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1.
Biological control involves the use of beneficial organisms, their genes, and/or products, such as metabolites, that reduce the negative effects of plant pathogens and promote positive responses by the plant. Disease suppression, as mediated by biocontrol agents, is the consequence of the interactions between the plant, pathogens, and the microbial community. Antagonists belonging to the genus Trichoderma are among the most commonly isolated soil fungi. Due to their ability to protect plants and contain pathogen populations under different soil conditions, these fungi have been widely studied and commercially marketed as biopesticides, biofertilizers and soil amendments. Trichoderma spp. also produce numerous biologically active compounds, including cell wall degrading enzymes, and secondary metabolites. Studies of the three-way relationship established with Trichoderma, the plant and the pathogen are aimed at unravelling the mechanisms involved in partner recognition and the cross-talk used to maintain the beneficial association between the fungal antagonist and the plant. Several strategies have been used to identify the molecular factors involved in this complex tripartite interaction including genomics, proteomics and, more recently, metabolomics, in order to enhance our understanding. This review presents recent advances and findings regarding the biocontrol-resulting events that take place during the Trichoderma–plant–pathogen interaction. We focus our attention on the biological aspects of this topic, highlighting the novel findings concerning the role of Trichoderma in disease suppression. A better understanding of these factors is expected to enhance not only the rapid identification of effective strains and their applications but also indicate the potentials for improvement of natural strains of Trichoderma.  相似文献   

2.
Cultivation reflects an intense relationship between human and plants. Therefore, the number of cultivated plant species is of general interest. The number of cultivated crop species amounts to about 7,000 (“Mansfeld’s approach”). Amenity horticulture is a quickly developing area comprising ornamentals and other plants connected with gardening and landscaping. 28,000 plant species have been estimated to belong to this group. Cultivated forest plants are partly included in the first group and mostly in the second group. Thus, we propose that the total number of cultivated plants amounts to 35,000 species, i.e. about 14% of the number of higher plant species of the world.  相似文献   

3.
How successful are plant species reintroductions?   总被引：1，自引：0，他引：1  
Reintroduction of native species has become increasingly important in conservation worldwide for recovery of rare species and restoration purposes. However, few studies have reported the outcome of reintroduction efforts in plant species. Using data from the literature combined with a questionnaire survey, this paper analyses 249 plant species reintroductions worldwide by assessing the methods used and the results obtained from these reintroduction experiments. The objectives were: (1) to examine how successful plant species reintroductions have been so far in establishing or significantly augmenting viable, self-sustaining populations in nature; (2) to determine the conditions under which we might expect plant species reintroductions to be most successful; (3) to make the results of this survey available for future plant reintroduction trials. Results indicate that survival, flowering and fruiting rates of reintroduced plants are generally quite low (on average 52%, 19% and 16%, respectively). Furthermore, our results show a success rate decline in individual experiments with time. Survival rates reported in the literature are also much higher (78% on average) than those mentioned by survey participants (33% on average). We identified various parameters that positively influence plant reintroduction outcomes, e.g., working in protected sites, using seedlings, increasing the number of reintroduced individuals, mixing material from diverse populations, using transplants from stable source populations, site preparation or management effort and knowledge of the genetic variation of the target species. This study also revealed shortcomings of common experimental designs that greatly limit the interpretation of plant reintroduction studies: (1) insufficient monitoring following reintroduction (usually ceasing after 4 years); (2) inadequate documentation, which is especially acute for reintroductions that are regarded as failures; (3) lack of understanding of the underlying reasons for decline in existing plant populations; (4) overly optimistic evaluation of success based on short-term results; and (5) poorly defined success criteria for reintroduction projects. We therefore conclude that the value of plant reintroductions as a conservation tool could be improved by: (1) an increased focus on species biology; (2) using a higher number of transplants (preferring seedlings rather than seeds); (3) taking better account of seed production and recruitment when assessing the success of reintroductions; (4) a consistent long-term monitoring after reintroduction.  相似文献   

4.
Abstract

High soluble‐sulfate (SO4) concentrations affect water quality, soil chemistry, plant sulfur (S) levels, and possibly ruminant‐animal health. The objective of this greenhouse pot study was to determine the potential for accumulating high levels of S by tansy mustard (Descurainia pinnata (Walt.) Britton), kochia (Kochia scoparia L. Schrad.), yellow sweet clover (Melilotus officinalis L.), slender wheatgrass (Elymus trachycaulus (Link) Gould ex Shinners), and sunflower (Helianthus annuus L.). Plants were grown on both a Brinegar (fine‐loamy Ultic Argixeroll) and Portneuf (coarse silty Durixerollic Calciorthid) soil. Each species received five‐SO4 levels. The saturation extract electrical conductivity (EC) of the cropped soils ranged from 6 to 16 dS/m, while the soluble SO4 varied from 16 to 200 mmolc/kg soil. Soil solutions were saturated or very nearly saturated with respect to gypsum at the conclusion of each study. Plant dry matter yield, except of grass growing on the non‐calcareous soil, was not reduced by SO4 treatment nor by the sulfate‐induced decrease in mole fraction of calcium (Ca)/(sum cations) to values less than 0.10 for kochia and grass. Sulfur concentration in the plants ranged from 2.5 mg/g in grass to 10 mg/g in mustard and for each species was linearly related to the SO4 treatment and soil‐SO4 activity. Plant SO4‐S values ranged from 70 μg/g in the grass to nearly 900 μg/g in mustard. Total nitrogen (N): organic S was 4.4, 7.5, 11.4, 16.5, and 5.8 for mustard, kochia, clover, grass, and sunflower, respectively. It was concluded that these species could accumulate high levels of S in the above ground tissue.  相似文献   

5.
Nanoplastics (NPs) are accumulating in the soil environment at a rapid rate, which may cause serious consequences for ecosystems and human health. However, environmental behaviour and toxicity of NPs in the soil–plant system remain poorly understood. This review summarizes current studies on NP–plant interactions to unravel uptake mechanisms and phytotoxicity of NPs. NPs could be taken up by plant roots and transported upwards through the xylem to all organs of the plant, even to the edible parts such as the grain, thereby threatening human health. The interaction of NPs with plants affects plant transport of water and nutrients. Besides, it induces significant oxidative stress leading to inhibition of physiological and biochemical activities such as photosynthesis, and thus adversely affects plant growth and development. In addition, the co-transport of NPs with other soil pollutants may induce the combined toxic effects. This study also discussed the potential mechanism of NP–plant interactions based on previous experience with engineered nanomaterials. Finally, a comprehensive assessment of the key challenges in each area was presented, and future perspectives are offered.  相似文献   

6.
Wang  Cong  Fu  Bojie  Zhang  Lu  Xu  Zhihong 《Journal of Soils and Sediments》2019,19(1):1-9
Journal of Soils and Sediments - Soil moisture is a key ecohydrological variable in the soil–plant–atmosphere systems; understanding soil moisture–plant interactions is at the...  相似文献   

7.
An attempt is made toward the application of IUCN criteria and Red List Categories to agricultural and horticultural plants (excluding ornamentals). The main sources for this study were Mansfeld’s Encyclopedia (2001) and the IUCN Red List of threatened plants (2001). About 200 threatened cultivated plants are considered and presented in the respective lists, among them completely extinct crop plants such as Anacyclus officinarum and Bromus mango. The information available about neglected and underutilized crop plants still lags behind that about wild plants, especially at the species level, and more studies are required. On the other hand studies of major crops at the infraspecific level, are very advanced and can serve as models for investigating the wild ones.  相似文献   

8.
Abstract

A survey of 12 service laboratories using ICP‐AES for routine plant analysis reveals a variety of sample preparation and instrument calibration procedures in use. With the continued growth of ICP applications in plant analysis laboratories, a need exists for inter‐laboratory quality control.

The assurance of data quality among laboratories cannot be expected unless a standardization of preparation methods and calibration is accomplished. In the selection of a method for multi‐element determination on the same sample solution, the completeness of elemental release and sensitivity for some elements may have to be compromised.

In addition to the above survey, 8 plant samples were sent to 5 ICP laboratories that handle large volumes of plant samples with each using different preparation and calibration methods. The results for 11 elements show that the best precision among laboratories was for P, Mg, Mn, Ca and K, and the poorest precision for Al, Zn, Fe, Na, Cu and B. The imprecision noted for some elements was presumed to be caused by the diversity of preparation and calibration methods. Quality control efforts taken by this laboratory will also be given.  相似文献   

9.
With increasing demand for sustainable production, the need to effectively utilise site-based resources increases. One such resource is the remaining crop residues, both above and below ground, after harvest. In order to assess the magnitude of this resource, this study determined the plant nutrient contribution of residues from 17 different crops in seven different regions of Slovakia over a nine-year period. The soil profile 0.0–0.3?m was taken into account at belowground residues sampling. The results showed that winter rape, mustard, corn maize, triticale, winter rye with straw and sunflower left the most residues, exceeding 8 tons of dry biomass per hectare. Root crops (sugar beet, potatoes) and peas left less than 3 tons of residual dry biomass per hectare. Using these data, the nutrient potential coefficient, i.e. the amount of nutrients left by production of one ton of the main product was calculated by polynomial regression. With these coefficients and the known yield of a given crop, it was possible to calculate how much nitrogen, phosphorus and potassium each crop leaves in the soil after harvest. It was found that the amount of nitrogen left ranged from 20 to 132?kg, phosphorus from 2 to 24?kg and potassium from 13 to 218?kg per hectare. This has to be taken into account when calculating the fertiliser requirement of the subsequent crop in order to achieve better resource utilisation, thereby reducing the risk of eutrophication and improving farm profits by reducing expenditure on fertiliser.  相似文献   

10.
Acid soils are widespread and limit global plant production. Aluminum(Al)/manganese(Mn) toxicity and phosphorus(P) deficiency are the major limiting factors affecting plant growth and productivity on acid soils. Plants, however, have evolved various strategies to adapt to these stresses. These strategies include using both external and internal mechanisms to adapt to Al toxicity, regulating Mn uptake, translocation, and distribution to avoid Mn toxicity, and orchestrating a set of P transport me...  相似文献   

11.
Does invasive plant management aid the restoration of natural ecosystems?   总被引：1，自引：0，他引：1  
Invasive alien plants of natural ecosystems, commonly referred to as weeds, can reduce the abundance and diversity of native flora and fauna, and alter ecosystem processes. Using Australia’s 20 ‘Weeds of National Significance’ (WoNS), we investigated how natural ecosystems responded following their management. We reviewed the literature and surveyed land managers involved in WoNS management programs by distributing a questionnaire through various e-mail networks. While most of the 95 papers reviewed measured the effect of management on the target WoNS, only 18 assessed the response of other plant species. In these studies, native plant species did not necessarily recover following management and in many instances the managed WoNS was replaced by other weed species. Three other studies investigated the response of invertebrate communities and an ecosystem process following WoNS management but none examined the response of vertebrates or microbial communities. A total of 168 replies were received to the land manager survey. Of the 142 land managers who evaluated their WoNS management program, 86 monitored the response of native plant species and/or other weeds, mostly using qualitative assessments. These managers reported no vegetation response after management of the WoNS (7%) or re-colonisation by a combination of native and weed species (52%) or only by native plants (33%) or the targeted WoNS (2%). Our results emphasise the need to select sites for weed management that are less degraded and thus have a higher likelihood of natural recovery and/or to incorporate activities that facilitate recovery of native plant communities in conjunction with weed removal.  相似文献   

12.
Abstract

Two field experiments measured variation of phosphorus (P) concentration in dried tops (plant‐test P) of individual lupin (Lupinus angustifolius cv. Merrit) and wheat (Triticum aestivum cv. Cadoux) plants collected from random locations in experimental plots treated with different levels of superphosphate. Plant‐test P for the individual tops varied by between 4 to 65% of mean values. Coefficient of variation for the 10 individual plants per plot varied from 10 to 24%. For each plot, mean plant‐test P for the 10 individual tops were similar to values for bulk samples of 30 plants collected at random within the plot. It is concluded that a bulk sample of 30 lupin or wheat plant tops need to be collected from uniform areas in farmer paddocks to provide a representative estimated of the current P status of the crop.  相似文献   

13.
The International Treaty on Plant Genetic Resources for Food and Agriculture entered into force in 2004 and is an important instrument by which plant breeders can access crop genetic diversity on the basis of multilateral “facilitated access”. To test how well access works, we sent seed requests to 121 countries that are Contracting Parties to the Treaty. Seeds were received from 44 countries, 54 countries did not respond, while for 23 countries contacts stopped for various reasons: loss of communication, the accessions we requested did not exist or were not in the multilateral system, or conditions or standard material transfer agreements were different from those specified in the Treaty. It is concluded that after nearly 10 years, “facilitated access” is not straightforward.  相似文献   

14.
Until recently, potassium(K) has not received considerable attention because of the general belief that soils contain ample amounts of this element. In addition, low rates of K fertilizer application in agriculture have led to rapid depletion of K in the rhizosphere soil in many underdeveloped countries. This results in various negative impacts, including preventing optimum utilization of applied nitrogen and phosphorus fertilizers. To compensate for these losses,massive use of K fertilizers in ...  相似文献   

15.

Purpose

The aim of this work was to select and assess the efficiency of different amendments applied to ordinary chernozems artificially contaminated with heavy metals (Zn and Pb).

Materials and methods

The effect of different amendments on ordinary chernozem contaminated with Zn and Pb acetate salts was studied in a long-term 3-year field experiment. Glauconite, chalk, manure, and their combinations were chosen as ameliorating agents. Spring barley (Hordeum sativum) was used as test culture for three successive years. The heavy metal concentration in all the soil samples decomposed by HF?+?HClO4 was determined by atomic absorption spectrophotometry (AAS). One normal concentration of CH3COONH4 at pH 4.8 was used to estimate the actual mobility of metals. The compounds of heavy metals extracted by 1 N HCl are regarded as mobile compounds. The concentration of metals in the plants was determined using the dry combustion in a mixture of HNO3 and HCl at 450 °C. The content of heavy metals in extracts from soil and plant samples was determined by AAS.

Results and discussion

The content of weakly bound metal compounds increased upon the contamination of the soil with Pb and Zn salts, which led to a low quality of barley grown in these soils. Metal concentrations in the barley grain exceeded the maximum permissible concentrations (MPCs). The content of Zn and Pb in grains was higher than the MPC for at least 3 years after the soil pollution. The application of amendments significantly decreased the mobility of metals, and the simultaneous application of chalk and manure was most significant. The share of weakly bound metal compounds in the contaminated soils decreased to the level typical for the clean soils or even below.

Conclusions

The combined application of chalk and manure to Zn- and Pb-contaminated ordinary chernozems decreased the content of weakly bound metal compounds in the soil and lowered their concentrations in barley plants. The polyfunctional properties of the soil components with respect to their capacity for metal fixation were established. The decrease in the intensity of Zn accumulation in grains of barley shows the presence of a barrier at the root–stalk and stalk–grain interfaces.
  相似文献   

16.
Summary The conuco in Cuba is a large garden or a small field where agriculture is practiced in a traditional way. The history of the conuco is discussed. Composition and structure of actual conucos are described on the basis of four cases studied in Eastern Cuba. Their cultivated plants came from nearly all regions of diversity of the world. The crops from the Central American and Mexican region are most important. The great diversity of different crops as well as the marked variation within most of the cultivated plants stress the importance of the conuco as a reservoir for plant genetic resources.
Der Conuco — ein bedeutendes Reservoir für pflanzliche genetische Ressourcen in Kuba
Zusammenfassung Der kubanische Conuco ist ein größerer Garten oder ein kleineres Feld mit traditioneller landwirtschaftlicher Produktion. Die Geschichte des Conuco wird diskutiert. Zusammensetzung und Struktur aktueller Conucos werden auf der Grundlage von vier ostkubanischen ausgewählten Fallbeispielen beschrieben. Ihre Kulturpflanzen stammen beinahe aus allen Mannigfaltigkeitszentren der Welt. Besonders bedeutsam sind die Kulturpflanzen der mittelamerikanischen und mexikanischen Region. Die große Mannigfaltigkeit unterschiedlicher Fruchtarten und die ausgeprägte infraspezifische Variabilität bei den meisten Kulturpflanzen unterstreichen die Bedeutung des Conuco als Reservoir für pflanzliche genetische Ressourcen.
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17.
The number of ex situ conservation facilities has grown dramatically in recent years, and they have become increasingly integrated under national and regional conservation initiatives. However, little information is available about the extent to which plant species are appropriately represented in ex situ collections. This paper assesses whether seed/spore collections stored in European seed banks cover or not, and to what extent, the species currently threatened with extinction in the wild. Although a substantial amount of the European flora (ca. 70%) is currently stored in seed banks, we highlight the relatively poor representation of threatened species: only 27% of the taxa listed on the European threatened plant list and 44% of the taxa listed in Annex II of the EU Habitat Directive are stored in European seed banks. Some taxonomical groups most at risk, e.g. Pteridophytes and Orchidaceae, are also under-represented in European seed banks. By examining the number of accessions per species and the number of seeds per accession, this study also gave some insight on how well species are conserved, considering that these two variables are surrogates for genetic diversity. We have highlighted that at least two thirds of the threatened species stored in European seed banks likely suffer from too low genetic diversity in the collections. These analyses were essential to identify those collections and additionally the standards needed to maximize the usefulness of future collections.  相似文献   

18.
During rhizogenesis, carbohydrates are an important source of energy for the plant tissues. It has been hypothesised that phenological phase of the shoot plays a major role in plant's response to rooting stimulants and affects the cuttings’ carbohydrate content. Therefore, the purpose of this study was to evaluate the impact of phenological phase of the shoots and the use of rooting stimulants of plant origin on the relationship between rooting abilities and the carbohydrate content in leaves and stems of cuttings. Single-node stem cuttings of Rosa beggeriana ‘Polstjärnan’ and Rosa helenae ‘Semiplena’ were harvested from shoots in four phenological stages: flower buds closed (P1), flowers open (P2), immediately after petal shedding (P3), and 7–14 days after petal fall (P4). The following rooting enhancers were used: 0.4% indole butyric acid (IBA) (Ukorzeniacz Aaqua); 0.2% naphthalene acetic acid (NAA) (Ukorzeniacz Baqua); Bio Rhizotonic; and Root Juice?; Bio Roots. Controls included untreated cuttings. The contents of reducing and total soluble carbohydrates in leaves and shoots were estimated before and after rooting. The rooting percentage and rooting degree were determined. A relatively high or moderate natural rooting ability without any treatment were shown by R. beggeriana ‘Polstjärnan’ in 63.8%–87.5% and by R. helenae ‘Semiplena’ in 41.3%–72.5% cuttings. IBA and NAA decreased the mean rooting percentage in ‘Polstjärnan’, but increased it for P4 cuttings in ‘Semiplena’. None of the preparations had any impact on the degree of rooting. The mean level of total soluble and reducing sugars in leaves and stems of cuttings before rooting was lower than that of after root formation. The preparations of plant origin positively affected rhizogenesis and sugar contents in plant tissues, but their effect depended on shoot's phenological phase and cultivar. Plant origin preparations may successfully replace those containing IBA or NAA.  相似文献   

19.
A 2‐yr study was conducted to evaluate the effect of within‐row spacing and nitrogen (N) fertility on sweetpotato [Ipomoea batatas (L.) Lam.] yield and quality. Conducted in North Alabama on a Hartsells fine sandy loam (fineloamy, siliceous, thermic Typic Hapludult), the study consisted of four replications of a factorial arrangement of four within‐row spacings (15, 20, 25, and 30 cm) and 4 N fertility rates (0, 36, 72, and 108 kg N/ha). Nitrogen fertilization did not affect yield or quality of harvested storage roots and there was no significant interaction between row spacing and N rate in either year. In 1994, greatest total yield ofsweetpotatoes occurred with the narrowest within‐row spacing (15 cm), but in 1995 within‐row spacing did not affect total yield. In 1994, as within‐row spacing increased, yield of Jumbo sweetpotatoes increased.  相似文献   

20.
Different aspects of Si biogeochemistry in the soil have been reviewed. Interaction mechanisms of monosilicic acid with aluminum, phosphorus, and heavy metal compounds have been generalized. Polysilicic acids are chemically inert substances, but they participate in the formation of soil structure. Organosilicon compounds in the soil are very little investigated. From literature and our own data, the cycle of mobile Si forms in the soil–microorganism–plant system has been suggested, which shows the main fluxes of soluble Si migration and transformation. A new classification of the Si compounds based on their physicochemical and biological activities in the soil has been suggested as well as a method for the determination of mono- and polysilicic acids in the soil matrix.  相似文献   

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