Increasing the appropriate seedling density for higher yield in dry direct-seeded rice sown by a multifunctional seeder after wheatstraw return

Dry direct-seeded rice(DDR) sown using a multifunctional seeder that performs synchronous rotary tillage and sowing has received increased attention because it is highly efficient,relatively cheap,and environmentally friendly.However,this method of rice production may produce lower yields in a rice–wheat rotation system because of its poor seedling establishment.To address this problem,we performed field experiments to determine the rice yield at five seedling density levels(B1,B2,B3,B4,and B5=100,190,280,370,and 460 seedlings m-2,respectively) and clarify the physiological basis of yield formation.We selected a representative high-quality rice variety and a multifunctional seeder that used in a typical rice–wheat rotation area in 2016 and 2018.The proportion of main stem panicle increased with increasing seedling density.There was a parabolic relationship between yield and seedling density,and the maximum yield(9.34-9.47 t ha-1) was obtained under B3.The maximum yield was associated with a higher total spikelet number m-2 and greater biomass accumulation from heading to maturity.The higher total spikelet number m-2 under B3 was attributed to an increase in panicle number m-2 compared with B1 and B2.Although the panicle numbers also increased under B4 and B5,these increases were insufficient to compensate for the reduced spikelet numbers per panicle.Lower biomass,smaller leaf area,and lower N uptake per plant from the stem elongation stage to the heading stage were partially responsible for the smaller panicle size at higher seedling density levels such as B5.The higher biomass accumulation under B3 was ascribed to the increases in the photosynthetic rate of the top three leaves m-2 of land,crop growth rate,net assimilation rate,and leaf area index.Furthermore,the B3 rice population was marked by a higher grain–leaf ratio,as well as a lower export ratio and transport ratio of biomass per stem-sheath.A quadratic function predicted that 260-290 seedlings m-2 is the optimum seedling density for achieving maximum yield.Together,these results suggested that appropriately increasing the seedling density,and thereby increasing the proportion of panicles formed by the main stem,is an effective approach for obtaining a higher yield in DDR sown using a multifunctional seeder in a rice–wheat rotation system.

Breeding and Seed Production Techniques of New Aromatic Danxiangyouzhenliang Rice Variety with Good Quality and High Yield

Danxiangyouzhenliang rice is a high-quality rice variety derived from the hybrid breeding of Danxiang 12A and Xianghuixiangmiao R133.Its unique temperature-sensitive three-line characteristics endow it with significant advantages of high and stable yield,and its rice fragrance is exquisite and its taste is delicate.Danxiangyouzhenliang rice showed good resistance to rice blast and bacterial blight.On June 10,2021,Danxiangyouzhenliang rice passed the Guangxi Crop Variety Approval(Guishendao 2021074).Danxiangyouzhenliang rice is suitable to be planted as early and late rice in southern,central and northern Guangxi.This study summarized the breeding process and high-yielding seed production techniques of Danxiangyouzhenliang rice,in order to provide useful reference for rice breeders and growers.

The Current Breeding Situation and Development Strategies on High-quality Inbred Rice in Guangxi

According to the rice quality,production and resistance of 50 high-quality inbred rice varieties bred and examined and approved in Guangxi during the period 2000-2011,we analyze the current breeding situation and existing problems concerning high-quality inbred rice va- riety in Guangxi: the rice quality has been greatly improved,but the amylose content is still low; a series of scented rice varieties with high quality and high yield have been bred,such as Zhongguangxiang No. 1,Sanxiang 628,Guixiang No. 1,Liufengxiangzhan,Jiafuxiang No. 1, Zhaoxiang No. 1; the production of high-quality inbred rice during the period 2009-2011 was significantly enhanced,annually more than 66 00 kg / ha,but the disease resistance of rice variety bred was generally poor,and disease-resistant breeding stuck in the mud. Henceforth it is necessary to be oriented by the rice market,and take the rice type with long grain,high adhesive strength,medium-low amylose content and low chalkiness degree as the breeding objectives; introduce the existing high-quality variety resources with medium amylose content at home and abroad,then directly use them or innovate upon them as hybrid strain; take the thick-and-long-grain rice type as breeding objectives,and further improve the yield per unit area of high-quality inbred rice by improving the thousand-grain weight; increase capital investment,improve breeding techniques,strengthen disease-resistant and degeneration-resistant breeding,and improve the application of modern biotechnology in the breeding of high-quality inbred rice.

Improvement of Rice Blast Resistance of High-Quality Rice Variety Xiangwanxian 13 by Molecular Marker-Assisted Selection

At present, most of high-quality rice varieties are susceptible to blast diseases. In this study, Gumei 2, a rice variety carrying broad-spectrum resistant Pi25 gene, was used as the donor, with Xiangwanxian 13 taken as the receptor and recurrent parent which is also of good quality but highly susceptible to rice blast, to improve the rice blast resistance of Xiangwanxian 13 by crossing and backcrossing based on molecular marker-assisted selection. The results showed that the resistance of the improved strains （i.e. Xiang C72, Xiang C76 and Xiang C77） to blast diseases had been enhanced signifcantly through feld resistance identifcation, equaling the resistance level of Gumei 2, and the main agronomic and quality-related traits of these improved strains had been restored to the level of Xiangwanxian 13, except the chalkiness and cooking-related traits, which suggested similar genomic loci of Xiang C72, Xiang C76 and Xiang C77 to those of Xiangwanxian 13. These three improved strains （i.e. Xiang C72, Xiang C76 and Xiang C77） can provide good intermediate materials for breeding elite varieties with high grain yields and superior blast resistance.

Breeding of High-Quality Late Rice Combination Taoxiuyouhuazhan

Taoxiuyouhuazhan is a high-quality fragrant late rice combination which was bred by the cooperation between Hu Nan Tao Hua Yuan Agricultural Technologies Co.,LTD.and Changde Institute of Agriculture and Forestry Science.With good yield,wide adaptability,resistance to rice blast,and the quality reaching third level of the national agricultural standard of Quality of Edible Rice Varieties.It has been authorized by the National Crop Variety Committee of the Ministry of Agriculture and Rural Affairs in February 2019.

Analysis of the Nationally Registered Rice Varieties in the Last Decade

The nationally registered rice varieties during 2006-2015 were analyzed and there were 49.4 varieties on average annually registered in the last decade. In terms of the structure of varieties, there was a decreasing trend for the proportion of three-line hybrid rice varieties but a rapid increase for that of two-line hybrid rice varieties. The percentage of rice varieties developed by scientific research institu- tions was decreasing but that developed by seed companies kept a rapid increase, indicating the commercial breeding conducted by seed companies has become a principal model in rice breeding. With regard to grain quality of varieties, the con- ventional rice varieties showed an increasing trend while the hybrid rice varieties had a decreasing trend in the proportion of high quality varieties, indicating hybrid rice needs improving more in grain quality in breeding programs.

多功能针式过滤器净化超高效液相色谱法测定大米和花生中玉米赤霉烯酮

建立了一种基于多功能针式过滤器净化的超高效液相色谱测定大米和花生中玉米赤霉烯酮的方法。样品经乙腈提取,采用多功能针式过滤器通过式净化,以超高效液相色谱法测定其中的玉米赤霉烯酮,色谱柱为ACQUITY UPLC BEH C_(18)柱(100 mm×2.1 mm,1.7μm),以甲醇-乙腈-水(体积比为8∶46∶46)为流动相等度洗脱,流量为0.3 mL/min,用荧光检测器检测,色谱峰面积外标法定量。玉米赤霉烯酮的质量浓度在2.5~500 ng/mL范围内与色谱峰面积线性关系良好,相关系数不小于0.9995。大米和花生样品的方法检出限分别为15.0、30.0μg/kg,定量限分别为50.0、100.0μg/kg。样品加标回收率为77.11%~93.65%,测定结果的相对标准偏差为0.49%~4.95%(n=6)。该方法简便快速,适用于大米和花生中玉米赤霉烯酮的日常检测。

超高效液相色谱-质谱联用法检测地理标志产品松江大米中8种真菌毒素的含量

建立超高效液相色谱-三重四极杆质谱法同时检测大米基质中8种真菌毒素的方法,对地理标志产品松江大米中真菌毒素的污染情况进行监测。大米样品经提取液乙腈水混合液(84∶16,体积比)超声提取后,取部分提取液加入内标溶液,混匀后过多功能净化柱MycoSep229净化,采用Waters Acquity UPLC BEH C18色谱柱(2.1 mm×50 mm,1.7μm),以体积分数0.1%甲酸水溶液-乙腈作为流动相进行梯度洗脱,分离黄曲霉毒素B 1(Aflatoxin B 1,AFB 1)、黄曲霉毒素B 2(Aflatoxin B 2,AFB 2)、黄曲霉毒素G 1(Aflatoxin G 1,AFG 1)、黄曲霉毒素G 2(Aflatoxin G 2,AFG 2)、伏马毒素B 1(Fumonisins B 1,FB 1)、伏马毒素B 2(Fumonisins B 2,FB 2)、伏马毒素B 3(Fumonisins B 3,FB 3)、赭曲霉毒素A(Ochratoxin A,OTA)8种真菌毒素化合物,该方法采用电喷雾离子化正离子模式,以多反应监测方式进行。AFB 1、AFG 1、FB 1、FB 2、FB 3、OTA 6种真菌毒素在0.5~15.0μg/L范围内线性良好,AFB 2、AFG 2在0.125~3.750μg/L范围内线性良好,线性相关系数r均大于0.999;8种化合物定量限(limit of quantifications,LOQs)范围为0.01~0.25μg/kg,比国标中相同方法的定量限降低2~80倍不等;在低、中、高三水平加标,其回收率均在95%~120%范围内,相对标准偏差(relative standard deviations,RSDs)为1.5%~8.9%(N=6)。本方法前处理简单,方法利用率高,结果准确可靠,利用该方法检测的20批新上市松江大米中真菌毒素污染情况比较乐观,对人体的健康危害较低。

Comparisons of Metabolic Profiles for Carbohydrates,Amino Acids,Lipids,Fragrance and Flavones During Grain Development in indica Rice Cultivars

We used a widely targeted metabolomics approach to examine the metabolic changes in three pedigreed indica cultivars(Meixiangzhan 2,Meisizhan and Qixinzhan),with different eating qualities,at 8,15 and 30 d after flowering(DAF)to explore the formation mechanism of rice eating and nutritional qualities at a global metabolic level.A total of 623 metabolites were identified,and results showed that metabolic variations among rice cultivars decreased with grain developmental stage,suggesting that sufficient carbohydrate and amino acid supply during grain development may contribute to excellent rice eating and nutritional quality formation.Lysophosphatidylcholines 19:0 and 16:1 were beneficial for excellent eating quality formation during grain development.Rice fragrance was attributed mainly to spermidine andγ-aminobutyric acid.Rice cultivars with excellent eating quality at 15-30 DAF had relatively higher flavone content,possibly because they had adequate carbohydrate and amino acid contents during grain development.These results provided insight into the mechanisms for establishing rice eating and nutritional qualities during grain formation at a global metabolic level,and can be applied towards improving rice quality.

High-quality genome assembly of Huazhan and Tianfeng,the parents of an elite rice hybrid Tian-you-hua-zhan

High-quality rice reference genomes have accelerated the comprehensive identification of genome-wide variations and research on functional genomics and breeding.Tian-you-hua-zhan has been a leading hybrid in China over the past decade.Here,de novo genome assembly strategy optimization for the rice indica lines Huazhan(HZ)and Tianfeng(TF),including sequencing platforms,assembly pipelines and sequence depth,was carried out.The PacBio and Nanopore platforms for long-read se-quencing were utilized,with the Canu,wtdbg2,SMARTdenovo,Flye,Canu-wtdbg2,Canu-SMARTdenovo and Canu-Flye assemblers.The combination of PacBio and Canu was optimal,considering the contig N50 length,contig number,assembled genome size and polishing process.The assembled contigs were scaffolded with Hi-C data,resulting in two“golden quality”rice reference genomes,and evaluated using the scaffold N50,BUSCO,and LTR assembly index.Furthermore,42,625 and 41,815 non-transposable element genes were annotated for HZ and TF,respectively.Based on our assembly of HZ and TF,as well as Zhenshan97,Minghui63,Shuhui498 and 9311,comprehensive variations were identified using Nipponbare as a reference.The de novo assembly strategy for rice we optimized and the“golden quality”rice genomes we produced for HZ and TF will benefit rice genomics and breeding research,especially with respect to uncovering the genomic basis of the elite traits of HZ and TF.

大米中16种真菌毒素同时检测分析

目的建立大米中黄曲霉毒素、伏马毒素、雪腐镰刀菌烯醇、脱氧雪腐镰刀菌烯醇类毒素、玉米赤霉烯酮、赭曲霉毒素A、T-2毒素、HT-2毒素以及杂色曲霉毒素等16种真菌毒素便捷准确的液相色谱-串联质谱法。方法大米样品经粉碎均质后采用70%甲醇水溶液浸泡提取,通过PriboFastRM226多功能净化柱净化,利用液相色谱串联质谱的多反应监测模式进行测定分析,采用内标法定量。结果 16种真菌毒素均具有良好的线性关系(r>0.99),3个加标水平回收率为85.2%~102.8%,相对标准偏差范围为2.05%~4.75%。在61件大米检测中,共有5件样品检出真菌毒素,检测到的真菌毒素有5种,其中雪腐镰刀菌烯醇、伏马毒素B1、伏马毒素B2、15-乙酰基脱氧雪腐镰刀菌烯醇各有1件样品检出,黄曲霉毒素B1有3件检出,检出率为8.33%,检出的5种真菌毒素含量在0.69~71.47μg/kg,均未超过国家食品安全标准规定的真菌毒素限量标准。结论大米中真菌毒素的检出率低,含量符合国家标准要求,该检测方法准确、可靠、便捷,可适用于大米中多种真菌毒素的检测。

多功能净化柱高效液相色谱法检测稻米中的黄曲霉毒素B_1的研究

建立多功能净化柱净化高效液相色谱法检测稻米中的黄曲霉毒素B，的方法。稻米样品经V（乙腈）：V（水）-84：16提取，多功能净化柱净化，三氟乙酸衍生化，高效液相色谱法荧光检测器检测。黄曲霉毒素B，浓度在o．010～100μg／L,范围内呈良好的线性关系，回归方程为y=60．431x＋0．1638．相关系数R^2=0．9999。该方法的检出限为0．1μg／kg．加标回收率为82．25％～98．52％，标准偏差（SD）为2．23％～3．62％，比普通的0．45μm微孔滤膜净化的要高。该法操作简便易行、选择性高、检测效果好，适合大批量粮油作物中黄曲霉毒素的检测，有利于推广应用。

中国水稻百年育种的一些标志性品种

在中国水稻百年育种史上,水稻育种工作者根据不同时代的需求,培育出了一系列的优良品种在生产上推广应用,基本解决了人民的吃饭问题。1919—1949年期间,培育出了我国第1个大面积推广品种中大帽子头,世界上第1个具有野生稻血缘品种并开创国内水稻杂交育种先河的中山1号,以及推广面积最大的改良品种南特号。1950—1979年期间,培育出了以“绿色革命”为标志的矮脚南特、珍珠矮11、广陆矮4号、桂朝2号等为代表的矮秆耐肥的高产水稻品种。1973年以袁隆平领导的全国水稻杂优利用协作组成功实现了籼型杂交水稻的三系配套,开始杂交水稻的产业化应用;此期间培育出了高产杂交水稻品种南优2号,1978年推广面积达到297.9万hm^(2)。1980年以后,育成了常规稻品种浙辐802、杂交水稻品种汕优63、超级两系杂交水稻品种两优培九等。进入21世纪,育成以超级稻品种甬优系列品种、Y两优1号等为代表的高产品种,以中嘉早17为代表的优质高产多功能水稻成为我国稻区的主导品种。展望未来,随着人民生活水平的提高,培育具有健康、环保等特性的优质高产多功能品种将成为水稻育种家的主攻方向。

多功能拌种剂对改善水稻秧苗素质及节水增产效果研究

试验针对我国南方地区频频发生的季节性干旱灾害气候,在江西省双季稻种植区,以双季晚稻为研究对象,研究了农业抗旱节水用多功能拌种剂与同类产品(蓝精灵、生根壮秧剂)对提高水稻秧苗素质影响的对比,及其节水增产的应用效果。结果表明,与蓝精灵和生根壮秧剂相比,农业抗旱节水用多功能拌种剂能够更加有效的矮化株高、增加茎粗、提高叶龄、增加根条数和根长、提高根干物质重;使用农业抗旱节水用多功能拌种剂较未拌种处理增产8.47%,节水18.18%,水分利用效率提高32.03%。

多功能拌种剂在水稻节水抗旱上的应用效果研究

研究了农业抗旱节水用多功能拌种剂对双季晚稻生理性状、水分吸收、养分积累和产量形成的影响,结果表明:农业抗旱节水用多功能拌种剂具有促根壮秧、增穗重粒、节水增产等作用。

QuEChERS法检测稻谷中的20种农药残留

目的:建立一种操作简单且稳定性强,可有效检测出稻谷中20种农药残留的分析方法。方法:稻谷样品粉碎后经1%乙酸乙腈提取,利用QuEChERS改良前处理技术进行合理地净化和过滤处理后,经液相色谱串联质谱仪测定。结果:目标化合物线性具有良好的关系,且R^(2)> 0.995,加标回收率在61.4%~113.3%,相对标准偏差在0.1%~14.2%。结论:该方法检测效率高、成本低,能够实现稻谷中20种农药残留的快速准确测定。

2FSD-15型多用机在水稻植保作业中的应用研究

2FSD-15型多用机在水稻生产中除完成必要的运苗、撒肥作业外,也可应用于水稻植保作业。对东港市北井子镇使用2FSD-15型多用机进行植保作业进行效益分析,证明机械植保具有显著的经济效益、社会效益和环保效益,并提出该机在植保作业时应注意的问题及相应的解决方法,以促进其在东港地区大面积推广应用。

China’s Ecological Agriculture: Progress and Perspectives

Agriculture is the basis of national economy. Through science and technology and the intensive utilization of land, great achievements have been made in agriculture. However, some agro-ecological and environmental problems are rising. Because of this, people have begun to reflect on agricultural developmental policy, patterns and technologies, and put forward new thoughts for agricultural development. In the late 20th century, China’s ecologists and agronomists co-sponsored the concept of ecological agriculture with Chinese characteristics. Its essence includes a series of concepts such as integration, coordination, circulation and regeneration within agroecosystems or within systems of agriculture production, processing and marketing. After nearly 30 years of practice and development, ecological agriculture in China has achieved remarkable outcomes. However, current eco-agriculture development is unsatisfactory due to the following two factors： （i） A lack of research and accounting across a variety of agro-ecosystem service functions; （ii） It is difficult to obtain remarkable economic benefits because of the lack of market-oriented guidance, scale management, specialized production and brand popularization for the traditional autarkic peasant economy. In order to further promote the development of ecological agriculture it is necessary to engage in serious reflection on ecological agriculture in China and arrive at new understandings about circular economy, multifunctional agriculture, high-quality agriculture, industrial development, integration of the traditional essence and modern technology, and finally, the sustainable development of rural areas.

多功能调节剂对杂交水稻制种母本颖花开闭和种子生产的影响

以2个三系杂交水稻组合和2个两系杂交水稻组合为材料,于母本抽穗开花盛期,采用3种多功能调节剂(MeJA+ALA、MeJA+ABA和MeJA+ALA+ABA)喷施盛花期母本稻穗的方法,研究了其对杂交水稻制种母本颖花开闭和种子生产的影响。结果表明,用MeJA+ALA、MeJA+ABA和MeJA+ALA+ABA喷施,能使本应在处理后第2天和第3天开放的成熟颖花提前到处理当天开放,从而促进母本成熟颖花在处理当天大量集中开放,极大提高母本午前花开放率,使父母本花时基本吻合;MeJA+ABA和MeJA+ALA+ABA处理能明显促进母本开放颖花集中关闭,缩短颖花开闭历时,提高颖花最终关闭率;MeJA+ALA和MeJA+ALA+ABA处理,其制种产量显著高于对照。因此,在杂交水稻制种中,用多功能调节剂MeJA+ALA+ABA喷施盛花期母本稻穗,能促进父母本花时相遇,提高母本受粉率和异交结实率,降低杂交种子的裂颖率,提高杂交种子产量和质量,具有很好的应用价值。