NaCl胁迫对棉花种子萌发和幼苗生长的伤害

采用盐化土壤盆栽方法,选择耐盐性较强品种枝棉３号和耐盐性较弱品种泗棉２号,研究了盐分对棉花（Ｇｏｓｓｙｐｉｕｍ ｈｉｒｓｕｔｕｍ Ｌ．）种子萌发、出苗和幼苗生长的伤害。结果表明,在－０．５５和－１．１０ＭＰａ盐分胁迫下,对棉花伤害起决定性作用的因子是Ｎａ＾＋。２００ｍｍｏｌ／Ｌ ＮａＣｌ胁迫下,枝棉３号种子萌发时电导率上升幅度和子叶ＣＡＴ下降幅度均显著小于泗棉２号。１００和２００ｍｍｏｌ／Ｌ Ｎａ     

1,2,4-三氯苯胁迫对萌发大豆种子中活性氧的影响

以盆栽法研究了不同浓度 1,2 ,4 三氯苯 (TCB)胁迫对萌发大豆种子中活性氧代谢的影响 .结果表明 ,10 0～ 30 0 μg·g-1TCB胁迫初期 (1～ 3天 )促使萌发大豆种子呼吸强度升高及其峰值提前出现 ,超氧阴离子自由基 (O2 - )及过氧化氢 (H2 O2 )的积累显著增加 ,同时伴随丙二醛 (MDA)含量升高 ,显示发生膜脂质过氧化作用 .TCB胁迫 1～ 6天使活性氧清除酶功能紊乱 ,其中过氧化物酶 (POD)活性升高 ,超氧化物岐化酶 (SOD)活性开始上升后转为下降 .在萌发大豆种子受TCB胁迫伤害过程中 ,活性氧代谢失衡造成的膜脂质过氧化将起着重要作用 .     

岷江上游景观变化评价

通过NetWeaver设计模糊知识库,利用EMDS模型定量评价了岷江上游1986--2000年景观变化．结果表明：整个流域景观的斑块类型、面积、数量及空间配置均发生了较大变化,且朝着有利于生态恢复的方向变化．森林类型的变化主要发生在北部（松潘县和黑水县）．草地类型的变化主要发生在北部（松潘县）和最南部（汶川县）．流域景观变化是人类活动强度增大和自然变化共同作用的结果．     

盐胁迫下野大豆种子萌发特性研究

采用不同浓度的NaCl、Na2SO4、Na2CO3及三者的混合盐的胁迫,对野大豆种子的发芽率、发芽势、发芽指数及胚生长的影响进行测定分析.结果表明,随盐溶液浓度的增加,野大豆种子的发芽率、发芽速度、发芽指数均呈下降趋势,而低浓度的Na2SO4（10 ～ 50 mmol/L）,Na2CO3（≤10 mmol/L）促进种子萌发,高浓度的NaCl（＞ 200mmol/L）、Na2SO4 （≥200 mmol/L）、Na2CO3（＞75 mmol/L）抑制种子萌发;胚根和胚轴对不同种类盐胁迫表现出不同的反应.低浓度的盐分促进了胚根和胚轴的生长.     

高浓度氧对种子萌发和幼苗生长的伤害

绿豆、木豆和水稻等种子在氧气下萌发生长会引起不同程度的氧伤害,这种伤害不因二氧化碳、光照和温度条件的改变而减轻或消除。水稻萌发生长对高浓度氧的忍耐是有限度的,氧处理1～2天后移置空气中,能恢复生长;处理3～4天恢复生长缓慢;处理5天失去生长能力。种子萌发的氧伤害,表现出种子吸水膨胀率和浸泡液电导率较高,糖和蛋白质外渗量大,以及膜脂过氧化产物丙二醛含量较高。     

CO2激光处理对大豆种子萌发及生理的影响

以大豆(Glycine max Merr.)为实验材料,研究了CO2激光不同功率密度和不同时间处理对大豆种子发芽率、淀粉酶活性、可溶性蛋白质、可溶性糖含量和氨基酸含量的影响。结果表明：(1)16mw／mm^2、18mw／mm^2、20mw／mm^2CO2激光处理均能提高种子发芽率、淀粉酶活力、可溶性蛋白质、可溶性糖含量和游离氨基酸含量,其中18mw／mm^2CO2激光处理效果最好;(2)相同功率(18mw／mm^2)不同时间处理均能提高种子发芽率、淀粉酶活力、可溶性蛋白质和游离氨基酸含量,处理时间以75s效果最好。     

混合盐碱胁迫对小白菜种子萌发的影响

用不同浓度的NaCl、Na₂SO₄、NaHCO₃和Na₂CO₃混合液对小白菜(Brassica chinensis L.)种子进行种子萌发试验,观察小白菜种子在不同浓度盐碱胁迫下的发芽率和发芽指数。结果表明,在混合盐碱胁迫下,小白菜种子的发芽率、发芽势、发芽指数和活力指数均随pH值增大和盐浓度的升高呈下降趋势,且各萌发指标与盐浓度的相关系数明显大于pH值,可见小白菜种子发芽受盐浓度的影响更大。低浓度(50mmol·L^-1)盐碱胁迫对小白菜种子萌发影响不大,高浓度(200mmol·L^-1)盐碱胁迫下小白菜的种子萌发受到严重影响。     

盐胁迫对荆条、白蜡、沙枣种子萌发的影响

用不同浓度的NaCl、Na₂CO₃混合盐胁迫梯度,对荆条、白蜡和沙枣种子进行了种子萌发实验,观察了3个物种在盐胁迫下的发芽率、发芽速度和胚根生长,比较了光照和黑暗条件下3种植物种子的萌发差异。结果表明：光照对3种植物种子的萌发有明显的促进作用,但对胚根生长的影响却各不相同。低浓度混合盐溶液对荆条、白蜡种子萌发有促进作用,对沙枣有轻度抑制。当盐胁迫浓度超过0.8%,3种植物种子的萌发均受到不良影响,尤其对荆条的影响较大。3种植物均能在盐渍化生境中生长,3者均可作为园林植物在天津试验栽培。沙枣在天津塘沽地区盐碱地上进行广泛种植完全具有可行性。     

盐胁迫对蓝蓟种子萌发及早期幼苗的影响

研究了不同浓度盐(NaCl)处理对蓝蓟种子发芽势、发芽率及幼苗生长的影响。结果表明:(1)不同盐胁迫处理对蓝蓟种子的萌发具有显著影响。随着盐处理浓度的增加,发芽率呈下降趋势,蓝蓟在无盐环境(蒸馏水)和低盐环境中(0.05 mol/L)长势最好、发芽率最高、发芽速度最快。(2)将不同盐溶液处理5 d的未萌发种子转移到蒸馏水后,蓝蓟种子的萌发能力均可恢复,原来较高盐浓度(0.3 mol/L～0.5 mol/L)下的种子在恢复后,其萌发恢复率均在75%以上,发芽率基本上随着原浓度的升高呈上升的趋势。研究表明,NaCl处理对蓟种子没有造成伤害,其抑制萌发是通过渗透效应而不是离子毒害。     

胀果甘草种子萌发对干旱胁迫的生理响应

为探讨胀果甘草种子萌发对干旱胁迫的生理生化适应机制,以聚乙二醇(PEG)-6000模拟干旱胁迫,分析了胀果甘草(Glycyrrhiza inflata)种子萌发过程中发芽率(GR)、丙二醛(MDA)及游离脯氨酸(Pro)、可溶性糖(SS)含量和超氧化物歧化酶(SOD)、过氧化物酶(POD)活性的动态变化规律。结果显示,水势为-0.1MPa时,GR达到100%,之后随着干旱胁迫增强而显著降低(P0.05);MDA、Pro含量及SOD、POD活性都表现出水势≥-0.2MPa时增加和-1.4MPa≤水势-0.2MPa时减少的明显趋势(P0.05),这4个指标两两之间的相关关系均达到显著水平(P0.05);而干旱胁迫增强使SS含量显著增加(P0.05)。     

沙埋对六种沙生植物种子萌发和幼苗出土的影响

研究了沙埋对科尔沁沙地6种优势植物的种子萌发和幼苗出土的影响．进行0．2、4、6、8、10和12cm等7个深度沙埋处理．结果表明,在不同沙埋处理时,沙蓬萌发差异显著。而差不嘎蒿2锄埋深与其他埋深的发芽差异显著,其他4种植物0cm埋深与其他埋深的发芽差异显著;沙埋对所有植物幼苗出土均有显著影响,埋深增加,出苗率减小;繁殖体大的物种与繁殖体小的物种相比,能从更深沙层中出苗,幼苗出土最大深度排序为苦参>东北木蓼≥沙蓬>山竹子>雾冰藜>差不嘎蒿．     

Gene expression in the soybean seed axis during germination and early seedling growth

Copy-DNA clones have been obtained that distinguish eight messenger mRNAs, moderately abundant in the axes of the germinating soybean (Glycine max (L.) Merr.) seedling. These clones have been used to characterize the size of the mRNAs and to anlyze the accumulation of the mRNAs at different time points and in different parts of the axis during germination and early seedling growth. Three of the mRNAs accumulate to a substantial level by 9 h, a time point before either the beginning of growth or the accumulation of polyribosomes. Four other mRNAs reach a substantial level only at 24 h, a period when rapid seedling growth is occurring. Those mRNAs whose accumulation begins at 24 h were found only in the top (hypocotyl) half of the 24-h seedlings, while the remaining mRNAs were present also in the bottom half of the seedlings in different amounts. By 44 h, the bottom 0.5 cm of the seedlings, i.e., the region of meristematic growth, had little or none of the mRNAs, with the exception of one mRNA. These temporal and spatial observations indicate that many of the mRNAs are not involved simply in the general maintenance of ongoing cell proliferation, but that they may be related to differentiation during early seedling formation. Further, the early accumulating mRNAs may be functioning in regulating the onset of seedling growth.Abbreviations cDNA copy DNA - poly(A)⁺RNA polyadenylated RNA     

城市污泥对作物种子发芽及幼苗生长影响的初步研究

不同类型污泥及其堆肥对通菜、菜心种子发芽和幼苗生长影响的研究表明 ,深圳生污泥、佛山生污泥和广州生污泥及其堆肥对通菜种子的发芽率有明显的影响 ,前者仅为73% ,其余的在 85%左右 ,均低于对照处理 ( 93% ) .而它们对菜心种子的发芽率 ,除了深圳生污泥有抑制作用外 ( 75% ) ,其余均表现为促进作用 ( 90 % ) ,均高于对照处理 ( 85% ) .它们对于两种作物幼苗的生长则均表现为不同程度的抑制作用甚至是损害作用 .污泥及其堆肥中抑制作物种子发芽和幼苗生长的物质主要是有机酸和醛类等有机物 .生污泥经过消化作用或适当的堆沤作用可降解这些有机物 ,从而减弱或消除这种抑制作用 .因此 ,生污泥经过消化作用或适当的堆沤作用后用于农业生产更为安全 .但对刚施用污泥或污泥堆肥的耕地最好不要直接播种 .     

Hg浸种对玉米种子萌发过程中几种酶活性的影响

1　引　　言Hg是环境污染的重要因素,有关Hg对植物生长发育的影响及危害机制已有报导[1,3],但Hg对玉米种子萌发作用尚未见报道.种子萌发依靠自身储存的淀粉、脂肪和蛋白质的分解来提供物质和能量,合成新的生命物质.因此环境对种子萌发的影响首先表现在对这些大物质分解代谢的影     

Nitric oxide accelerates seed germination in warm-season grasses

The nitric oxide (NO) donor sodium nitroprusside (SNP) significantly promoted germination of switchgrass (Panicum virgatum L. cv Kanlow) in the light and in the dark at 25°C, across a broad range of concentrations. SNP also promoted seed germination in two other warm-season grasses. A chemical scavenger of NO inhibited germination and blocked SNP stimulation of seed germination. The phenolic (+)-catechin acted synergistically with SNP and nitrite in promoting seed germination. Acidified nitrite, an alternate NO donor also significantly stimulated seed germination. Interestingly, sodium cyanide, potassium ferricyanide and potassium ferrocyanide at 200 μM strongly enhanced seed germination as well, whereas potassium chloride was without effect. Ferrocyanide and cyanide stimulation of seed germination was blocked by an NO scavenger. Incubation of seeds with a fluorescent NO-specific probe provided evidence for NO production in germinating switchgrass seeds. Abscisic acid (ABA) at 10 μM depressed germination, inhibited root elongation and essentially abolished coleoptile emergence. SNP partially overcame ABA effects on radicle emergence but did not overcome the effects of ABA on coleoptile elongation. Light microscopy indicated extension of the radicle and coleoptiles in seeds maintained on water or on SNP after 2 days. In contrast, there was minimal growth of the radicle and coleoptile in ABA-treated seeds even after 3–4 days. These data indicate that seed germination of warm-season grasses is significantly influenced by NO signaling pathways and document that NO could be an endogenous trigger for release from dormancy in these species.     

Influence of heat on seed germination of seven Mediterranean Leguminosae species

The influence of high temperatures (dry heat and hot water) on germination of seven Mediterranean Leguminosae species typical of fire-prone ecosystems in southern Spain is analyzed, in order to know the response of seeds to wildfires and the possible implications in their regeneration after this disturbance. Seeds were heated to a range of temperatures (50 °–150 °C) and exposure times (1–60 min) similar to those registered in the upper soil layers during wildfires. Germination tests were carried out in plastic Petri dishes over 60 days. In general, the degree of seed germination promotion by dry heat treatments showed a wide interspecific variation, although the final germination level was increased in all the studied species except for Scorpiurus muricatus. The thermal pretreatment of 50 °C, however, was not effective for germination in any species, and rising the temperature to 70 °C only slightly enhanced the germination in Cytisus patens. The preheatings of 90 °C (5 and 10 min), 120 °C (5 and 10 min), and 150 °C (1 min) were the most effective in promoting seed germination. Hot water (100 °C) scarification also increased the final germination level in all cases, with the exception of C. patens. The germination rates after preheating were much lower than in mechanically scarified seeds and closely resembled those of the untreated seeds, except for C. reverchonii, whose seed germination rate decreased with heat. The response of species to heat shock had no clear relationship with life trait or with the specific post-fire regeneration strategy (obligate seeder or facultative resprouter). Those species coexisting in the same habitats had different heat optimal requirements for seed germination, an strategy suggested by some authors as minimizing interspecific competition in the secondary succession started after fire.     

Phytochrome regulation of seed germination

Seed germination of many plant species is influenced by light. Of the various photoreceptor systems, phytochrome plays an especially important role in seed germination. The existence of at least five phytochrome genes has led to the proposal that different members of the family have different roles in the photoregulation of seed germination. Physiological analysis of seed germination ofArabidopsis thaliana (L.) Heynh. with phytochrome-deficient mutants showed for the first time that phytochrome A and phytochrome B modulate the timing of seed germination in distinct actions. Phytochrome A photo-irreversibly triggers the photoinduction of seed germination after irradiation with extremely low fluence light in a wide range of wavelengths, from UV-A, to visible, to far-red. In contrast, phytochrome B mediates the well-characterized photoreversible reaction, responding to red and far-red light of fluences four orders of magnitude higher than those to which PhyA responds. Wild plants, such asA. thaliana, survive under ground as dormant seeds for long periods, and the timing of seed germination is crucial for optimizing growth and reproduction. It therefore seems reasonable for plants to possess at least two different physiological systems for sensing the light environment over a wide spectral range with exquisite sensitivity of different phytochromes. This redundancy seems to enhance plant survival in a fluctuating environment.     

Proteomic insights into seed germination in response to environmental factors

Seed germination is a critical process in the life cycle of higher plants. During germination, the imbibed mature seed is highly sensitive to different environmental factors. However, knowledge about the molecular and physiological mechanisms underlying the environmental effects on germination has been lacking. Recent proteomic work has provided invaluable insight into the molecular processes in germinating seeds of Arabidopsis, rice (Oryza sativa), soybean (Glycine max), barley (Hordeum vulgare), maize (Zea mays), tea (Camellia sinensis), European beech (Fagus sylvatica), and Norway maple (Acer platanoides) under different treatments including metal ions (e.g. copper and cadmium), drought, low temperature, hormones, and chemicals (gibberellic acid, abscisic acid, salicylic acid, and α‐amanitin), as well as Fusarium graminearum infection. A total of 561 environmental factor‐responsive proteins have been identified with various expression patterns in germinating seeds. The data highlight diverse regulatory and metabolic mechanisms upon seed germination, including induction of environmental factor‐responsive signaling pathways, seed storage reserve mobilization and utilization, enhancement of DNA repair and modification, regulation of gene expression and protein synthesis, modulation of cell structure, and cell defense. In this review, we summarize the interesting findings and discuss the relevance and significance for our understanding of environmental regulation of seed germination.     

Climate warming could shift the timing of seed germination in alpine plants

Background and Aims

Despite the considerable number of studies on the impacts of climate change on alpine plants, there have been few attempts to investigate its effect on regeneration. Recruitment from seeds is a key event in the life-history of plants, affecting their spread and evolution and seasonal changes in climate will inevitably affect recruitment success. Here, an investigation was made of how climate change will affect the timing and the level of germination in eight alpine species of the glacier foreland.

Methods

Using a novel approach which considered the altitudinal variation of temperature as a surrogate for future climate scenarios, seeds were exposed to 12 different cycles of simulated seasonal temperatures in the laboratory, derived from measurements at the soil surface at the study site.

Key Results

Under present climatic conditions, germination occurred in spring, in all but one species, after seeds had experienced autumn and winter seasons. However, autumn warming resulted in a significant increase in germination in all but two species. In contrast, seed germination was less sensitive to changes in spring and/or winter temperatures, which affected only three species.

Conclusions

Climate warming will lead to a shift from spring to autumn emergence but the extent of this change across species will be driven by seed dormancy status. Ungerminated seeds at the end of autumn will be exposed to shorter winter seasons and lower spring temperatures in a future, warmer climate, but these changes will only have a minor impact on germination. The extent to which climate change will be detrimental to regeneration from seed is less likely to be due to a significant negative effect on germination per se, but rather to seedling emergence in seasons that the species are not adapted to experience. Emergence in autumn could have major implications for species currently adapted to emerge in spring.     

种子萌发和幼苗生长对沙丘环境的适应机制

综述了植物沙生适应机制的研究及其进展.一些植物的种子在刚成熟时具有休眠特性.种子需要适度沙埋促进萌发并实现幼苗定居,但过度沙埋则会抑制种子萌发和出苗.在沙层深处,没有萌发的种子会进入休眠状态,形成土壤种子库.幼苗通过增加节数和延长节间来适应沙埋.沙埋深度超过植物的忍耐限度会抑制幼苗生长,甚至导致幼苗死亡.沙生植物必须适应其他环境因子,如盐风与土壤盐分、昆虫采食、土壤养分亏缺等,才能在沙丘上成功生长.沙蚀可导致幼苗根系暴露并干燥脱水.一些沙漠植物的幼苗在萌发后可忍耐一段时期的干燥,水分条件得到满足之后,幼苗能够恢复生长.