提高玉米杂交种纯度应注意的问题

多年生产实践证明，使用玉米杂交种是提高玉米单产最经济最有效的途径，随着玉米杂交种使用面积的不断扩大，种子本身的质量显得越来越重要。从玉米杂交种生产制种的主要环节分析，造成杂交种子纯度下降的主要原因有：(1)用于生产玉米杂交种的自交系统纯度达不到标准；(2)制种田“去雄、去杂”质量差；(3)隔离条件不严格；(4)机械人工混杂及人为掺杂使假。为了保证玉米杂交种的纯度，真正发挥其品种本身所具有的增产潜力，必须认真把好玉米制种主要环节的质量关。     

提高玉米杂交种种子纯度的技术措施

玉米杂交种质量是玉米产量的关键，而杂交种的种子纯度是保证杂交种质量的根本。 从玉米杂交种生产的主要环节入手分析造成种子纯度下降的主要原因。为了保证玉米杂交种种子纯度，应当注意以下几点： 严把亲本质量关一定要严格控制亲本种子的来源。地（市）级种子部门按计划组织自交系繁殖和供应，严禁县级及其以下单位或个人等通过其它渠道调进繁殖。选用来源可靠和纯度、净度、发芽率高的自交系种子，是获得高质量杂交种的首要条件。 选择适宜的制种区，保证安全隔离玉米制种田应选择隔离条件好，集中连片的地块。 保证安全隔离的方法，如…     

实现夏玉米高产的几个关键措施

玉米是河南省的主要粮食作物,常年种植面积在200万hm2左右,其中90%是夏玉米。因此夏玉米产量的高低,对全省粮食生产和畜牧业发展有着举足轻重的作用。为了进一步提高我省夏玉米的产量水平,我们通过试验、示范,提出了实现我省夏玉米高产的几项关键措施。1选用高质量的优良杂交种杂交种在玉米增产中起着重要作用,据国内外研究证明,近代玉米增产效益中,杂交种的增产作用占20%～40%。因此,合理选用优良杂交种是玉米高产栽培的基础。根据我省实际情况,在生产上应选用高产稳产、耐肥抗倒、熟期适中、增产潜力大的紧凑型玉米杂交种,如郑单958、安玉…     

山东省玉米杂交种的种质基础

对山东省玉米杂交种的种质基础进行的分析表明：我省玉米杂交种生产已完全进入单交种时代；生产上使用的杂交种以省内自育的中晚熟、紧凑型杂交种为主；省内自育系×省外育成系组成的杂交种面积较大；杂交种的亲本利用更趋集中，种质基础狭窄；自交系的主要来源是二环系，国外种质在自交系种质中具有突出地位。     

玉米雄性不育系原种繁育技术

玉米杂种优势的利用使玉米产量有了很大的提高，但由于玉米是异花授粉作物，在配制杂交种时需要人工去雄，不仅增加了劳动强度，提高了种子生产成本，而且会因去雄不彻底难以保证杂交种的质量。利用雄性不育系配制玉米杂交种是提高玉米杂交种子质量的关键措施之一。泰安市农科所自１９９５年起致力于玉米雄性不育系的选育及利用技术研究，现已对部分骨干自交系成功地实现了雄性不育基因转育，育成了不育株率达到１００％且遗传稳定、抗逆性好、配合力高的雄性不育系，在部分组合上实现了不育系、保持系和恢复系三系配套，育成了强恢复型的杂…     

玉米自交系种子质量管理

对于主营玉米杂交种的种业公司而言，确保玉米自交系的种子质量，是企业技术工作的头等大事之一。玉米自交系种子质量的保障，主要体现在自交系种子的贮存和繁育过程中。贮存和繁育的目标，是为杂交种的生产提供优质、足量的自交系良种。这里，数量目标相对容易完成，而保证质量是技术人员必须严肃对待和妥善解决的重要课题。     

中熟高产玉米杂交种主要农艺性状演变规律的研究

通过对山东省１９７６￣１９９５年中熟玉米高产杂交种主要农艺性状的分析，认为中熟高产玉米杂交种产量的提高，主要由于选育了紧凑型品种而增加了密度（公顷株数和公顷穗数）、公顷粒数和提高了籽粒千粒重；１９７６￣１９９５年中熟高产玉米杂交种主要农艺性状的演变规律是，公顷产量、公顷株数、公顷穗数、公顷粒数和千粒重等性状呈上升趋势，穗长呈下降趋势，穗行数、穗粒数、株高、穗位高、大斑病、小斑病和生育期等性状则变化     

提高杂交玉米种子质量的措施

玉米是雌雄同株的异花授粉作物，其杂种优势利用主要是靠人工去雄杂交实现的。玉米杂交制种的成败，所制种子质量的好坏，与生产过程中的各个环节是密不可分的。目前，在生产中影响种子质量的因素很多，只有严格做好各环节的工玉米是雌雄同株的异花授粉作物，其杂种优势利用主要是靠人工去雄杂交实现的。玉米杂交制种的成败，所制种子质量的好坏，与生产过程中的各个环节是密不可分的。目前，在生产中影响种子质量的因素很多，只有严格做好各环节的工作，才能保证杂交种的种子质量。现将提高杂交种制种质量的关键性措施介绍如下。１提高杂交…     

30%胺鲜酯-乙利水剂对玉米杂交种主要农艺性状的影响

在75000株/hm2的种植密度下,研究了玉米专用增效剂对玉米杂交种主要农艺性状的影响。结果表明:不同剂量的玉米增效剂对玉米杂交种农艺性状的影响存在明显差异;合理使用增效剂可以降低玉米杂交种株高、穗位高、倒伏率、空秆率、秃尖长,增加茎粗和千粒重,稳定穗长、穗粗、行数、行粒数、出籽率,提高玉米籽粒产量。玉米杂交种洛玉5号的适宜施用浓度为150～200mL/hm2。     

玉米杂交种纯度与产量的关系初探

玉米杂交种纯度与产量的关系初探甘肃省平凉地区种子管理站（７４４０００）郭柏勤，马爱莲，高宏伟，张学仁玉米是我区主要粮食作物之一，年种植面积在４万公顷以上，“九五”期间将扩大到６万多公顷。玉米杂交种纯度的高低直接影响到玉米产量的高低，也关系到我区“九五...     

冬小麦新品种选育专家系统的设计与实现

“冬小麦新品种选育专家系统”是在总结我国著名小麦遗传育种学家经验的基础上,应用知识工程方法和专家系统技术建立的计算机程序系统,用以进行亲本选配、后代处理和品种评价。系统以Turbo-Prolog语言实现,可在长城系列微机和兼容机上运行。 本文介绍了系统的基本结构、知识表示方法、推理策略、主要功能、特点和应用情况。     

几种分子标记技术在玉米自交系类群划分中的应用

分子标记技术的开发利用推动了玉米育种的发展,概述了5种常用分子标记SSR、RFLP、RAPD、AFLP、SNP的原理及特点。综述了分子标记技术在玉米自交系类群划分中的应用。     

Farmers’ participation and breeding for durable disease resistance in the Andean region

In the Andean region, the Preduza project and its partners combined breeding for durable disease resistance using locally adapted cultivars and farmer participatory methods. The approach taken resembles participatory variety selection (PVS). Farmers participated in the selection of advanced materials, rather than finished cultivars. This paper describes this approach and reports experiences with farmers–breeders collaboration. As breeders involved farmers as participants, they learned more about the most important criteria of male and female farmers for preferred cultivars in the marginal environments of Andean cropping systems. This approach encouraged the use of locally adapted cultivars (often landraces), made the breeders less dependent on foreign materials, and has resulted in selection and development of new wheat, barley, common bean, quinoa, potato and maize cultivars. Breeding programmes based on crossing locally adapted cultivars followed by selection by the breeders in the early phases of the breeding programmes and by participatory selection with the farmers in the more advanced stages of the breeding programmes appeared successful. It became clear that breeders must be well acquainted with the farmer preferences such as the requirements for specific agronomic, storage, processing and marketing traits. Over a period of five years the centralized formal breeding approach predominantly based on material produced by the international institutes was replaced by decentralized breeding approaches based largely on local germplasm with extensive farmer participation.     

玉米自交系铁C 8605-2的育成与持续利用分析

20世纪80年代,铁岭市农业科学院育种者以美国玉米杂交种选系铁7922和沈5003为基础材料育成了自交系铁C 8605-2.铁C 8605-2自育成以来得到了广泛应用,直接或间接参与选系组配了众多品种,而且经历近40年仍为许多育种者使用.本文介绍了铁C 8605-2的育成及应用情况,并着重探讨了进一步持续利用的可能和方...     

Genomic selection and enablers for agronomic traits in maize (Zea mays): A review

Maize is a commodity crop providing millions of people with food, feed, industrial raw material and economic opportunities. However, maize yields in Africa are relatively stagnant and low, at a mean of 1.7 t ha⁻¹ compared with the global average of 6 t ha⁻¹. The yield gap can be narrowed with accelerated and precision breeding strategies that are required to develop and deploy high-yielding and climate-resilient maize varieties. Genomic and phenotypic selections are complementary methods that offer opportunities for the speedy choice of contrasting parents and derived progenies for hybrid breeding and commercialization. Genomic selection (GS) will shorten the crop breeding cycle by identifying and tracking desirable genotypes and aid the timeous commercialization of market-preferred varieties. The technology, however, has not yet been fully embraced by most public and private breeding programmes, notably in Africa. This review aims to present the importance, current status, challenges and opportunities of GS to accelerate genetic gains for economic traits to speed up the breeding of high-yielding maize varieties. The first section summarizes genomic selection and the contemporary phenotypic selection and phenotyping platforms as a foundation for GS and trait integration in maize. This is followed by highlights on the reported genetic gains and progress through phenotypic selection and GS for grain yield and yield components. Training population development, genetic design and statistical models used in GS in maize breeding are discussed. Lastly, the review summarizes the challenges of GS, including prediction accuracy, and integrates GS with speed breeding, doubled haploid breeding and genome editing technologies to increase breeding efficiency and accelerate cultivar release. The paper will guide breeders in selection and trait introgression using GS to develop cultivars preferred by the marketplace.     

Breeding for provitamin A biofortification of maize (Zea mays L.)

Vitamin A deficiency is widely prevailing in children and women of developing countries. Deficiency of vitamin A causes night blindness, growth retardation, xerophthalmia and increases the susceptibility against epidemic diseases. Among different interventions of overcoming malnutrition, biofortification is the most acceptable and preferred intervention among researchers, growers and consumers. Maize is grown and consumed in those regions where vitamin A deficiency is most prevalent; thus, targeting this crop for provitamin A biofortification is the most appropriate solution. Different breeding strategies including diversity analysis, introduction and stability analysis of exotic germplasm, hybridization, heterosis breeding, mutagenesis and marker‐assisted selection are practised for exploring maize germplasm and development of provitamin A‐enriched cultivars. Genome‐wide association selection and development of transgenic maize genotypes are also being practised, whereas RNA interference and genome editing tools could also be used as potential strategies for provitamin A biofortification of maize genotypes. The use of these breeding strategies for provitamin A biofortification of maize is comprehensively reviewed to provide a working outline for maize breeders.     

Participatory plant breeding in maize: A case study from Gujarat, India

This paper describes how plant breeders and farmers worked together to produce improved varieties of maize for the low-resource farmers of the Panchmahals district of Gujarat, India. Initially, farmers tested a range of maize varieties in a participatory varietal selection (PVS) programme. However, none of these proved to be very popular with farmers, although farmers who had more fertile fields adopted the variety Shweta from Uttar Pradesh. Hence, in 1994 a participatory plant breeding (PPB)programme was begun to generate new, more appropriate varieties. Yellow- and white-endospermed maize varieties were crossed that had been either adopted to some extent following PVS or had attributes, such as very early maturity,that farmers had said were desirable. In subsequent generations, the population was improved by mass selection for traits identified by farmers. In some generations,farmers did this in populations which were grown by breeders on land rented from a farmer. Soil fertility management was lower than that normally used on the research-station. The breeding programme produced several varieties that have performed well in research-station and on-farm trials. One of them, GDRM-187, has been officially released as GM-6 for cultivation in hill areas of Gujarat state,India. It yielded 18% more than the local control in research-station trials, while being seven days earlier to silk. In farmers' fields, where average yields were lower, the yield advantage was 28% and farmers perceived GDRM-187 to have better grain quality than local landraces. PPB produced a variety that was earlier to mature than any of those produced by conventional maize breeding, and took fewer years to do so. The returns from PPB,compared to conventional breeding, are higher because it is cheaper and benefits to farmers are realised earlier. This revised version was published online in August 2006 with corrections to the Cover Date.     

玉米预防转基因漂移试纸条快速检测方法

本研究旨在使用试纸条检测方法在玉米苗期从常规玉米育种材料中发现转基因植株,以预防非预期的转基因漂移。以转基因和非转基因玉米为材料,以笔者过去开展转基因玉米材料筛选的经验总结为基础,开发出试纸条快速检测方法。本研究介绍了检测所需用品和取样方法,并且详细讨论了样品数量、操作步骤及注意事项等。还具体演示分析了2个典型检测案例的过程和结果。本方法的操作步骤简便易学,适合专业和非专业育种者或检测人员对田间材料在自查或检验中使用。熟练掌握试纸条快速检测法,能有效筛查和预防由于花粉或种子非预期混杂造成的转基因漂移。     

Chromosome doubling of haploid maize seedlings using nitrous oxide gas at the flower primordial stage

In maize, inbred lines are used for the production of hybrid varieties. Corn breeders and researchers have considered using haploids to develop inbred lines; however, this procedure has not been practically applied because of the inefficiency of chromosome doubling of maize haploid seedlings. In this report, a procedure has been developed to overcome this difficulty. Maize haploid seedlings obtained from eight different genotypes were treated with nitrous oxide gas (2 days at 600 kPa). Treatment at the six‐leaf stage (flower primordia formation stage) significantly increased the occurrence of fertile sectors on both tassels and ears so that approximately half (44%) of the treated haploids produced kernels after self‐pollination. In the control, only 11% of haploids produced selfed kernels owing to spontaneous chromosome doubling. A strong genotypic effect on the occurrence of fertile sectors after the treatment was observed. This procedure can be used for inbred line development in maize breeding programmes.     

Discrimination of haploid and diploid maize kernels via multispectral imaging

The use of doubled haploids (DHs) in maize has become ubiquitous in maize breeding programmes as it allows breeders to go from cross to evaluation in as little as 2 years. Two important aspects of the in vivo DH system used in maize are as follows: (i) the identification of haploid progeny and (ii) doubling of the haploid genome to produce fertile inbred lines. This study is focused on the first step. Currently, identification of maize haploid progeny is performed manually using the R1‐nj seed colour marker. This is a labour‐intensive and time‐consuming process; a method for automated sorting of haploids would increase the efficiency of DH line development. In this study, six inbred lines were crossed with the maternal haploid inducer ‘RWS/RWK‐76’ and a sample of seed was sorted manually for each line. Using the VideometerLab 3 system, spectral imaging techniques were applied to discriminate between haploids and hybrids. Using DNA markers to confirm the haploid/diploid state of the tested seed, for the majority of genotypes haploid identification was possible with over 50% accuracy.