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.     

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...     

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.     

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.     

Constitutive expression of a PR10 protein enhances the germination of Brassica napus under saline conditions

Pathogenesis-related (PR) proteins are expressed by virtually all plants in response to pathogen infection and, in many cases, in response to abiotic stresses as well and include the PR10 family. However, the precise roles of the PR10 protein family in abiotic stress responses are not clear. In this paper we report, for the first time, that the constitutive expression of a pea PR10 gene in Brassica napus enhances their germination and growth in the presence of NaCl. Our findings are discussed within the context of PR10 protein function and their utility in engineering stress tolerant crops.     

Vermicompost treatment differentially affects seed germination,seedling growth and physiological status of vegetable crop species

Vermicompost preparations are increasingly used in agricultural practice. There is a possibility, that crop plants are sensitive to negative effect of vermicompost at early stages of development. The aim of the present study was to test the effects of vermicompost on seed germination and seedling growth of different vegetable crop species. Vermicompost substitution inhibited seed germination and seedling growth with almost linear decrease of growth with increasing concentration of vermicopost in the substrate. However, both leaf chlorophyll content and photochemical activity of photosynthesis increased in all crop species with the exception of pea seedlings. Vermicompost extract as a watering solution showed positive effect on growth of bean and pea seedlings. Germination response of vermicompost extract-imbibed seeds was clearly crop species-dependent. Hypocotyl growth was stimulated by low and moderate vermicompost extract concentrations. Radicle growth was more sensitive to negative effect of vermicompost extract. It is reported that both solid vermicompost and vermicompost extract contain number of active substances of both phenolic and humic nature, each with own dose- and genotype-dependent effect of seed germination and early stages of seedling development. Findings of this study suggests that vermicompost must be used cautiously for practical purposes of plant propagation.     

Seed dispersal, germination and seedling growth of six helophyte species in relation to water-level zonation

1. Seed dispersal, germination, and seedling growth characteristics of six helophyte species. Iris pseudacorus, Phalaris arundinacea, Phragmites australis, Typha angustifolia, T. latifolia and Scirpus lacustris, were investigated in relation to their water-level zonation. 2. The experiments demonstrated a large variation in these characteristics between the species. 3. Propagule floating capacities range from < 1 h (S. lacustris) to > 1000 h (I. pseudacorus). 4. Seed germination in a water-level gradient revealed two groups with respect to germination percentage - exposed soil species (I. pseudacorus, Phalaris arundinacea, Phragmites australis) and submerged soil species (T. angustifolia, T. latifolia). 5. There were two contrasting types of seedling growth response to submergence and exposure: one group of species formed longest leaves under exposed conditions (Phalaris arundinacea, Phragmites australis, I. pseudacorus), and the other under submerged conditions (S. lacustris, T. latifolia, T. angustifolia). 6. The results suggest that early life-history characteristics of the species relate to their locations in the riparian zonation: Phalaris arundinacea and Iris pseudacorus at the higher end, Phragmites australis intermediate, and Typha spp. and Scirpus lacustris at the lower end. Species occurring at lower locations show adaptations to (periodical) flooding of the soil (submersed germination and growth), while those from higher locations require prolonged exposed soil conditions to germinate and to survive the establishment stage.     

Seed survival and seasonal pattern of seedling emergence in some Leguminosae

Seeds of 11 species of Leguminosae were collected, usually in each of 3 years, and mixed with the top 7·5 cm of sterilised soil confined in cylinders sunk in the ground outdoors and cultivated three times yearly. Emergence was recorded for at least 3 yr. Some seedlings of all species emerged soon after sowing but their numbers varied both within and between species, a probable reflection of the percentage of ‘hard’ seeds in the samples. Appreciable numbers of seedlings appeared in the following 3 yr but few seeds remained viable and dormant after 5 yr. The annual weed Vicia hirsuta was an exception, with an average of 11% of the seeds sown still viable at this time. Most seedlings of Lotus corniculatus, Medicago lupulina, Melilotus altissima, Trifolium repens and Vicia cracca emerged in spring, V. cracca rather later than the others. In contrast, maximum emergence of Trifolium arvense, T. campestre and T. dubium took place from June to September. Limited data indicated a similar pattern for T. striatum and Lathyrus pratensis. Seedlings of Vicia hirsuta emerged from October to May but scarcely at all in summer. Although variation in the percentage of hard seeds influenced the extent of immediate germination and seed persistence, the seasonal patterns in seedling emergence of most species were found to be very consistent.     

Crop production and management under saline conditions

Summary This review evaluates management practices that may minimize yield reduction under saline conditions according to three strategies: (I) control of root-zone salinity; (II) reduced damage to the crop; (III) reduced damage to individual plants. Plant response to salinity is described by an unchanged yield up to a threshold soil salinity (a), then a linear reduction in relative yield (b), to a maximum soil salinity that corresponds to zero yield (Y_o). Strategies I and II do not take into consideration any change in the parameters of the response curve, while strategy III is aimed at modifying them.Control of root zone salinity is obtained by irrigation and leaching. From the review of existing data it is concluded that the effective soil salinity parameter should be taken as the mean electrical conductivity of the saturated paste extract or of the soil solution over time and space. Several irrigation and leaching practices are discussed. It is shown that intermittent leaching is more advantageous than leaching at each irrigation. Specific cultivation and irrigation practices that result in soil salinity reduction adjacent to young seedlings and the use of water of low salinity at specifically sensitive growth stages may be highly beneficial. Recent data do not show that reduced irrigation intervals improve crop response more under saline than under nonsaline irrigation. Alternate use of water of different salt concentrations results in mixing in the soil and the crop responds to the mean water salinity.Reduced damage at the fiel level when soil or irrigation water salinity is too high to maintain full yield of single plants requires a larger crop stand. For row crops reduced inter-row spacing is more effective than reduced intra-row spacing.Reduced damage at the plant level while the salinity tolerance of the plants remains constant shows up in the response curve parameters as larger threshold and slope and constant salinity at zero yield. This is the effect of a reduced atmospheric water demand that results in reduced stress in the plant under given salinity. Management can also change the salt tolerance of the crop. This will show up as higher salinity at zero yield, as well as changes in threshold and slope. Such changes in the response curve were found at different growth stages, under different atmospheric CO₂, under different fertilization, and when sprinkler irrigation was compared with drip irrigation.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. 1111-E 1984 series.     

Seed germination,plant growth and physiological responses of Salsola ikonnikovii to short-term NaCl stress

Salsola ikonnikovii (Chenopodiaceae), a drought-tolerant plant species that is distributed in sand or light-saline soil in Xinjiang, China, produces seeds (fruits) with attached winged perianths. To study the role of the wing in seed germination under salt stress and to further investigate the growth and physiological responses of the plants to salt stress, the germination behaviour of S. ikonnikovii was determined after winged and non-winged seeds were treated with 0–1000 mmol · L^?1 NaCl. Several parameters of two-month old plants that had been treated with NaCl for three weeks were measured. The results revealed that the winged perianths limited germination but protected the seeds from salt damage. The growth of the plants was stimulated by lower concentrations of salt (≤100 mmol · L^?1 NaCl), while increasing salt concentrations inhibited growth. The level of reactive oxygen species and malondialdehyde increased significantly at high concentrations of salt. Correspondingly, concentrations of the osmolytes proline, betaine, and soluble sugars, and the activities of antioxidative enzymes (catalase, peroxidase and superoxide dismutase) increased, but the levels of non-enzymatic antioxidants (carotenoids, glutathione) were significantly reduced at high salt concentrations. These results imply that osmotic adjustment and the antioxidative system may work synergistically to ensure that a plant grows normally under high salt concentrations.     

Seed germination at different temperatures and seedling emergence at different depths of Rhamnus spp

Rhamnus alaternus and R. ludovici-salvatoris, two Mediterranean shrubs with different geographic distributions, have shown important differences in seedling recruitment capacity. The objectives of this work were to determine the ability of these species to germinate seeds under different temperature ranges, as well as the capacity of seedlings to emerge from different burial depths, in order to better understand their regeneration processes. Two different experiments were performed. In the first one, seed germination was studied in Petri dishes and in the dark at different temperature regimes: a) 5–15°C, b) 10–20°C and c) 15–25°C (12h/12h). In the second experiment, seedling emergence capacity from different burial depths (0.5, 2 and 5 cm) was tested. R. ludovici-salvatoris showed a significantly higher final germination rates, a lower dormancy period, and average time response at 10–20°C than at other temperature ranges, although differences were much greater when seeds were subjected to the 5–15°C temperature regime. By contrast, R. alaternus did not show significant differences between treatments (5–15°C and 10–20°C) in germination behavior. Seedling emergence of both species was lower and slower when seeds were buried at 5 cm. However, R. ludovici-salvatoris always showed a lower seedling emergence capacity than R. alaternus at any burial depth. The low ability of R. ludovici-salvatoris to germinate seeds and emerge between 5–15°C, even from shallow depths, is discussed in relation to its low regeneration capacity and declining geographic distribution.