Seed germination in response to diurnal fluctuations of temperature

Diurnal fluctuations in temperature may initiate or accelerate germination in certain flowering plants, and the effectiveness of the stimulus varies according to the amplitude of fluctuation and the presence or absence of light. Attempts to assess the adaptive significance of the phenomenon, however, have been limited by the scarcity of data for species of contrasted ecology. We report here an investigation of germination responses to fluctuating temperatures, conducted on seeds of herbaceous species collected from native populations near Sheffield. The results suggest that requirements for diurnal fluctuations in temperature are characteristic of the germination of species from particular types of habitat and provide mechanisms which cause seeds to germinate at times and in places favourable for seedling establishment.     

水杨酸浸种对水稻种子萌发的影响与水杨酸浓度和萌发温度的相关性

用不同浓度水杨酸对水稻种子进行浸种预处理,研究了水杨酸对不同温度下水稻种子萌发的影响,结果表明：不同浓度水杨酸对种子萌发指数－萌发高同知,发芽率,根冠比,生物学产量,根长,根活力指数,芽长,芽活力指数的作用不同,随着萌发温度从30℃降低至15℃,最达水杨酸浓度不断增大。     

青藏高原特有植物肋果沙棘种子萌发对不同温度的响应

研究了青藏高原特有植物肋果沙棘(Hippophae neurocarpa)种子萌发对不同温度的响应.结果表明:肋果沙棘种子萌发温幅较宽,在15～35 ℃范围内均有较高的发芽率.肋果沙棘种子在温度为15 ℃和20 ℃时发芽率达90%以上,显著高于30 ℃和35 ℃处理的发芽率;生长结束时胚根及下胚轴长度(37.22±2.910,52.41±3.030 mm)也大于30 ℃(33.32±1.313 mm)和35 ℃(23.28±1.641 mm)的长度,表明肋果沙棘种子在较低温度下萌发和生长情况较好.此外,肋果沙棘种子在各温度处理下,1～2 d内开始萌发,4～7 d完成萌发过程,具有迅速萌发的特性.较宽的萌发温幅、在较低温度下的高萌发率以及迅速萌发的特性保证了肋果沙棘能够在低温环境和较为短促的生长季节里顺利完成萌发过程,迅速占有生存资源与空间,这体现出该植物对青藏高原高寒环境的一种生存适应机制.     

不同温度和化学处理对四川嵩草种子萌发的影响

研究了四川嵩草(Kobresia setchwanensis)种子对不同温度和化学试剂的响应.用3种不同浓度的化学试剂(NaOH、GA3和CaCl2)分别处理种子,将其置于5,10,15,20,25 ℃恒温条件下进行光照培养.结果表明:四川嵩草种子萌发温度幅较宽,在10～25 ℃范围内均能萌发,但在20 ℃和25 ℃恒温条件下,种子的萌发率和萌发指数较高,最佳萌发温度为20 ℃,萌发率和萌发指数分别可达96%和7.06.不同温度条件下,3种化学试剂处理对四川嵩草种子的萌发率和萌发指数均有显著性影响,对种子萌发有一定的促进作用,其中,用适当浓度NaOH处理过的种子其萌发率和萌发指数高于用其它两种试剂处理的结果.10 ℃条件下,NaOH的最佳处理浓度为30 g·L-1;15～25 ℃温度条件下,最佳处理浓度为20 g·L-1.对于GA3和CaCl2,在不同温度条件下(10～25 ℃)有不同的最佳处理浓度.     

沙埋对几种沙生植物种子萌发和幼苗的影响

研究了沙埋对科尔沁沙地7种植物的种子萌发和幼苗存活的影响.9个沙埋处理深度为1、2、3、45、、6、7、8和10 cm.结果表明,在不同沙埋处理下,7种植物的萌发率存在显著差异,除山竹岩黄芪外,其他6种植物的萌发趋势均随着沙埋深度的增加而下降,山竹岩黄芪在不同沙埋处理下均有较高的萌发率,在8 cm埋深处萌发率最小.沙埋对7种植物的幼苗出土均有显著影响,埋深增加,出苗率减小,幼苗出土与植物繁殖体的大小有关,繁殖体大的物种具有较深沙层的幼苗出土,幼苗出土的沙埋深度顺序为小叶锦鸡儿≥沙米>山竹岩黄芪≥大果虫实>地肤≥灰绿藜>差巴嘎蒿.     

几种不同楸树花粉萌发率的测定及花粉超低温保存方法

对5种不同楸树(楸树、滇楸、梓树、灰楸和黄金树)花粉萌发率的研究表明:花粉在恒温25℃培养6 h时萌发率较好,培养基为:10%蔗糖 0.01%硼酸 1%琼脂。在室温水培条件下,花粉在3 d内都保持较好的萌发率,第4天至第7天萌发率快速下降。花粉在液氮和-70℃条件下贮藏生活力较好,随贮藏时间延长生活力下降幅度也较小;常温贮藏时花粉萌发率最低,且生活力丧失快;而0℃和-20℃贮藏花粉生活力居中。超低温保存后花粉的解冻方式对花粉的萌发率影响较大,楸树各树种均以温水浴(35~38℃)下解冻5 min效果最好。     

Characterization of Arabidopsis calreticulin mutants in response to calcium and salinity stresses

As an important calcium-binding protein,calreticulin plays an important role in regulating calcium homeostasis in endoplasmic reticulum (ER) of plants.Here,we identified three loss-of-function mutants ofcalreticulin genes in Arabidopsis to demonstrate the function of calreticulin in response to calcium and salinity stresses.There are three genes encoding calreticulin in Arabidopsis,and they are named AtCRT1,2,and 3,respectively.We found that both single mutant of crt3 and double mutant of crtl crt2 were more sensitive to low calcium environment than wild-type Arabidopsis.Moreover,crt3 mutant showed more sensitivity to salt treatment at germination stage,but tolerance to salt stress at later stage compared with wild-type plant.However,there was no obvious growth difference in the mutant crt1 and crt2 compared with wild-type Arabidopsis under calcium and salt stresses.These results suggest that calreticulin functions in plant responses to calcium and salt stresses.     

云杉属植物种子形态及萌发特征的种间变异

在实验室条件下观测了云杉属(Picea)10个树种的种子形态和萌发特性,分析了它们与种源地地理气候因子之间的关系。结果表明:种子长、宽、千粒质量的差异在种间达到极显著水平;除种子萌发高峰期外,种子发芽率、发芽起始时间和发芽持续时间在种间具有极显著的差异。相关性分析则表明:种子长和宽呈极显著正相关;种子长、种子宽与千粒质量呈极显著正相关;而种子千粒质量与发芽率、发芽起始时间和持续时间呈显著正相关;纬度与种子长、种子宽和千粒质量呈显著正相关;年均温与种子长、种子宽、千粒质量和发芽持续时间呈显著负相关。因此,纬度和温度是影响云杉属植物个体间种子大小变异的主要因子。     

Model-data divergence in global seasonal temperature response to astronomical insolation during the Holocene

Insolation change is a primary driver for climate variation at orbital scales [1,2].During the Holocene (ca.11.7 ka BP to present),orbitally induced seasonal va...     

Seed priming with chitosan improves maize germination and seedling growth in relation to physiological changes under low temperature stress

Low temperature stress during germination and early seedling growth is an important constraint of global production of maize. The effects of seed priming with 0.25%, 0.50%, and 0.75% (w/v) chitosan solutions at 15 °C on the growth and physiological changes were investigated using two maize (Zea mays L.) inbred lines, HuangC (chilling-tolerant) and Mo17 (chilling-sensitive). While seed priming with chitosan had no significant effect on germination percentage under low temperature stress, it enhanced germination index, reduced the mean germination time (MGT), and increased shoot height, root length, and shoot and root dry weights in both maize lines. The decline of malondialdehyde (MDA) content and relative permeability of the plasma membrane and the increase of the concentrations of soluble sugars and proline, peroxidase (POD) activity, and catalase (CAT) activity were detected both in the chilling-sensitive and chilling-tolerant maize seedlings after priming with the three concentrations of chitosan. HuangC was less sensitive to responding to different concentrations of chitosan. Priming with 0.50% chitosan for about 60~64 h seemed to have the best effects. Thus, it suggests that seed priming with chitosan may improve the speed of germination of maize seed and benefit for seedling growth under low temperature stress.     

Changes in fossil-fuel carbon emissions in response to interannual and interdecadal temperature variability

Relationships on interannual and interdecadal timescales among global mean air temperature,CO2 concentrations and fossil-fuel carbon emissions in four major developed countries (the United States,the United Kingdom,France,and Germany) were analyzed.On an interannual timescale,the United States fossil-fuel carbon emissions tend to increase during cold winters and decrease during warm winters,which is opposite to the situation in summer.On an interdecadal timescale,cold (warm) periods both in the United States and globally agree with high (low) periods of fossil-fuel carbon emissions,with the temperature variability leading by 5–7 years.The leading correlation on the interdecadal timescale and the asymmetry in seasonal correlation on the interannual timescale indicate that temperature variability is a possible cause of changes in fossil-fuel carbon emissions.     

Similar response of labile and resistant soil organic matter pools to changes in temperature

Our understanding of the relationship between the decomposition of soil organic matter (SOM) and soil temperature affects our predictions of the impact of climate change on soil-stored carbon. One current opinion is that the decomposition of soil labile carbon is sensitive to temperature variation whereas resistant components are insensitive. The resistant carbon or organic matter in mineral soil is then assumed to be unresponsive to global warming. But the global pattern and magnitude of the predicted future soil carbon stock will mainly rely on the temperature sensitivity of these resistant carbon pools. To investigate this sensitivity, we have incubated soils under changing temperature. Here we report that SOM decomposition or soil basal respiration rate was significantly affected by changes in SOM components associated with soil depth, sampling method and incubation time. We find, however, that the temperature sensitivity for SOM decomposition was not affected, suggesting that the temperature sensitivity for resistant organic matter pools does not differ significantly from that of labile pools, and that both types of SOM will therefore respond similarly to global warming.     

无损检测血液灌注率的常热流方法

建立了无损测量活体组织血液灌注率的皮肤表面常热流加热方法。基于 Pennes生物传热方程 ,得出体表温度响应与组织血液灌注率之间的计算关系式。研究了不同体表热流、血液灌注率下的组织温升 ,分析了体表接触热阻对估测血液灌注率的影响。该法中接触热阻的影响可通过在皮肤与热偶间采用高热导率油脂减少到可忽略的程度。该文方法与其他方法相比 ,简便易行精度高     

不同温度对花背蟾蜍心电图和心率的影响研究

对花背蟾蜍(Bufo raddei Strauch)在不同温度下的心电图和心率进行了研究.主要结果:T波有正向、负向和平坦的波形,与蜥蜴的T波为正向、鸟类的T波钝而宽阔不同.不同温度对花背蟾蜍心电图影响较大,P-R,Q-T和QRS间期随温度升高而减小.心率与温度的变化关系呈直线型.     

不同温度及赤霉素处理对盐步秋茄种子萌发与出苗的影响

研究了不同温度及赤霉素处理对盐步秋茄种子萌发与出苗的影响。结果表明,适宜其种子的萌发和出苗的温度范围为24~30℃,种子萌发的临界温度为16.67℃,有效积温范围在11~63日度,出苗的临界温度为17.13℃,有效积温的范围在13~112日度;赤霉素处理浓度在100~200 mg·L-1对种子发芽势、发芽率和出苗率均有明显提高。     

复合材料墙体室内温度响应的研究

针对建筑物内人体的热舒适性与内墙壁面温度的相关性,建立了具有复合材料墙体的房间内温度响应的数学模型。结果显示,在相同的加热(制冷)条件下,由相同材质、相同尺寸组合构成的复合材料墙体,在不同的材料排列方式的情况下,室内的温度响应有很大的不同,这对间歇性供热房间内人体的热舒适性有较大的影响。     

光照及种子大小对青藏高原东缘43种石竹目植物种子萌发特征的影响

以青藏高原东缘43种石竹目植物种子为对象,在自然光照和遮阴两种实验处理下研究了光照对种子萌发能力的影响以及不同实验处理下种子萌发能力与种子大小的关系.结果显示:整体上,全光照下的萌发开始时间和萌发持续时间显著高于遮阴下的,光照强度对萌发率和萌发速率指数没有影响;科分类水平上,不同科内萌发参数对光照强度的响应存在一定差异...     

七种真藓科(Bryaceae)植物孢子萌发与原丝体发育研究

采用显微照相的方法描述了七种真藓科植物孢子萌发与原丝体发育特征,结果表明:(1)七种真藓科植物的萌发孢子型均为真藓型(Bryum-type);(2)孢子萌发和原丝体发育特征对真藓科植物系统分类具有重要价值。