马占相思人工林温湿效应的时空动态

对马占相思人工林温湿两方面11年定位观测资料进行了总结。分析了马占相思人工林空气及土壤温湿度在空间（水平的和垂直的）和时间尺度（年、季、日）上的动态变化。从功能上来看,可把马占相思人工林的温湿效应简要地概括为调温（湿季降温、干季保温0、滞缓温变以及增温3个方面,具体体现在：①约7龄的马占相思人工林即可表现出较为明显而稳定的温湿效应。林内11年的平均气温（21.7℃）比林外低0.5℃,表层土壤（0－20cm）的平均温度（21.3℃）比林外低2.0℃。马占相思林内极端最高温小于林外,极端最低温则高于林外。林分的降温效应湿季比干季明显,保温效应主要体现在湿季的深夜和干季气温较低的时候。②林内白天各垂直层的气温随距地高度的增加而降低,诳晚出现随高度增加气温升高的逆温现象。干季各层气温间的分异要比湿季明显。在湿季,土壤温度从地表层开始向下逐渐递减;干季0－5cm处的地温呈递减趋势,深于5cm则土温随浓度的增加而增加。一般林内的气温变化要滞后于林外1－2h。③马占相思林内的平均相对湿度为82％,比林外高4％。在晴天,林内相对湿度的变化呈“U”型,林内空气湿度随高度增加而下降,但在湿季,接近林冠约7m处的湿度要大于近地表和林冠上层。土壤湿度在0－40cm处随土层浓度的增加而增加,40－120cm处则随土层浓度的增加而逐渐减少。     

羊草草地生长季放牧山羊采食量和食性选择

在松嫩平原羊草草地,通过控制放牧实验对山羊的时限采食量和食性选择进行了研究。结果表明：（1）5－9月份,山羊的时限（1h）采食量平均为0.42kg干物质,其季节动态为5月份最低,随季节推移不断增大,8月份达到最大,9月份又有所减小;时限采食量基本上随放牧率减小而增大,但在最低放牧率小区有所减小。（2）山羊的食性选择随季节推移和放牧率不同而变化。（3）山羊对20－25cm高度草层的选择性最高;各高度草层的食性选择指数随季节推移和放牧率不同而变化;山羊对不同植物的高度选择性存在差异,但高度选择指数的最大值都在15－30cm范围内。     

蛋白质营养对异育银鲫生长和免疫力的影响

用蛋白质水平和必需氨基酸指数（EAAI）不同的饲料喂养异育银鲫,每种饲料喂3箱鱼,各组鱼根据所喂饲料蛋白质水平不同分别称为10％组、20％组、30％组、40％组、50％组,饲养6周和14周后分别作分析测定。结果表明,饲养6周后相对生长率随蛋白质含量的增加而升高,14周后则以40％组相对生长率最高,30％组、40％组、50％组差异不显著但均显著高于另两组;14周时10％组和50％组的蛋白质效率（PER）比6周时显著降低,且以30％组最高,相对生长率和PER均随EAAI下降而下降。免疫力以20％组最高,20％组和30％组差异不显著,而且免疫力也随EAAI下降而下降。上述结果说明生长速度最快的鱼其免疫力并不一定最佳。体脂含量的增加与免疫力下降有一定的相关性。     

黄土高原小流域不同地形下土壤有机碳分布特征

研究了黄土高原小流域尺度塬面、坡地、沟道和梯田4种地形条件下土壤有机碳总量和活性组分的分布、储量及碳库管理指数的差异.结果表明,小流域土壤有机碳和不同活性有机碳的变异系数介于32％-70％之间,表现出中到高度的变异特征.4种地形下各组分有机碳含量和储量以塬面土壤最高,沟道土壤最低,并随土层深度的增加而降低,降低程度随有机碳活性增强而增加.以塬面土壤为对照所获得的碳库管理指数可灵敏指示有机碳对地形条件的响应特征,中活性有机碳库管理指数的指示效果最好.研究结果可部分解释黄土高原土壤有机碳地带性分布特征.     

拓扑树间的通经拓扑距离

给出了一种新的系统树间的拓扑距离,使用NJ,MP,UPGMA等3种方法对13种动物的线粒体中14个基因（含组合的）DNA序列数据进行系统树的构建,利用分割拓扑距离和本文给出的通经拓扑距离对这14种系统树这间及其与真树进行比较。结果显示,NJ法对获得已知树的有效率最高,MP法次之,UPGMA法最低。这14种DNA序列所构建的系统树与已知树的拓扑距离基本上是随其DNA序列长度增加而减小,但两者的相关系数并未达到显著水平,分割拓扑距离在总体上可反映树间的拓扑结构差异,但其测度精确度比通经拓扑距离要低。     

胡杨当年生小枝茎构型对展叶效率的影响

枝叶异速生长关系对理解荒漠植物生物量分配和生活史策略具有重要意义。该研究以小枝茎长度、茎纤细率和茎体积表征茎构型, 以叶密度(单位茎长度的叶数量)、叶面积比(单位小枝茎干质量的总叶面积)和叶茎质量比(单位小枝茎干质量的总叶干质量)表征展叶效率, 采用标准化主轴回归(SMA)方法研究胡杨(Populus euphratica)当年生小枝茎构型对展叶效率的影响及二者沿地下水埋深(GWD)梯度的权衡策略。结果显示, 胡杨当年生小枝茎直径、展叶效率和比叶面积、叶大小随GWD增加而降低, 小枝茎长度、茎纤细率及其上的叶数量则增大。小枝茎构型性状均与展叶效率呈显著负相关关系, 即随小枝茎长度、茎纤细率和茎体积的增加, 展叶效率逐渐降低, 这可能是枝叶大小、水分传导与机械支撑间的权衡结果。小枝茎构型与展叶效率的异速生长指数(斜率)随GWD增加而增大, 是由于单位小枝茎投资获得的叶面积或者叶质量降低所致, 反映出随GWD增加胡杨采取了高消耗低收益的保守型策略。胡杨应对环境压力时, 倾向于在长枝上着生数量较多的小叶, 短枝上着生数量较少的大叶, 体现出胡杨小枝的资源利用策略与枝叶大小的权衡机制。综上所述, GWD显著影响胡杨小枝茎构型-展叶效率的权衡关系, 低展叶效率是胡杨应对日益旱化荒漠环境的适应策略。     

冬玉米对氮肥的吸收利用和需求

在不同施氮量下 ,研究了冬玉米对氮肥的吸收利用 ,结果表明 :(1 )冬玉米地上各部分中氮的累积随着用氮量的增加而增加 ,花丝期前的吸收量均多于后期 ,但高氮区的前期吸氮比大于低氮区 ;(2 )营养体氮的转移率随施氮量的增加而降低 ,但绝对量依然是高氮处理大于低氮处理 ,其中雄穗的转移率最高 ,叶的转移量最大 ;(3 )氮肥利用率随施氮量的增加而提高 ,但氮的生产力下降。根据试验结果 ,在肥力好的土地上种植冬玉米以 1 80～ 2 70 kg N/hm2比较适宜     

甲醛胁迫下四种盆栽植物的生理动态反应

选择巢蕨(Neottopteris nidus)、巴西铁(Dralaena fragrans)、虎尾兰(Sansevieria trifasciata)和黑美人(Aglaonema commutatum)4种室内盆栽植物作为典型的试验材料,以15 mg·m-33甲醛分别进行熏蒸处理,测定单位干物质甲醛的吸收量、相对电导率、丙二醛含量和叶绿素含量等,以研究这些植物在甲醛胁迫下的生理动态反应。结果表明:在甲醛胁迫的4 d时间内,巢蕨和巴西铁的单位干物质甲醛吸收量均在第3天达到峰值,而黑美人和虎尾兰则一直在缓慢增加,其中以巢蕨吸收的量最多,巴西铁单位干物质甲醛吸收量最少; 4种植物的相对电导率、丙二醛的含量均随甲醛胁迫时间的增加而增加,以巢蕨的相对电导率最高,虎尾兰最低,但巴西铁的丙二醛的含量最高,巢蕨最低; 4种植物的叶绿素含量均随甲醛胁迫时间的增加而降低,其中黑美人降低幅度最高,虎尾兰最低。     

甲醛胁迫下四种盆栽植物的生理动态反应（英文）

选择巢蕨(Neottopteris nidus)、巴西铁(Dralaena fragrans)、虎尾兰(Sansevieria trifasciata)和黑美人(Aglaonema commutatum)4种室内盆栽植物作为典型的试验材料,以15mg·m~(-3)甲醛分别进行熏蒸处理,测定单位干物质甲醛的吸收量、相对电导率、丙二醛含量和叶绿素含量等,以研究这些植物在甲醛胁迫下的生理动态反应。结果表明:在甲醛胁迫的4d时间内,巢蕨和巴西铁的单位干物质甲醛吸收量均在第3天达到峰值,而黑美人和虎尾兰则一直在缓慢增加,其中以巢蕨吸收的量最多,巴西铁单位干物质甲醛吸收量最少;4种植物的相对电导率、丙二醛的含量均随甲醛胁迫时间的增加而增加,以巢蕨的相对电导率最高,虎尾兰最低,但巴西铁的丙二醛的含量最高,巢蕨最低;4种植物的叶绿素含量均随甲醛胁迫时间的增加而降低,其中黑美人降低幅度最高,虎尾兰最低。     

红树植物对不同海滩面高度的适应性研究

通过研究华南沿海珠江口深圳湾红树植物无瓣海桑、海桑和秋茄在不同海拔高度的滩面中的生长适应性,揭示红树植物对海水淹浸的适生特性.研究结果表明:(1)在一定的滩面高度范围内,红树植物无瓣海桑(滩面高度为-12～35.5 cm)、海桑(滩面高度为-1～24 cm)幼树的保存率和生长量随着滩面高度的降低(即海水淹浸程度的加强)而逐渐减低,秋茄(滩面高度为12～24 cm)的保存率和生长量则无明显差异.(2)随生长期的延长,各树种幼树的保存率逐渐减低.当生长期未超过1年时,幼树生长和成活极不稳定,保存率骤减;当生长期超过1年后,无瓣海桑和海桑保存率趋于相对稳定,秋茄保存率继续下降,极难长久保存和定居.(3)无瓣海桑能够忍耐海水淹浸的限度是滩面高度最低为10 cm,海桑是滩面高度最低为6.5 cm,秋茄是滩面高度至少在24 cm以上,在低于此海拔高度的滩面上各树种极难长期保存和定居.为了保证各树种正常生长发育,种植红树林要选择高于此滩面高度的泥滩区域.     

不同海拔高度高寒草甸光能利用效率的遥感模拟

利用植被光合模型模拟了藏北高原3个海拔高度(4300,4500 m和4700 m)的高寒草甸生态系统的光能利用效率.海拔4500 m的光能利用效率均值(0.47 g C/MJ)显著高于海拔4300 m(0.38 g C/MJ)和4700 m(0.35 g C/MJ),而海拔4300 m和4700 m两者间差异不显著.相关分析和多重逐步回归分析表明,影响每个海拔光能利用效率季节变化的主要因子为空气温度,相对湿度以及地表水分指数,这3个因子共同解释了99％以上的光能利用效率的季节变化,其中空气温度的贡献最大,相对湿度的贡献次之,地表水分指数的贡献最小,这说明在3个海拔的任何一个海拔高度,温度对光能利用效率季节变化的胁迫作用大于水分对光能利用效率季节变化的胁迫作用.多重逐步线性回归分析表明,生长季节均土壤含水量是决定生长季节均光能利用效率沿海拔高度分布的主导因子.单因子线性回归分析表明,地表水分指数可以定量化高寒嵩草草甸生态系统水分状况,它同时可以反应土壤水分、近地表空气湿度以及生态系统植被含水量状态.因此,在高寒嵩草草甸生态系统,用地表水分指数反应生态系统尺度水分对光能利用效率的胁迫作用是可行的.     

相依模型参数估计的相对效率

本文考虑相依模型,对其未知参数向量给出了其最佳线性无偏估计相对于协方差改进估计的四种相对效率,同时,还给出了最小二乘估计相对于协方差改进估计的三种相对效率,在不同条件下,分别给出了相对效率的上界与下界。     

不同大豆品种磷吸收利用特性比较研究

土壤缺磷和低磷利用率是现代农业生产发展的主要限制因素之一,筛选和培育磷商效吸收利用品种是提高磷素利用率的有效途径。采用土壤盆栽试验方法进行了不同大豆（Glycine max（L.）Merr．）品种磷吸收利用特性比较研究。结果表明。在缺磷和正常供磷条件下,不同大豆品种植株在株离、根干重、地上部干重、根冠比率、植株磷含量和其相对值、磷吸收量和其相对值、磷利用效率和其相对比值等方面表现出显著的差异。多数达到了极显著水平。相关分析表明,在缺磷条件下,大豆不同品种植株磷的利用效率及其相对比值与植株磷含量和磷吸收量以及它们的相对值呈显著或极显著负相关。植株磷含量与植株磷吸收量呈极显著正相关。以植株干物质量和其相对值、植株磷吸收量和其相对似以及植株磷利用效率为筛选指标,筛选出3个大豆磷高效品种。     

利用合成生物学原理提高光合作用效率的研究进展

我国人口增多与耕地面积减少的矛盾日益突出,粮食安全已成为我国国民经济可持续发展的重要保障。光合作用是作物产量形成的物质基础,提高作物光能利用效率是提高作物产量的重要途径之一。本文从光合作用过程中光能高效吸收、传递与转化,光能高效利用和碳同化等三大模块综述了近期科学家利用合成生物学对光合作用改造的最新进展。最后我们对其在农业中的应用前景进行了展望,通过合成生物学原理提高光合作用效率可能将为增加粮食产量提供重要理论支撑和关键生物技术。     

On the Quantum Yield Determination of UV Emitting Up-Converters

This work deals with the determination of the external quantum yield of some selected inorganic up-conversion materials, which are able to convert blue light, as typically emitted using blue (In,Ga)N LEDs, into UV radiation. Recently, these materials have drawn tremendous attention due to their potential application in antimicrobial coatings of surfaces. To judge the viability of this approach to reduce the density of germs onto arbitrary surfaces upon indoor or outdoor illumination, the quantum efficiency for the conversion of blue light into UV is of large interest. We found that the quantum efficiency is between about 0.1% and 1%, which might be good enough if the illumination of the respective surface is performed for several hours. Then, a relevant reduction of the number of active microorganisms per area can be achieved.     

Nutrient-uptake and nutrient-use efficiency ofPinus thunbergii Parl. along a topographical gradient of soil nutrient availability

To examine responses of a plant species to nutrient availability, we investigated changes in soil nutrient availability, litterfall production and nutrient content in litterfall along a topographic gradient in aPinus thunbergii Parl. plantation. Responses were evaluated in terms of three efficiency indices: (i) nutrient-uptake efficiency (the ratio of nutrient return in litterfall to soil nutrient availability); (ii) nutrient-use efficiency (the ratio of litterfall mass to nutrient return in litterfall); and (iii) nutrient-response efficiency (the ratio of litterfall mass to soil nutrient availability). These indices can distinguish the ability of a species to acquire nutrients and its ability to use them in litterfall production. Nitrogen and phosphorus availabilities in soil were lower in upper slope positions. The three efficiencies were higher in upper slope positions and negatively correlated with soil nutrient availability for both nitrogen and phosphorus. An increase in nutrient-response efficiency was achieved by both increases in nutrient-uptake and nutrient-use efficiencies.     

Measuring trap efficiency for bark beetles (Col., Scolytidae)

Abstract:  The relative efficiency of cylindrical, linear and cross-barrier traps for trapping bark beetles was investigated based on a theoretical model. Using this model, the effective trap interception area of each trap type was calculated and trap efficiency was defined as the ratio of the effective interception area to the trap surface area. The relative efficiencies of the three trap types were calculated as the ratios of their respective effective interception areas. Based on this approach, assuming random directional movement of dispersing beetles, the order of efficiency of the three trap types, from highest to lowest, was linear, cross-barrier and cylindrical. The expected ratios of trap catches based on the relative efficiencies of the three trap types were fitted to data from trapping experiments with the mountain pine beetle ( Dendroctonus ponderosae Hopkins). In general, there was large variation in trap catches among traps of the same type but the ratios of mean catches per trap conformed to the expected ratios. The results indicate that the model of trap efficiency could be used for designing efficient traps. The methods presented are amenable for assessing the efficiency of other trap designs.     

Flow dependent changes in the effective surface area of microdialysis probes

The relative efficiencies of microdialysis probes were determined both in vitro and in vivo using tritiated water. Tritiated water (THO) freely distributes throughout the fluid spaces of an experimental animal and, at equilibrium, the brain extracellular concentration of THO is the same as the plasma concentration. Microdialysis probes were inserted into the right caudoputamen of anesthetized rats. The rats were injected with THO and after one hour microdialysis samples were collected at flow rates between 0.2 and 10.0 ul/min. The in vitro relative efficiency for THO was computed as the ratio of the THO concentration in the dialysate to that of the solution the probe was immersed in. The in vivo relative efficiency was computed as the ratio of the concentration of THO in the brain dialysate to that measured in the plasma of the rat. Both the in vitro and in vivo relative efficiencies for THO decrease with increasing flow rates, but they differ from each other except at very low flow rates (less than 0.25 ul/min). The in vitro relative efficiency at a given probe flow is the maximum efficiency that can be attained in vivo at that flow. The surface of effective exchange (Se) is the fraction of that maximum which is attained in vivo. This study also demonstrates how the effective surface area can be computed at any probe flow rate and how it can be used as a correction factor.     

Some effects of light on the energetics of Daphnia pulex and implications for the significance of vertical migration

Energy budgets were computed from data obtained for Daphnia pulex cultured under nine light intensities, polarized light and four wavelength ranges. The percent assimilation of preadult animals is highest at intensities above 7 ft-c. Net efficiency of growth was highest (> 50%) and the net efficiency of respiration was lowest ( < 49%) at intensities less than 28 ft-c. The percent assimilation of adult animals was highest ( > 10%) at 110, 55 and 14 ft-c. Under the nine intensities the gross efficiencies of growth were less than 1 % and net efficiencies of growth varied from 3.9 to 7.3%. Gross efficiencies of respiration were highest above 7 ft-c. The net efficiency of respiration usually varied between 20 and 30% and the lowest was 9.8% at 1.7 ft-c. and the highest was 50.1% at 110 ft-c. Gross efficiency of reproduction varied from 2.6% at 3.5 ft-c to 12.6% at 14 ft-c and generally varied between 4 and 7.5%. Net efficiency of reproduction varied from 45.9% at 110 ft-c to 84.3% at 1.7 ft-c and usually varied from 62 to 75% at other light intensities. The ratio of energy of respiration to energy of growth and reproduction ranged from 12% to 1.7 ft-c to 105.3% at 110 ft-c. This ratio usually varied from 25 to 34% at 14 ft-c or less and exceeded 37% at intensities above 14 ft-c. The percent assimilation (3.5%), gross (2.0%), and net (56.3%) efficiencies of respiration of preadult animals raised under polarized light were higher than for those at a similar, nonpolarized, intensity. The net efficiency of growth (43.7%) was lower under polarized light. The percent assimilation, gross efficiencies of growth, reproduction and respiration, net efficiencies of growth and reproduction of adult animals under polarized light (6.6 ft-c) were lower than for those under 7 ft-c. For preadult animals assimilation efficiencies were lower in wavelength treatments than in white light or darkness. The gross efficiencies of growth and respiration were lowest under red wavelengths and the net efficiencies of growth were lowest and respiration highest under green wavelengths. For adult animals, the assimilation efficiencies were lower in the wavelength treatments than those obtained in other light treatments. While the gross efficiencies of growth, reproduction and respiration were generally lower, the net efficiencies of growth and reproduction were generally within the range of values for other light conditions. The net efficiencies of respiration, except for red wavelengths, were lower than those for other light conditions except at 1.7 ft-c. The ratio of energy of respiration to energy of growth and reproduction showed similar trends. The effects of wavelength are generally separable from the effects of light intensity.     

The effects of nitrogen, light and water availability on tropic leaf movements in soybean (Glycine max)

Abstract. Rapid, tropic leaf movements and photo-synthetic responses of the heliotropic plant, soybean, Glycine max cv. Cumberland, grown under two different nitrogen, three different light and two different water treatments were examined. Measurements of leaf orientation during midday periods outdoors, and tropic reorientation of leaflets in response to vertical illumination indoors, revealed a positive, linear relationship between leaf water potential and the cosine of the angle of incidence between the leaf and the direct beam of the excitation light. This relationship was altered by nitrogen availability, such that a lower cosine of incidence (lower leaf irradiance) for a given leaf water potential was measured for plants grown under low nitrogen compared to those grown under high nitrogen. Additionally, plants grown under low nitrogen and low water availability showed more rapid rates of leaf movement compared to plants receiving high levels of these resources. Light regime during growth had no effect on the relationship between the cosine of incidence and leaf water potential. Reduced water and nitrogen availabilities during growth resulted in lower photosaturated rates of photosynthesis and stomatal conductance, as well as alterations in the relationship between these parameters. Thus, higher values for the ratio of intercellular CO₂/ambient CO₂ were measured for low-N grown plants (higher nitrogen use efficiencies) and lower values of this ratio for water stressed plants (higher water use efficiencies). The results show that environmental growth conditions other than water availability have the potential to modify leaf orientation responses to vectorial light in heliotropic legumes such as soybean. This has implications for the potential of heliotropic movements to minimize environmental stress-induced damage to the photosynthetic apparatus, and to modulate leaf-level resource use efficiencies.