籼型耐高温三系不育系巨风2A的选育

以优质常规材料9526为母本,宜陵1B为父本杂交,优选后代与宜陵1A回交而育成的早熟中籼型三系不育系巨风2A,具有耐高温、高异交率、高配合力,所配杂交稻熟色好等优点,应用前景广泛。2014年8月通过了湖北省农作物品种审定委员会的现场鉴定,2015年通过了湖北省审定。     

多叶苜蓿自交二代农艺性状分析

多叶苜蓿(Medicago sativa L.)的形态特征与苜蓿的产量和品质有直接关系,建立多叶苜蓿自交系进一步研究评估苜蓿多叶性状的遗传特性和规律,为多叶苜蓿新品系的选育提供科学依据。筛选多叶苜蓿自交亲本,进行亲本选配,田间试验观察测量多叶苜蓿自交S2代的多叶率、株高等农艺性状,与亲本材料进行比较分析。发现多叶苜蓿自交S2代农艺性状变异较为丰富,变异系数达19.54%~55.66%,分离出单株多叶率达100%的单株,S2群体生长速率变缓,多叶性状的表达呈多样化。     

Comparison of dietary essential amino acid requirements determined from group‐housed versus individually‐housed juvenile bluegill,Lepomis macrochirus

Two 60‐day experiments were conducted sequentially to determine (i) lysine requirement of juvenile bluegill, Lepomis macrochirus based on the dose–response method, (ii) requirements for other essential amino acids (EAAs) using whole‐body amino acid profile and (iii) whether differences in growth rates of group‐housed versus individually‐housed bluegills lead to different lysine requirement levels because of the presence and absence, respectively, of social hierarchies. Seven, semi‐purified, experimental diets (isonitrogenous, isocaloric) were prepared to contain graded levels of digestible lysine (10–31 g kg⁻¹). Experiment‐1 involved group‐housed bluegills (approximately 27 g, n = 10 fish/chamber, 4 chambers/diet) whereas experiment‐2 involved individually‐housed bluegills (approximately 30 g, n = 1 fish/chamber, 14 chambers/diet). Fish were fed twice daily to apparent satiation. Bluegill growth responses in both experiments generally improved (P < 0.05, anova ) with increasing dietary lysine levels from 10 to 16 g kg⁻¹, and then levelled off with further increase in lysine level (P > 0.05). Optimal dietary lysine level (digestible basis) was estimated to be 15 g kg⁻¹ based on broken‐line regression analyses of relative growth rate and feed conversion ratio with no differences being observed between the two rearing methods. Determined dietary requirement levels for other EAAs ranged from 2.4 g kg⁻¹ (tryptophan) to 15.3 g kg⁻¹ (leucine).     

卡放式接车台板总成在轮式拖拉机总装线上的设计与应用(上)

提供一种卡放式接车台板总成,不仅可使其接车台板总成的接车台面可依据需要,在外部传递的驱动力作用下,平升、平降或倾转,而且还解决了原有轮式拖拉机总装线接车下线技术所存在的不足,且其结构构思新颖,简单可靠,适用面宽,易于制作,具有可推广的价值。     

发动机装配线技术现状及发展趋势

汽车发动机在装配中,因为发动机工艺的复杂性、零部件的多样性,发动机装配线就显得十分重要。文章主要阐述了汽车发动机装配线应具有的要求以及发动机装配线应具备的基本功能,并对发动机装配线技术现状提出发展趋势的预测。     

玉米不同自交系幼苗光合对 UV-B 辐射增强的响应

为了探讨玉米不同自交系对UV-B辐射增强的响应，在摸拟光照培养条件下，研究了增强UV-B辐射对玉米不同自交系气体交换参数的影响。结果表明，五叶期UV-B辐射处理6 d后，供试的48个自交系中近一半以上材料的幼苗叶片光合速率、气孔导度和蒸腾速率显著降低10％以上，其材料比例分别为64．6％，47．9％，54．2％；而有62.5％的材料胞间CO2浓度表现为显著增加；相关分析发现，气孔导度与蒸腾速率对UV-B辐射增强的响应值间存在极显著正相关关系；根据气体交换参数对UV-B辐射增强的响应程度将48个材料分成6类，其中对增强UV-B辐射反应比较敏感的材料和能够忍耐UV-B辐射增强的材料均占12．5％。说明玉米不同自交系幼苗叶片气体交换参数对UV-B辐射增强反应敏感程度具有显著的基因型差异，从中能够筛选出对UV-B辐射增强反应敏感和有忍耐能力的材料。     

Changes in soil organic carbon and nitrogen in an area of Andisol following afforestation with Japanese cedar and Hinoki cypress

Abstract

To determine the rates of increase in C and N stocks in the soil and organic layers following afforestation in Andisols, we measured C and N densities in the organic and soil layers at depths of 0–5, 5–15 and 15–30?cm, together with a chronosequence analysis of 4-year-old, 14-year-old and 23-year-old Japanese cedar (Cryptomeria japonica) and 4-year-old, 12-year-old and 25-year-old Hinoki cypress (Chamaecyparis obtusa) plantations. The short-term changes in C and N were confirmed by repeated sampling 5?years after the first sampling. Tree growth, biomass accumulation and organic layers were much greater in Japanese cedar than in Hinoki cypress plantations. Soil C density (kg?m^?3) increased and bulk density decreased with stand age in the surface layer (0–5?cm). The average soil C accumulation rate was 22.9?g?C?m^?2?year^?1 for Japanese cedar and 21.1?g?C?m^?2?year^?1 for Hinoki cypress. Repeated sampling showed that the rate of increase in C in the surface soil was relatively slow in young stands and that soil C density (kg?m^?3) in the subsurface soil did not change over a 5-year period. Although N accumulated in the tree biomass and organic layers, the soil N density (kg?m^?3) did not change after afforestation. Although the andic properties of the soil and differences in the planted species did not influence the rate of increase in soil C, soil C density was expected to increase to a concentration greater than 80?g?kg^?1, possibly because of the large C accumulation capacity of Andisols.     

小型猪近交系新品种的培育与开发利用

小型猪近交系是中国农业科学院北京畜牧兽医研究所以2头五指山猪(Sus scrofa)为系祖,历时15年,采用“近亲交配”、提高营养水平、同期发情以及笼架等饲养技术,逐步克服后代畸形率高、弱仔率高、成活率低等3大阶段性难题,育成国际上首个近交系猪.本文介绍小型猪近交系的培育过程、近交系研究鉴定、新遗传资源种质特性,以及开发利用.该研究成果填补了国内外近交系猪的研究空白,为大型哺乳近交系动物培育理论和应用研究提供了新的视角.     

Screening of Probiotics Inhibiting E. coli K88 in vitro

The probiotics tested in the experiment were isolated from the intestinal of weaning piglets.The isolated probiotics and E.coli K88 were inoculated into the culture of intestinal porcine epithelial cell-1 (IPEC-1).The activity of lactate dehydrogenase (LDH) in the supernatant was measured after incubating for 2.5 h.At the same time, the probiotics and E.coli K88 were co-cultured in vitro, the number of E.coli K88 was counted and the probiotics which could be resistant to the E.coli K88 were selected 2.5 h later.The results showed that the Lactobacillus casei and Bacillus coagulans could significantly reduce LDH activity (P<0.05), decrease the damage of E.coli K88; Bacillus coagulans could inhibit the growth of E.coli K88.At the same time, Bacillus coagulans could resist high temperature, acid and bile salt.The results showed that Bacillus coagulans strains had great potential as the application of probiotics strains.The methods could be used as a model of screen probiotics which could inhibit the growth of E.coli K88 in vitro.     

小麦异代换系的选育及其应用研究进展

综述了小麦异代换系的主要选育方法,分析了小麦异代换系的应用现状及存在问题,提出了进一步的研究方向.