Cold tolerance at the booting stage is crucial for the reproductive function of rice (Oryza sativa L.), as it affects anther development and can lead to a significant decrease in seed setting rate and overall yield. The levels of certain growth regulatory substances, such as sugars, reactive oxygen species (ROS), and plant endogenous hormones like abscisic acid (ABA) and gibberellin (GA), are closely related to cold tolerance during the booting stage of rice. In this review, we systematically summarize the effects of cold stress on anther development in rice at the booting stage, the changes in growth regulatory substances, and the functional analysis of quantitative trait loci (QTL) and cold tolerance regulatory genes. This review aims to provide theoretical guidance for the breeding and improvement of cold-tolerant rice varieties and the development of materials at the booting stage.

As one of the most important food crops in the world, the growth and development characteristics of rice significantly impact agricultural production. The mesocotyl is a crucial part of rice that connects seeds and seedlings, playing an essential role in the processes of seed germination and emergence. Its elongation characteristics are particularly important in the direct seeding of rice. The elongation performance of the mesocotyl directly affects the emergence rate, emergence speed, and stress resistance of rice seedlings, making it a key link in rice breeding and cultivation management. With the advancement of modern agricultural technology, especially the rise of rice direct seeding technology, research on rice mesocotyl has become increasingly urgent and important. This manuscript reviews the cell morphology, environmental factors, physiological factors, mesocotyl-related QTLs, gene mining, and their applications in breeding. The goal is to lay a theoretical basis and explore new strategies for the utilization of rice mesocotyl and to guide future breeding directions.

The cultivation and popularization of semi-dwarf varieties have promoted the “Green Revolution” of rice. The semi-dwarf gene sd1 in rice is a key gene responsible for gibberellin synthesis, which decreases plant height, increases harvest index. The application of sd1 addressed the problem of high yield and lodging under conditions of increased nitrogen fertilizer application. In this paper, the isolation and functional analysis of the sd1 gene were reviewed, the differences in important agronomic traits among different haplotypes of sd1 were analyzed, and the mechanisms by which the sd1 gene regulated key agronomic traits such as growth period, plant height, number of panicles per plant, yield per plant, lodging resistance, seed dormancy, and nitrogen use efficiency were reviewed. The effect of the sd1 gene on rice yield was discussed, along with the application of gene editing technology to generate sd1 mutations for the rapid improvement of rice varieties. Moreover, the potential application of the sd1 gene was anticipated.

Ratoon rice is a green and efficient planting method that is significant for enhancing the profitability of rice cultivation and ensuring food security in China. Due to differences in growth environments and cultivation management practices, there are notable variations in rice quality between the main season and the ratoon season. Typically, the quality of rice in the ratoon season is superior to that of the main season. Factors such as ratooning characteristics, environmental temperature, and water and fertilizer management can influence rice quality by regulating source-sink relationships, the grain filling process, the synthesis of grain nutrients, and the physicochemical characteristics of starch granules. Numerous high-quality and high-yield rice varieties have been identified as suitable for ratoon rice cultivation, considering their ratooning capacity and yields. However, the quality of rice in both the main and ratoon seasons remains a limiting factor for ratoon rice production. This work briefly introduces the rice quality characteristics of the main and ratoon seasons and reviews the factors affecting the quality of ratoon rice and its cultivation regulations in terms of the formation process of rice quality. This review may lay a theoretical basis for the production of high-quality and high-yield ratoon rice.

【Objective】 This study aims to explore the distribution of Hd6 alleles in japonica rice and indica rice from Jiangsu Province, and to enhance the application value and selection efficiency of Hd6 alleles in the genetic improvement of rice heading date. 【Method】 We designed and screened various types of gene functional markers based on the single nucleotide polymorphisms in the functional regions of the Hd6 alleles in Kasalath and hd6 in Nipponbare. Through PCR amplification and sequencing, we selected the gene markers K-Hd6-21F/Hd6-1R and N-Hd6-22F/Hd6-1R to genotype japonica rice varieties from different ecological types in Jiangsu Province and indica rice varieties from various sources.【Result】 We found that K-Hd6-21F/Hd6-1R and N-Hd6-22F/Hd6-1R could effectively distinguish different genotypes at the Hd6 locus. The results indicated that 42% of the 48 medium-maturing japonica rice varieties carried the Hd6 allele, 50% of the 30 late-maturing japonica rice varieties carried Hd6, and 77.5% of the 48 early-maturing japonica rice varieties carried Hd6. The two alleles of Hd6 were distributed among varieties from three different ecological regions in Jiangsu Province, and the genotype frequency of functional Hd6 alleles increased with the heading date. The Hd6 gene is highly conserved in indica rice and was tested in all 62 indica varieties.【Conclusion】 This study lays a foundation for the utilization of the Hd6 gene and molecular marker-assisted selection in rice breeding, providing a new basis and effective approach for the breeding of early-maturing varieties in indica rice.

【Objective】Exploring the haploid induction ability of rice DMP family genes to provide new gene resources for haploid breeding.【Methods】Selecting OsDMP family genes with high homology to the ZmDMP gene and high expression level in pollen as candidate genes. Using CRISPR/Cas9 multi-gene editing technology to create single-gene knockout and multi-gene combination knockout mutants of the selected OsDMP family genes and haploid induction gene OsMTL in the indica and japonica hybrid rice Chunyou 84. Conducting morphological observations and pollen fertility identification on the mutants. Investigating and statistically analyzing the seed setting rate and haploid induction rate of the T₀ materials. 【Results】A total of 13 homologous genes of maize haploid induction gene ZmDMP were retrieved from the rice RAP-DB database. OsDMP1 and OsDMP2 showed the highest homology with ZmDMP, with similarity percentages of 41.24% and 37.32%, respectively; Moreover, OsDMP1 and OsDMP3 were the most highly expressed OsDMP genes in anthers. Therefore, OsDMP1, OsDMP2 and OsDMP3 were selected as candidate genes. Using CRISPR/Cas9 gene editing technology, single-gene knockout and combined knockout mutants of OsDMP1, OsDMP2, and OsDMP3 were created (osdmp1, osdmp2, osdmp3, osdmp1-osdmp2, osdmp1-osdmp3, osdmp1-osdmp2-osdmp3). Additionally, single-gene knockout mutants of OsMTL were generated (osmtl), as well as combined knockout mutants between OsDMP1, OsDMP2, OsDMP3, and OsMTL (osmtl-osdmp1, osmtl-osdmp2, osmtl-osdmp3, osmtl-osdmp1-osdmp2, osmtl-osdmp1-osdmp3, osmtl-osdmp1-osdmp2-osdmp3). Phenotypic investigation showed that compared with the wild type, plant morphology and pollen fertility of all mutants did not visibly change, but the seed setting rate decreased significantly in single gene knockout and multi-gene combination knockout mutants containing osmtl. Haploid detection results indicated that the haploid induction efficiency of the combined mutants between OsDMP1, OsDMP2, OsDMP3 and OsMTL was 0.4%±0.6%, 2.6%±2.8%, 1.4%±0.6%, 1.5%±1.3%, 2.1%±2.4%, 2.2%± 0.6%, respectively, which was not significantly different from that of osmtl mutant (1.5%±0.5%). However, no haploid was produced when OsDMP family genes were mutated individually or in combination. 【Conclusion】CRISPR/Cas9 gene editing technology was used to create single and multi-gene knockout mutants between OsDMP1, OsDMP2, OsDMP3, and OsMTL in rice. It was found that OsDMP1, OsDMP2 and OsDMP3 had no independent haploid induction ability, nor could it improve the haploid induction efficiency of OsMTL genes. These results promoted the understanding of OsDMP homologous genes in rice, and provided reference for the subsequent studies on the haploid induction gene.

【Objective】This study aims to explore the formation mechanism of the superior panicle type in Zhejing 99 and lays a scientific foundation for understanding the developmental mechanisms of rice panicle types and their breeding  applications.【Method】We used ethyl methanesulfonate (EMS) to induce mutations in Zhejing 99, resulting in a short panicle and small grain mutant. Molecular markers were employed to obtain linkage intervals, and candidate genes were identified through RNA sequencing (RNA-Seq) and DNA sequencing. The subcellular localization of the mutant gene was observed using a laser confocal microscopy. Additionally, transcriptome sequencing was conducted to analyze gene expression and the expression characteristics of related genes.【Result】Phenotypic identification revealed differences in plant type, panicle type, and grain type of the Ossp3 mutant compared to Zhejing 99. The mutant phenotype was caused by a base insertion in the candidate gene Os02g0450000. Subcellular localization showed that the gene product is located in the nucleus. In the young panicles of the Ossp3 mutant, 329 differentially expressed genes (DEGs) were identified, primarily distributed on chromosomes 1, 3, and 4. KEGG enrichment analysis highlighted significant biological processes, including plant hormone signaling pathways and MAPK signaling pathways in plants. Analysis of related gene expression suggests that the evolutionarily conserved plant-specific gene OsSP3 influences auxin and cytokinin content and their corresponding signaling pathways through the MAPK signaling pathway or by interacting with bZIP transcription factors, thereby regulating rice panicle development.【Conclusion】 The gene mutation in the superior panicle type variety Zhejing 99, specifically in Os02g0450000, results in the phenotype of short panicles and small grains. Its biological function is mediated through nuclear localization. RNA-Seq analysis indicates that the mutated gene may synergistically regulate the growth and development of rice panicles by affecting auxin and cytokinin signaling pathways and may also directly or indirectly influence grain type through interaction with OsbZIP47.

【Objective】 Low temperature is a primary abiotic stress that inhibits rice development and growth, ultimately reducing its yield. Identifying and utilizing cold tolerance genes to breed cold tolerant cultivars is a simple and effective way to address this issue.【Method】 A recombinant inbred line (RIL) population consisting of 144 lines derived from the cross between ‘Lijiang Xintuan Heigu’ (LTH) and ‘Shennong 265’ (SN265) was used to evaluate cold tolerance at the seedling stage in a phytotron. Quantitative trait loci (QTL) for cold tolerance at the seedling stage were detected using a high-density linkage map comprising 2818 markers.【Result】 A total of four cold tolerance QTLs at the seedling stage were identified on chromosomes 1, 8, 10, and 12 using the composite interval mapping (CIM) method. The phenotypic variations of these QTL ranged from 5.33% to 19.86%. Among them, the cold tolerance alleles of qCTS1, qCTS10, and qCTS12 were derived from the cold-tolerant parent LTH, while the cold tolerance allele of qCTS8 was from SN265. The major QTL, qCTS12, was located in a 396.67 kb interval from 15.98 Mb to 16.37 Mb on chromosome 12. The qCTS1 was located in a 299.85 kb interval from 9.20 Mb to 9.50 Mb on chromosome 1. The qCTS8 was located in a 55.05 kb interval from 26.09 Mb to 26.15 Mb on chromosome 8. The qCTS10 was located in an 85.82 kb interval from 11.13 Mb to 11.21 Mb on chromosome 10. Further analysis indicated that most interactions between QTLs are additive, except for the negative interaction between qCTS1 and qCTS8. 【Conclusion】 Four cold tolerance QTLs were identified using the LTH/SN265 RIL population and its linkage map of 2818 markers at the seedling stage. Three cold tolerance alleles were derived from the cold-tolerant parent LTH. These results not only provide valuable genetic resources for breeding cold-tolerant rice but also offer references for elucidating the genetic and molecular mechanisms of cold tolerance in rice seedlings.

【Objective】 The objective of this study was to investigate the effects of nitrification inhibitor application under aerated irrigation on rice growth, yield formation, and nitrogen fertilizer  utilization. 【Method】 The experiment was carried out with the rice variety Zhongzheyou 8 as material under two irrigation treatments, including: conventional flood irrigation (CF) and micro-nano bubble water oxygenation irrigation (MB). Additionally, two nitrogen fertilizer treatments were applied: urea alone (U) and urea combined with a nitrification inhibitor (NI). The study compared and analyzed the yield and its components, tillering dynamics, leaf area, leaf chlorophyll content, nitrogen accumulation in various parts of rice plants (stems, leaves, grains), and nitrogen utilization at different growth stages.【Result】 The results indicated that the application of nitrification inhibitors under aerated irrigation significantly increased rice yield, with the aerated irrigation treatment yielding an increase of 7.3% to 10.0%. Compared to urea alone, the yield with the nitrification inhibitor treatment increased significantly by 2.9% to 5.6%. The highest yield recorded for the aerated irrigation and nitrification inhibitor treatment was 6756.4 kg·ha⁻¹. In terms of yield components, both aerated irrigation and the addition of nitrification inhibitors primarily affected the number of effective panicles and the seed setting rate, with minimal impact on the number of grains per panicle and 1000-grain weight. Compared to the CF+U treatment, the effective panicle count and seed setting rate increased by 9.4% and 11.0%, respectively. The application of nitrification inhibitors under aerated irrigation significantly enhanced nitrogen accumulation in rice. At the full heading stage, stem nitrogen accumulation and leaf nitrogen accumulation in the MB+U+NI treatment increased by 4.5% and 6.1%, respectively, compared to the CF+U treatment. Aerated irrigation increased nitrogen accumulation and total nitrogen accumulation per panicle by 8.6% and 9.3%, respectively, compared to flooded irrigation under the same nitrogen fertilizer treatment at maturity. Furthermore, the combined application of nitrification inhibitors increased nitrogen accumulation per panicle by 3.4% and total nitrogen accumulation by 2.9% compared to urea alone under the same irrigation conditions. The MB+U+NI treatment significantly improved the nitrogen harvest index, nitrogen grain production efficiency, nitrogen partial productivity, and nitrogen use efficiency compared to other treatments.【Conclusion】 The application of nitrification inhibitors under aerated irrigation promotes rice tillering and increases the number of effective panicles, which aids in dry matter accumulation and enhances grain filling in the later stages. This, in turn, significantly improves the seed setting rate and yield of rice, increases nitrogen accumulation, and enhances nitrogen use efficiency.

【Objective】 This study was conducted to explore the physiological mechanisms underlying inter-varietal differences in early-tillering characteristics and their responses to nitrogen, laying a theoretical basis for the breeding and cultivation of high-yield, high-efficiency rice varieties.【Method】 A pot experiment was carried out using different rice varieties that exhibit significant differences in tillering speed at various nitrogen supply levels. The varietal differences in tillering characteristics and associated agronomic and physiological traits were analyzed, including biomass accumulation, yield and yield components, photosynthetic assimilation, root activity, plant nitrogen concentration, hormone contents in tillering nodes, and their responses to nitrogen.【Result】Based on the maximum number of tillers and tillering speed, Shanyou 63, Liangyoupeijiu, and R3012 were identified as early-tillering varieties, while Yangdao 6 was classified as a variety with general tillering speed. Huaidao 5 and Nanjing 9108 were classified as late tillering varieties. The early-tillering varieties were more sensitive to nitrogen supply. The biomass, number of panicles per pot, and yield of the early-tillering varieties, along with plant nitrogen concentration, activity of key enzymes involved in nitrogen metabolism, leaf photosynthetic rate, root oxidation capacity, and bleeding flow at the tillering stage, were significantly higher than those of the other varieties. The root systems of these varieties were more developed compared to others, with lower auxin content and higher cytokinin content in the tillering nodes. The responses of these agronomic and physiological traits to nitrogen in the early-tillering varieties were more sensitive. Similar trends in varietal differences were observed across various types of rice varieties.【Conclusion】High photosynthetic rates, enhanced root activity, elevated activities of key enzymes involved in nitrogen metabolism, low auxin content, and high cytokinin content in the tillering nodes are important mechanisms that accelerate tillering in rice.

【Objective】To elucidate the impact and mechanism of elevated CO₂ and elevated temperature on the quality of indica rice.【Methods】Using the free-air CO₂ enrichment and temperature increase (T-FACE) system, the rice cultivar Yangdao 6 (indica) was used to assess the effects of elevated CO₂ (increased by 200 μmol/mol) and elevated temperature (increased by 2 ℃, with both night-time and day-time temperatures elevated in 2021, and only day-time temperature elevated in 2022) on rice processing, appearance, nutritional quality, eating quality, starch synthesis enzyme activities, and non-structural carbohydrates (NSC) content.【Results】Generally, under the treatment combining elevated CO₂ and elevated night-time and day-time temperatures, rice processing and nutritional quality were not affected. However, eating quality improved as the amylose content decreased by 31.57%. The appearance quality of rice also improved, evidenced by a decrease in both the percentage of chalky grains and the degree of chalkiness under elevated CO₂ and/or elevated temperature. Specifically, under the combination of elevated CO₂ and elevated night-time and day-time temperatures, the percentage of chalky grains and the degree of chalkiness decreased by 25.98% and 34.82%, respectively. The degree of chalkiness showed a significantly positive correlation with the sucrose synthase (SuSy) activity and the cell wall invertase (CWI) activity, but a significantly negative correlation with NSC content and starch synthase (SS) activity. The potential mechanisms underlying the reduction in chalkiness under elevated CO₂ and elevated temperature include: (i) elevated CO₂ could increase NSC content and SS activity, providing adequate substrates for rice grain filling; and (ii) elevated temperature, along with the combination of elevated CO₂ and elevated temperature, decreased both SuSy activity and CWI activity during the later stages of grain filling, which could slow down the grain-filling rate.【Conclusion】Under the combined conditions of elevated CO₂ and elevated night-time and day-time temperatures, the chalkiness and amylose content of rice grain of Yangdao 6 decreased, and the rice appearance quality and eating quality improved.

 comparison of the simulated disaster damage rates from the system with the actual disaster damage rates of local rice production and the trends in meteorological yield changes indicates that the warning effect is effective. Regardless of spatial and temporal variations, the simulation results align well with the actual situation.