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1.
A long term seed storage experiment with rye was started in 1978 in the Gatersleben genebank. Seeds of 3.7 and 5.5% moisture content were kept at –15, 0 and 10 °C in hermetically sealed glasses filled with air, CO2, N2, and also evacuated. The initial germination was 72% and germination was tested after 1, 5, 15 and 17 years of storage. After 17 years at –15 °C the smallest losses in germination and smallest interactions with the gas atmosphere were observed. At 0 and 10 °C there were greater, but variable losses in germination and inconsistent interactions with the gas atmosphere. Generally, air promoted and N2 reduced germination loss.  相似文献   

2.
Germination of wild and managed populations of columnar cacti was compared to analyze differences associated to management intensity. The species studied: Polaskia chende, Escontria chiotilla, Myrtillocactus schenckii, Polaskia chichipe, and Stenocereus pruinosus are in a gradient from lower to higher management intensity, respectively. Within each species wild, silvicultural, and cultivated populations also represent a gradient from lower to higher management intensity. We hypothesized that seeds of plants under higher management intensity would require more water to germinate than others since managed environments are relatively wetter than unmanaged environments. Such pattern could be visualized within and among species according to management intensity. We tested germination of seeds from different populations of the different species to the water potentials: 0.0, ?0.2, ?0.4, ?0.6, ?0.8, and ?1.0 MPa. In all species studied seeds of managed populations had significantly more mass than seeds from wild populations. Each species had different susceptibility to water availability decrease, which could be related to particular adaptations to drought resistance. Stenocereus pruinosus and Polaskia chende were the most and least susceptible species, respectively. In control treatments of all species, seeds of managed populations had higher germination rate than seeds from wild populations, but when water availability decreased the pattern was the contrary. Our results suggest that artificial selection for larger fruits and heavier seeds in plants established in wetter environments have affected germination patterns. Although species have particular critical points of water availability for germination, differences in germination patterns are more pronounced according to management and artificial selection intensity.  相似文献   

3.
Summary Acacia nilotica ssp. indica, a multipurpose tree species occurs throughout semi-arid India. The present study reports the variation in seed germination and seedling growth of 21 sites (provenances) collected between the latitude 11°N and 31°23N, and 19 m to 650 m altitude throughout India. There were significant differences (P<0.05) between the sites for seed germination that varied from 16 to 90% in the incubator, and 14 to 84% in the nursery. Significant variations were also observed in seedling growth up to 28 days in the incubator. There was no significant relationship between seed germination and seedling growth and the latitude or longitude of the original seed source. However, in general the South Indian provenances showed lower germination as compared to North Indian provenances. The observations are important for selection of vigorous provenances concerning seed germination and early seedling growth.  相似文献   

4.
Two experiments are discussed. In the first, rates of root elongation during the first four days of growth at 25 °C were studied in Chamaecrista rotundifolia (34 accessions), C. nictitans (2 accessions), C. pilosa (1 accession) and C. serpens (3 accessions). In the second, a comparison was made of germination characteristics of 14 accessions of C. rotundifolia and one of C. pilosa at nine constant temperatures (11–27 °C). Entries included accessions from a wide latitudinal range. There were statistically significant differences in root length on all four days of measurement. No accession had significantly longer roots than the commercial cultivar cv. Wynn on day 1, but over the following three days, 4, 10 and 13 accessions had significantly longer roots, respectively. Root length on day 4 was positively correlated with latitude of origin. In the second experiment, maximum germination occurred at 25.5–27 °C, with progressively lower percentages at lower temperatures. There were highly significant differences between accessions at each temperature (P<0.001), and a highly significant accession × temperature interaction. No accession had a higher germination percentage than cv. Wynn at any temperature. Percentage mortality differed significantly (P<0.05) at all temperatures except 27 °C. Mortality at low temperature was negatively correlated with latitude of provenance. Increased temperatures up to 22.5 °C reduced the time taken to reach 50% of maximum germination (T50), and thereafter it was reasonably constant. With one exception (22.5 °C), no accession germinated significantly more quickly than cv. Wynn, and at 13 °C cv. Wynn germinated significantly more rapidly than all other entries. Over all temperatures, there was a significant negative correlation between days to 50% germination and latitude of provenance. Estimated base temperature for germination (T b ) ranged from 10.6 °C to 13.6 °C. T b was positively correlated with latitude of provenance. It is argued that accessions from higher latitudes have developed mechanisms for survival of soft seed at low temperatures, low base germination temperature, germination rates and root elongation rates that adapt them to an environment with summer-dominant rainfall and winters which are too cool to support growth.  相似文献   

5.
Three vegetative crops of sect. Cepa in genus Allium (Top onion, French grey shallot and viviparous triploid onion) of suspected hybridogenic origin were studied with genomic in situ hybridization (GISH) and random amplified polymorphic DNA (RAPD) markers. Related wild and cultivated species were included in the analysis in order to assess their contributions to the genomes of the investigated species. In A. × proliferum, the parental chromosomes derived from A. fistulosum and A. cepa were unequivocally identified by GISH, proving the hybrid status of this crop. The French grey shallot proved to belong to A. oschaninii according to the RAPD analysis and the GISH results, it is clearly separate from the normal shallots of A. cepa var. aggregatum. Thus the grey shallots are a new crop species and can be considered as an aggregatum form of the wild progenitor species A. oschaninii. The triploid viviparous onion comprises mostly A. cepa derived DNA in its genome. A non-cepa component could not be attributed to any of the sect. Cepa species included in this study and is most likely derived from one of the species of this section not yet identified by molecular means.  相似文献   

6.
Vigna vexillata is considered as a pantropical distributed wild species closely related to the cowpea (Vigna uniculata) and adapted to infertile soils. The species is occasionally used for its storage roots as well as forage and erosion control plant. The objective of this study was to pursue personal communications that V. vexillata has be transformed into a cultivar in Indonesia. Seven Indonesian islands were visited (Java, Bali, Sumba, Flores, Timor, Kalimantan and Sulawesi). Wild V. vexillata was found in Java, Bali, Sumba, Flores and Timor, occasionally used as wild ‘forest food’, and cultivated V. vexillata was found in Bali and Timor, Seven cultivars were collected and two of these were made available for the National Botanic Garden of Belgium. The cultivars were primarily cultivated for their storage roots, propagated by seeds, required no scarified seeds for good germination and formed non-dehiscent pods. On-farm root yields of 18–30 t ha−1 and seed yields of 0.7–1.2 t ha−1 were estimated. A brief discussion about the common names of wild V. vexillata is given and it is proposed to use the name ‘tuber cowpea’ for V. vexillata accessions which are cultivated for their storage roots. The material may be of interest for regions, where the growing season is too short or the rainfall too low for sweet potato and cassava as well as to incorporate cultivar characteristics into wild V. vexillata accessions which are used for their storage roots.  相似文献   

7.
China, the native home of ramie (Boehmeria nivea (L.) Gaud. var. nivea), possesses many wild species in the genus Boehmeria Jacq., including many those rare valuables in some characteristics such as stress resistance and fiber qualities that can be used for biological engineering, genetics and breeding research. From 1995 to 1999, 130 samples of the genus Boehmeria that belong to 22 species and 6 varieties, were collected in 34 counties of 14 provinces in China in the region of N18.8–34.2° and E101–121°. The gene pool of wild species of the genus Boehmeria was constructed at Yichun, Jiangxi Province and 77 samples belonging to 8 species and 4 varieties were conserved alive. The collected species are classified into 5 sections i.e. Boehmeria, Tilocnide Bl., Zollingerianae Satake, Phyllostachys W. T. Wang and Duretia Bl., according to the morphology. They may also be divided into hygric type, moderately hygric type, semi-shade-hygrophyte and xeromorphy, based on their ecological adaptability and primitive growing circumstances. The distribution of the wild species and populations in the genus Boehmeria is related to the altitude.  相似文献   

8.
The collection and consumption of wild (including naturalized) and semi-domesticated (cultivated and reverted to wild status, and neglected cultivated plants for food) edible plants in the rural communities of the Arribes del Duero (western Spain), a highly heterogeneous Mediterranean agroecosystem, were analysed. Through semi-structured interviews with 80 informants, data on the gathering, preparation and consumption of 76 wild edible plant species were acquired. To analyze how traditional knowledge varies with the characteristics of the informants, we performed an ANCOVA. The “age” variable was found to have a significant effect. The most frequently cited species in the study area (i.e. Rubus ulmifolius, Foeniculum vulgare, Quercus ilex, Laurus nobilis, Origanum vulgare) are widely consumed in the Mediterranean region. Also, from a cluster analysis it was observed that the grouping succession this territory matches those of analysed areas of the Iberian southwest. Certain species have traditionally been consumed as an important supplement to the diet, particularly during food shortages (i.e. Rumex induratus, Chondrilla juncea). Several species are ethnobotanical novelties, among which are Erodium botrys and Astragalus pelecinus, whose immature fruits are eaten raw as a snack. Some ecological and cultural aspects of the gathering of wild plants for food are discussed.  相似文献   

9.
Montia fontana L. is an aquatic plant traditionally consumed in the Centre and West of the Iberian Peninsula, where it is one of the most highly valued wild vegetables. The aim of this work was to evaluate both the natural yield and nutritional value of this scarcely known plant. Two wild populations, from two different sites of Central Spain, were sampled during three consecutive years. Plant production was estimated by two parameters: production per unit of surface and plant percentage cover in the selected site. Nutritional analyses included proximate composition and total energy, mineral macro and microelements, vitamin C, and organic acids. Mean yield at the growing areas was 2.64 kg/m2, though significant differences among sites and years were found. There was a positive correlation between production and accumulated rainfall from the beginning of the year till the collecting dates. The percentage cover of the species in the potential growing area was 8.25%, without significant differences among sites and years. Therefore, the wild populations of the species can reach a total mean production of 2,138 kg/ha in this Spanish region. This is the first report of a global nutrient composition for Montia fontana. After moisture, the major constituent was fibre (4.44%), much higher than many cultivated vegetables. Also appreciable amounts of vitamin C (34 mg/100 g) and Mn (1.07 mg/100 g) were found. Due to its high lipid content (1.94%) this wild vegetable could be regarded as one of the richest source of omega-3 fatty acids among the leafy vegetables. This species can be considered an interesting wild resource for being included in the diet. Further research is needed for addressing its potential for being cultivated under different culture systems and for selecting accessions with lower oxalate content.  相似文献   

10.
Summary The biology of the oriental vermicomposting species, Perionyx excavatus, is poorly understood. Quantitative observations were made at 25°C in urine free cattle manure in order to study the growth of this species. The rate of maturation and cocoon production were studied under conditions of favourable moisture and nutrition over a period of 250 days. The results obtained showed that while P. excavatus grows relatively slowly compared to other vermicomposting species, it attains sexual maturity much earlier and maintains a relatively high cocoon production rate. The study revealed that copulation is not a prerequisite for production of viable cocoons, indicating that P. excavatus may be parthenogenetic and possibly capable of alternating between modes of reproduction.  相似文献   

11.
作为一种分布广泛的农田恶性杂草,野燕麦具有很强的环境胁迫适应能力,并且在种间竞争中常处于优势地位。本试验对野燕麦种群的繁殖与扩散特性、种子与幼苗抗逆特性及其根系分泌物对小麦的异株克生作用进行了研究,以期为找寻治理野燕麦的有效措施提供参考。结果表明:(1)野燕麦具有很强的种子繁殖与扩散能力,开花结实比小麦早,种子产量大、地下储量多、扩散距离远;(2)野燕麦种子对温度的适应范围较广,在室温与变温条件下均可以正常萌发,而冷冻后置于室温环境是其萌发最佳条件,总发芽率可达93.33%;(3)野燕麦种子对盐胁迫具有一定的适应性,在浓度低于1.8%的NaCl溶液中均可正常萌发;(4)野燕麦幼苗对盐胁迫和干旱胁迫具有较强的适应性,随着NaCl浓度和PEG浓度的升高,野燕麦幼苗叶片的脯氨酸含量显著增加(P0.01),过氧化氢酶活性呈现先增加后下降的趋势;(5)野燕麦根系水浸提液对小麦幼苗株高、干重、根长及根系活力均有极显著影响(P0.01),证明野燕麦根系分泌物对小麦幼苗生长具有异株克生作用。以上结果表明,野燕麦的竞争优势主要体现在强大的繁殖扩散能力、较强的抗逆性以及异株克生效应,相关研究可为大田野燕麦防除提供一定理论参考。  相似文献   

12.
It is necessary to understand the effects of environmental conditions, especially temperature, on weed seed germination patterns, in order to make comprehensive and effective weed management decisions. The effect of cardinal temperature (0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C and 40°C) on the germination pattern of three noxious weeds, such as wild barley (Hordeum spontaneum Koch.), barley grass (H. murinum L.) and hoary cress (Cardaria draba L.) in wheat fields of Iran, was studied in three separate experiments. The experiments were conducted based on completely randomized design (CRD) with four replications. The result showed that the germination of all three species started at low temperatures and there was no significant difference in germination percentage (GP) at lower temperatures. About 50% of the weed population germinated within a short period when using a dent-like model indicating the high ability of these weeds to compete for space and resources. Segmented and dent-like models were used to evaluate the cardinal temperatures. The results showed that dent-like model was the preferred model to evaluate germination rate in relation to variable temperatures in hoary cress, while the segmented model was better in wild barley. However, there was no significant difference between the two models for barley grass. The results of this study showed that mechanical, cultural (pre-planting irrigation) and chemical practices could be more useful and effective at 10–30°C.  相似文献   

13.
Summary Axenically grown alfalfa (Medicago sativa L. var. Peace) was simultaneously inoculated with Canadian commercial Rhizobium meliloti strains NRG-185 and BALSAC. The plants were grown for 7 weeks in sealed units at five different root temperatures (8°, 13°, 17°, 21°, and 25°C) and at a relatively constant air temperature (24°–30°C). Nodule occupancy by each strain was determined by enzyme-linked immunosorbent assay (ELISA). Nitrogenase activity, nodule fresh weight, and plant dry weight were also measured. The lowest root-temperature regime (8°C) resulted in substantially lower nodule numbers and weights, and plant dry weights, than the higher temperature regimes. Development of nitrogenase activity was completely inhibited at 8°C. The immunoassay of nodule-strain occupancy showed markedly different strain-nodulation responses to the various root-temperature regimes. At 8°C, 63% of nodules were occupied by both strains. Dual strain occupancy decreased from 63% to 2% with increasing root-growth temperature, while the proportion of nodules containing only strain NRG-185 increased from 9% to 75%. Nodules containing only strain BALSAC remained relatively constant at 25% from 8° to 21°C, decreasing slightly at 25°C. The results suggest that root-environment temperatures during the period of nodule formation may have major differential effects on the success of competing rhizobial strains. If this is so, then selection of Rhizobium strains with enhanced low-temperature nodulation capabilities should be possible.  相似文献   

14.
Temperature dependant mineralization dynamics during fire of litter species characteristic of the New Jersey pine barrens was determined. Senescent leaf material of pitch pine (Pinus rigida), white oak (Quercus alba) and black huckleberry (Gaylusssacia baccata) were collected at the time of abscission; sorted, ground and oven-dried at 70 °C. Replicate samples were then heated for 2 h at: 70, 100, 200, 300, 400, and 550 °C. Mass loss and total nitrogen and total phosphorus concentration of the heated material were determined. Additional samples of the residual material were extracted with deionized water, and the filtrate was assayed for the anions: , , ; and cations: , K+, Mg++, and Ca++.By heating leaf litter over a range of temperatures, to simulate the heterogeneous nature of forest litter burning, we identified patterns of nutrient mineralization characteristic of specific temperatures, some of which were common to all three litter species and others unique to individual species. In general, it appears that black huckleberry leaf litter was the most nutrient rich and the most labile. In huckleberry litter, there was a large reserve of soluble nitrogen, sulfur, phosphate, calcium and magnesium that became available upon heating to 200 °C. Pitch pine litter was the most nutrient poor, and the rates of nutrient mineralization were also generally the lowest of the three species studied. White oak litter nutrient concentration and rates of mineralization along the temperature gradient were intermediate. For all three litter species examined organic and inorganic nitrogen losses due to volatilization were >99% upon heating to 550 °C, and soluble magnesium concentrations declined significantly at temperatures of 300 °C, despite having a volatilization temperature greater than 1100 °C. Under the temperature range employed, heating of leaf litter resulted in little volatilization loss of phosphorus; however, the amount of soluble phosphate phosphorus was much lower in all three litter types at temperatures of 300 °C and above. With increasing temperatures, inorganic phosphate ions presumably became bound to cations in the ash, forming insoluble metal phosphates. The dramatic increase of the ratio of total phosphorus to soluble inorganic phosphate at higher temperatures, the loss of soluble magnesium above 300 °C, and the near complete loss of nitrogen at 550 °C suggests that after intense fires availability of these minerals may be dramatically reduced.  相似文献   

15.
A collection of 11 natural and synthetic podolactones have been tested as allelochemicals in a range between 10(-4) and 10(-9) M, and their potential use as natural herbicide models is discussed. Their effects on the germination and growth of the dicots Lactuca sativa (cv. Nigra and cv. Roman), Lepidium sativum, and Lycopersicon esculentum and the monocots Allium cepa, Hordeum vulgare, and Triticum aestivum as standard target species have been studied. An important inhibitory effect on the germination and growth of all tested species (average = 90%) was produced by compounds 9-11 at 10(-4) M. The specific structural requirements related to their activities are studied. On the basis of these results, their use as potential natural herbicide models is proposed.  相似文献   

16.
Vascular plants associated to natural peatland pools do not spontaneously colonize edges of man‐made pools in restored peatlands and have proven to be recalcitrant to the usual restoration techniques. The goal of this study was to evaluate the effect of the species used as a seedbed (Cladopodiella fluitans, Sphagnum cuspidatum, or Sphagnum magellanicum) and its developmental stage (established carpet or newly reintroduced fragments) on establishment success in the field of the seeds of four vascular species: Carex limosa, Carex magellanica, Carex oligosperma, and Scheuchzeria palustris. The germination rate was measured after one season and growth after two seasons. Seedbed composition and developmental stage had no effect on Carex, whereas the germination of S. palustris was higher on S. cuspidatum. Growth of vascular plants was slightly improved on S. magellanicum carpets and was lower on seedbeds of C. fluitans. Our results lead us to recommend seeding at the same time as bryophyte fragments are spread and fostering introduction of Sphagnum mosses, preferably to C. fluitans, around artificial pool edges. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

17.
Chlorinated macrolides, haterumalide NA, B and NE, and a new haterumalide X, were produced by the soil bacterium Serratia plymuthica. Haterumalides NA, B and NE caused complete suppression of apothecial formation in sclerotia of Sclerotinia sclerotiorum at a concentration of 0.5 μg ml−1. Ascospore germination of this fungus was inhibited in the concentration range 0.8-3.0 μg ml−1. Haterumalides NA, B and NE prevented spore germination of several other filamentous fungi as well as Oomycetes at concentrations ranging from 0.4 to 40 μg ml−1, but did not show any effect against the yeast Candida albicans. Inhibition data could not be collected for haterumalide X due to its rapid conversion to haterumalide NA. The bacterium also produced two other antifungal metabolites: pyrrolnitrin and 1-acetyl-7-chloro-1-H-indole, which in contrast to the haterumalides, did not inhibit the apothecial formation on sclerotia. Pyrrolnitrin, and haterumalide NA, B and NE effectively inhibited spore germination of tested filamentous fungi at concentrations ranging from 0.06 to 50 μg ml−1, whereas 1-acetyl-7-chloro-1-H-indole inhibited spore germination only at concentrations above 50 μg ml−1. The minimal inhibitory concentrations of the respective compounds needed for total inhibition of spore germination varied for the fungal species tested.  相似文献   

18.
Asian turtles are overharvested for food, medicinal purposes and pets, and most species are now at risk of extinction (‘Asian turtle crisis’). As a result of high levels of trade, some species of Asian turtles are known to science mostly or only from animals found in trade. The Vietnamese box turtle (Cuora picturata) was described in 1998 and is known only from markets. This species is likely to be highly threatened, and identifying the origin of this “market species” is imperative if it is to be conserved. We used evidence from phylogeny, biogeography and trade patterns to focus field searches for this species, and in July 2010–January 2011 found it in the wild at three localities on the Langbian Plateau of southern Vietnam. This discovery provides the first opportunity to conserve the Vietnamese box turtle, and provides hope for determining the wild origin of other rare Asian turtles that remain known only from commercial trade.  相似文献   

19.
Environmentally friendly control measures are needed for the soil-borne pathogen, Pythium ultimum. This pathogen can cause severe losses to field- and greenhouse-grown cucumber and other cucurbits. Live cells and ethanol extracts of cultures of the bacterium Serratia marcescens N4-5 provided significant suppression of damping-off of cucumber caused by P. ultimum when applied as a seed treatment. Live cells of this bacterium also suppressed damping-off caused by P. ultimum on cantaloupe, muskmelon, and pumpkin. Culture filtrates from strain N4-5 contained chitinase and protease activities while ethanol extracts contained the antibiotic prodigiosin, the surfactant serrawettin W1, and possibly other unidentified surfactants. Production of prodigiosin and serrawettin W1 was temperature-dependent, both compounds being detected in extracts from N4-5 grown at 28 °C but not in extracts from N4-5 grown at 37 °C. Ethanol extracts from strain N4-5 grown at 28 °C inhibited germination of sporangia and mycelial growth by P. ultimum in in vitro experiments. There was no in vitro inhibition of P. ultimum associated with ethanol extracts of strain N4-5 grown at 37 °C. Prodigiosin, purified from two consecutive thin-layer chromatography runs using different solvent systems, inhibited germination of sporangia and mycelial growth of P. ultimum. Another unidentified compound(s) also inhibited germination of sporangia but did not inhibit mycelial growth. There was no in vitro inhibition associated with serrawettin W1. These results demonstrate that live cells and cell-free extracts of S. marcescens N4-5 are effective for suppression of damping-off of cucumber caused by P. ultimum possibly due in part to the production of the antibiotic prodigiosin.  相似文献   

20.
Few plants can tolerate the loose sandy‐soils of the arid deserts. Selection of native plants that could be used in rehabilitation of degraded deserts necessitates information about their seed dormancy and germination requirements. This study assessed the effects of light and temperature requirements during germination for eight common perennial grasses that have the potential to rehabilitate the arid Arabian deserts. The selected grasses vary considerably in seed mass. Germination of clonally propagated grasses (six species) was significantly greater, but slower, than that of two non‐clonal grasses. Four of these six species (Lasiurus scindicus , Panicum turgidum , Aeluropus lagopoides and Halopyrum mucronatum ) produce larger seeds and attained greater germination in both light and darkness at a wide range of temperatures. However, the other two (Centropodia forsskaolii and Coelachyrum piercei ) produce medium‐sized seeds with higher dormancy. Smaller seeds of Sporobolus arabicus were positively photoblastic at all temperatures, but those of Sporobolus spicatus were neutrally photoblastic at lower temperatures and positively photoblastic at higher temperatures. There was a significant negative relationship between seed mass and relative light germination, indicating that small seeds require more light during germination. It is recommended to use seeds of the six clonal grasses for restoration of degraded arid deserts. The ability of these grasses to germinate in different light and temperature regimes indicates their ability to germinate at any time of the year, even when seeds are buried. The light and temperature requirements of the different grasses are explained in the light of their adaptation and distribution in natural habitats. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

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