夜间低温对2种桉树幼苗光合特性的影响

以人工气候箱模拟夜间低温处理尾叶桉和邓恩桉幼苗,研究其对2种桉树的光合特性和叶绿体超微结构的影响.结果表明:夜间低温使尾叶桉和邓恩桉的净光合速率、气孔导度和蒸腾速率均降低;胞间CO2浓度和气孔限制值升高;2种桉树幼苗的水分利用率变化有一定的差异,邓恩桉的水分利用率随低温胁迫升高,而尾叶桉的水分利用率则先升高然后下降;同时,低温胁迫下尾叶桉和邓恩桉气孔导度与净光合速率和蒸腾速率均呈明显的线性关系.夜间低温导致2种桉树叶绿体肿胀变形,淀粉粒降解,对尾叶桉的影响要比邓恩桉的影响大.     

模拟大气硫酸铵污染对香樟幼苗生长及光合特性的影响

通过室内盆栽实验研究了大气颗粒污染物硫酸铵对香樟幼苗生长及光合特性的影响。结果表明,香樟幼苗叶片涂抹硫酸铵处理对植物生长无显著影响;低浓度硫酸铵(2 g·L^-1)提高了叶片叶绿素含量,而高浓度(4 g·L^-1)却降低了叶片叶绿素含量;与对照相比,低浓度处理的香樟叶片净光合速率、气孔导度、胞间二氧化碳浓度与蒸腾速率无显著差异;高浓度处理的香樟叶片净光合速率与蒸腾速率高于对照,而气孔导度与胞间二氧化碳浓度与对照无显著差异。机理分析表明,硫酸铵颗粒物主要通过影响叶片气孔导度来影响植物光合特性。     

云锦杜鹃夏季气体交换和水分利用效率日变化

云锦杜鹃净光合速率和气孔导度日变化曲线为"双峰"型,光合效率午间明显降低,主要由非气孔限制引起。表观量子效率和实际光化学效率的降低是非气孔限制形成和发展的深层原因。蒸腾速率的日变化为"单峰型",午间最高。水分利用效率早晚较高、午间较低。净光合速率、蒸腾速率、气孔导度和水分利用效率分别与一些环境因子的相关性达到0.01或0.05显著水平。利用多元逐步回归方法分别得到了净光合速率、胞间CO2浓度、蒸腾速率、气孔导度和水分利用效率与环境因子的最优方程。     

夜间低温胁迫后外源SA对恢复中黄瓜幼苗光合特性的影响

为明确低温胁迫后恢复过程中水杨酸(SA)对植物光合特性的影响,以黄瓜品种‘津研四号’幼苗为材料,通过沙培试验,研究了外源SA对夜间5℃低温胁迫后常温(25℃)恢复中黄瓜幼苗叶绿素含量、光合速率、叶绿素荧光参数、气体交换参数等的影响。结果显示:(1)与喷施清水处理相比,外源SA处理显著促进了夜间低温胁迫后的常温(25℃)恢复效果,显著提高了恢复速度和水平,表现在黄瓜幼苗叶绿素含量、净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和胞间CO2浓度(Ci)显著升高,黄瓜幼苗净光合速率在恢复6h时达到对照水平的82.18%。(2)外源SA还明显加快了恢复过程中黄瓜幼苗叶片最大光化学效率(Fv/Fm)、实际光化学效率(ΦPSⅡ)及非循环电子传递速率(ETR)的恢复,提高了非光化学猝灭系数(NPQ)值,增强了幼苗自身光保护能力。(3)外源SA也促进了黄瓜幼苗叶片表观量子效率(AQY)和羧化效率(CE)的恢复,它们在恢复2d时分别达到对照水平的92.59%和90.62%。研究表明,在夜间低温胁迫后的常温恢复过程中,外源SA可有效地促进黄瓜幼苗光合作用的恢复,增强其对低温环境的适应能力。     

不同形态氮素配比对盐胁迫下菊芋幼苗生理的影响

采用砂培方法研究了不同铵硝配比(NH4+/NO3-分别为4/1、1/1、1/4)的氮素营养和盐分胁迫耦合作用下菊芋幼苗的光合作用和离子吸收运输.结果表明:低浓度的盐胁迫对植物生长的抑制作用不大,而高浓度的盐胁迫却能明显抑制菊芋幼苗生物量的积累,在同一盐浓度下,提高硝态氮比例能够缓解盐胁迫对菊芋幼苗生长的抑制,促进菊芋幼苗鲜重和干重的增加;随着盐浓度的增加,菊芋幼苗地上部和地下部的Na+含量显著增加,而K+、Ca2+含量较对照显著降低,提高硝态氮比例有利于菊芋幼苗对K+和Ca2+的吸收和向上运输,从而维持地上部较高的K+/Na+和Ca2+/Na+;在3种铵硝比的氮素营养处理下,随着盐浓度的增加,菊芋幼苗叶片叶绿素含量、净光合速率、蒸腾速率、气孔导度和水分利用效率较对照均呈显著下降的趋势,细胞间隙CO2浓度则显著增加,提高硝态氮比例可显著提高盐胁迫下菊芋幼苗的叶绿素含量、净光合速率、蒸腾速率、气孔导度和水分利用效率,同时也能显著降低胞间CO2浓度,其中以铵硝比为1/4的氮素营养供应对盐胁迫的缓解作用相对较好,在100 mmol·L-1NaCl处理下其叶片叶绿素含量、净光合速率、蒸腾速率、气孔导度和水分利用效率分别是铵硝比为4/1的氮素营养处理值的1.63、1.57、1.39、1.37、1.2倍,而胞间CO2浓度则减少了17%.因此相对于铵态氮来说,硝态氮比例的增加有利于维持盐胁迫下菊芋幼苗体内矿质营养元素含量平衡,促进盐胁迫下菊芋光合功能的改善,增强菊芋对盐胁迫的抗性.     

纳米SiO2对髯毛箬竹叶片光合特征参数日变化的影响

采用叶面喷施的方法,研究了0(CK)、150、300和450 mg.L-1纳米SiO2对髯毛箬竹(Indocalamus barbatusMcClure)叶片净光合速率、气孔导度、蒸腾速率、胞间CO2浓度、气孔限制值和水分利用效率等光合特征参数日变化(7:00至16:00)的影响。结果表明:对照组髯毛箬竹叶片的净光合速率、气孔导度、蒸腾速率和气孔限制值的日变化曲线均为"双峰"型,有明显的"午休"现象;胞间CO2浓度的日变化曲线则为"W"型;水分利用效率的日变化曲线为"U"型。与对照相比,喷施150、300和450 mg.L-1纳米SiO2均能不同程度提高髯毛箬竹叶片的净光合速率、气孔导度和蒸腾速率,减小气孔限制值及胞间CO2浓度的变化幅度,提高"午休"时的水分利用效率,缓解光合作用的"午休"现象;其中,300 mg.L-1纳米SiO2处理组的效果最佳,在出现最大峰值的10:00时300 mg.L-1纳米SiO2处理组的净光合速率、气孔导度和蒸腾速率分别比对照提高了13.98%、71.21%和49.09%,且均与对照差异显著(P<0.05)。综合分析结果说明:髯毛箬竹叶片光合能力的提高是气孔和非气孔限制因素共同作用的结果,而喷施适量的纳米SiO2能够在一定程度上改善非气孔限制因素,从而增强髯毛箬竹叶片的光合能力。     

干旱生境中接种丛枝菌根真菌对三叶鬼针草

为阐明丛枝菌根真菌对石灰岩地区适生植物三叶鬼针草(Bidens pilosa L.)光合作用的影响,设置正常浇水(A)、中度干旱胁迫(B)和重度干旱胁迫(C)3个水分处理梯度,比较了不同水分处理条件下接种丛枝菌根真菌Glomus mosseae和未接种三叶鬼针草之间净光合速率、气孔导度、蒸腾速率、胞间CO2浓度、羧化效率、水分利用效率等特征的差异.结果表明,水分胁迫显著降低三叶鬼针草的净光合速率、气孔导度、蒸腾速率和羧化效率.胞间CO2浓度在处理的前期(7d)因干旱胁迫而降低,在后期随土壤含水量的降低而升高;水分利用效率则是中度胁迫的植株、正常浇水处理植株、重度胁迫植株依次降低.在正常浇水条件下接种G. mosseae 对三叶鬼针草光合参数没有产生显著性影响;在中度胁迫条件下,接种植株较未接种植株在水分处理的前28d有更高的净光合速率、气孔导度、蒸腾速率和羧化效率;在重度胁迫条件下,虽然净光合速率、气孔导度、蒸腾速率和羧化效率接种植株高于未接种植株,但是二者并不显著.研究认为,干旱胁迫对三叶鬼针草光合作用的影响在水分处理的前期表现为气孔因素制约,在后期则主要是非气孔因素的影响;在正常浇水条件下接种G. mosseae 对三叶鬼针草的光合作用没有显著性影响,在干旱胁迫条件下,丛枝菌根真菌通过改善三叶鬼针草气孔导度和羧化效率等减弱干旱胁迫对植株的伤害,但是这种保护作用因为土壤水分的严重匮乏以及土壤干旱的时间延长而受到限制.     

镉胁迫下硒对罗汉果组培苗光合特性的影响

实验以罗汉果组培苗为材料,室内栽培在内装市售营养土的塑料盆中,以0、10、50、100、200mg·kg-1浓度镉离子和1mg·kg-1浓度硒处理,培养20d后分析罗汉果幼苗的相关光合生理指标。结果表明:低浓度Cd2+对叶片叶绿素含量、光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)影响不大或稍有上升,但高浓度镉离子处理植株叶片的叶绿素含量、光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)明显下降;随Cd2+处理浓度的增加,叶片胞间CO2浓度(Ci)呈现上升趋势;加硒则延缓叶绿素下降,促进光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)上升,降低叶片胞间CO2浓度(Ci)。表明高浓度镉离子的毒害导致罗汉果组培苗叶片光合性能受到伤害,从而影响罗汉果幼苗生长。镉硒混合处理反映出硒对镉的毒害有缓解作用。     

土壤水分交替变化对湿地松幼苗光合特性的影响

以盆栽湿地松幼苗为材料,通过实验室模拟三峡库区从水淹到干旱的过程,设置常规供水(CK)、常规供水-轻度干旱-复水(DR),水淹(FL),水淹-轻度干旱-复水(FD)4个实验组,研究土壤水分交替变化对湿地松幼苗光合参数及叶绿素含量的影响.结果表明:(1)不同土壤水分处理条件对湿地松幼苗的净光合速率、气孔导度、蒸腾速率、胞间CO2浓度、气孔限制值、水分利用效率和光合色素含量都有一定影响.(2)在实验的前中期,DR、FL和FD组湿地松幼苗的光合速率、气孔导度、蒸腾速率都显著下降,DR和FD在实验后期回升到较高水平.(3)在整个实验期间各处理组的水分利用效率较对照都有不同程度上升,并以DR组的最大(4.95μmol·mmol-1).(4)随着处理时间延长,各处理组湿地松幼苗的总叶绿素含量及叶绿素a/b值均呈先降后升的趋势,其中叶绿素/类胡萝卜素的比值在4.379～6.019间波动,而叶绿素a/b值则在2.207～2.850间波动.研究发现,湿地松幼苗在水分代谢、光合生理等方面等能够很好地适应水淹以及"淹-干"的水分交替变化环境,并且在解除胁迫后能够迅速恢复生长,可以考虑用于三峡库区消落带的植被修复和重建.     

BTH和SA处理及白粉菌接种对甜瓜叶片光合特性的影响

以抗病品种Tam Dew和感病品种卡拉克赛为材料,研究了BTH和SA处理及白粉菌接种对甜瓜叶片叶面积、叶绿素含量、净光合速率、气孔导度、胞间CO2浓度的影响.结果表明,BTH和SA处理及白粉菌接种对甜瓜苗期叶面积扩展无显著影响;BTH和SA处理植株的叶片(第3叶)和新生叶片(第5叶)的净光合速率、叶绿素含量和气孔导度显著高于对照;白粉菌接种后,2个甜瓜叶片的叶绿素含量、净光合速率和气孔导度显著降低,而BTH和SA处理能缓解由白粉菌接种带来的叶绿素含量、净光合速率和气孔导度的下降趋势.说明BTH和SA处理能延长甜瓜叶片的光合寿命,延缓甜瓜叶片的叶绿素含量、净光合速率和气孔导度的下降趋势.     

REGULATION OF MATURATION RATE OF MOUSE GRANULOCYTES

Regenerating mouse bone marrow cells were cultured i.p. in diffusion chambers (DC) to study factors affecting the maturation rate of granulocyte precursors. One day after exposing 3-day-old DC cultures to ³H-thymidine the cultures were harvested, and labelled proliferative and non-proliferative granulocytes were counted in radioautographs. The relative maturation rate—defined as the fraction of proliferative precursors maturing into the non-proliferative compartment per unit time—could be increased by different experimental procedures that inhibit cell production. Inhibition was obtained (a) by increasing culture cellularity; (b) by implanting DC into normal rats or rats with huge s.c. chloroma tumours rather than into mice; and (c) by treating the cells with leucocyte extracts (granulocyte chalone) during the last day of culture. Furthermore, a sudden inhibition of rapidly proliferating granulocytes by leucocyte extracts resulted in an increase (apparently transient) in the absolute number of labelled non-proliferative granulocytes. Such an increase was not detected in experiments involving a stronger or sustained inhibition of granulopoiesis, evidently because the size of the precursor population had been markedly reduced.     

哺乳动物最大代谢率的研究进展

最大代谢率（Maximum metabolic rate,MMR)是动物代谢的生理有限。本阐述了其有关概念,测定方法,发育过程中的变化,两种不同方法导致的MMR及其得验性,制约因子,影响因素（包括个体大小,系统发生,环境温度,海拔梯度,寄生虫与病毒）,与非颤抖性产热（Nn-shivering thermogenesis,NST)和基础代谢率（Basal metabolic rate,BMR)的关系,以及其未来的研究方向。其中NMR和BMR的关系涉及到了内温性进化的呼吸能力模型,介绍了相关的生化基础及验证。     

盐度对异育银鲫呼吸和氨氮排泄生理的影响

研究了异育银鲫(Carassius auratus gibeliovar. E′erqisi)从淡水向盐度1.5‰、3‰、6‰、9‰、12‰突变与适应过程中的呼吸和氨氮排泄生理的变化规律。结果表明:盐度突变开始时,异育银鲫的耗氧率和排氨率随外界盐度的升高而增大,随盐度作用时间延长,耗氧率和排氨率升到最大值后又开始下降并最终维持在稳定水平,但开始下降的时间和下降的幅度以及最终的稳定水平与外界盐度有关。盐度1.5‰和3‰处理组在作用12h时耗氧率升到最大值,此后下降,于第3天后保持在比淡水对照组略低的稳定水平,但二者差异不显著(P0.05);盐度6‰和9‰处理组在作用到第3天后才开始缓慢下降,并分别于第10、15天时保持在显著高于淡水对照的稳定水平(P0.05);盐度12‰处理组也在第3天后下降,到第10天后保持在比淡水对照组略低的稳定水平,但二者差异不显著(P0.05)。各盐度处理组的排氨率均在盐度作用24h时达到最大值,其中盐度1.5‰处理组的变化不显著(P0.05),其他各组均显著升高(P0.05),并都于第10天时下降到稳定水平,其中盐度3‰处理组的稳定水平略低于对照组(P0.05),盐度6‰、9‰、12‰处理组的稳定水平显著高于对照组(P0.05)。     

THE RATE OF GROWTH OF THE DOMESTIC FOWL

This paper points out the fact that the growth period of the domestic fowl is analogous to that of the mammal, being composed of three, or perhaps four, cycles; two of these cycles are postembryonic with maxima at about 8 and 18 weeks varying somewhat with the breed and two or at least one, are embryonic with maxima at 11 to 12 and 15 to 16 days of age. Hatching occurs during the first part of the second or third cycle resembling in this respect the guinea pig rather than the mouse. The velocity curves of each of these cycles are similar to and can be represented by the equation of an autocatalytic monomolecular reaction.     

ADAPTIVE LIMITATION OF THE REPRODUCTIVE RATE OF BIRDS

Some biologists have held that the rate of reproduction in birds tends to be adjusted to the average annual mortality; others, that it is limited only by the parents' ability to raise sturdy young. The latter theory, that of maximum reproduction, is likely to be true only if three related propositions are true:(1) that an increase of clutch size is more likely to occur than some other mutation affecting the rate of reproduction; (2) that a genotype with a wastefully high rate of reproduction can supplant a genotype with a more conservative but adequate rate; and (3) that an excessive rate of reproduction is not harmful to the species. None of these assumptions has been proved. In a population not obliged to employ its full reproductive potential to maintain itself at a favourable level, mutations which limit this potential may arise and persist. They may effect this limitation by means of:(i) reduction in clutch size; (ii) reduction in the number of broods; (iii) failure of the male to attend the nest, often followed by failure to form pairs; (iv) deferment of reproductive maturity; (v) developments in territorialism that limit the number of nesting birds or the number of progeny they can rear; (vi) restriction of nesting to traditional sites; and (vii) the time-consuming construction of elaborate nests. These limitations of the rate of reproduction must be regarded as adaptive because, like other adaptations, they adjust the birds more perfectly to the conditions in which they live and reduce the stress to which they are subjected. In both tropical and temperate regions, species in which only the female feeds the nestlings have broods as large as species in which both parents feed them. It follows that the two parents are not rearing as many young as they could nourish. The view that hole-nesting birds can rear larger broods than open-nesters because their young develop more slowly, and require less food per capita per day, is untenable. Nestlings raised in holes and burrows gain weight about as rapidly as those in more exposed nests, but for safety they remain longer in their protected abodes. The larger broods of hole-nesters evidently compensate for the difficulty of obtaining nest sites, which delays the breeding of some pairs and prevents that of others. Clutch size is by no means closely adjusted to the number of young the parents can raise. If given additional nestlings, some birds attend them adequately. In other species, young are rarely fledged from all the eggs. In many cases, asynchronous hatching is not, as has been claimed, an arrangement which permits the parents to adjust to a varying food supply the number of young that they rear. In many raptors, fratricide and cannibalism reduce the size of the brood, sometimes to a single nestling, regardless of the abundance of food. The more stable the environment, the more closely the reproductive rate tends to be adjusted to the mortality; the more a population is subject to catastrophic reductions, the more the rate will approach the maximum. Primarily, the reproductive rate is controlled by heritable characters, which can adjust the rate to a stable environment but rarely respond to short-term fluctuations in external conditions or population density. The last fine adjustment of a population to its habitat is effected by processes that are density-dependent:either density-dependent regulation of the reproductive effort, or density-dependent mortality of adults or young, or a combination of the two. The general evolutionary trend in the Metazoa is toward producing fewer offspring and taking better care of them. This would hardly be possible if the more prolific genotype always prevails over those which raise smaller families and in consequence can attend their young somewhat better. The regulation of the rate of reproduction is a unique evolutionary problem, because a mutation conferring greater fertility, although often detrimental to the species, tends to diffuse through it as no other harmful mutation can. Yet it is counteracted by many factors, chiefly ecological, which operate subtly and are more difficult to appreciate than the force of numbers.