N添加对墨西哥柏人工林土壤碳氮磷含量 及其生态化学变化特征的影响

对墨西哥柏人工林开展野外施N试验,探讨不同施N量对林地土壤碳氮磷含量及其生态化学计量特征变化的影响。结果表明：（1）在墨西哥柏生长初期（5月）和速生期阶段（7月、9月）,土壤SOC在N3样地达到最大值,分别是2.39%、2.24%和2.30%;TN含量在N3样地达到最大值,分别是0.19%、0.18%和0.17%。（2）不同施N处理下林地土壤C/N呈先降低后增加的趋势,在11.66～14.35范围内波动。N添加对林地土壤N/P、C/P值的影响差异性较大。在N4、N5样地,土壤C/N、N/P、C/P值均显著高于N0样地。（3）同一施N样地内,不同生长阶段林地土壤SOC、TN、C/N和N/P含量变化不显著,但在N2、N3和N4样地,土壤TP含量、C/P值出现显著差异。（4）根据多因素方差分析结果,施N对土壤SOC、TP、TN、N/P和C/P均有显著影响。     

Oculomotor neurons in fish: electrotonic coupling and multiple sites of impulse initiation

Oculomotor neurons are electrotonically coupled in three teleosts. Electron microscopy revealed axosomatic synapses with close appositions of pre- and postynaptic membranes. Similar junctions are associated with electrotonic coupling in many other cases. Stimulation of the ipsilateral eighth nerve usually initiated impulses at sites distant from the cell bodies; stimulation of the ipsilateral ophthalmic nerve initiated impulses close to the cell bodies. Electrotonic coupling may synchronize impulses arising near the, cell bodies to generate synchronous muscle contractions. Impulses arising distant from the cell bodies may lead to contractions of graded strength.     

不同叶龄期氮磷钾缺失对棉花生长及养分积累的影响

[目的]利用不同叶龄期棉花营养供应的中断,探寻不同时期棉花缺素症状及其养分的吸收积累状况.[方法]设计缺N、缺P、缺K和对照处理的水培试验,分析测定棉花株高、叶面积、营养元素含量和干物质积累量等指标,研究了N、P、K素缺失对棉株生长性状及N、P、K养分吸收的影响.[结果]缺素对棉株的生长发育有明显的抑制作用,缺氮、缺磷、缺钾处理的棉株株高和倒四叶叶面积平均较正常棉株分别降低了37.4;、20.8;、27.6;和33.3;、32.5;、20.3;.同时,缺素严重影响了棉株对N、P、K养分的吸收积累,缺氮处理的棉株在四叶期、八叶期和十二叶期的N吸收积累量分别比正常棉株的降低了53.3;、37.8;和27.5;;缺磷处理的棉株在四叶期、八叶期和十二叶期的P吸收积累量分别比正常棉株的降低了75.2;、73.1;和74.1;;缺钾处理的棉株在四叶期、八叶期和十二叶期的K吸收积累量分别比正常棉株降低了44.9;、38.3;和37.4;.氮磷钾的缺失均会显著降低棉花整株干物质的积累量,分别比正常棉株下降了24.1;、13.4;和24.0;.[结论]大量元素的缺失显著影响棉花生长发育和光合产物的积累,在生育前期(八叶期以前)氮磷钾缺失显著延缓棉花生长和减少养分吸收,后期(十二叶期以后)氮磷钾缺失显著降低棉花干物质积累.因此,依叶龄合理施肥能及时供给棉花养分需求,提高养分利用效率,为棉花高效生产提供理论依据.     

双峰驼桡神经的解剖

双峰驼桡神经起于第８颈神经、第１、２胸神经腹侧支。桡神经的肌支主要分布于臂三头肌内侧头、外侧头、长头，时肌，腕桡侧伸肌，指内侧伸肌，指外侧伸肌，指总伸肌，腕斜伸肌及尺骨外侧肌。桡神经分出的前臂外侧皮神经分布于前臂外侧面的筋膜和皮肤，分出的其余皮支分布于前臂前外侧面、腕内侧面前部、掌内侧面和第３指系关节远轴侧面的筋膜和皮肤，还分布于腕关节囊的背侧面。前臂内侧皮神经也山桡神经分出，分支分布于前臂前内侧面，掌近端半部内侧面的筋膜和皮肤。     

冬小麦水氮配合关键期和亏缺敏感期的确定

 通过盆栽试验研究了干旱胁迫和正常供水条件下施氮对冬小麦的效应，以期确定出其水氮配合的关键期和亏缺敏感期。结果表明，干旱胁迫条件下，氮肥早施比晚施好，低量氮肥比高量氮好。而且不同施氮处理对有效穗数和穗粒数的影响差异显著，但对千粒重无明显影响。水氮配合条件下，氮素的作用得到充分发挥，产量大幅度提高，而且对有效穗数、每穗粒数和千粒重都产生显著的影响。拔节期是冬小麦对水氮配合效应的关键期和亏缺敏感期。拔节期供水供肥可以显著地提高产量，同时增加穗粒数和千粒重。分析其机制发现拔节期供水供肥可以促进作物地上部的迅速生长和发育，增强作物吸收和利用氮素的能力，同时还可延缓根系衰老，保持后期旺盛的根系活力。     

黄斑长翅卷叶蛾性信息素生物学研究初报

黄斑长翅卷叶蛾是我国北方果园中重要害虫之一。本文通过室内生物测定，确定了其性信息素腺体位于雌虫腹部８—９节节间膜；触角电位进一步证明了雄虫触角对１—５ＦＥ性信息素浓度有明显反应；大型风洞行为研究表明５ＦＥ可诱导的定向行为反应与３头活雌蛾基本一致，１ＦＥ抽提物与５ＦＥ诱导效果在低级反应中有显著差异，在高级反应中差异不显著。     

Study on the Key and Sensitive Stage of Winter Wheat Responses to Water and Nitrogen Coordination

Pot experiments were carried out to study the effect of nitrogen application on winter wheat under different status of soil moisture, so that the key and sensitive stage of winter wheat responses to water and nitrogen coordination were determined. The results showed that the application of N fertilizer was more effective in early stage than in later stage, and at the lower N rates than at the higher N rates under non-irrigated conditions. N treatments had great effect on spikelet bearing number and grain number per spike, but had no effect on 1 000-grain weight; Grain yield and yield component responses to N treatment were greater under irrigated conditions than under non-irrigated conditions. The joining stage was the key and sensitive stage of winter wheat responses to water and nitrogen coordination, and the grain yield, grain number per spike and 1000-grain weight increased, when water and N Fertilizer were applied at this stage. The mechanism is that water and fertilizer supply at joining stage can speed up the growth of above-ground crops, enhance the abilities to absorb and utilize nitrogen fertilizer, and meanwhile, delay the aging of the root and keep the root vigor for a longer period.     

Cerebellar Purkinje cell projection to the peripheral vestibular organ in the frog

Neurones located 200 to 300 microns from the surface of the auricular lobe of the frog cerebellar cortex, and identified as Purkinje cells, were activated antidromically from the eighth cranial nerve. A parallel anatomical study confirmed the existence of this projection. On the basis of these findings the existence of a cerebello-vestibular efferent system is postulated, the precise significance of which is as yet unclear. However, since Purkinje cells in other species have an inhibitory action on their target cells, the Purkinje efferent system to the vestibular organ may have an action similar to that ascribed to the olivo-cochlear bundle upon the cochlea, that is, to serve as an inhibitory control system.     

Auditory frequency-following response: neural or artifact?

An electrical response which reproduces the waveform and frequency of the sound stimulus can be recorded from the central neural pathway for audition. Controversy has existed for some years over whether this frequency-following response (FFR) is neural or an artifact such as remote pickup of the cochlear microphonic or cross talk in the recording system. Two experiments resolve this issue by demonstrating that the frequency-following response depends upon functionally intact neural pathways. The frequency-following response, as well as auditory evoked potentials, is abolished by section of the eighth nerve; it is reversibly abolished by cooling of the cochlear nucleus.     

长期施肥对水稻土有机氮组分及氮素矿化特性的影响

以湖南省3个国家级稻田土壤肥力变化长期定位监测点(新化、宁乡和桃江)的土壤为对象,研究了20年不同土壤培肥方式(不施肥、单施化肥、化肥配施中量/高量猪粪和化肥配施秸秆)对土壤全氮、有机氮组分及氮素矿化的影响.结果显示,与不施肥相比,单施化肥对土壤全氮的影响在新化和宁乡点均不显著,但化肥配施猪粪或秸秆在三个试验点均显著提高了土壤全氮、碱解氮和微生物量氮的含量.总体来看,长期施肥能够提高土壤有机氮各组分的含量,并提高氨基糖氮和氨基酸氮在全氮中的占比,但不同类型肥料施入后对有机氮组分的影响因试验点的不同而异,这可能是不同试验点土壤理化性质差异导致的.相关分析显示土壤酸解有机氮组分与氮矿化势极显著相关,且在三个监测点,有机物配施化肥的处理土壤氮矿化势均高于单施化肥处理.研究表明,虽然土壤性质上的差异可能导致土壤氮组分对施肥措施的响应不同,但有机无机肥配施提高土壤供氮潜力的效果均优于单施化肥.     

Physiological limits for "subliminal" perception

Cortical, subcortical, and peripheral sensory nerve potentials were studied in cats to determine comparative thresholds of response. Stimuli capable of eliciting responses in peripheral nerve also invariably elicited responses from thalamus and cortex. Together with relevant data from human studies, the results indicate that stimuli subthreshold for perception do not affect the nervous system. They also have implications for studies of "subliminal" perception.     

Plasticity of motor behavior in monkeys with crossed forelimb nerves

Monkeys in which nerves innervating the flexor muscles of the forearm and hand (the ulnar or the median nerve) had been surgically cross-united with the nerve innervating the extensor muscles (the radial nerve), and vice versa, showed excellent (ulnar-radial crosses) to moderate (median-radial crosses) control of movement performance after regeneration. Antagonistic movement responses were seen occasionally, but these were corrected almost immediately. Stimulation of the crossed nerves showed that they had innervated the antagonistic muscle groups. The results reveal the capacity of the primate central nervous system to adapt to gross disturbances imposed on the execution of movements by changes in peripheral innervation.     

N沉降下土壤动物群落的响应:1年研究结果总述2681258920

2003年7月至2004年8月,选择了苗圃、针叶林、混交林和季风林4个生态系统,采用模拟的方法,人为构建N沉降增加梯度系列,即对照、低N处理（50 kg/(hm2·a)）、中N处理（100 kg/(hm2·a)）、高N处理（150 kg/(hm2·a)）和倍高N处理（300 kg/(hm2·a)）,在14个月的时间内,对土壤动物群落在N沉降下的响应进行了持续观测研究.研究结果表明,土壤动物群落无论在时间尺度和空间尺度（垂直分布）都发生了明显的变化.生态系统类型的影响很显著,季风林和针叶林增长模式的不同,最终导致3个森林土壤动物分布格局的根本改变.苗圃样地N处理具有明显的阈值效应.虽然整体上森林样地N处理梯度未产生显著影响,但它在与不同植被、不同取样期的交互作用中可以清楚表现出来.N沉降存在明显的累积效应.在持续大量N沉降的作用下,动物向土壤深层趋避,显示N处理的负效应.N沉降的阈值效应和累积效应也都符合中度干扰理论.最后,该文还对N沉降对土壤动物群落的影响机制进行了初步探讨,认为N沉降可能通过对土壤无机环境的改变间接影响较高营养阶——土壤动物群落,而N沉降处理的阈值效应、生态系统成熟度及处理时间累积对试验效果的影响,本质上可能均反映了生态系统N饱和状态对N沉降的响应.      

青海省祁连圆柏天然林林地土壤生态化学计量特征

以青海省祁连圆柏天然林林地土壤为研究对象,分析土壤有机碳（SOC）、全N（TN）、全P（TP）及化学计量比对海拔与土层的响应及其与环境因子的关系,以期深入了解青海省祁连圆柏林土壤养分限制状况。结果表明:1）土壤SOC、TN、TP、C:P、N:P随海拔与土层深度增加均呈现减小趋势;不同海拔与土层深度间C:N无明显变化。SOC与TN在不同土层深度与海拔梯度间表现出协同变化特征;TP的空间变异性小。2）土壤理化性质、气候、植被因素对土壤C、N、P化学计量有显著影响（P＜0.05）。其中,土壤含水率是主要影响因素,解释了变异信息的44.0%。3）祁连圆柏天然林林地土壤C:P（57.96）、N:P（5.43）高于全国土壤平均水平（52.90、3.9）,说明土壤N有效性高,P素缺乏。林木正常生长受土壤中可利用性P限制。     

A comparison of crop data measured by two commercial sensors for variable-rate nitrogen application

Nitrogen (N) fertilizer rates applied spatially according to crop requirements can improve the efficiency of N use. The study compares the performance of two commercial sensors, the Yara N-Sensor/FieldScan (Yara International ASA, Germany) and the GreenSeeker (NTech Industries Inc., Ukiah, California, USA), for assessing the status of N in spring wheat (Triticum aestivum L.) and corn (Zea mays L.). Four experiments were conducted at different locations in Quebec and Ontario, Canada. The normalized difference vegetation index (NDVI) was determined with the two sensors at specific growth stages. The NDVI values derived from Yara N-Sensor/FieldScan correlated with those from GreenSeeker, but only at the early growth stages, where the NDVI values varied from 0.2 to 0.6. Both sensors were capable of describing the N condition of the crop or variation in the stand, but each sensor had its own sensitivity characteristics. It follows that the algorithms developed with one sensor for variable-rate N application cannot be transferred directly to another sensor. The Yara N-Sensor/FieldScan views the crop at an oblique angle over the rows and detects more biomass per unit of soil surface compared to the GreenSeeker with its nadir (top-down) view of the crop. The Yara N-Sensor/FieldScan should be used before growth stage V5 for corn during the season if NDVI is used to derive crop N requirements. GreenSeeker performed well where NDVI values were >0.5. However, unlike GreenSeeker, the Yara N-Sensor/FieldScan can also record spectral information from wavebands other than red and near infrared, and more vegetation indices can be derived that might relate better to N status than NDVI.     

Within-field nitrogen response in corn related to aerial photograph color

Precise management of nitrogen (N) using canopy color in aerial imagery of corn (Zea mays L.) has been proposed as a strategy on which to base the rate of N fertilizer. The objective of this study was to evaluate the relationship between canopy color and yield response to N at the field scale. Six N response trials were conducted in 2000 and 2001 in fields with alluvial, claypan and deep loess soil types. Aerial images were taken with a 35-mm slide film from ≥1100 m at the mid- and late-vegetative corn growth stages and processed to extract green and red digital values. Color values of the control N (0 kg N ha⁻¹) and sufficient N (280 kg N ha⁻¹ applied at planting) treatments were used to calculate the relative ratio of unfertilized to fertilized and relative difference color values. Other N fertilizer treatments included side-dressed applications in increments of 56 kg N ha⁻¹. The economic optimal N rate was weakly related (R ² ≤ 0.34) or not related to the color indices at both growth stages. For many sites, delta yield (the increase in yield between control N and sufficient N treatments) was related to the color indices (R ² ≤ 0.67) at the late vegetative growth stage; the best relationship was with green relative difference. The results indicate the potential for color indices from aerial photographs to be used for predicting delta yield from which a site-specific N rate could be determined.     

Physiological and Molecular Response of Wheat Roots to Nitrate Supply in Seedling Stage

The objective of this study was to understand the morphological, physiological, and molecular responses of wheat roots to nitrate supply at seedling stage. Two wheat genotypes, Jimai 22 and Shannong 15, were grown in Hoagland's nutrient solution with different nitrate levels at seedling stage. Results indicated that the plant dry weight and N accumulation increased with the increase of nitrate supply. The number of axial root, total uptake area (TUA), and active uptake area (AUA) increased with more nitrate supply. Correlation analysis indicated that significant positive correlations existed between N accumulation and dry weight, N accumulation and AUA, and N accumulation and AUA/TUA. Although, the expressions ofNRT2.1, NRT2.2, and NRT2.3 decreased with nitrate supply increased, the expressions of NRTI, NRT2.1,and NRT2.3 could maintain high level at N3 treatment. The free amino acid and NO3- content in shoot also increased with the increased nitrate application, but no significant difference was found in root among the treatments. These results implied that the increase of N uptake by nitrate supply was due to the morphological and physiological responses of wheat roots and the high expression level of TaNRT genes. Similarly, the contribution of morphological, physiological,and molecular parameters was different between two genotypes of wheat.     

模拟氮沉降对油松林土壤有机碳和全氮的影响

本文通过长期原位模拟氮沉降试验,研究暖温带油松林土壤有机碳和全氮对外源氮添加的响应过程与机制。从2009至2011年,氮处理水平分别为对照(0 kg/(hm2·a),N0),低氮(50 kg/(hm2·a),N1),中氮(100 kg/(hm2·a),N2)和高氮(150 kg/(hm2·a),N3)。利用土钻法研究油松人工林和天然林不同土壤深度土壤有机碳和全氮对模拟氮沉降的响应。结果表明,氮沉降降低了人工林和天然林不同土层深度有机碳含量,有机碳含量下降幅度随氮沉降量的增加而增大,且表层土壤(0~20 cm)下降幅度大于深层土壤(20~40 cm,40~60 cm)。天然林表层土壤有机碳下降幅度大于人工林。氮沉降显著增加了人工林表层土壤全氮含量(P0.05),但对天然林表层土壤全氮含量无显著影响(P0.05)。      

降雨条件下西安蔬菜地土壤中氮的迁移规律

[目的]研究西安市蔬菜地土壤中氮（N）元素在降雨条件下的迁移转化规律。[方法]采用自制的模拟降雨装置,通过室内模拟试验研究了降雨条件下土壤中N的迁移规律。[结果]每次降雨后,各个深度土壤的含N量均比背景值高;土壤含N量的变化呈现出明显的急剧变化段和缓慢变化段。土壤中含N量的最高值均出现在10～20cm土层,最低值出现在60～70cm土层,10和60cm是降雨条件下土壤含N量变化的折点;随降雨次数的增加这2个折点均有向下移动的趋势。在20cm以下土层中,3次降雨后同一深度处土壤的含N量依次为：N第1次〉N第2次〉N第3次。在60cm土层中,每次降雨后的土壤含N量均达最低值,约为730μg/g。[结论]该研究为合理施用氮肥提供了依据。     

不同灌溉和施肥水平对东尼罗河三角洲地区甜菜产量、品质及部分水分指标的影响

【目的】2008~2009、2009~2010年分别在埃及El-Sharkia省Zankalon研究站进行不同灌溉和氮肥水平对甜菜产量、品质及水分指标的影响试验。【方法】采用裂区设计,分别设3个灌溉处理即 I1（60%田间持水量）、I2（80%田间持水量）和I3（100%田间持水量）和3个施肥处理即N1（50 kg N/fed）、N2（70 kg N/fed）和N3（90 kg N/fed）。【结果】灌水处理I1的甜菜块根和糖产量最高、根径最大,其次为处理I2,处理I3的最低。随着灌溉水平的提高,甜菜块根长和蔗糖含量明显下降。当施用90 kg N/fed氮肥,甜菜根长、根径、块根和糖产量明显提高,但糖分则有所降低。灌溉和施氮肥处理均对蔗糖纯度没有明显影响。3个灌溉处理I1、I2和I3的水分利用量分别为3579.7、3042.0和2504.0 m2/fed,季节耗水量分别为58.12、52.06和47.29 cm,而甜菜块根产量、糖产量的水分利用率分别为15.86、13.78、13.35 kg 块根/m3水和2.73、2.61 and 2.56 kg 糖/m3水。随着施氮水平的提高,获得一定甜菜根产量和糖产量,所需的实际耗水量和水分利用率也不断提高。在东尼罗河三角洲地区的甜菜平均季节作物系数为0.87。【结论】可在东尼罗河三角洲地区推荐使用Kc经验值来计算耗水量。