Rice

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Effects of Slow-release Nitrogen Fertilizer Before Transplanting on Yield and Quality of Rice

CHEN Qiuli, ZHAO Yipeng, DING Zhenqian, WANG Youshuang, HE Wanwan, XUE Pao, FAN Yunxin, HU Tingting

Chinese Agricultural Science Bulletin 2025, 41 (12): 1-8. DOI: 10.11924/j.issn.1000-6850.casb2024-0643

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To explore the effects of slow-release liquid nitrogen fertilizer as the nitrogen fertilizer before transplanting instead of tiller fertilizer on rice, the field experiment was conducted using ‘Huazheyou 210’ as the experimental variety. Two groups were established: the control group (CK), which received conventional fractional fertilization, and the treatment group (T), which was treated with slow-release liquid nitrogen fertilizer as the before transplanting nitrogen application instead of tiller fertilizer. The research aimed to evaluate the effects of these fertilization methods on the growth, yield and quality of rice. The results showed that the T treatment had no significant effect on the stem tiller number, SPAD value and morphological characteristics of rice when compared with CK. However, it significantly promoted the accumulation of aboveground dry matter during the middle and late growth stages and increased the root-shoot ratio in the early growth stage, thereby establishing a foundation for robust seedlings. Conversely, it reduced the root-shoot ratio in the middle and late growth stages, which contributed to the accumulation of aboveground biomass and laying a foundation for high yield. Although the T treatment resulted in a slight decrease in the effective panicle number, consequently, a marginally lower yield compared to CK, the difference was not statistically significant. Moreover, T treatment could significantly improve the processing quality, appearance quality and cooking taste quality of rice, but no obvious effect on the nutritional quality of rice. These results indicated that the application of slow-release liquid nitrogen fertilizer as nitrogen fertilizer before transplanting instead of tiller fertilizer can achieve the purpose of saving labor, cost, and being efficient on the premise of ensuring yield and quality.

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Adaptation Evaluation and Screening of 12 Conventional Indica Rice Varieties in Wenshan Prefecture

LI Jian, WANG Dingkai, XIONG Jianyun, WANG Tianming, WEI Kangbi, WANG Wenxin, WEI Dongmei, LI Yun

Chinese Agricultural Science Bulletin 2025, 41 (12): 9-18. DOI: 10.11924/j.issn.1000-6850.casb2024-0432

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This experiment aimed to select high-quality conventional indica rice varieties which are suitable for planting in Wenshan Prefecture, and to improve rice planting efficiency. Using 12 conventional indica rice varieties selected from 9 breeding units in Yunnan Province as experimental materials, 18 indicators including growth period, main agronomic traits, disease resistance, quality and yield were measured, and the correlation analysis and principal component analysis methods were used for comprehensive evaluation. The results showed that all 12 rice varieties tested could mature normally in the local area. The varieties with better main agronomic traits included 'Wendao 33', 'Nanjing Xiangzhan', and 'Sandao 16'. The average yield of 12 varieties was 8619.52 kg/hm², among which 'Hongdao 12' (9653.5 kg/hm²), 'Zhongke Jinghao' (9501.4 kg/hm²) and 'Caihe 17' (9312.8 kg/hm²) had the highest yield, with the increase of 13.37%, 11.58% and 9.37% respectively compared to CK. The variety with best rice quality was 'Wendao 33', and its rice quality met the national first-class high-quality rice standard. The correlation analysis showed that filled spikelets per panicle was significantly positively correlated with head rice rate; plant height and spike length were significantly negatively correlated with amylose content; thousand kernels weight was significantly positively correlated with the chalky grain rate and gel consistency, and was significantly negatively correlated with amylose content. 14 main indexes were simplified into 5 principal components by principal component analysis, and the cumulative contribution rate reached 86.956%, which basically reflected most of information carried by the original data of 12 varieties. Through comprehensive analysis and evaluation, the comprehensive performance of 'Hongdao 12', 'Sandao 16', 'Jinxian 168' and 'Wendao 33' was relatively outstanding. These research results can provide reference for the breeding and promotion of high-quality conventional indica rice varieties in Wenshan Prefecture.

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Effects of Silicon and Zinc Fertilizer on Yield and Lodging Resistance of Rice Under Side Deep Nitrogen Reduction Fertilization

ZHANG Yan, CHEN Jingdu, XIN Haibin, LIU Cuilian, XU Ruiheng, FAN Xiaokai, WANG Ying

Journal of Agriculture 2025, 15 (4): 7-12. DOI: 10.11923/j.issn.2095-4050.cjas2024-0060

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To investigate the synergistic effect of side deep nitrogen reduction fertilization and silicon plus zinc fertilizer on the yield and the lodging resistance of rice, traditional fertilization and side deep nitrogen reduction fertilization were carried out using ‘South japonica 9108’ as material, with four treatments including silicon fertilizer, zinc fertilizer, silicon plus zinc fertilizer and no fertilizer, respectively. The number of stems and tillers, the physical characteristics of culm, the lodging resistance, the yield were studied under different treatments. The results showed that: (1) compared with traditional fertilization, side deep nitrogen reduction fertilization could increase the number of stems and tillers, the number of effective panicle, the yield, the stem width, and enhance the lodging resistance significantly. (2) Applying side deep nitrogen reduction fertilization with silicon fertilizer could reduce the basal inter node length, enhance the bending resistance and reduce the lodging coefficient; applying side deep nitrogen reduction fertilization with silicon plus zinc fertilizer had the best tillering ability, the most big number of effective panicle, the strongest culm and the highest yield. (3) Under fertilization methods, applying silicon plus zinc fertilizer could promote the growth of rice effectively, and reach the biggest number of effective panicle, but the effect of other traits on rice was more complicated, the superposition effect could not be achieved.

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Effects of Different Sowing Dates on Seedling Quality and Tillering Dynamics of Rice During Field Nutritional Growth Period in Sanjiang Plain

CHU Chunyan, LI Chenhui, WANG Yan, PANG Yunchao, HAN Junjie, WANG Ping, ZHAI Mo, JIANG Lixia

Chinese Agricultural Science Bulletin 2025, 41 (11): 1-7. DOI: 10.11924/j.issn.1000-6850.casb2024-0466

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By studying the effects of different sowing dates on the growth characteristics and tillering dynamics of rice seedlings during the vegetative growth stage, this paper provides a basis for scientifically selecting the sowing and transplanting dates for rice production and promoting stable and high yields. Taking the main cultivar ‘Longjing 31’ in the Sanjiang Plain as the test material, four sowing periods were set with a time step of 10 d between adjacent sowing periods, the local multi-year average sowing period was set as the second period (T₂), and one forward phase (T₁) and two backward phases (T₃-T₄) were set together to carry out the trial. The results showed that as the sowing date delayed, the rice development period was delayed and shortened, the development process of rice accelerated, the number of unsuitable days of daily temperature suitability decreased, the temperature suitability during the development period increased, and the effective accumulated temperature of ≥ 10℃ decreased. The coefficient of determination of effective accumulated temperature (≥10℃ ) and tiller number was above 92.8 %, and the influence coefficient of effective accumulated temperature (≥10℃ ) on tiller number was between 4.7 and 8.9; T₁ sowing stage encountered a stage low temperature with the lowest temperature of 3.3 °C from regreening to tillering stage, and the daily temperature suitability for 7 consecutive days was less than 0.3, of which 4 days was 0, and the seedling trait index was the lowest; the maximum plant height and leaf area per plant were 73 cm and 103.27 cm² at T₂ sowing stage, the dry matter of each plant was 1.01 g, the maximum number of tillers in the hole reached 18 plants. Above all, the seedling quality index was the highest in T₂, followed by T₃, and May 11-21 was the best transplanting period. The research results can provide theoretical basis for the scientific selection of transplanting period, seeking benefits and avoiding harm, and promoting stable and high yield in rice planting.

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Research Progress on Comprehensive Prevention and Control Techniques of Rice Spike Rot Disease

DENG Xing, DUAN Lingtao, YIN Yuling, YIN Changfa, LAN Bo, YANG Yingqing, SHAO Jianyang, TU Xueqin, LI Yunpeng

Chinese Agricultural Science Bulletin 2025, 41 (10): 127-132. DOI: 10.11924/j.issn.1000-6850.casb2024-0556

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The pathogen and symptoms of rice spike rot disease were introduced. The occurrence regularity of rice spike rot disease was expounded from the occurrence conditions and epidemic regularity of the disease. The agricultural control measures of rice spike rot disease were introduced from the aspects of cultivation management, fungus source accumulation and selection of resistant varieties. The control effects of different pesticides on rice spike rot disease were also introduced. It is suggested that the control of rice spike rot disease should be based on agricultural control measures, including scientific cultivation, timely elimination of fungal sources and selection of disease-resistant varieties, and the chemical control should be included at the opportune moment. The occurrence and damage of spike rot disease were expected to be effectively controlled to a certain extent while ensuring the safety of grain production.

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Effect of Graphene Oxide on Rice Seed Germination Under Salt Stress

LIANG Wenzhao, ZHOU Shiyi, WEI Ruiyan, SHI Linya, LIU Naixin, YU Qingtao

Chinese Agricultural Science Bulletin 2025, 41 (9): 1-7. DOI: 10.11924/j.issn.1000-6850.casb2024-0491

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To explore the effect of graphene oxide (GO) treatment on rice seed germination under salt stress, this experiment used the rice variety 'Harbin Japonica Rice 15' as the experimental material. Under normal conditions and salt stress (0.05 mol/L NaCl), GO was induced at different mass concentrations (0, 25, 50, 100 mg/L) to detect the changes in antioxidant enzyme activity, malondialdehyde, and osmotic regulator content of rice seeds after different treatments. The results show that: (1) low concentrations of GO (25 mg/L) can promote the germination of rice seeds, while high concentrations of GO (50, 100 mg/L) significantly inhibit their germination. 25 mg/L GO can increase seed vitality and improve germination rate under salt stress; (2) high concentrations of GO and NaCl combined treatment can further exacerbate the inhibitory effect of salt stress on rice seed growth, increase antioxidant enzyme activity, reduce malondialdehyde content, and alleviate oxidative stress response; (3) GO treatment promotes the synthesis and accumulation of osmotic regulators, increases the osmotic regulation ability and salt resistance of rice seeds, strengthens the salt tolerance of seedlings, and significantly improves their emergence and seedling efficiency in salt environments. Low concentration GO can promote rice germination, while high concentration GO has certain harm to rice growth. Especially under salt stress, high concentrations of GO can increase the toxicity of salt stress on rice growth. It is suggested that high concentration GO related fertilizers should be used with caution in rice production practice in saline alkali areas.

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Effects of Microbial Product Coupling Urea on Straw Decomposition Rate and Yield of Rice

LI Yangyang, CHEN Shuaimin, XU Minghong, CHI Chang, MA Wei, WANG Yinping, SONG Yan, FAN Zuowei, WU Haiyan

Chinese Agricultural Science Bulletin 2025, 41 (9): 18-24. DOI: 10.11924/j.issn.1000-6850.casb2024-0317

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To select the most effective microbial product for in-situ decomposition of rice straw under cool conditions in Northeast China, and to determine the optimal dosage of microbial product coupling urea, this study conducted comparative experiments, and used the decomposition rate of rice straw, biological characteristics and yield of rice as indicators to define the optimal microbial product and the dosage of urea. The results showed that the independently developed microbial product NKY showed better field application effects. The straw decomposition rates of Hongqi Farm and Wanchang Town were 68.8% and 67.2%, respectively, which were 38.5% and 35.5% higher than CK. The height, tiller number, and dry weight of rice were also increased, and the rice yield increased by 6.0% and 6.8%, respectively. The optimal dosage for coupling urea with microbial product NKY was 75 kg/hm². Compared with no urea application, the straw decomposition rate increased by 8.7%, and the yield increased by 6.2%. In summary, the microbial product NKY not only has good degradation ability of rice straw, but also could promote crop growth and improve crop yield, which has a better application prospect.

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Effects of Different Exogenous Silicon Fertilizers Application on Yield, Dry Matter and Nutrient Accumulation and Transport of Rice in Tidal Flat

CHEN Pengjun, ZHANG Jiao, HAN Jijun, MIAO Yuanqing, CUI Shiyou

Chinese Agricultural Science Bulletin 2025, 41 (9): 8-17. DOI: 10.11924/j.issn.1000-6850.casb2024-0619

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A field experiment was carried out from June to November 2021 in tidal flat of Nantong, Jiangsu Province to study the effects of different exogenous silicon fertilizers spraying on rice yield, dry matter and nutrient accumulation and transport in various organs and rice quality, with ‘Nanjing 5055’ as the test variety. Five treatments were set up in the experiment, including spraying water treatment (CK), sugar alcohol silicon treatment (SF₁), seaweed liquid silicon treatment (SF₂), liquid silica-zinc fertilizer treatment (SF₃) and highly active ionic liquid silicon treatment (SF₄). The results showed that (1) compared with CK, rice yield under SF₁, SF₂, SF₃ and SF₄ increased by 9.24%, 7.31%, 0.28% and 3.64%, respectively, and reached a significant level under SF₁. At the same time, the number of grains per panicle, the number of solid grains, the weight of thousand grains, the length of panicle and the density of grains were increased significantly under SF₁ (P<0.05). (2) The above ground dry matter accumulation of rice at maturity was SF₁>SF₂>SF₄>SF₃>CK. At heading stage, nitrogen accumulation in the above-ground part and potassium accumulation in the upper part of the ground under SF₁ and SF₃were significantly increased under each spraying treatment. Nitrogen accumulation in the lower panicle and above-ground parts of SF₁, SF₃ and SF₄ at maturity was significantly increased (P<0.05). The distribution of nitrogen and potassium accumulation in each organ of rice at heading stage was in the order of stem sheath>leaf>ear. The distribution of nitrogen accumulation at maturity was in the order of spike>sheath>leaf, and the distribution of potassium accumulation was in the order of sheath>ear>leaf. (3) Compared with CK, leaf dry matter transfer (SF₃) and ear dry matter increase (SF₁, SF₂ and SF₃) were significantly increased. Nitrogen transfer in stem sheath (SF₂, SF₃ and SF₄) and leaves (SF₁) and nitrogen increase in panicle (SF₁, SF₃ and SF₄) were significantly increased. The transfer volume of potassium in stem sheath (SF₃) and leaf (SF₁) and the increase of potassium in panicle (SF₃) were significantly increased (P<0.05). (4) Rice yield was positively correlated with spike dry matter increase and nitrogen transfer, significantly positively correlated with dry matter accumulation and spike nitrogen accumulation at maturity, and significantly negatively correlated with leaf potassium accumulation. (5) Different exogenous silicon fertilizers spraying had no significant effects on the appearance and processing quality of shoal rice under the experimental conditions. Therefore, spraying appropriate exogenous silicon fertilizer (especially sugar alcohol silicon) on the leaf surface could significantly increase rice yield in this coastal mudflat area. Spraying exogenous silicon fertilizer mainly improves the number of grains per spike and the quality of 1000 grains, increasing the accumulation of dry matter and nitrogen in the rice spike.

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Spectral Characteristics of Soil Water-soluble Organic Carbon Affected by Cultivation Methods During Rice Growth Period

DONG Linlin, YAN Kai, SHENG Xuewen, LU Changying, SHI Linlin, WANG Haihou, WU Zhenggui

Chinese Agricultural Science Bulletin 2025, 41 (9): 99-106. DOI: 10.11924/j.issn.1000-6850.casb2024-0624

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Soil water-soluble organic carbon (WSOC) changed with cultivation methods is of great significance to crop growth and soil carbon cycle. In this study, a field experiment was conducted to compare the effects of rotary tillage (RT) and no tillage (NT) on the content and spectral characteristics of WSOC during the key growth period of rice in rice-wheat rotation system in the Taihu Lake Region. The results showed that the content of soil organic carbon (SOC) in RT and NT treatments increased from 21.73 g/kg and 21.30 g/kg before rice planting to 21.95 g/kg and 23.49 g/kg after rice harvest, respectively. Meanwhile, the content of water-soluble organic carbon in RT and NT treatments increased from 1.74 g/kg and 1.66 g/kg before rice planting to 3.74 g/kg and 4.35 g/kg after rice harvest, respectively. No tillage for rice-wheat rotation system was more conducive to increasing soil carbon sequestration and water-soluble organic carbon. Under the both tillage methods, the SUVA₂₅₄ and SUVA₂₆₀ of WSOC after rice harvest decreased slightly compared to that before planting rice, and the SUVA₂₅₄ and SUVA₂₆₀ of NT were higher than those of RT, while E₂/E₃ and E₃/E₄ were both increased. No tillage was more conducive to improving the aromaticity and humification of WSOC than RT for rice-wheat rotation system. Compared to rotary tillage, no tillage was more conducive to improving the stability of WSOC and had a positive effect on increasing soil carbon sequestration in paddy soil of rice-wheat rotation system.

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Effect of Irrigation on Rice Grain Yield and Water Use Efficiency During Critical Growth Period Under Drought Stress

WANG Junjiang, YIN Yuanhong, LU Chusheng, LU Zhanhua, CAI Haoyang, YE Qunhuan, LIAO Jiahui, LU Yusheng, LIANG Kaiming, FU Youqiang

Chinese Agricultural Science Bulletin 2025, 41 (8): 1-10. DOI: 10.11924/j.issn.1000-6850.casb2024-0540

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In order to investigate the effect of irrigation of the critical growth period on rice grain yield and water use efficiency, rice cultivar 'Yuehesimiao' was conducted with five irrigation treatments, namely, irrigation during mid-tillering (IMT), irrigation during panicle initiation (IPI), irrigation during heading (IHD), and irrigation during panicle initiation and heading periods (IPI+IHD), and the whole growth period flooding irrigation (CK). The effects of irrigation at different growth periods on tiller number, plant height, photosynthesis, grain yield and water use efficiency of rice was studied. The results showed that compared with CK treatment, rice grain yield in IMT, IPI, IHD and IPI+IHD treatments decreased by 97.0%, 37.9%, 34.7% and 21.9%, respectively. Productive panicle number in IPI, IHD and IPI+IHD treatments decreased by 28.6%, 25.7% and 31.4%, respectively, but no significant difference in IMT treatment. Spikelet per panicle and panicle length in IMT and IHD treatments decreased by 49.0%, 20.0% and 13.9%, 6.4% respectively. No significant difference in plant height, spikelet per panicle and panicle length was observed in the IPI and IPI+IHD treatments relatively to control. The setting rate in the IHD and IPI+IHD treatments increased by 22.9% and 10.7%, respectively. The net photosynthetic rate in IPI, IHD and IPI+IHD treatments increased by 27.3%, 29.6% and 32.4%, stomatal conductance increased by 45.5%, 24.1% and 42.8%, and transpiration rate increased by 33.9%, 23.6% and 31.5%, respectively. Intercellular CO₂ concentration in IPI and IPI+IHD treatments increased by 0.8% and 4.1% respectively. Compared with the control, water use efficiency in IPI, IHD and IPI+IHD treatments increased by 13.6%, 19.9% and 14.6%, respectively. Irrigation during the mid-tillering period was beneficial to the increase of tiller number, irrigation during panicle initiation could increase the number of spikelets per panicle, and irrigation during heading period could increase the setting rate of rice. The panicle initiation and heading periods are critical periods for rice irrigation, which is conducive to minimizing the yield loss and improving water use efficiency. The results of the study are of great significance for water-saving, yield-enhancing and efficiency-enhancing rice cultivation in arid areas.

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Effect of Individual Rice Plant Selection Based on Harvest Index

MO Junjie, ZHENG Jiacheng, CAI Jiwei, LIU Jiawei, FENG Yongcheng

Chinese Agricultural Science Bulletin 2025, 41 (7): 1-8. DOI: 10.11924/j.issn.1000-6850.casb2024-0413

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Further understanding the genetic regularity of rice harvest index in different segregating generations is beneficial to provide theoretical references for rice breeding based on the rice harvest index. In this research, isolated descendants from four distinct rice hybrid combinations were selected based on their harvest index. And then the coefficient of variation for main agronomic traits and the selection efficiency regarding the harvest index were subsequently compared and analyzed across different generations. The characteristics such as SPAD value at booting stage, plant height, and panicle length exhibited stability among different rice materials. In contrast, there was considerable variability in sword leaf length, thousand-grain weight, seed setting rate, and harvest index among hybrid rice progeny; however, these four traits remained stable in their parental lines. Notably, aboveground biological yield and panicle number per plant displayed significant variation both in hybrid parents and their offspring. The generalized heritability of the harvest index for F₃, F₃ lines and F₄ lines across all tested hybrid combinations exceeded 97%. Furthermore, selection efficiency for the harvest index in F₄ lines derived from ‘Hongxin-1S/Yuxiangyouzhan’, ‘Hongxin-1S/FL478’, and ‘Hongxin-1S/HD-YX’ surpassed that observed in their respective F₃ and F₃ lines; thus indicating a pronounced effect of single-plant selection based on harvest index within these three hybrids. Conversely, single-plant selection among offspring of ‘Hongxin-1S/Guanghong 3’ with high harvest indices did not enhance selection efficiency. It was effective to select individual plant with elevated harvest index for most of the tested rice materials from F₂ generation, which could significantly improve the selection efficiency of harvest index.

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Analysis of Genetic Effects on Stem Lodging Resistance in Hybrids of Indica and Japonica Rice

LING Bo, LI Xiangyi, LIANG Yingying, WANG Hongchao, CHEN Xiaoling, XIE Zhanwen, ZHANG Yuting, CHENG Zuxin, LIN Lihui

Chinese Agricultural Science Bulletin 2025, 41 (6): 1-9. DOI: 10.11924/j.issn.1000-6850.casb2023-0899

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The lodging resistance of rice is a complex character, and the analysis of its genetic effect is valuable for improving the lodging resistance of rice. The genetic patterns and parameters of 16 lodging resistance traits in indica and japonica crossbred progeny were analyzed by using additive and dominant genetic model of plant quantitative traits. The variation of additive variance in the ratio of main effect of 9 traits ranged from 49.9% to 72.1%. The dominant variance in the ratio of dominant effect of 7 traits ranged from 48.2% to 87.1%. The additive and dominant variances of 9 traits accounted for significant or extremely significant phenotypic variances, which were controlled by both additive and dominant effects of genes. The 8 characters, such as basal folding resistance and sheath leaf thickness, were negatively correlated with lodging index, which was conducive to improving basal folding resistance and toppling resistance of rice. Indica japonica intermediate type parents have strong lodging resistance heterosis and high breeding value. Effective use of the genetic characteristics of each character has important guiding significance for breeding lodging resistant indica and japonica hybrid generation.

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Research Progress on Cadmium Uptake and Control in Rice

WANG Mingjiao, MAO Ruiqing, KUANG Na, CHEN Yumei, ZOU Dan, ZHANG Ming, XIAO Fangxi, LIU Gui

Chinese Agricultural Science Bulletin 2025, 41 (6): 94-99. DOI: 10.11924/j.issn.1000-6850.casb2024-0458

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To understand the current status of Cd contamination and regulation in rice, this review comprehensively summarizes the following aspects: the absorption and translocation patterns of Cd in rice, Cd accumulation characteristics in different rice varieties and plant organs, the impacts of Cd on rice yield and quality, the effects on seed germination, as well as the influences on rice growth and physio-biochemical processes. Additionally, mitigation strategies for reducing Cd accumulation are systematically discussed. Based on China's current situation of rice Cd contamination, future research directions are proposed: (1) developing novel in-situ passivation materials, such as nano-adsorbent materials, which should have the characteristics of eco-friendly, cost-effective, high-efficiency, and user-friendly features; (2) creating more scientifically sound soil remediation technologies that can efficiently remove various heavy metals without damaging soil structure and ecological balance; (3) employing novel molecular breeding techniques to cultivate Cd-tolerant and stable ultra-low Cd-accumulating rice varieties, along with developing corresponding cultivation practices. This study aims to provide valuable references for Cd contamination control.

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Characteristics of Heavy Metal Pollution in Rice Grains and Human Health Risk Assessment in A County of Southern Henan

ZHANG Hui, YAN Huiyuan, SHI Yaying, ZHAO Nana

Journal of Agriculture 2025, 15 (2): 22-26. DOI: 10.11923/j.issn.2095-4050.cjas2024-0016

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In order to explore the pollution status and health risks of heavy metals in rice grains in a county of southern Henan, 68 rice grain samples were collected in the area in September 2021. The contents of chromium, arsenic, cadmium, lead, and mercury were determined by inductively coupled plasma mass spectrometry (ICP-MS-TQ) and direct mercury detection. The risk degree of heavy metals in rice was evaluated by single factor and Nemerowcomprehensive pollution index method, and the potential health risk of heavy metals from rice grains was evaluated by target hazard quotient (THQ) promoted by US EPA. The results showed that the average content of heavy metals in 68 rice grains did not exceed the Chinese Food Hygiene Standards, but the arsenic and cadmium contents in some samples exceeded the standards. The comprehensive pollution index (P_N) of heavy metals in rice grain was 0.49, which was safe. ADD of adults and children was higher than RfD, and hazard quotients (HQ) of As were 3.11 and 4.80, which indicated that there was a certain risk of arsenic content in rice grains. The total hazard index (HI) of heavy metals to the exposed population was greater than 1, indicating that the long-term consumption of the rice by local residents may cause adverse health effects. In summary, the rice grain samples in the research area have been contaminated with arsenic, posing certain health risks. The local government needs to strengthen dynamic monitoring of the rice planting process, pay attention to the changes in the form and effective state of arsenic, ensuring food security.

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Evaluation of Heavy Metal Enrichment and Correlation in Paddy Soil and Rice in Sichuan Basin

HUANG Miao, YANG Guotao, DIAO Yan, ZHANG Lei, YAN Yu, LI Yu, XU Wei, YANG Liang

Chinese Agricultural Science Bulletin 2025, 41 (5): 103-109. DOI: 10.11924/j.issn.1000-6850.casb2024-0509

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To study the environmental pollution of paddy fields in a region of Sichuan, this paper focused on paddy soil and rice as the main research objects. A total of 216 soil and rice samples were collected from the area, and the heavy metal pollutants in soil and rice in the study area were evaluated by testing the content of eight heavy metal elements, namely arsenic, lead, cadmium, chromium, mercury, copper, zinc and nickel in soil, and the content of five heavy metals, namely arsenic, lead, cadmium, chromium, and mercury in rice, using the single-factor pollutant index method and the Nemero composite pollutant index method, as well as performing the quantitative analysis of the association between various heavy metal elements in soil and rice. The results showed that: (1) the average content of cadmium and mercury in the soil of this study area was 0.47 and 0.98 mg/kg, respectively, which exceeded the standard, and their exceedance rates were 27.78% and 34.26%, respectively. The combined pollution index of Nemero in this study area was 1.11 mg/kg and the pollution level was mild. (2) There were significant correlations between the eight elements in the soil and the pathways of heavy metal accumulation might be the same. The coefficient of variation of soil Hg was 163.20%, which was highly variable, indicating that local pollution sources had a strong influence on heavy metals in soil, and the exceeding of Hg content in soil was mainly anthropogenic. (3) Cadmium, chromium and lead in rice had exceeded the standards, with exceedance rates of 19.44%, 3.70% and 19.44%, respectively. The study shows that the degree of heavy metal enrichment in rice has some correlation with soil heavy metal content and is related to the chemical form of heavy metals. It has certain guiding significance for food safety and heavy metal pollution remediation and treatment.

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Colored Rice and Its Related Genes: A Review

WU Yue’e, DUAN Haiyan, JIANG Gonghao

Chinese Agricultural Science Bulletin 2025, 41 (4): 19-24. DOI: 10.11924/j.issn.1000-6850.casb2024-0158

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To understand the research progress of colored rice and its related genes, the functions of colored rice were summarized, and the effects of Ra, Rc, Rd, OsC1 and OsB2 genes on the traits of colored rice were analyzed. These genes determine the red, black, and purple colors of rice grains by influencing the accumulation of anthocyanins and proanthocyanidins. In this paper, we point out the limitations of related rice color genes in rice breeding. And the current research is not systematic enough to make full use of the diversity of these genes and prove the role of these genes in other rice traits. It is believed that genome-wide association analysis and population genetics method can be used to systematically analyze the variation and expression patterns of these genes in different rice varieties, and provide data support for rice genetic improvement. We can also use genetic methods and modern biotechnology methods to explore the functions of these genes in other traits of rice, to provide theoretical basis for the improvement of multiple traits of rice.

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Composition and Diversity of Microbial Bacterial Communities in Paddy Rice Rhizosphere Soil

WANG Chenlong, MIN Jie, LIANG Rui, TAN Xiongyu, WANG Shuo, Umut Hasan

Chinese Agricultural Science Bulletin 2025, 41 (4): 84-93. DOI: 10.11924/j.issn.1000-6850.casb2024-0385

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The microbial composition and function in the rhizosphere is the research focus of microbial ecology. Analysis of the diversity of soil microbial communities in the root system of paddy rice and the effects of environmental factors on soil microorganisms can provide reference value for the sustainability of soils in the growing areas of paddy rice and the conservation of land resources. In this study, we used 16S rRNA high-throughput sequencing technology to determine the bacterial composition of soil microorganisms in the rhizosphere of paddy rice, and analyze the composition and diversity of microbial communities sampled from different regions, and explore the relationship between soil microbial diversity and soil physicochemical properties. The results showed that a total of 33862 OTUs, belonging to 38 phylums, 88 orders, 214 orders, 514 families and 2268 genera, were obtained from the paddy rice rhizosphere soil samples collected from the four regions by sequencing. At the phylum level, the dominant phyla of paddy rice rhizosphere soil bacteria collected from the four regions were Proteobacteria, Bacteroidetes and Firmicutes. At the genus level, Limisphaera was the dominant taxon of paddy rice rhizosphere soil bacteria. As shown by the Alpha diversity index, the species diversity and richness of paddy rice inter-root soil bacteria collected from the four regions were generally as followed: 68^th Regiment of the Corps (D)> Dairy Farm of Yili Prefecture (A)> Chabchal Town (B)> Sundzach Niuzhu Township (C); the Beta diversity index indicated that the paddy rice rhizosphere soil collected from the four regions differed accordingly in their bacterial community compositions, with greater differences existed between group A and other groups. The correlation analysis between soil bacteria and environmental factors concluded that the main influencing factors on the composition of microbial bacterial communities in paddy rice rhizosphere soils might be nitrogen, total potassium, and organic carbon. This study clarified the rhizosphere soil conditions and rhizosphere soil bacterial community characteristics of paddy rice distributed in the Ili River Valley, and provided theoretical support for the study of soil ecosystems in the Ili River Valley.

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‘Si te’ Late Indica Rice: Breeding, Yield Advantage and Growth and Development Characteristics

LI Xinghua, CAI Xingxing, WANG Huan, ZHANG Sheng, LIU Xia, ZHOU Qiang

Chinese Agricultural Science Bulletin 2025, 41 (3): 1-8. DOI: 10.11924/j.issn.1000-6850.casb2024-0112

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The aim was to explore the growth and development characteristics of ‘Si te’ late indica rice and provide theoretical support for its promotion and application. Many years field tests were conducted, with the typical ‘Si te’ late indica rice variety ‘Xiyou 447’ and the main rice variety ‘Jinyou 207’ in the middle and lower reaches of Yangtze River as experimental materials. Yield and growth characteristics were measured and breeding progress of ‘Si te’ late indica rice was summarized. Whole growth period of ‘Xiyou 447’ was 3-5 days shorter than that of ‘Jinyou 207’, and yield was increased by 7.5%-19.4%. Yield advantage of ‘Xiyou 447’ was mainly due to its synergistic improvement of dry matter accumulation and harvest index, as well as the higher total grain number per spike. The initial and terminal time of fast accumulation period of dry matter, nitrogen, phosphorus and potassium of ‘Xiyou 447’ were later than ‘Jinyou 207’, and mean accumulation speed was higher than ‘Jinyou 207’. Methane emission flux of ‘Xiyou 447’ was higher than ‘Jinyou 207’ at vegetative growth stage, but lower than ‘Jinyou 207’at heading and filling stage. In addition, ‘Xiyou 447’ had higher lodging resistance, which was mainly due to its lower plant height, shorter basal internode and higher stem wall thickness. ‘Si te’ late indica rice has short growth period, high yield, low methane emission and strong lodging resistance, so it has a good prospect for promotion and application.

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Effects of Two Rhizosphere Promoting Bacteria on Nutritional Quality of Rice

XIANG Weiwei, WANG Yusi, PENG Jun, WANG Jianwu, CHEN Hua

Chinese Agricultural Science Bulletin 2025, 41 (3): 158-164. DOI: 10.11924/j.issn.1000-6850.casb2024-0169

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This study aims to investigate the effects of Kocuria rosea SDB9 and Brevibacterium frigoritolerans SDB5 on the nutritional quality of rice. Using rice as the experimental material, the seeds were soaked with SDB9, SDB5, and a 1:1 mixture of both strains. The content of nine nutritional components in the rice grains was measured after harvest. The results were as follows. Compared to the control group (CK), the starch content in the experimental groups increased by only 1%, which was not statistically significant; crude protein content decreased by 3%-5%, also was not significant; crude fat content increased in all treatments, with a significant increase of 14.9% in the SDB9+5 treatment; soluble total sugar content decreased by 52.5%-58.3%, which was highly significant; reducing sugar content increased in all treatments except for a slight decrease of 0.6% in the SDB5 treatment, with a significant increase of 25.9% in the SDB9 treatment and an 8% increase in the SDB9+5 treatment, which was not significant; soluble protein content decreased in all treatments, with a significant decrease of 14.9% in the SDB9+5 treatment; cellulose content increased by 0.8%-0.9% in all treatments except for a slight decrease of 0.2% in the SDB9+5 treatment; vitamin C content decreased in all treatments, with a highly significant decrease of 64.5% in the SDB9 treatment and a significant decrease of 16.1% in the SDB5 treatment, while the SDB9+5 treatment showed a significant decrease of 35.5%; nitrate content decreased by 1%-12.8%, with no significant differences observed. In summary, treatment with SDB9 and SDB5 alone or in combination resulted in a slight increase in starch content and an approximate 8% decrease in crude protein content, improving rice palatability. The increase in crude fat and decrease in nitrate levels contributed positively to quality improvement. This indicates that Kocuria rosea SDB9 and Brevibacterium frigoritolerans SDB5 can improve the nutritional quality of rice to some extent. The evaluation of these two strains based on nutritional quality ranked them as follows: SDB9 > SDB9+5 > SDB5 > CK.

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Research on Identification of Rice Disease and Pest Based on Transfer Learning and ResNet-18

ZHANG Zhicong, CUI Dong, GUO Jinfeng, UMUT Hasan, LI Liang

Chinese Agricultural Science Bulletin 2025, 41 (2): 109-116. DOI: 10.11924/j.issn.1000-6850.casb2024-0387

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The study aims to improve the automatic recognition of rice pest and disease images and better guide agricultural pest and disease control. Using a combination of transfer learning and ResNet-18 model, we organized open source plant disease data on the internet, and obtained images of 9 rice pests and diseases, including bacterial blight, blast and Tungro, as well as a healthy leaf as the research objects. 11414 cleaned images were selected to establish a dataset for model training, and the 30% dataset was split as the test set. On the basis of six pre trained models such as ResNet-18, GoogLeNet, VGG-16, and MobileNet-v2, a series of parameter adjustments were made to the transfer model. The results show that: (1) under the consistent training parameters, the proposed model ResNet-18 has significantly higher validation accuracy and lowest loss value compared with MobileNet-v2, AxeNet, VGG-16, GoogLeNet, SqueezeNet, and the original ResNet-18 model. The final accuracy of the model is 96.97%. (2) Compared with the original model, the training accuracy of all transferred learning models has been improved significantly, with the improved accuracy ranging from 5.03% to 13.90%. The optimized training model has the characteristics of fast recognition speed and improved accuracy, which can accurately and quickly identify the type of crop disease, providing support for the automatic diagnosis of crop diseases.

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