Responses of Root Nodule Formation and Nitrogen Fixation Activity to Nitrate in a Split-Root System in Peanut (Arachis hypogaea L.)   总被引：1，自引：0，他引：1  

H. Daimon  & M. Yoshioka 《Journal of Agronomy and Crop Science》2001,187(2):89-95

Peanut is an important constituent of crop rotation systems with various vegetable crops, which need large amounts of inorganic nitrogen. Nitrate inhibits nodule formation and nitrogen fixation of the peanut plants in these cropping systems. To elucidate this nitrate-induced inhibition, an experimental method using a split-root system was designed and the inhibitory level of nitrate (14 m M ) was applied to half of the roots for 5 or 30 days in pot experiments. In the application of nitrate for 5 days, the dry weight, the nitrogen content, and both the number and the fresh weight of nodules for each half of the roots were unaffected by the nitrate applied to the other half. However, the nitrate induced significantly lower nitrogenase activity in the applied half. In the application for 30 days, nitrate induced a significantly higher nitrogen content in the applied half of the roots, and the inhibitory effect on nodulation and nodule development was observed not only in the applied half but also in the other half. Thus, the inhibitory effect of long-term nitrate application on the nodulation and nitrogenase activity of peanut may be systemic, but that of short-term nitrate application, in which external nitrate may regulate nitrogen fixation, may not be systemic.  相似文献   

Heterosis of interspecific soybean hybrids for traits related to N2 fixation     

P. B. Cregan  P. van Berkum  C. Sloger  R. G. Orellan 《Euphytica》1989,40(1-2):89-96

Summary Three greenhouse experiments were conducted to compare the performance of soybean (Glycine max (L.) Merr.), wild soybean (G. soja Sieb. et Zucc.), and soybean x wild soybean hybrids for traits relating to N₂ fixation including nodulation, acetylene reduction, nodule leghemoglobin concentration, and nitrogen (N) accumulation and dry matter (DM) accumulation. In all three experiments G. max generally exceeded G. soja in nodulation, acetylene reduction, and N and DM accumulation while the soybean possessed higher nodule leghemoglobin concentration. In Experiment I, the mean of the hybrids did not differ significantly from the G. max parent in nodule mass, acetylene reduction activity, nodule leghemoglobin concentration, or DM accumulation. The hybrids did exceed the soybean parent in N accumulation, thus demonstrating high parent heterosis. In Experiments IIA and IIB with a more carefully chosen set of G. soja parents, high parent heterosis of individual crosses was common. Across the three experiments average high parent heterosis was 34, 28, and 28%, respectively, for nodule mass, N accumulation, and DM accumulation. If one accepts the assumption that hybrid vigor results from the accumulation of dominant alleles, then these alleles could theoretically be accumulated via selection in a homozygous genotype. If this is true than the results of the experiments reported here suggest that interspecific soybean x wild soybean crosses could serve as sources of homozygous lines which would exceed currently available soybean cultivars in nodule mass, and N and DM accumulation.This work was supported in part by the USDA Competitive Grants Program, Grant 82-CRCR-1-1039 and Cooperative Agreement 58-32U4-2-370 between the U.S. Department of Agriculture and the Agronomy Department, University of Maryland, Scientific Article No. A-4648, Contribution No. 7644 of the Maryland Agricultural Experiment Station.  相似文献   

Chlorophyll fluorescence as a tool in soybean improvement for N2 fixation efficiency     

M. H. Paul  C. Planchon 《Euphytica》1990,45(1):43-47

Summary Chlorophyll fluorescence, and more particularly the fluorescence decrease ratio (Rfd) which indicates the potential photosynthetic activity of the leaf is highly correlated with the plant nitrogen fixation activity, at stage R₂ (onset of flowering), under controlled growth conditions, using nutrient solutions where mineral nitrogen supply is decreasing. The Rfd value affords the analysis of the efficiency of the nitrogen fixation related to the host plant and the rhizobial strain, and the characterization of the best strain-genotype pairs. The rapidity of the measurement together with the availability of portable fluorescence determination systems make possible an application to soybean improvement for increased nitrogen fixation.  相似文献   

A Treatment to the Isoline for Finite Element Solution to Ferrite-Martensite Microstructure     

Xie Xiaojia Liu Tianino 《保鲜与加工》1993,(2):137-141

The numerical solution of sample point stress field in finite element network of ferrite-martensite microstructure under finite deformation has a high-gradient distributive characteristic whose stress gradient between ferrite and martensite crystalline element is very high. If the interpolation method is used in the whole region,the isogram will be seriously smooth so that the original high-gradient sample point stress field will become untrue. This paper presents a new method for drawing isogram of ferrite-martensite microstructiire stress field by interpolating sample points in an element one by one. This method can make the post-treatment of high-gradient discrete stress field in crystalline network approach to a truer condition and solve the problem of arbitrary curve boundary of the deformed two phase steel.  相似文献   

飞来峡社岗堤水平位移监控指标拟     

黄善和  姚惠芹  段亚辉 《中国农村水利水电》2007,(6):89-91

针对飞来峡社岗堤的结构特点，采用平面有限元结合强度储备法分析研究了大坝特征点坝顶位移变形规律，得出在多种水位组合情况下大坝坝顶的水平位移，并用一元多次回归方法建立了坝顶水平位移与上游水位的关系模型，拟定了该坝段的水平位移安全监控指标。这些水平位移监控指标可供该坝段实际运行观测时参考，为监控大坝安全运行提供了重要依据。  相似文献   

粪肥添加明矾对降低农田磷和重金属流失的作用   总被引：1，自引：0，他引：1  

章明奎  郑顺安  王丽平 《水土保持学报》2007,21(1):65-67,175

施用粪肥引起农田氮、磷流失的增加已引起人们广泛的关注。为了解粪肥中添加明矾可否降低农田污染物的流失,采用化学分析与田间试验相结合的方法研究了添加明矾对粪肥中水溶性养分和重金属浓度及施粪肥后农田养分、重金属流失的影响。结果表明,粪肥中添加明矾可大大降低其中的水溶性P和重金属浓度,其中水溶性P的下降幅度达79.3%。添加明矾后,粪肥施入农田形成的径流中P和重金属浓度明显低于不添加明矾的处理。但添加明矾对农田可溶性总N、NO3-N和NH4-N流失的影响不大。粪肥中添加明矾不会引起地表径流中铝浓度明显增加,对蔬菜产量影响不明显。  相似文献   

2:1矿物结构与阳离子固定及释放的关系   总被引：8，自引：0，他引：8  

FENG Ke  WANG Xiao-Li  WANG Xiao-Zhi  TANG Yan 《土壤圈》2003,13(1):81-86

The effects of different structures of 2:1 layer minerals,layer charge location,and changes of structure and charge during the weathering process on the fixation and release of interlayer cations are reviewed.It could be concluded that the fixation capacity is determined by the total amount of interlayer charge originating from both octahedral and tetrahedral sheets.The realtionship between interlayer cation fixation and octahedral structure of the secondary minerals may be different from that of the primary mineralls.The oxidation and reduction of cations with varable valence can greatly influence the cation-fixation capacity.  相似文献   

滑动接触失效判据的适用性研究     

沈萌红  崔云峰 《农业工程学报》2003,19(2):45-48

界面温度是影响滑动摩擦副失效的重要因素。该文在考虑热源强度的非均匀性和表面膜影响的基础上对微凸体滑动接触时的界面瞬时温度进行了研究,并通过量纲分析给出了计算混合润滑状态下微凸体滑动接触界面瞬时温度的近似公式。针对滑动接触失效时普遍存在的塑性变形特征,以该公式为基础并综合考虑表面膜丧失对微凸体塑性变形的影响,对摩擦副失效的温度判据——Blok闪温理论、临界速度和临界PV值等判据的适用性问题进行了分析。指出对于不同的微凸体几何特征、压力、速度组合,发生失效时的界面温度可低于或高于Blok闪温,并据此给出了Blok闪温理论的适用范围。  相似文献   

马占相思根瘤菌结瘤固氮特性的分析   总被引：1，自引：1，他引：1  

蒋艳明  凌云  秦建丽  侯远瑞  韦莉莉  栾桂龙  樊妙姬 《广西农业生物科学》2005,24(3):215-219

相思属（Acacia）树种是速生的热带、亚热带豆科植物。对现在大面积种植的相思树品种——马占相思的根瘤菌进行分离和筛选，获得菌株若干株，对它们的结瘤固氮特性和对马占相思、大叶相思及厚荚相思生长的影响等进行了初步研究。结果表明。无氮条件下接种马占相思根瘤菌，能显著促进这3个树种的株重、株高和生物量的增长；苗圃接种马占相思根瘤菌。马占相思苗高增加27．6％，地径增加14．8％，植株鲜重增加32．6％，结瘤数增加83．8％。  相似文献   

分子氢对红萍固氮活性的支持作用(英文)     

宋未  徐瑞姬  吴天云  尤崇杓 《核农学报》1988,2(3):177-183

本工作研究了分子氢对不同生长条件下三种红萍:细绿萍(Azollsa filiculoides),卡洲萍(Azolla caroniana)和小叶萍(Azolla microphylla)的固氮活性的支持作用,结果表明,在5000—20000lx不同光照强度下,分子氢对红萍固氮活性均有支持作用,当光照强度为10000lx时,10％的分子H_2可使红萍的固氮活性增加30—80％,在5000lx弱光条件下,相同浓度分子氢使红萍固氮活性增加的幅度比10000lx光照时大。在相同的光照条件下,大叶萍的固氮活性较高,分子氢对其固氮活性的支持作用也较强,说明了在萍藻共生体系中,光能利用、固氮效率与分子氢利用效率呈正相关。同时,分子氢对于红萍固氮活性受尿素毒害所致的抑制也有减慢作用。在培养液中尿素浓度超过5ppm时,红萍的固氮活性受到抑制,当尿素浓度达到50ppm时,其固氮活性抑制率达50—60％,但20％的分子氢可使其固氮活性恢复到正常培养下的70％以上。在一定的尿素浓度范围内,红萍固氮活性受抑程度愈大,分子氢对其减慢的作用也愈强。  相似文献