供氮水平对小麦生殖生长时期叶片光合速率、NR活性和核酸含量及产量的影响

在水培条件下，研究了氮素水平对小麦生殖生长时期一些生理特性及产量的影响。结果表明：生殖生长时期，外源供氮水平供应增加，叶面积、叶片光合速率及叶绿素含量均随之增加；叶片和根系硝酸还原酶活性（NRA）、叶片铵态氮含量和外源供氮水平间有显著正相关；根系DNA及RNA含量均随供氮水平升高而升高；孕穗期用不同氮素水平处理15 d，对小麦成熟后生物量及经济产量有明显影响。     

CO2倍增对不同氮水平下小麦幼苗根系及叶片NR活性的影响

以小麦品种'小偃22'幼苗为材料,采用开顶式气室和水培实验研究了不同供氮水平(2.5、5.0、10.0和 15.0 mmol·L-1)下小麦幼苗植株生长量、根系形态、有机碳分泌速率和硝酸还原酶(NR)活性对大气CO2浓度升高的响应.结果显示,大气CO2浓度倍增均增加了小麦幼苗各生长阶段根冠生物量以及根系长度、面积、有机碳分泌速率和叶片NR活性.随供氮水平的提高,各生长阶段幼苗根冠生物量、根长和面积以及叶片NR活性呈上升趋势,而有机碳分泌速率呈下降趋势;根冠比变化不同阶段表现不一致,一叶一心期呈下降趋势,二叶一心期和三叶一心期分别以15.0和10.0 mmol·L-1氮水平较高.研究表明,大气CO2浓度升高可促进小麦幼苗根系生长和有机碳分泌速率,提高其氮素同化能力;增加介质供氮有利于高CO2浓度条件下小麦幼苗根冠生长和氮素同化,提高根冠比,减少根系有机碳过度分泌引起的碳损耗.     

外源亚精胺对高温胁迫下黄瓜幼苗氮素代谢的影响

以较为耐热的黄瓜品种‘津春4号’为试材,在人工气候箱中,采用石英砂培加营养液浇灌的栽培方式,研究了外源亚精胺( Spd)对高温胁迫(42℃)下黄瓜幼苗氮素代谢的影响.结果表明:短期高温胁迫处理,尤其是4h内,植株硝态氮含量降低而铵态氮含量升高;外源Spd预处理使幼苗体内硝态氮和铵态氮含量升高且硝酸还原酶(NR)活性增强.较长期高温胁迫处理下,幼苗根系中硝态氮含量升高但向地上部运输受阻,根系NR钝化,根系和叶片中铵态氮含量均显著升高;高温胁迫下喷施Spd,除进一步促进根系吸收硝态氮且向地上部运输外,根系和叶片NR活性亦有所升高,从较长期的效果看,外源Spd还具有防止铵态氮过度积累、促进幼苗体内氮素代谢趋于正常的作用.     

低氮胁迫对不同苦荞品种苗期生长和根系生理特征的影响

以2个耐低氮苦荞品种(‘迪庆苦荞’、‘广苦1号’)和2个不耐低氮苦荞品种(‘西荞1号’、‘黑丰1号’)为材料,采用盆栽试验研究了低氮胁迫对苦荞苗期生长和根系生理特性以及氮素利用的影响,以揭示苦荞耐低氮胁迫的生理响应机制。结果显示:(1)与正常供氮处理(15mmol/L)相比,低氮(0.5mmol/L)和极低氮(0.05mmol/L)胁迫处理下,苦荞幼苗的株高、茎粗、叶面积、地上部干重、根系平均直径、根系体积及根系表面积均呈下降趋势,主根长和根冠比呈升高趋势,但在低氮(0.5mmol/L)条件下各品种根系干重均有所增加,且耐低氮品种增加幅度较大(13.69%、19.26%)。(2)低氮胁迫使苦荞叶片的叶绿素含量、最大荧光产量(Fm)和最大光化学效率(Fv/Fm)以及根系活力、硝酸还原酶(NR)活性和可溶性蛋白含量显著降低,而叶片初始荧光产量(Fo)及根系超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、丙二醛(MDA)、可溶性糖及游离脯氨酸含量呈升高趋势。(3)低氮胁迫使苦荞植株全氮含量及氮积累量显著降低,却使氮素吸收效率显著升高。研究表明,不同耐低氮苦荞品种对低氮胁迫的响应存在显著差异,在低氮胁迫下,耐低氮品种(‘迪庆苦荞’、‘广苦1号’)具有明显的生长优势,不仅农艺性状、叶片光合作用及根系活性受低氮胁迫影响小,而且具有较高的根系保护酶活性、渗透调节物质含量以及全氮量和氮积累量。     

稻麦叶片氮含量与冠层反射光谱的定量关系

作物氮素含量是评价作物长势、估测产量与品质的重要参考指标,叶片氮素含量的无损快速监测对于指导作物氮素营养的精确管理及生产力的预测预报具有重要意义.以5个小麦品种和3个水稻品种在不同施氮水平下的3a田间试验为基础,综合研究了稻麦叶片氮含量与冠层反射光谱的定量关系.结果显示：（1）不同试验中拔节后稻麦叶片氮含量均随施氮水平呈上升趋势;（2）稻麦冠层光谱反射率在不同施氮水平下存在明显差异,在可见光区（460～710 nm）的反射率一般随施氮水平的增加逐渐降低,而在近红外波段（760～1100 nm）却随施氮水平的增加逐渐升高;（3）就单波段光谱而言,610、660 nm和680 nm处的冠层反射率均与稻麦叶片氮含量具有较好的相关性;（4）在光谱指数中,归一化差值植被指数NDVI（1220,610）与水稻和小麦叶片氮含量均具有较好的相关性,且相关性好于单波段反射率;（5）对于小麦和水稻,可以利用共同的波段和光谱指数来监测其叶片氮含量,采用统一的回归方程来描述其叶片氮含量随单波段反射率和冠层反射光谱参数的变化模式,但若采用单独的回归系数则可以提高稻麦叶片氮含量估测的准确性.     

光照强度和氮水平对白三叶幼苗生长与光合生理特性的影响

采用植物生长箱溶液培养方式,对白三叶幼苗进行了不同光强(2个水平)和氮浓度(5个水平)处理,探讨其生长、生物量和光合生理特征对生境变化的响应.结果表明:两种光强下白三叶幼苗茎和叶生物量随氮素浓度呈先升高后降低,而根系生物量和根冠比则随氮素浓度增高而降低.光照强度降低使白三叶幼苗根、茎、叶和整株生物量分别降低67.8%、29.9%、42.5%和45.2%;低光处理使幼苗的根冠比显著下降,而比叶面积(SLA)明显提高.幼苗根系体积随氮素浓度增高而降低,高生长光强根系体积显著高于低生长光强下的白三叶.幼苗根系表面积、根系长度和根系直径随氮素浓度增加呈先增加后降低趋势,两种不同生长光强下幼苗根系长度和根系直径差异显著,而根系表面积差异不明显.白三叶叶片光合速率(Pn)随氮素浓度增加呈先增加后降低趋势,高生长光强白三叶Pn显著高于低生长光强下的白三叶.两种生长光强间叶片气孔导度(Gs),胞间CO2浓度(Ci)和蒸腾速率(Tr)无显著差异,但氮素浓度对叶片Gs、Ci和Tr均有显著影响.光、氮及其交互作用对白三叶幼苗生长发育产生了显著影响,光照不足和氮缺乏都将导致白三叶幼苗生长减弱,但幼苗对这些不利环境具有较强的调节和适应能力.     

氮素营养水平对冬小麦碳氮运转的影响

在大田试验条件下,研究了不同施氮水平对2种穗型冬小麦品种花后干物质和氮素积累与运转的影响及其与产量和品质的关系,以探讨氮素营养水平对冬小麦碳氮运转的影响.结果显示,适宜的施氮量（180 kg·hm^-2）能够极显著增加2种穗型冬小麦品种叶片、茎鞘等营养器官花前贮藏物质及花前贮藏氮素的再运转量和运转率以及总再运转量和运转率,也能够极显著增加成熟期籽粒氮素含量和花前贮藏氮素总运转量对籽粒氮素含量的贡献率.各施氮处理对2种穗型小麦品种花后氮素积累量对籽粒氮素含量贡献率的影响效应不明显.结果表明,适宜的施氮量有利于小麦籽粒和蛋白质产量的提高.     

施氮和增温对降香黄檀幼苗生长发育和生理特征的影响

采用添加氮素模拟氮沉降和人工气候箱模拟增温的方法,设置了对照、施氮、增温以及增温×施氮交互作用4个处理,分析不同处理对降香黄檀(Dalbergia odorifera T. Chen)幼苗生长形态变化、生物量的积累、叶片和根系生理方面的影响。结果显示:与对照相比,增温、施氮以及增温×施氮交互作用均促进了降香黄檀幼苗的生长形态发育、增加了生物量的积累、光合参数、最大光化学量子产量、叶片硝酸还原酶及根系活力,但降低了叶片相对电导率和丙二醛含量;增温×施氮交互作用下降香黄檀幼苗的生物量积累、光合参数、最大光化学量子产量、叶片硝酸还原酶及根系活力的增幅最大,而叶片相对电导率和丙二醛含量降幅最显著;隶属函数分析结果表明,增温×施氮交互作用对降香黄檀幼苗生长发育的促进效果最好,其次为单独增温,最后为施氮处理。     

施氮及不同根系分隔模式对尾叶桉和降香黄檀幼苗生长及叶片生理特性的影响

豆科与非豆科树种混交作为一种人工林培育可持续发展模式,在保证木材产量和维持氮素平衡中发挥了重要作用。该研究通过大棚盆栽试验,设计3个施氮水平(0、3、6g·株-1)及3种根系分隔方式(不隔、网隔、膜隔),分析了不同氮素水平及根系分隔模式对尾叶桉(Eucalyptus urophylla)与降香黄檀(Dalbergia odorifera)植株幼苗生长、叶片生理特性、根系形态及生物量的影响。结果表明:(1)随施氮量的增加,尾叶桉与降香黄檀的苗高、地径均呈递增趋势;不同根系分隔模式下,尾叶桉苗高、地径均在不隔模式下生长最好,降香黄檀则在膜隔模式下生长最好。(2)与不施氮处理相比,施氮3、6g·株-1水平下尾叶桉与降香黄檀叶片的超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性及可溶性蛋白含量均显著升高,而丙二醛(MDA)含量则呈降低趋势。(3)尾叶桉与降香黄檀根系的总长度、总表面积、总体积、平均直径、根尖数和比根长均随氮素水平的增加而增加,且各氮素水平间的差异显著;同一氮素水平下,尾叶桉的根系生长总体表现为不隔网隔膜隔,而降香黄檀根系生长则表现为膜隔不隔网隔,且两树种不同分隔模式间差异显著。(4)尾叶桉与降香黄檀各器官生物量及总生物量均随施氮量的增加而增加,并在6g·株-1施氮水平下生物量最大;各器官生物量分配中,尾叶桉各器官生物量所占比例大小依次为:茎(40.59%)叶(32.37%)根(27.04%),降香黄檀各器官生物量所占比例大小依次为:根(47.67%)茎(40.08%)叶(12.25%)。研究表明,尾叶桉与降香黄檀混交一定程度上扩展了根系横向和纵向水平的养分生态位,扩大了根系吸收土壤养分的空间,同时根系互作提高了降香黄檀的固氮能力,对土壤有效氮的产生有较大影响。     

施氮量对小麦氮磷钾养分吸收利用和产量的影响

高产条件下研究了不同施氮量对小麦植株氮、磷、钾养分吸收利用及籽粒产量的影响.结果表明,适量施氮可促进小麦植株对氮素的吸收与积累,较高的施氮量不利于起身期之后的氮素积累,致使成熟期小麦氮素积累量未能显著提高;与不施氮肥相比,施氮显著提高植株磷素积累量;随施氮量增加,植株磷素积累量增加不显著;施氮量增加促进小麦生育前期对钾素的吸收积累,在生育后期降低植株钾素的流失.随施氮量增加,籽粒氮素含量呈先增后降的趋势,氮素向籽粒的分配比例趋于降低,植株氮素利用效率无显著变化,氮素收获指数下降;不同施氮处理之间籽粒磷素含量和钾素含量无显著差异,施氮量增加,营养器官钾素含量、钾素积累量和钾素向叶片的分配比例均呈增加趋势;同时,磷素和钾素利用效率降低;不同施氮处理间,植株磷素、钾素收获指数无显著差异.籽粒产量随施氮量增加呈先增加后降低的趋势,以施氮195 kg/hm2的处理籽粒产量最高.     

Characteristics of the membranes of the pellicle of the ciliatePseudomicrothorax dubius

Summary The membranes of the pellicle of the ciliatePseudomicrothorax dubius are investigated using thin section electron microscopy and freeze-fracture replicas. The plasma membrane is covered by a surface coat and is connected to the outer alveolar membrane by short, sometimes branched, bridges. The inner alveolar membrane is coated on both sides. The epiplasm lies in intimate contact with the cytoplasmic surface of this membrane, and there is a corresponding deposit on the other surface. This deposit is regularly striated.The epiplasmic layer and the alveoli are interrupted at sites of cytotic activity,e.g., the attachment sites of trichocysts, the cytoproct, and the parasomal sacs. The striated deposit ends where the epiplasm ends, indicating a direct relationship between these two epimembranous layers.There is a deposit along the sides of the first part of the tip of the trichocysts, and in this region the trichocyst membrane is free of intramembranous particles.The membrane of the parasomal sacs has a coat on both surfaces. That on the extraplasmic surface is similar to the surface coat of the plasma membrane. The origin of the cytoplasmic coat is unknown. The cytotic activity of these sacs is indicated by their highly irregular profiles.     

The early development of the tail and the transformation of the shape of the nucleus of the spermatid of the domestic fowl,Gallus gallus

Summary The differentiation of the spermatid, especially in reference to the formation of the flagellum, and transformation of the shape of the nucleus was investigated in the domestic fowl.In the early stage of the spermatid, a prominent Golgi apparatus appears around the centrioles. The Golgi vesicles then surround the axial-filament complex which develops from the distal centriole. These vesicles fuse to form continuous membrane at the earliest stage of flagellar formation, and in the succeeding stage Golgi lamellae are attached to the plasma membrane of the developing flagellum. From these observations, it is assumed that Golgi apparatus may be a source of the membrane system of the flagellum.The microtubules distributed around the nucleus form the circular manchette. The anterior region of the nucleus with the manchette is cylindrical in shape and the posterior region without it remains irregular in shape. When the circular manchette has been completed, the whole nucleus acquires a slender cylindrical shape. The circular manchette then changes into the longitudinal manchette. The nuclei of spermatids without a longitudinal manchette are abnormal in shape. In view of these observations it is assumed that the nuclear shaping of the spermatid may be accomplished by circular manchette and the maintenance of shape of the elongated nucleus by longitudinal manchette.The authors wish to thank Mr. Takayuki Mori for his helpful suggestions and technical advices     

Characterization of the composition of the aqueous humor and the vitreous body of the eye of the frog Rana temporaria L

This study aimed to analyze the aqueous humor (AH) and the vitreous body (VB) of the eye of the adult frog Rana temporaria L. as a representative species of amphibians, which lead a semi-terrestrial life. The presence of collagen, albumin, uric acid and electron donors was shown in both media; however, there are slight differences in their concentrations. To determine collagen, a spectral-fluorescent probe, cyanine dye, was used. The presence of collagen in AH of the frog was found at the first time. The total content of electron donors (ascorbic and uric acids, tryptophan, and tyrosine) in VB and HA was roughly estimated at ~ 1.5 × 10^− 4 mol/L. Both VB and AH absorb light in similar UV regions. The total protein and albumin contents in AH were found to be somewhat higher than those in VB. The uric acid content was at an equally low level in both intraocular media. It is supposed that the similarity of VB and AH compositions shown in this work is due to some exchange between VB and AH contents in the course of accommodation. The role of intraocular fluids in physiological functions of the eye and in protecting the retina against UV light is discussed.     

Observations on the permeability of the choriocapillaris of the eye

Summary The choriocapillaris is a fenestrated capillary bed located posterior to the retinal pigment epithelium. It serves as the main source of supply to the photoreceptors, retinal pigment epithelium, and other cells of the outer retina. The permeability of these capillaries to intravenously injected ferritin (MW — approx. 480,000; mol. diam. 11 nm) was examined in the mouse, rabbit, and guinea pig, each of which is characterized by a different type of retinal vascularization. In all three species, the bulk of the ferritin remained in the capillary lumina, where it appeared to be blocked at the level of the diaphragmed fenestrae. Some ferritin was present in endothelial cell vacuoles. The results confirm previous work on the rat choriocapillaris and indicate that the barrier function of the choriocapillary endothelium is present even among species in which the retinal circulation differs significantly.Supported by NIH grant EY03418