玉米种子杂种优势的利用

经多年研讨,种性不同的玉米杂交后所产生的种子比亲本自交产生的种子具有杂种优势,优势率10%左右,这种优势可应用到玉米生产上。利用方式：种性不同的杂交种间,混种和立体栽培,但在应用前要先进行组合试验,注意选择血缘关系远、粒色相同、株高差异不太大等优缺点互补的组配用于生产。     

外源果糖、葡萄糖与一氧化氮供体(SNP)对玉米种子萌发的影响

测定了一氧化氮供体(SNP)、葡萄糖(G)、果糖(F)单独或组合浸种发芽特性,探讨了玉米种子萌发过程中信号传导途径。结果表明,各处理不同程度提高了玉米种子发芽指数、根长、苗高、根干重、苗干重、β-淀粉酶活性和早期萌发率,通过测定萌发早期不同时间段种子含水量证实,不是由于促进种子吸胀引起的。进一步用果糖、葡萄糖分别与SNP混合后浸种,G与SNP单独浸种在各项指标中表现出相同的趋势,相对于G、SNP单独处理,G+SNP对苗干重和根干重影响小于二者单独处理且差异显著。F对各项指标的影响弱于SNP;相对于F,F+SNP浸种提高了根和苗的干重。G+SNP浸种对β-淀粉酶活性的影响相对于单独处理具有趋中的趋势,而F+SNP则低于二者单独处理。表明葡萄糖与一氧化氮可能存在相同的信号途径,而果糖则有另外的信号通路。     

玉米种子活力的杂种优势分析

对12个玉米组合及其亲本的种子活力指标进行了杂种优势和亲子相关分析。结果表明,所有玉米种子活力指标均表现正向杂种优势。F₁代田间幼苗干重与父本值、高亲值、双亲差值呈显著正相关;F₁代低温发芽率与双亲差值呈显著负相关;F₁代发芽指数与母本呈显著正相关;F₁发芽势与母本值、低亲值呈显著正相关;F₁代田间出苗率、幼苗高、标准发芽率、活力指数受亲本的影响较小,与父本、母本、中亲值、高亲值、低亲值和双亲差值相关系数均不显著。     

玉米种子萌发阶段的吸水率研究

研究采用13个玉米杂交种及其相应的亲本自交系共32个基因型为材料,在人工控制条件下,研究种子萌发率达到60%以上时的吸水率.结果表明,不同基因型的吸水率差异很大,最低仅27.17%,最高达39.88%;一般情况下,自交系的吸水率高于杂交种的吸水率;杂交种及其相应亲本自交系的吸水率表现为多数杂交种低于双亲自交系,少数杂交种介于双亲自交系之间,1个杂交种比双亲自交系更高.双亲自交系吸水率高于相应杂交种的吸水率这一现象预示着种子萌发阶段吸水率的高低可能与基因型的抗旱性有关。     

玉米种子室内发芽率与田间出苗率的相关性研究

发芽率是决定种子用价的依据,是种子质量的重要指标之一.发芽率直接影响田间出苗率,通过对玉米种子发芽率与田间出苗率的调查与相关回归分析,得出两者之间呈直线正相关,相关系数r=0.936 7.回归方程y=0.86x+8.29,为玉米播种保全苗提供科学依据。     

丸粒化玉米种子干燥质量的试验研究

根椐种子发芽率的数学模型,研究热风温度和种子初始水分对种子发芽率的影响。结果表明,随着热风温度升高,种子发芽率损失速率将增大,热风温度在45℃以下,为玉米种子干燥过程中的安全热风温度;随着种子初始水分的增大,种子发芽率损失速率将增大,种子的初始水分越大,选择的热风温度越低。经发芽率实验证明,玉米种子经丸粒化后,发芽率没有变化。在低水分情况下,丸粒化种子比未丸粒化种子发芽率稍高,丸粒化种子含水量在丸粒化前、丸粒化后及贮存一定时间无太大变化,丸粒化种子的加工工艺和干燥工艺合理。     

霉菌对储藏期玉米种子发芽率的影响

研究了霉菌对储藏期玉米种子发芽率的影响,结果表明．当储藏玉米水分为14．5％和16．O％时,30℃下储藏50d,霉菌带菌量显著增多．发芽率降幅达到13％和34％;降低储藏温度可以抑制霉菌的生长．降低霉菌对玉米发芽率的影响。进一步的研究表明．玉米种子储藏在高湿环境下．子粒上含有分解能力强的霉菌种群或原始霉菌带菌量较高等因素均可加速种子发芽率的下降。     

对当前玉米种子标签标注问题的思考

农作物种子标签真实制度是《中华人民共和国种子法》确立的一项基本制度,要求种子生产商、进口商或分装单位必须在种子标签上真实、合法、规范地标注相关信息。但当前玉米种子标签标注潜在问题之多、隐患之大,令人忧虑。为此,本文就在市场检查中发现的问题、产生的原因、带来的危害及对策建议谈几点粗浅的思考。     

浅析我国玉米种子加工技术的现状与发展趋势

概述了我国玉米种子加工技术发展的历史与现状,对我国玉米种子加工技术今后的发展方向提出了建议。提高玉米种子加工技术水平,实现玉米种子的精细加工,才能提高我国玉米种子加工质量和商品竞争力,促进玉米产业的发展与进步。     

玉米种子水分变化及烘干对芽率的影响

室内发芽试验结果表明,在正常条件下,玉米种子含水量在25%~30%之间,存在着极显著差异,低于25%种子发芽率趋于正常发芽水平;高于30%在不同品种和不同含水量之间存在着显著差异,但总的趋势是随着含水量降低芽率提高较为明显。对玉米种子进行烘干,种子水分高于27%芽率降低明显。玉米种子烘干与品种、水分和温度有着密切的关系。     

杂交大豆配合力及杂种优势分析

为了提高杂交大豆育种效率,进一步提高杂交大豆产量。本研究以5份大豆细胞质雄性不育系为母本,12份恢复系为父本,采用NCⅡ设计方法组配60个杂交组合,对产量、单株荚数、单株粒数和每荚粒数分别进行杂种优势、配合力效应、及其与F1性状的相关性分析。结果表明,F1产量性状中亲优势组合占全部组合的55%,超高亲优势组合占30%,中亲和超高亲优势均?20%的占15%。单株荚数、单株粒数、每荚粒数等产量相关性状的中亲优势组合分别占55%、56.67%和23.33%,超高亲优势率均为负值。17份亲本材料的一般配合力（general combining ability,GCA）变化范围为-27.94%～56.62%,其中6份材料表现为正效应;30个杂交组合的特殊配合力（special combining ability,SCA）为正值,占总体的50%。此外,SCA与F1籽粒产量和单株荚数的杂种优势及其性状值均相关;GCA与产量性状值和单株粒数的中亲优势呈极显著相关,与单株荚数的中亲优势、单株粒数、每荚粒数的超高亲优势及性状值呈显著相关;各性状SCA与GCA之间不相关。单株荚数和单株粒数对产量的贡献较大。产量杂种优势强的组合双亲除具有高的一般配合力,而且兼具有较高的特殊配合力。     

Combining ability analysis to identify suitable parents for heterosis in seed cotton yield,its components and lint % in upland cotton

Combining ability and heterosis were studied in a 6 × 6 diallel cross to see the nature of gene action in Upland cotton (Gossypium hirsutum L.) during 2002 to 2004. Analysis of variance revealed highly significant differences among all the F₁ and F₂ hybrid means and their respective six parental values for all the traits examined. In both generations, the mean squares due to general combining ability (GCA) and specific combining ability (SCA) were also highly significant. SCA genetic variances were greater than GCA and more important for the traits, i.e. boll weight, boll number and seed cotton yield per plant, showing the predominance of non-additive gene action. Lint % in both generations and boll weight in F₂s only were controlled by additive type of gene action due to maximum GCA variances. Cultivar CIM-1100 was found to be the best general combiner and its utilization produced valuable hybrids with desirable SCA in both generations. F₁ and F₂ hybrids, viz., CIM-1100 × CRIS-9, CIM-1100 × FH-682, CIM-1100 × BH-36 and CIM-109 × CIM-1100 as high × low and low × high parents performed well in SCA determination, outstanding mean performance and heterosis. Better SCA effects associated with useful heterosis were more pronounced for yield traits. In F₁ hybrids, maximum heterosis was observed for seed cotton yield followed by boll number, boll weight and lint %. The heterosis over better parent was +3.13 to +65.63% for bolls per plant, +0.75 to +24.40% for boll weight, +0.82 to +115.22% for seed cotton yield and +0.27 to +3.88% for lint %. Involvement of CIM-1100 in most of the F₁ and F₂ hybrids resulted in the synthesis of superior genotypes for most of the traits studied. Inbreeding depression was elevated in good performing hybrids and was the highest for seed cotton yield. Highest yielding F₁ hybrids yielded lesser in the subsequent generation due to over-dominance and inbreeding depression, whereas moderate yielding F₁ hybrids were found more stable even passing through process of segregation due to additive gene action. The combined performance of F₁ and F₂ hybrids could be a good indicator to identify the most promising populations to be utilized either as F₂ hybrids or as a resource population for further selection.     

Utilization of heterosis in corn breeding and the production of hybrid seed

Summary The phenomenon of heterosis or hybrid vigour was recognized byKoelreuter, 1761, and in all probability by earlier naturalists. The explanation of heterosis, however, required modern genetics and is of recent attainment.The utilization of hybrid vigour in practical breeding has had greatest success in maize. The essential feature of the breeding technique is the evaluation of combining ability of inbred lines. Hybrid seed is produced by combining the appropriate lines in single, double and other crosses. The theoretical possibility of obtaining a homozygous line equalin vigour to the best hybrids, appears to be beyond reach because of the large number of dominant vigour genes involved. This fact diverts current attention toward improvement in technique directed toward cheaper production of hybrid seed.

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Résumé Le phénomène de hétérose ou de vigueur hybride a été déjà observé et reconnu parKoelreuter en 1761 et même très probablement par des naturalistes, dans des temps encore plus anciens. Néanmoins l'explication de l'hétérose n'est que d'une portée assez récente, ce phénomène n'ayant pu être expliqué que par les connaissances de la génétique moderne.L'utilisation de la vigueur hybride dans l'application pratique a été le plus réussi dans la production du mais. Le trait principal de la technique de la production repose sur l'évaluation de la propriété à s'unir des lignées consanguines. On obtient les semences hybrides en combinant les lignées appropriées par des croisements simples doubles et autres.

     

甘蓝型油菜种子贮藏蛋白遗传距离与杂种优势关系研究

对38份不同生态区来源的甘蓝型油菜种质进行了贮藏蛋白电泳多态性分析,并对165个杂交组合农艺、品质性状表现及杂种优势与亲本贮藏蛋白距离进行相关分析,探讨了贮藏蛋白标记遗传距离辅助甘蓝型油菜农艺及品质杂种优势利用的可能性。结果表明：甘蓝型油菜种子贮藏蛋白多态性丰富;谷蛋白标记遗传距离（GDglu）、清蛋白标记遗传距离（GDalu ）与农艺、品质性状杂种后代表现及中亲优势存在不同程度的相关性,可以利这种相关性及谷蛋白标记遗传距离聚类辅助甘蓝型油菜杂交育种和品质育种的亲本选配,提高选配效率。     

甘蓝型油菜杂种优势及其与亲本配合力和亲本系数间的关系

用１４个亲本所配制的９１个杂交组合进行产量比较试验,分析组合的产量优势,及其与亲本的配合力和亲本系数的关系,结果表明：油菜杂交种的产量优势普遍存在,４９．５％组合的超亲优势达到了显著水平,配合力、亲本系数与杂种产量和杂种优势间均存在极显著的相关,杂种组合选配时应考虑配合力和亲缘关系。６个最高产杂种组合的分析表明,杂交种亲本的亲缘关系较远、配合力较高,则产量优势明显。这６个组合的亲本中均含有中国亲本。     

玉米优化施肥模式的研究

通过常规施肥模式下磷、钾用量基础上的氮肥用量试验;氮、磷用量基础上的钾肥试验;氮、钾和密度的三个因素试验及优化施肥模式与常规施肥模式的对比研究,提出了优化施肥模式对提高氮肥肥效、增加玉米产量具有显著作用。     

Use of random amplified polymorphic DNA markers to estimate heterosis and combining ability in tomato hybrids

Random Amplified Polymorphic DNAs (RAPD) were used to estimate genetic distances and determine the correlation between genetic distance and hybrid performance of 29 tomato lines that were the parents in a diallel mating design. Among 97 observed bands, 69 showed polymorphism and were used for establishing genetic distances based on the Nei coefficient between parents. A UPGMA dendrogram and Multi-Dimensional Scaling (MDS) analysis based on Nei genetic distances clearly clustered each group, confirming the variation at a molecular level. Correlations between genetic distances of the parents and performances of hybrids were established for various quantitative traits. Significant correlations were found between RAPD markers estimated genetic distances and MPH, HPH, SCA for some traits. The low correlation between parental genetic distances and hybrid performances for some quantitative traits suggested that RAPD markers have low linkage to Quantitative Trait Loci (QTLs) or have inadequate genome coverage for these traits. The results indicated that RAPD markers can be used as a tool for determining the extent of genetic diversity among tomato lines, for allocating genotypes into different groups and also to aid in the choice of the superior crosses to be made among tomato lines, so reducing the number of crosses required under field evaluation.     

玉米多穗现象研究进展

多穗是玉米果穗在形成过程中受遗传和环境双重影响而异常发育的现象,分为分蘖多穗和单秆多穗,其中单秆多穗又分为多节多穗和一节多穗。对双穗遗传研究证明,多穗性状为隐性遗传,由基因的累加效应即多基因控制,属于数量性状遗传范畴。密度、氮素营养胁迫、温度、水分和光照以及玉米螟、蚜虫、玉米叶斑病等危害都会影响玉米果穗数量。大量培育优良玉米种质资源及混合选种可能是造成玉米雌穗异常发育的原因之一。一节多穗的出现跟环境密切相关,密度越大、播期越晚,多穗率越高,高温干旱、拔节期水肥过多、激素调控也是形成一节多穗的重要原因。因此,构建稳定的多节多穗和一节多穗遗传群体,通过分子标记等技术,确定控制该性状的基因,不仅可以在分子水平揭示该现象,还可用于辅助育种。