Direct and Residual Contributions of Symbiotic Nitrogen Fixation by Legumes to the Yield and Nitrogen Uptake of Maize (Zea mays L.) in the Nigerian Savannah

Field experiments were conducted to determine the direct and residual contributions of legumes to the yield and nitrogen (N) uptake of maize during the wet seasons of 1994 and 1995 at the University Farm, Abubakar Tafawa Balewa University, Bauchi, Nigeria, located in the Northern Guinea savannah of Nigeria. Nodulating soybean, lablab, green gram and black gram contributed to the yield and N uptake of maize either intercropped with the legumes or grown after legumes as a sole crop. Direct transfer of N from the nodulating soybean, lablab, green gram and black gram to the intercropped maize was 24.9–28.1, 23.8–29.2, 19.7–22.1 and 18.4–18.6 kg N ha^–1, respectively. However, the transfer of residual N from these legumes to the succeeding maize crop was 18.4–20.0, 19.5–29.9, 12.0–13.7 and 9.3–10.3 kg N ha^–1, respectively. Four years of continuous lablab cropping resulted in yields and N uptake of the succeeding maize crop grown without fertilizer N that were comparable to the yields and N uptake of the succeeding maize crop supplied with 40–45 kg N ha^–1 and grown after 4 years of continuous sorghum cropping. It may therefore be concluded that nodulating soybean, lablab, green gram and black gram may be either intercropped or grown in rotation with cereals in order to economize the use of fertilizer N for maize production in the Nigerian savannah.     

Effect of sodium nitrite and sodium chloride on growth of lactic acid bacteria.

The effect of NaNO2 and NaCl on the growth of 24 lactic acid bacteria strains isolated from vacuum-packed cooked ring sausages were examined by analyzing different growth parameters with Bioscreen. NaNO2 had a very limited effect on the growth of lactic acid bacteria at 50 and 100 mg/l but at 400 mg/l a more pronounced inhibitory effect was found. Bacterial growth was enhanced by 1-2% (w/v) of added NaCl, while NaCl concentrations above 3% (w/v) had a clear inhibitory effect. Leuconostoc isolates seemed to be more sensitive to sodium nitrite and sodium chloride than homofermentative lactobacilli strains. Among homofermentative lactobacilli, the strains resembling Lactobacillus curvatus were more sensitive to NaCl than those resembling Lactobacillus sake.     

小叶锦鸡儿根瘤固氮活性的动态变化

对多年生小叶锦鸡儿不同生育期根瘤固氮能力、不同树龄小叶锦鸡儿根瘤固氮能力进行调查,结果表明:开花期固氮酶活性最高,此时土壤含氮量和植株含氮量最高;新瘤多发生于果后营养期,植株生物量的峰值出现在结实期;二年生和五年生植株的根瘤固氮能力强于三年、四年生植株,随生长年限的延长,植株生物量逐渐增大,含氮量呈小幅度下降趋势。     

基于纵向传导的蔬菜批零价格关系研究——以北京市果类蔬菜为例

从蔬菜产业的纵向看,批发和零售是两个重要环节,蔬菜批发价格和零售价格的走势以及它们之间的关系是各界关注的焦点。本文以北京市场为例,以番茄和黄瓜两种果类蔬菜的按日批零价格为对象,运用有限分布滞后模型和误差修正模型进行实证分析,研究蔬菜批零价格间的传导关系,并在此基础上揭示蔬菜批发价格在蔬菜价格形成中的作用。研究发现:蔬菜批零价格走势基本一致,相关系数很高;批零价格间存在批发价格向零售价格单向传导的因果关系;批零价格的传导是顺畅的,但不同种蔬菜传导的时间效应有所不同;批发价格在蔬菜价格形成中占据主导作用,当蔬菜价格受到冲击时,若零售价格过高则其会向着批发价格下调,若批发价格过高则零售价格会随之走高。     

大豆GmNRT1.2a和GmNRT1.2b基因的克隆及功能探究

拟南芥中硝酸盐的吸收、转运和分配是通过硝酸盐转运蛋白(nitrate transporter, NRT)实现的。尽管之前的生物信息学分析推测大豆GmNRT1.2s可能参与共生固氮过程,但尚未开展相应的功能研究。本研究通过对其表达模式分析収现,GmNRT1.2a和GmNRT1.2b分别在根和叶中高表达,且受硝酸盐诱导,在接种根瘤菌与结瘤因子(nodfactors,NFs)后表达量明显升高。功能研究结果显示,过表达GmNRT1.2a或GmNRT1.2b后大豆根瘤数目显著增加。本研究为深入探究GmNRT1.2a和GmNRT1.2b调控大豆共生固氮过程的分子机制提供了一定的数据支持。     

自动润滑装置在数控无卡轴旋切机上的应用

数控无卡轴旋切机的刀台进给系统通过丝杠螺母的传动可实现刀体座的进退,传动丝杠螺母都是依靠人工润滑,如果润滑不及时就会出现粘牙现象而导致整个设备不能工作。介绍了一种自动润滑装置,其可实现对丝杠螺母的自动润滑。     

Surgical treatment of a complicated distal tibia epiphyseal Salter–Harris type I fracture in a yearling

This article describes the management of a complicated distal epiphyseal Salter–Harris type I fracture of the left tibia in a yearling horse. Closed reduction and internal fixation was attempted in the first surgery using tension band wires. Due to fracture instability 2 weeks after surgery, a full-limb transfixation pin cast was applied to the tibia and maintained for 7 weeks to prevent further fracture displacement and to achieve axial alignment. The full-limb cast was maintained for a total of 12 weeks, including the time with the transfixation pin cast. Cast sores and tendon laxity resolved without further complications. Ten months after the first surgery, the fracture had radiographically healed, and the horse was sound at the walk and trot in a straight line.     

Effects of soybean variety and Bradyrhizobium strains on yield,protein content and biological nitrogen fixation under cool growing conditions in Germany

Soybean (Glycine max (L.) Merr.) is able to fix atmospheric nitrogen in symbiosis with the bacteria Bradyrhizobium japonicum. Because these bacteria are not native in European soils, soybean seeds must be inoculated with Bradyrhizobium strains before sowing to fix nitrogen and meet their yield potential. In Central Europe soybean cultivation is still quite new and breeding of early maturing soybean varieties adapted to cool growing conditions has just started.Under these low temperature conditions in Central Europe the inoculation with different, commercially available Bradyrhizobium inoculants has resulted in unsatisfactory nodulation. The aim of this study was: (i) to test the ability of commercially available inoculants to maximize soybean grain yield, protein content and protein yield, (ii) to study the interaction of different inoculants with different soybean varieties for two different sites in Germany under cool growing conditions over three years and (iii) to determine the variability of biological nitrogen fixation. Field trials were set up on an organically managed site at the Hessische Staatsdomäne Frankenhausen (DFH) and on a conventionally managed site in Quedlinburg (QLB) for three consecutive seasons from 2011 to 2013. Three early maturing soybean varieties—Merlin, Bohemians, Protina—were tested in combination with four different Bradyrhizobium inoculants—Radicin No.7, NPPL-Hi Stick, Force 48, Biodoz Rhizofilm—and compared with a non-inoculated control. Effective inoculation with Bradyrhizobium strains increased grain yield, protein content and protein yield by up to 57%, 26% and 99%, respectively. Grain yield, protein content and protein yield were generally higher in DFH. Average grain yield was 1634 kg ha⁻¹ in QLB (2012–2013) and 2455 kg ha⁻¹ in DFH (2011–2013), average protein content was 386 g kg⁻¹ in QLB and 389 g kg⁻¹ in DFH and average protein yield was 650 kg ha⁻¹ in QLB and 965 kg ha⁻¹ in DFH. The percentage of nitrogen derived from air (Ndfa) ranged between 40% and 57%. Soybeans inoculated with Radicin No. 7 failed to form nodules, and crop performance was identical to the non-inoculated control. Biodoz Rhizofilm, NPPL Hi-Stick and Force 48 are suitable for soybean cultivation under cool growing conditions in Germany. Interactions between soybean variety and inoculant were significant for protein content and protein yield at both sites, but not for nodulation, grain yield, thousand kernel weight and Ndfa. The variety Protina in combination with the inoculant Biodoz Rhizofilm can be recommended for tofu for both tested sites, while Merlin and Protina in combination with Biodoz Rhizofilm are recommended for animal fodder production in DFH. Animal fodder production was not profitable in QLB due to low protein yields.