full-heading date (SFHD), and the grain-filling termination date (GFTD). 【Result】 The results show that both the SFHD and GFTD of ratoon rice exhibited a significant delaying trend from 1981 to 2022, with climate tendency rates of 1.58 d·(10a)⁻¹ and 2.0 d·(10a)⁻¹, respectively. The dates with 80% climatic guarantee probability ranged from September 10-17 for SFHD and October 15-28 for GFTD. The spatial distributions of SFHD and GFTD were similar, showing a progressive delay from the northwest to the southeast of the basin. Thermal resources during the heading and grain-filling stages showed a significant increasing trend, with growing degree days (GDD) generally ranging between 100 and 300 ℃·d and a climate tendency rate of 9.72 ℃·d·(10a)⁻¹. Spatially, GDD increased from the northwest to the southeast of the basin. From the 2010s onward, the area with GDD above 200 ℃·d expanded significantly toward the northwest, increasing by more than 10,000 km² compared to that in the 1980s. Since the 2000s, the interdecadal durations of both SFHD and GFTD have lengthened overall, while fluctuations in thermal resources during these stages have intensified. 【Conclusion】 Under climate change, the heading and grain-filling stages of ratoon rice in the Sichuan Basin are characterized by more abundant thermal resources, which is conducive to expanding the cultivation area and promoting diversified planting patterns. However, the increasing impact of extreme high- and low-temperature events on the stability of thermal resources has become an unfavorable climatic factor for ratoon rice production.