浅析南方丘陵地区土地平整中的表土问题及对策

土地平整工程是土地整理项目的核心内容,但是,南方丘陵地区土地平整中出现不科学的工程措施导致的表土破坏的潜在问题却一直没有引起重视。在此,针对南方丘陵地区土地整理中土地平整工程的特点及现状,总结土地平整从规划设计到项目实施表土保护问题并进行分析,提出加强表土保护的相应措施。     

适合RAPD分析的三种玉米基因组DNA提取方法比较

本文通过对3种玉米基因组DNA提取方法的比较得出，DNA提取时采用一次氯仿／异戊醇抽提方法，得到的DNA质和量都较为理想，并且能够达到RAPD实验的要求。     

60Coγ射线种子辐射对大花高代 组培苗的生长及诱变效应

以0Gy、10Gy、50Gy、100Gy、150Gy和200Gy不同剂量的60Coγ射线辐射种子，研究其对大花高代组培苗生长影响的结果表明，在50~200Gy范围内，根和真叶的生长以及植株高度都不同程度地受到了抑制，且抑制程度与辐射剂量呈正相关，而10Gy则能促进根和真叶的生长。随着剂量的增高，死亡率增高，组培苗生长41d时的半致死剂量(LD50)为150Gy。各处理组培苗培养70d后，少量瓶内开花，出现花型、花色和花瓣变异。花型变异主要由对照的正常花形变为蝴蝶形。花色变异主要是颜色变浅，甚至变为白色。花瓣变异可由原来的单瓣变为重瓣花。以上结果表明，60Coγ射线辐射可以提高突变频率且诱变效应明显，有利于在大花高代育种中产生色彩丰富，花型、株型美观的变异类型     

Improving Drought Tolerance of Rice by Designed QTL Pyramiding

Drought is the most important factor limiting rice yields in the rainfed areas of Asia. To overcome the problem, we developed a new strategy ＇designed QTL pyramiding＇ to more efficiently develop drought tolerant （DT） rice cultivars. In the first phase of this strategy, we developed large numbers of introgression lines （ILs） in elite backgrounds using backcross （BC） breeding, each of which carries multiple genomic segments for improved DT from a known donor. Then, we genotyped all ILs with SSR markers to track the genomewide pattern of introgression in the DT ILs of 16 BC populations derived from crosses between 2 recipients （IR64 and Teqing） and four different donors. X^2 tests and linkage disequilibrium analyses of introgression in the DT ILs revealed significant frequency shifts at many loci across the genome and non-random associations at the multilocus level as a result of selection for DT in the ILs, which led us to the discovery of putative genetic networks underlying DT in the ILs. The networks each containing all DT loci detected in ILs from a BC population showed some interesting features.     

QTL analysis of seed dormancy in rice (Oryza sativa L.)

Effective cumulative temperature (ECT) after heading would be a more reasonable parameter for seed sampling of pre-harvest sprouting/seed dormancy (SD) tests in segregating populations than the days after flowering. SD is an important agronomic trait associated with grain yielding, eating quality and seed quality. To identify genomic regions affecting SD at different grain-filling temperatures, and to further examine the association between SD and ECT during grain-filling, 127 double haploid (DH) lines derived from a cross between ZYQ8 (indica)/JX17 (japonica) by anther culture were analyzed. The quantitative trait loci (QTLs) and their digenic epistasis for SD were identified using a molecular linkage map of this population. A total of four putative QTLs for SD (qSD-3, qSD-5, 6 and 11) were detected on chromosomes 3, 5, 6 and 11, together explaining 41.4% of the phenotypic variation. Nine pairs of digenic epistatic loci were associated with SD on all but chromosome 9, and their contributions to phenotypic variation varied from 2.87%–8.73%. The SD QTL on chromosome 3 was identical to the QTLs found in other mapping populations with different genetic backgrounds, which could be a desirable candidate for gene cloning and marker-assisted selection in rice breeding.     

Relative susceptibility of different male-sterile cytoplasms in sorghum to shoot fly, <Emphasis Type="Italic">Atherigona soccata</Emphasis>

Summary The shoot fly, Atherigona soccata is an important pest of sorghum, and host plant resistance is one of the most effective components for managing this pest. Most of the hybrids grown in India based on milo cytoplasm (A₁ cytoplasm) are highly susceptible to shoot fly. Therefore, the present studies were undertaken to evaluate different male-sterile cytoplasms (CMS) for their relative susceptibility to sorghum shoot fly. Oviposition and deadheart formation were significantly lower on the maintainer lines as compared to the corresponding male-sterile lines. Among the cytoplasms tested, A₄M cytoplasm showed antixenosis for oviposition and suffered lower deadheart formation than the other cytoplasms tested. The A₄G₁ and A₄M cytoplasms suffered lower deadhearts in tillers than the other cytoplasms. Recovery following shoot fly damage in A₄M, A₃, and A₂ cytoplasms was better than in the other cytoplasms tested. The larval and pupal periods were longer and male and female pupal weights lower in A₄M and A₄VzM CMS backgrounds compared to the other CMS systems. Fecundity and antibiosis indices on CMS lines were lower than on the B-lines. The A₄M cytoplasm was found to be relatively resistant to sorghum shoot fly, and can be exploited for developing shoot fly-resistant hybrids for sustainable crop production in future.     

小麦灌浆后期青枯骤死原因分析及控制

小麦灌浆后期植株衰老与活性氧自由基毒害和膜脂质过氧化密切相关。灌浆后期株体内活必砼谢平衡失调是青枯发生的主要内因：造成青枯的外因除与“Ｖ”型变温有关外，雨后骤晴的强光与高温协同作用亦是青枯发生的重要外因一。灌浆后期“Ｖ”型变温使麦株各器均受到伤害，尤其穗下茎受到伤害。青枯能否发生取决于植体内酶活力的高低、非酶清除剂含量的多少以及“Ｖ”型变温的强度和持续时间。选择优良品种、适时播种、合理施肥和加强     

珍稀树种伞花木组织培养技术研究

以伞花木下胚轴、子叶、腋芽和花柄作为外植体,采用MS作为基本培养基与不同种类、不同浓度的激素组合进行组织培养.结果表明,下胚轴、子叶和花柄愈伤组织诱导的最佳培养基分别为MS 6-BA1.0 NAA0.1、1/2 MS 6-BA2.0 IBA0.1和MS 6-BA10.0 IAA0.5;芽分化和增殖的理想培养基分别为1/2MS 6-BA1.0 NAA0.1、1/2MS 6-BA1.0 IBA0.1和MS 6-BA10.0 IAA0.5.以腋芽为外植体芽分化的理想培养基为1/2MS 6-BA1.0 IAA0.1.伞花木组培苗生根的理想培养基为1/2MS IBA2.0 BA0.2,生根率达80%以上.以泥炭和珍珠岩(2:1)混合作移栽基质,采用两步移栽法取得了较好的移栽效果,移栽成活率达90%.     

陆地棉（G．hirsutumL．）茎尖分生组织培养及其在基因导入上的应用

陆地棉栽培品种的种子无菌发芽１～３天。将萌动种子的顶端分生组织培养在无激素或附加低浓度激素ＭＳ基本培养基上，直接再生完整小植株。从顶端分生组织到再生植株所需的最短培养时间约１０天。顶端分生组织供体种芽的萌芽天数及其所连接的胚轴长度对植株再生频率有明显影响，但与品种的关系较小，不同品种均能获得再生植株。应用基因枪轰击法将ＣＰＴⅠ基因和ＮＰＴⅡ基因的重组质粒导入到棉花茎尖分生组织，培养获得卡那霉素抗性株。     

大豆花粉管通道技术转化雪花莲凝集素(GNA)基因

采用花粉管通道技术，用雪花莲凝集素基因（Galanthus nivalis agglutinin，GNA）转化吉林省主推品种吉林20号、吉林30号、吉林45号品种大豆。通过接蚜鉴定和PCR鉴定，从所获得的种子苗中筛选出转基因植株。对转基因植株的后代进行分子生物学鉴定：（1）PCR分析，转基因植株97TGR1和97TGR2的T2代表现阳性，第5代表现阳性纯合；97TGR1、97TGR2和98FD1～98FD20的T3代Western blotting检测结果证明，GNA基因在蛋白质水平有表达，最高表达量占总可溶性蛋白的0．7％；97TGR1、98TGR2和99JI45 TGR2的Southern blotting检测结果显示，GNA基因已插入大豆基因组；（2）遗传学分析，97TRG1的T2代呈孟德尔3：1分离，97TGR2的T3代出现种皮颜色不规则分离。经过抗蚜性鉴定和连续的筛选，获得抗性纯系；（3）抗蚜性鉴定，转基因株的T1、T2世代转基因植株可抑制蚜虫繁殖量50％～90％；（4）品系鉴定，转基因大豆的抗蚜性达到农学标准抗（R）和高抗（HR）水平；大面积环境释放试验自然感蚜鉴定，转基因系蚜虫发生的高峰比对照延迟，高峰期过后群体蚜量的下降速度也比对照快。本研究认为，大豆花粉管通道技术可以利用于大豆的转基因研究和应用中，GNA基因在改良大豆的抗蚜性上是可取的。