Nitrogen Fixation, Growth and Yield of Intercropped Mungbean (yigna radiata L.) and Groundnut (Aracbis bypogaea L.) as Affected by the Genotype

¹⁵N-aided investigations were conducted to ascertain the Nj fixation and the nitrogen (N) contribution by mungbean ( Vigna radiata L.) and groundnut ( Aracbis hypogaea L.) when intercropped with maize ( Zea mays ). The study involved growing seven genotypes of the above legumes with maize in alternate rows in two separate experiments. A sole crop of maize was used as the reference crop to determine N2 fixation by the ¹⁵N methodology. Significant genotypic differences in pod yield and stover N content were observed in intercropped mungbean and groundnut. The percentage N derived from the atmosphere showed a genotypic variation of 31 to 45 % (7 to 10 kg N₂ fixed ha⁻¹O in mungbean and 47 to 69 % (9 to 18 kg N₂ fixed ha⁻¹) in groundnut. Harvest index for N varied from 58 to 77 % in mungbean and 55 to 75 % in groundnut. In groundnut, the uptake of soil N was significantly affected by the genotype. Assuming that the N contribution to the soil by the helow-ground plant parts was negligible, the removal of seeds at maturity resulted in a negative N balance in the soil in all the genotypes of mungbean. In groundnut, some genotypes produced a positive N balance in the soil. Owing to high N₂ fixation capacity and low harvest index for N, groundnut showed a greater N supplementing ability than mungbean.     

Effects of Temporary Water Stress After Anthesis on Grain Yield and Yield Components in Different Tiller Categories of Two Spring Wheat Varieties

Water stress might limit grain yields of cereals under humid conditions. The objective of this study was to investigate the effect of a temporary water shortage at three different stages after anthesis on the grain yield and yield components of different tiller categories in two spring wheat varieties. A pot experiment with controlled water supply and rain shelters was conducted in 1984 and 1985 in Kiel, N. W. Germany. The water stress (pF 2.9 to 3.4) was imposed either between anthesis to early milk development of the caryopsis (WS1) (EC 65 to EC 72 according to Z adoks scale), early milk development to late milk development of the caryopsis (WS2) (EC 72 to EC 77) and late milk development to maturity (WS3) (EC 77 to EC 92). The control had a constant water supply throughout the growing season of between pF 2.2 to 2.5.
The water stress treatment WS1 significantly reduced the single plant yield by 10 % (1984) and 15 % (1985) in one variety (Selpek), whereas the other variety was unaffected. The response of both varieties to the two later treatments was smaller and insignificant.
In the first year the yield decrease in the variety Selpek after the WS1 treatment was mainly caused by a lower number of ears per plant compared with the untreated control (WS0). In the second year (1985) additionally a lower grain weight of the second category shoots caused by a reduction of the number of kernels per ear contributed to the decrease of the single plant yield. The yield component thousand grain weight could not compensate for the reduction in the number of kernels per ear.     

不同基因型烤烟的钾素营养特性

基因型差异是影响烟叶产量和质量的重要因素之一。本试验以74种烤烟品种(系)为试验材料,在无菌条件下研究低钾(0.05 mmol/L)、中钾(2.50 mmol/L)和高钾(20.00 mmol/L)3种钾浓度下各烤烟品种的钾素营养特性。结果表明:低钾处理抑制了烟草生长,其地上部鲜重、干重均低于高钾和中钾处理。随着钾浓度的降低,烟叶钾含量明显降低。对74种烤烟叶片钾含量进行聚类分析,结果表明,22种烤烟为富钾基因型烤烟,45种烤烟为高钾基因型烤烟,7种烤烟为低钾基因型烤烟。     

水稻镉、铅、砷低含量基因型的筛选

筛选低重金属含量水稻品种或减少水稻对种植土壤中重金属的吸收是控制稻米重金属含量的最直接有效的办法.本研究采用ICP-MS法测定了78份水稻品种的糙米中镉(Cd)、铅(Pb)、砷(As)含量.同时比较其中的20份品种在3个试验点的糙米Cd,Pb,As含量.结果表明:水稻籽粒中Cd,Pb,As的积累存在着明显的品种差异,其中Cd和Pb积累的基因型明显较As积累的基因型丰富;相关性分析表明,糙米中Cd和Pb含量存在极显著相关性(P＜0.01);筛选得到Cd,Pb含量低的基因型5个,Cd,As含量低的基因型1个,As,Pb含量低的基因型2个,Cd,Pb,As含量均低的基因型1个;土壤Cd,Pb,As含量对糙米Cd,Pb,As含量有较明显的影响;且糙米Cd,Pb和As含量对土壤环境的反应也各不相同.     

品种基因型和2,4-D浓度对青稞成熟胚出愈率的影响

 成熟胚培养是转基因的关键技术之一,研究品种基因型和2,4 D浓度对成熟胚培养的影响,有利于提高青稞转基因的效率。本文采用加入20g/L麦芽糖的MS培养基［m（麦芽糖）：m（蔗糖）=1∶2］和完全随机设计,分析了5种2,4-D浓度对5个青稞品种成熟胚出愈率的影响,比较了14个青稞品种的成熟胚出愈率。结果表明,2,4-D浓度和品种基因型均极显著地影响青稞成熟胚出愈率,两者之间具有显著的互作效应;青稞成熟胚出愈率随2,4-D浓度的增加而增加,并在4mg/L处理中出愈率达到最高,随后出愈率随2,4-D浓度的增加而降低;对照（0mg/L）的出愈率极显著地低于其他处理的出愈率,但其他4个2,4-D浓度处理的出愈率之间没有显著差异;14个青稞品种的成熟胚出愈率之间具有极显著差异,其中ZJ45等7个品种的出愈率达到了（90.00 ±7.07）%,显著高于D-5等6个品种的成熟胚出愈率。ZJ-45等7个品种可用于成熟胚培养;用PEG和双蒸水先后浸种3h和19h,将成熟胚置于加入20g/L麦芽糖和4mg/L 2,4-D的MS培养基［m（麦芽糖）：m（蔗糖）=1∶2］上培养是ZJ-45等7个青稞品种成熟胚培养的适宜方法。     

一种高效的农杆菌介导大豆子叶节转化体系的建立

以子叶节为外植体的农杆菌介导的大豆遗传转化体系,其转化效率受到受体基因型、无菌苗状态、丛生芽诱导及伸长和生根过程涉及的多种因素的影响。作者筛选了10个大豆栽培品种,选择诱导率最高的东农50作为转化的受体品种,建立子叶节为外植体的遗传转化化体系。还对萌发培养基中6-BA添加量和生根方式进行了研究。结果表明:萌发培养基中不添加6-BA伸长率可达2.51%～20.59%;伸长芽切下后浸入1mg/L的IBA中处理1min后于1/2MS培养基中生根,生根时间缩短,生根率提高至85.25%。经PCR检测,本转化体系的转化率最高可达7.10%。     

一株对鳞翅目蔬菜害虫具有广谱高毒力的新Bt菌株

从河北省土壤分离出苏云金芽胞杆菌(Bacillus thuringiensis,Bt)MB-15菌株,利用室内生物活性测定的方法,与Bt标准菌株HD-1的杀虫毒力进行比较,结果发现该菌株胞晶混合液对棉铃虫(Helicoverpaarmigera)、甜菜夜蛾(Spodoptera exigua)、小菜蛾(Plutella xylostella)、斜纹夜蛾(Spodoptera litura)和菜青虫(Pieris rapae)等5种鳞翅目蔬菜害虫的毒力均高于标准菌株Bt HD-1胞晶混合液。对发酵液各组分活性的分析发现,该菌株的上清液对胞晶混合物的杀虫活性有明显的增效作用。光学显微镜下观察该菌株伴胞晶体为菱形,SDS-PAGE分析显示其伴胞晶体主要由130.0 kDa和65.0 kDa两种晶体蛋白组成。利用PCR-RFLP对其杀虫基因型进行鉴定,结果表明该菌株含有cry1Ac、cry2Aa、cry1I和vip3Aa基因。推断该菌株是一株对鳞翅目蔬菜害虫的防治具有潜在的商业开发价值的Bt野生株。     

菜薹花药培养出胚率的影响因素研究

以红菜薹、白菜薹、菜心24个品种为试验材料,采用不同的培养基及培养方式,研究基因型、培养基成分及培养方式对不同品种菜薹花药培养诱导率的影响。结果表明:有15个品种的花药诱导出胚,各品种间的出胚率差异显著;红菜薹、白菜薹、菜心中出胚率最高的分别为H08-4(1.38胚/蕾)、B08-7(,0.757胚/蕾)、C08-4(0.682胚/蕾);采用Keller培养基+10%蔗糖+0.1%活性炭作为花药胚状体诱导培养基;花药培养出胚率以接种在双层培养基中的效果最佳。     

Frequency of latent equine herpesvirus type-1 infection among a sample of horses in the central North Island of New Zealand

ABSTRACT

Aim: To estimate the frequency of infection with equine herpesvirus type-1 (EHV-1) among horses from the central North Island of New Zealand, including the frequency of detection of the D₇₅₂ genotype.

Methods: Samples of retropharyngeal lymph nodes (RLN) and submandibular lymph nodes (SLN) were dissected from the heads of 63 horses that were humanely killed for various unrelated reasons between March and November 2015. DNA extracted from these tissues was subjected to enrichment for EHV-1 sequences by hybridisation with biotin-labelled EHV-1 specific probe, followed by recovery of EHV-1 sequences on streptavidin-coated magnetic beads. Enriched samples were tested for the presence of EHV-1 using nested quantitative real-time PCR. The EHV-1 amplicons were sequenced to determine the genotype of the virus.

Results: The median age of the horses was 6 (min 2, max 30) years, and 47/63 (75%) were Thoroughbreds. EHV-1 DNA was detected in RLN samples from 6/63 (10%) horses, and three of these horses were also positive for EHV-1 DNA in SLN. The remaining horses were negative for EHV-1 DNA in both RLN and SLN samples. The N₇₅₂ genotype was detected in all positive samples and the D₇₅₂ genotype was not detected in any of the samples.

Conclusions: EHV-1 continues to circulate among horses in New Zealand. The frequency of latent EHV-1 infection among sampled horses may have been underestimated due to the sensitivity limit of the assay or because of the limited anatomical sites sampled in the study. Lack of detection of the D₇₅₂ genotype suggests that infection with this genotype is not common in horses in New Zealand.

Clinical Relevance: If live animals are tested for EHV-1 using SLN biopsy it should be kept in mind that negative results do not rule out the presence of latent EHV-1 infection at other sites inaccessible for testing. The RLN appear to be the preferred sample for detection of EHV-1 DNA in horses following recent euthanasia.