Pb胁迫条件下狭叶香蒲种子的萌发特性及其幼苗的生理响应

对0、30、150、300、450和600μmol·L-1Pb胁迫条件下狭叶香蒲（TyphaangustifoliaLinn.）种子的萌发特性进行了研究,并分析了0、450、900、1800和2700μmol·L-1Pb胁迫对狭叶香蒲幼苗叶片及根系中部分生理生化指标的影响。结果表明：随Pb浓度提高,狭叶香蒲种子的发芽率、发芽势、发芽指数和活力指数以及下胚轴长度均逐渐下降且低于对照,而其下胚轴长度抑制指数则逐渐增大,但在30μmol·L-1Pb胁迫条件下各项萌发指标均与对照无显著差异。叶片叶绿素a、叶绿素b及总叶绿素含量随Pb浓度提高呈逐渐下降趋势,但在450和900μmol·L-1Pb胁迫条件下与对照无显著差异,而在1800和2700μmol·L-1Pb胁迫条件下显著低于对照。在Pb胁迫条件下叶片和根中SOD活性均显著高于对照但变化趋势不同;随Pb浓度提高,叶片SOD活性呈波动但整体上升的趋势,而根中SOD活性则呈逐渐降低的趋势。叶片和根中POD活性均随Pb浓度提高呈持续上升的趋势,其中,在450和900μmol·L-1Pb胁迫条件下叶片的POD活性低于对照、根的POD活性高于对照,但均与对照无显著差异;而在1800和2700μmol·L-1Pb胁迫条件下叶片和根的POD活性均显著高于对照。在Pb胁迫条件下叶片和根中AsA和MDA含量均高于对照。随Pb浓度提高,叶片的AsA含量总体上逐渐增加但在450和900μmol·L-1Pb胁迫条件下与对照无显著差异;而根的AsA含量则呈先增加后降低的趋势且均与对照差异显著。随Pb浓度提高,叶片的MDA含量先增后降但均与对照无显著差异;而根的MDA含量呈“高-低-高”的波动趋势且仅在450μmol·L-1Pb胁迫条件下与对照差异显著。综合分析结果显示：狭叶香蒲幼苗根系对Pb胁迫的敏感性可能强于叶片;狭叶香蒲种子可在轻度Pb污染水体中萌发和生长;其幼苗对Pb胁迫具有一定的耐性,可用于中度Pb污染水体的修复。     

Seed germination and seedling survival in a colony of the common cormorant,Phalacrocorax carbo

Germination and seedling survival of some woody plants were examined in a colony of the common cormorant at Unoyama, central Japan. The germination ofQuercus serrata andPinus densiflora was less successful in the colony than outside the colony. The percentage of germination success was negatively correlated with the amount of cormorant faeces scattered on the ground and also with the soil water conent. Most of the germinated seedlings inside of the colony died with symptoms such as necrosis spreading from the edge of leaves. Saplings ofQ. serrata also tended to die more in the colony than outside the colony. The survival rate ofQuercus glauca seedlings with scattered faeces on their leaves and/or on the the surrounding soil was significantly lower than the rate of those free of faeces. These results suggest that in the cormorant colony, germination of seeds and seedling survival are greatly inhibited due to both the direct and indirect effects of cormorant faeces.     

Non-targeted metabolomic evaluations during seed germination and seedling growth in Salicornia brachiata (Roxb.) under saline conditions

Experimental studies were conducted for metabolomic profiling during seed germination and seedling development in Salicornia brachaita under saline conditions. The results revealed accumulation of sucrose, mannose, glycerol, methionine, tryptophan, glycerol, protocathechoic acid, and mannonic acid in germinating seeds. Abundance of rhamnose, glucose, glutamine, fructose, ornithine, quininic acid, proline and ketoglutaric acid were recorded during emergence of radical (EoR) and cotyledonary stage (CS) at 50% strength of seawater (SW) salinity. Higher levels of myo-inositol, ethanolamine, isoleucine and talose at 48 hours (hrs) of imbibition, EoR and CS stages; while glycine, tyrosine and turanose were so at CS stage only. Under 200 mM NaCl, richness of stearic acid, quercetin, leucine, erythritol and psicose were noted at 48 hrs of imbibition followed by EoR stage. Fructose, ornithine, mannitol, asparagine, mallic acid, glucose and citric acid were abundant at EoR whereas aminobutanoic acid, hexanedioic acid and tyramine were so at CS stage. Among detected metabolites maximum number of metabolites showed hits with amioacyl-tRNA biosynthesis pathway and the amino acid biosynthesis pathway had maximum impact during seedling development. Role of metabolic pathways (including amino acid metabolism) and differential expression of genes related to these pathways are suggested in meeting the energy needs for varied biological activities during seed germination and subsequent seedling development in S. brachiata.     

Seed priming with smoke water and karrikin improves germination and seedling vigor of Brassica napus under varying environmental conditions

Plant Growth Regulation - Environmental cues are major determinants in commercial cultivation of leafy vegetables, especially for resource-limited farmers. The aim of the study was to examine the...     

Reaction and survival of four types of sunflowers against Sclerotinia sclerotiorum under controlled conditions

Sclerotinia wilt of sunflower caused by Sclerotinia sclerotiorum (Lib.) De Bary is the major disease of sunflower (Helianthus annuus L.) in Iran. North-western areas of Iran demonstrate the most yield losses through the disease. Development of cultivars with adequate genetic resistance is necessary to avoid these losses. Evaluation of sunflower genotypes varies based on researchers and environmental conditions. Meanwhile, greenhouse tests of the sunflower genotypes are more reliable because of controlled conditions during the assessment activities. To study the reaction of the host plants under controlled conditions, three stem inoculation techniques, including mycelium plug (MP), oxalic acid solution (OAS) and wheat seeds infested (IWS) with Sclerotinia mycelium, were employed. Wounded and non-wounded treatments were used in the experiment to find their effect on the disease progress. Four genotypes, including Ghalami (local variety in market), Confeta, Alstar and Master, were inoculated in this study. The factor was the lesion length to evaluate the effectiveness of different inoculation procedures. The lesion length was measured after 3, 7, 10 and 14 days post inoculation. The analysis of variance demonstrated significant differences between IWS and two other methods (MP and OAS), where the IWS produced the longest lesion lengths. In contrast, the non-significant differences between MP and OAS methods might help researchers to employ the pathogenicity factor (oxalic acid) as an alternative inoculum for their studies. Master variety was the most tolerant genotype among the treatments and its viability was 100% even at 14?days after inoculation and incubation. Interestingly, there was no mortality in all cultivars before 7-day incubations, regardless of resistant or susceptible reactions.     

The role of hormones in regulating the germination of polymorphic seeds and early seedling growth of Atriplex triangularis under saline conditions

Germination of the polymorphic seeds and seedling growth of Atriplex triangularis under various salinity, gibberellic acid and kinetin treatments were determined. Gibberellic acid (GA₃; 2.9 m M ) promoted germination and growth at high NaCl concentrations (345 m M ). Kinetin (4.7 μ M ) stimulated germination at all salinities and seed sizes tested. GA₃ and kinetin generally increased seedling growth at all concentrations of salinity studied. Higher concentrations of kinetin were found to be inhibitory.     

苜蓿种子萌发和幼苗生长对温度、光照和埋深的响应

紫花苜蓿(Medicagosativa)是世界人工草地重要的优良牧草.研究其种子萌发和幼苗生长对温度、光照及埋深等环境因子的响应,对苜蓿草地的种植及管理具有重要的实践指导意义.采用室内控制实验,分析了紫花苜蓿种子萌发和幼苗生长对恒温(10、15、20、25、30℃)、变温(6/15、10/20、15/25、15/30、...     

胜红蓟种子萌发/出苗对环境因子的响应

胜红蓟为我国南部低海拔区域农田和果园恶性杂草。为揭示胜红蓟环境适应规律、明确其危害性,评价和分析了胜红蓟种子萌发对光照、温度、pH、盐度、渗透势等环境因子的响应特征。结果表明:胜红蓟种子在10—30℃内均能萌发,最适萌发温度为20℃,交替温度处理可提高种子的萌发率。胜红蓟种子萌发对光照敏感,无光照处理种子不萌发。土壤相对湿度在50%—100%范围内,种子出苗率均高于55%,最适相对湿度为70%。胜红蓟种子仅能在土壤表面萌发,1 cm的播种深度完全抑制种子萌发。pH值在5—10之间,种子萌发率高于85%,最适pH值为7。NaCl浓度在0—80 mmol/L以内种子萌发率超过88%,浓度为160 mmol/L时萌发率接近30%。渗透势在-0.40—0 MPa以内种子萌发率高于70%,渗透势为-0.6 MPa时种子不能萌发。由此可见,胜红蓟种子萌发具有广阔的环境适生范围,对农作物具有较强的早期危害性。     

Seed germination and seedling establishment of an invasive tropical tree species under different climate change scenarios

Increasing air temperature and atmospheric CO₂ levels may affect the distribution of invasive species. Whereas there is wide knowledge on the effect of global change on temperate species, responses of tropical invasive species to these two global change drivers are largely unknown. We conducted a greenhouse experiment on Terminalia catappa L. (Combretaceae), an invasive tree species on Brazilian coastal areas, to evaluate the effects of increased air temperature and CO₂ concentration on seed germination and seedling growth on the island of Santa Catarina (Florianópolis, Brazil). Seeds of the invasive tree were subjected to two temperature levels (ambient and +1.6 °C) and two CO₂ levels (ambient and ~650 ppmv) with a factorial design. Increased temperature enhanced germination rate and shortened germination time of T. catappa seeds. It also increased plant height, number of leaves and above‐ground biomass. By contrast, increased atmospheric CO₂ concentration had no significant effects, and the interaction between temperature and CO₂ concentration did not affect any of the measured traits. Terminalia catappa adapts to a relatively broad range of environmental conditions, being able to tolerate cooler temperatures in its invasive range. As T. catappa is native to tropical areas, global warming might favour its establishment along the coast of subtropical South America, while increased CO₂ levels seem not to have significant effects on seed germination or seedling growth.     

Seed germination and seedling morphology of the seagrass,Halophila engelmannii (Hydrocharitaceae)

Seeds of Halophila engelmannii Aschers., that were collected in Redfish Bay, Texas, at weekly intervals from mid-May to mid-June 1986, began to germinate 3–4 weeks after collection. Most of the collections subsequently showed an increase in the rate of germination under increased light intensity and all had a stoppage of germination after transfer to darkness, indicating a light requirement to break endogenous seed dormancy. During the 5 weeks after seeds germinated, seedlings in soil culture produced a rosette of six leaves before the appearance of a rhizome bud in the axil of the third leaf. The first node of the rhizome produced a root and an upright shoot with a pseudowhorl of three to five leaves.     

Seed germination and early seedling growth of fenugreek (Trigonella foenum-gracium L.) under Cu,Ni and As stress

Metals and metalloids were known to have a real problem and serious risk to the environment and the ecosystems as well as human beings. In the present experiment, phyototoxicity of essential metals (Cu and Ni) and non-essential metalloids (As) at 10, 50, 100 and 200 mg L^?1 were evaluated on seed germination and early seedlings growth of fenugreek. Higher concentrations of Cu had almost no effect on the parameters tested. By contrast, As was found to reduce germination, root and shoot elongation, seeds vigor index and dry biomass within range dose of 50–200 mg L^?1. Accordingly, tolerance index showed that fenugreek seeds have zero tolerance at higher concentration of As. The decreasing order of sensibility of fenugreek seeds to tested metals and metalloid followed the order: As > Ni > Cu.     

Seed priming improves the emergence potential,growth and antioxidant system of Moringa oleifera under saline conditions

Moringa oleifera is a multipurpose plant which is now being promoted as a fodder crop. The present study was conducted to induce the tolerance in moringa plants to emerge and grow under saline conditions. For this, moringa seeds were primed with aerated water (hydropriming) and moringa leaf extract (MLE) for 12 and 24 h and studied for its emergence, potential growth behaviour, mineral composition, chlorophyll contents and antioxidant activities in comparison with unprimed seeds to investigate the physiological changes in moringa plants under saline conditions. The seeds were sown in plastic pots filled with acid washed sand at four salinity levels (3, 6, 10, 14 dS m^?1) in a completely randomized design with three replications. It was found that salinity >6 dS m^?1 reduced the emergence, growth and vigour of moringa plants but hydropriming (12 h) enhanced moringa emergence at 10 dS m^?1 followed by MLE priming (12 h). Maximum aboveground biomass and photosynthetic pigments were recorded when the seeds were hydroprimed (12 h) but maximum root length and number of roots were found in MLE primed (12 h) moringa plants. Significant decrease in K⁺:Na⁺ ratio with increasing salinity levels resulted in low K⁺ and Mg²⁺ uptake and Na⁺ toxicity in moringa leaves which resulted in reduced chlorophyll contents at 14 dS m^?1 but a significant increase in chlorophyll a and b contents and total phenolics were found in hydroprimed seeds (12 h) while the antioxidant activities of superoxide dismutase, peroxidase and catalas were improved by MLE priming (12 h). This study concludes that moringa emergence and growth performance can be improved by hydropriming under saline conditions.     

Effect of salinity on seed germination,seedling growth,and physiological characteristics of Perilla frutescens

Abstract

Salt stress is one of the major environmental factors limiting crop growth and yield. To understand the effect of salt stress on plant growth, we investigated the response of three perilla varieties (Suyin 1, Ziye 7, and Ziye 10) to NaC1 exposure at concentrations of 0, 50, 100, 150, 200, and 250 mM in terms of seed germination, seedling growth, root activity, contents of soluble sugar, proline, and malondialdehyde (MDA), and peroxidase (POD) enzyme activity. Germination characteristics, such as the percentage of seed germination, tended to decrease with increasing NaC1 concentrations. After three weeks of salt stress, the three varieties exhibited different salt tolerance in terms of seed germination, seedling growth, and physiological changes: seedling growth was inhibited to various degrees, seedling vigor and root activities decreased, and MDA, proline, and soluble sugar contents increased with increasing NaCl concentrations. POD enzyme activity, a protective mechanism against salt stress, increased at low NaC1 concentrations in Suyin1 (0–150 mM) and Ziye 7 (0–100 mM), and then decreased at higher NaCl concentrations. In Ziye 10, on the other hand, POD activity dropped significantly with increasing NaCl concentrations. These results suggest that among the three varieties Suyin 1 is more salt tolerant than Ziye 7 and Ziye 10, and that Ziye 10 is the most sensitive to salt stress.     

壳聚糖对小麦种子萌发及幼苗生理生化特性的影响

用不同浓度的壳聚糖溶液包衣处理“8802”和“徐州-24”两个小麦品种,在20℃下发芽,并测定种子发芽率、α-淀粉酶活性及幼苗的湿重、干重、叶绿素、可溶性糖和可溶性蛋白质等的含量。结果表明:壳聚糖处理后,能够有效地提高小麦种子发芽率、α-淀粉酶活性、幼苗湿重、干重及幼苗叶片中叶绿素、可溶性糖、可溶性蛋白质等的含量。     

Seed dispersal, germination and early seedling establishment of Populus alba L. under simulated water table declines in different substrates

Populus alba L. is an autochthonous species dominating the overstory of the floodplain forests across the Mediterranean region. In contrast to some other Populus spp., very little is known about its regeneration strategies. Poplars yearly disperse huge amounts of wind- and water-dispersed, non-dormant, short-lived tiny seeds that need the bare, open and moist substrates created by fluvial-geomorphic events to germinate and establish. To survive, the growing roots must keep pace with the falling water table and associated soil moisture zone. Using a greenhouse experimental facility, 9-day-old P. alba seedlings were subjected to five hydrological treatments (permanent saturation, drawdown rates of 1, 2.5, 5 cm day⁻¹ and immediate drainage) in two different substrates (coarse and sandy), and their survival and growth were evaluated. Also, P. alba seed dispersal was monitored in the field, and seed germinability and longevity were tested in the laboratory. No seedlings survived the water table declines in the coarse substrate although survival was high (85%) under saturated conditions. In the sandy soil, survival was significantly greater in the permanent saturation (87%) and 1 cm day⁻¹ (88%) treatments than in the 2.5 cm day⁻¹ (58%), 5 cm day⁻¹ (25%) and immediate drainage (22%) treatments. The lowest root and shoot growth rates occurred under the saturated and immediate drainage conditions. Seed dispersal lasted 6–8 weeks and peaked in mid-April, initial seed germinability was high (92%) and seed longevity was relatively long (half viability period, 30 days). The creation of nursery sites and release of controlled floods in mid-April, followed by water table declines of less than 1 cm day⁻¹ in coarse substrates and less than 5 cm day⁻¹ in sandy substrates are recommended for enhancing the initial establishment of P. alba seedlings.     

The biology and autecology of Nitraria L. in Australia. II. Seed germination,seedling establishment and response to salinity

Detailed investigations were undertaken to determine the requirements for optimal germination and establishment of Nitraria billardieri. Germination of N. billardieri on the Riverine Plain is aided considerably by prior ingestion of the fruit by the emu (Dromaius novaehollandiae). Experiments suggested that the increase in germination of emu-ingested seed is largely a response to the removal of the saline outer pericarp during digestion. In one experiment, 62% of emu-ingested seed germinated after 24 days compared with 6% of the hand-picked seed. Studies of field populations of N. billardieri seedlings indicated that they are susceptible to competition from cool season annual species. A competition experiment in sand boxes between seedlings of N. billardieri and Atriplex vesicaria showed N. billardieri to have a slower growth rate and to be susceptible to competition by the seedlings of the perennial A. vesicaria. Studies of the root extension of N. billardieri and Atriplex nummularia in root observation boxes demonstrated the poor performance by the Nitraria roots which grew only 53 cm in 7 weeks whereas the Atriplex roots grew 160 cm in 4 weeks. These data suggest that N. billardieri establishes and successfully competes in the field only with severely weakened saltbush stands. Other important factors are the availability of 'safe sites’ and the degree of competition from annual species. Glasshouse experiments using sand culture indicated that both Nitraria and Atriplex vesicaria could survive in salinities of 0.9 M NaCl and both responded in terms of dry matter production to low salt inputs (e.g. 0.3M NaCl) although growth of Nitraria decreased more rapidly as salinity increased.     

Seed germination and salinity tolerance in plant species growing on saline wastelands

Seven plant species including three chenopods:Suaeda fruticosa, Kochia indica, Atriplex crassifolia and four grasses:Sporobolus arabicus, Cynodon dactylon, Polypogon monspeliensis, Desmostachya bipinnata, varied greatly in their seed germination and growth responses to soil moisture or salinity. The germination percentage of each species was significantly lower at soil moisture level of 25 % of water holding capacity than at the levels ranging from 50 to 125 %. Increase in salinity resulted in gradual decrease in seed germination of each species. Growth responses of species to salinity varied widely from significant decrease with slight salinity to stimulation up to salinity levels of 20 dS m^-2. Higher K⁺Na⁺ratios in plant shoots of all species compared to that in the root medium indicated selective K⁺uptake. Higher tolerance in chenopod species seems to be attendant on their ability for internal ion regulation. We are thankful to Mr. Noor Ahmad for his assistance in experimental work.     

Effects of phenanthrene on seed germination and some physiological activities of wheat seedling

Polycyclic aromatic hydrocarbons (PAHs) are one of the highly persistent organic pollutants, and they are toxic to plants and other living organisms, including human beings. To analyze the response of higher plant to PAHs, we investigated the effects of phenanthrene (PHE) on seed germination and various physiological changes of wheat seedlings. Specifically, we investigated growth, chlorophyll content, lipid peroxidation (LPO), activities of antioxidant enzymes and H₂O₂ accumulation. The results showed that PHE inhibited seed germination, affected the growth and chlorophyll level of wheat seedlings. Furthermore, PHE elevated the levels of LPO and induced H₂O₂ accumulation in leaf tissues in a dose-dependent manner, accompanied by the changes in the antioxidant status. The activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), displayed a decreasing trend with the increasing of PHE concentration. The results indicated that PHE could exert oxidative damages in the early development stage of wheat and the harmfulness occurred mainly in samples with higher concentrations of PHE.