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1.
Crenate broomrape (Orobanche crenata Forks.) is a major constraint for grain and forage legume cultivation in Mediterranean agriculture, to which little resistance is available. We studied the response to O. crenata of a germplasm collection of chickling pea (Lathyrus cicera L.) in field trials over two seasons showing that resistance although scarce and masked by confounding factors, is available and can be used in breeding. The level of infection was highly influenced by environmental factors and plant growth cycle. Earlier accessions were less infected due to competition of the earlier settled pods with O. crenata tubercles. O. crenata infection strongly reduced host biomass and grain yield. Deviations from the polynomic regression gave an improved approximation of the true genetic resistance levels present in the germplasm.  相似文献   

2.
Onion (Allium cepa L.) is an important vegetable crop in Korea, but its production is severely affected by fungal pathogens during plant growth and bulb storage. We investigated the occurrence of fungi on market onion bulbs; identified the predominant fungal species based on the internal transcribed spacer region, β-tubulin region, and elongation factor 1-α gene sequences; and tested the pathogenicity of each predominant fungal species in onion bulbs. The genera Aspergillus (63.9%), Penicillium (15.5%), Fusarium (6.4%), Rhizopus (5.2%), and others (9.0%) were detected in the samples. Among these genera, Aspergillus awamori, Fusarium oxysporum, Penicillium brasilianum, and Rhizopus oryzae were identified as the predominant species. All of the fungi tested could infect both the inner layers and outer surfaces of onion bulbs and be re-isolated from the infected tissues. To our knowledge, this is the first report that P. brasilianum is a fungal pathogen of onion bulbs.  相似文献   

3.
Temperate pasture legumes (e.g. Trifolium and Medicago spp.) often have a higher phosphorus (P) requirement for maximum productivity than pasture grasses. This is partly attributed to differences between legumes and grasses in their ability to acquire P from soil. We are the first to report differences in root morphology traits important for soil P acquisition in a range of novel pasture legumes being developed for use in temperate pastures of southern Australia. Up to a 3·6‐fold range in specific root length (SRL) (79–281 m root g?1 root) and 6·1‐fold range in root hair length (RHL) (0·12–0·75 mm) was found between the pasture species. The commonly used Trifolium subterraneum and Medicago sativa had relatively low SRLs and short root hairs, while Ornithopus compressus, O. sativus and Biserrula pelecinus had RHLs and SRLs more similar to those of two grass species that were also assessed. Specific root length was highly correlated with average root diameter, and root traits were relatively stable at different plant ages. We surmise that large differences among pasture legume species in the effective volume of soil explored could translate into significant differences in their critical P requirements (i.e. soil P concentration to achieve 90% of maximum shoot yield).  相似文献   

4.
There are 32 species of Flourensia genus with 9 native to Mexico. These species contain compounds with potential use for pest control. In this paper, we report the antifungal activities of ethanol extracts from three endemic species in Coahuila state: Flourensia microphylla, Flourensia cernua, and Flourensia retinophylla. Also, preliminary information on the chemical composition of the extracts is included. Antifungal activity was tested against three pathogens attacking commercial crops: Alternaria sp., Rhizoctonia solani, and Fusarium oxysporum. The extracts concentration varied from 10 to 1500 μl l−1. The ANOVA showed highly significant differences (P  0.01) with the extracts, the doses, and on the interaction extract × dose. Inhibition effect was observed from 10 μl l−1 in all three species. Total inhibition was found only with F. cernua and F. retinophylla at 1000 μl l−1 for R. solani, the three species inhibited the three pathogens at 1500 μl l−1. Infrared analysis showed similar absorption signals for the extracts of the three species although in different concentration. This suggests that similar compounds may be present. The control of these pathogens by natural compounds is interesting both for environmental and economic reasons. The use of semiarid lands plants may improve the socioeconomic level of the people within the region.  相似文献   

5.
The leaves (needles) of eastern red cedar (Juniperus virginiana L.) contain two important natural products: essential oil and podophyllotoxin. The hypothesis of this study was that it may be possible to extract both essential oil and podophyllotoxin from the leaves of the tree, by using a dual extraction method. Podophyllotoxin was obtained from the leaves following steam distillation of the leaves to produce the essential oil, indicating that steam distillation did not degrade podophyllotoxin. Furthermore, a product with 6% purity podophyllotoxin was obtained from the steam-distilled plant material, demonstrating the possibility for the establishment of an industrially economic protocol for dual extraction of these two natural products. Our study demonstrated that J. virginiana leaves, currently a waste-product from the timber industry, could be sequentially extracted for essential oil and podophyllotoxin and utilized as a by-product instead. We also found that the J. virginiana heartwood (a traditional source for cedarwood essential oil) does not contain podophyllotoxin. This is the first study to report both podophyllotoxin and essential oil in J. virginiana, and the first report on the dual extraction of these two natural products from the same biomass samples.  相似文献   

6.
Summary The highlands of South America are the probable geographic origin for the potato gangrene fungusPhoma exigua var.foveata (Foister) Boerema which was found parasitizing plants ofChenopodium quinoa in the Altiplano area of Peru. In vitro studies showed no dissimilarities between it and the antibiotic ‘E’ producing virulent European isolates ofP. exigua var.foveata. It is as pathogenic to potatoes as the virulent European isolates but onC. quinoa andC. album it is more pathogenic than the European isolates. So far the fungus has not been found on potato tubers in South America and the reasons why gangrene problems have not arisen there are discussed.  相似文献   

7.
Biochemical pathways of a bulb forming plant (Allium cepa L.) have been studied between 1957–1960 (Schuphan). New experiments involving different techniques were started in 1969 (Schwerdtfeger). The results from the investigations to-date can be summarized as follows: 1. a) In the portion of the young plant developing into a ripe bulb via one or two states of growth there is a continued increase in dry matter content, particularly as the bulb develops from phase I to phase II, it remains practically stationary between phase II to phase III and declines slightly in phase IV, the state in which the bulb reaches its physiological ripeness and is suitable for winter storage. b) Monosaccharides show a similar though modest rise, whilst disaccharides show a marked increase particularly between phase I and phase II. c) There is a considerable increase in S-containing essential onion oils, whilst d) ascorbic acid decreases only moderately. e) The ‘Relative Protein Content’ (Protein-N as % of total-N) undergoes a characteristic decrease; the bulb could be thought of as trying to shed the surplus of certain N-compounds which are not conducive to the storage life of the bulb. f) Amino acids do not react uniformally. This is probably due to their different functions e.g. in transamination. In this respect arginine in addition to glutamic acid appears to play a special role providing evidence thatA. cepa belongs to a rather small number of plants using arginine as a pool for N. Arginine has 4 molecules of N of which 2 belong the very active guanidino group. 2. We have chiefly concentrated on the Essential Amino Acids (EAA), since Schuphan (1960) elucidated its special role in plant function. Animal and man are not able to synthesize their EAA, but the plant synthesises all AA including the essential ones. It has been established that growing points (buds) and layers of meristematic tissues — so called ‘active zones’ (Schuphan) — need EAA and accumulate them preferentially. During growth ofA. cepa, arginine content increases by 29%, glutamic acid/glutamine by 7%, whilst most of the contents of the other AA decreases more or less. We believe that these results are highly significant — at least as far as EAA are concerned. Parallel findings were obtained in 1957, 1960, and 1969 independent of the methods of estimation used (microbiology and columm chromatography). 3. The special role of arginine as a pool for N in A.cepa can be eluicidated from results other than those described. In February 1958 we found that the arginine content of sprouted bulbs was 43% of that of non-sprouted controls. On the other hand the content of 8 EAA increased in sprouts, two of them (valine and tryptophan) failed. 4. We are also able to locate the arginine pool in the bulb. The inner scales surrounding the buds contained the highest concentration of arginine. The outer fleshy scales contained 27%, the buds 35% less arginine than the inner scales.  相似文献   

8.
Biochemical and nutritional changes were studied during the ripening process of three Opuntia morphospecies with different ripening behavior: Naranjona (O. ficus-indica), Blanca Cristalina (Opuntia sp.), and Esmeralda (Opuntia sp.) of early, early-intermediate, and intermediate-late ripening, respectively. In loss of fresh weight, Naranjona showed the highest values, while in Blanca Cristalina and Esmeralda, a discrete weight loss was found. No significant differences were found among morphospecies in soluble solids, total titratable acidity and pH during the postharvest days. Blanca Cristalina and Esmeralda showed an increase in the content of carotenoids, while these diminished in Naranjona. The cell wall enzymes evaluated showed particular behaviors during the ripening of each morphospecies suggesting a fine biochemical control and not a clear relationship between fruit softening and enzyme activity. This study provides basic information on prickly pear ripening, in order to understand this process for its control and for improving shelf life.  相似文献   

9.
Establishing forage legumes into endophyte‐infected tall fescue (Festuca arundinacae Schreb.) pastures is problematic, especially in well‐established stands. A oversowing field experiment determined if this problem was because of poor nodulation. Four renovation techniques, clipped sward (treatment A), herbicided + rye seeding in the previous autumn (treatment B), herbicided in the autumn and spring (treatment C) and herbicided to suppress the sward (treatment D), were investigated to determine their effect on nodulation and root growth of lucerne (Medicago sativa L.), red clover (Trifolium pratense L.) and white clover (T. repens L.) at 16, 22 and 29 d after sowing the legumes. A pot experiment was also conducted under optimal growth conditions and using the same soil to determine the nodulation and root growth potentials of these legume species. At adequate rhizobial populations (>6 × 104 cfu g?1 soil), substantial nodulation of all species occurred by 29 d after sowing in treatments C and D, whereas nodulation of clovers was usually reduced in treatment A. Total root lengths for all sampling dates, species and treatments were severely restricted, especially under treatment A. A general correspondence of nodulation with root growth was observed for all species, with high correlations (r ≥ 0·85) between these variables for all legume species and treatments, suggesting that soil moisture, and possibly competition for light, were the limiting factors. These results demonstrate that weak stands of forage legumes, typically found when sown into tall fescue swards, are probably not because of inadequate nodulation. Rather, inhibition of root growth by detrimental physical/chemical conditions or allocation of limited photosynthate to shoots instead of roots is suggested.  相似文献   

10.
The twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most important and highly polyphagous pests of vegetables and other crops worldwide. Experiments were conducted in the laboratory and greenhouse to evaluate corn (Zea mays L.) as a banker plant for the predatory gall midge, Feltiella acarisuga (Vallot) (Diptera: Cecidomyiidae) to potentially control T. urticae. Choice and no-choice experiments were carried out to determine the host plant preference of an alternative prey, Oligonychus pratensis (Banks)(Acari: Tetranychidae) to corn and green bean (Phaseolus vulgaris L.). Results showed that O. pratensis adults strongly preferred corn as a host plant and posed no risk to green bean. F. acarisuga was found to fly at least 7.0 m to search for new preys on green bean plants, and over 176 F. acarisuga larvae per leaf were recorded at 14 d after dispersal. F. acarisuga proved to be an excellent predator of both T. urticae and O. pratensis. The predation by F. acarisuga to T. urticae and O. pratensis ranged from 43.7 to 67.9% and 59.2 to 90.3%, respectively, under laboratory conditions. In a non-cage study, 81.2% of T. urticae population was suppressed by F. acarisuga in reference to the control (cage treatment). The results showed that this banker plant system has potential for controlling T. urticae in greenhouse vegetable production.  相似文献   

11.
Flooding has globally become common, and thus cultivation techniques to adapt to the stress are required. We have developed a technique called “close mixed-planting” using flood-adapted rice (Oryza sativa L.) and upland crops with tangled root systems, showing that this technique can mitigate the damage caused to upland crops by flooding. However, the plant response during the reproductive stage has not yet been examined. In this study, we estimated the alleviative effects of close mixed-planting on the growth inhibition and physiological damage to pearl millet (Pennisetum glaucum) caused by flooding at the reproductive stage in northern Namibia. Pearl millet and NERICA4 (Oryza spp., interspecies of O. sativa and O. glaberrima) were used. Four-week-old single- and mixed-crop pearl millets were transplanted and grown for 22 days, and then flooding treatment was administered for 28 days. The growth and physiological parameters of single pearl millet were significantly decreased by flooding stress, and the parameters did not recover during a 14-day recovery period compared with those of unflooded single and mix-cropped pearl millet. On the other hand, the damage to mix-cropped pearl millet by flooding was suppressed. Thus, the mixed-cropping mitigated the anoxic stress of pearl millet caused by flooding at the reproductive stage and contributed to the improved growth after the recovery period. This result suggested that the close mixed-planting with rice can contribute to the mitigation of flooding damage not only at the vegetative stage but also at the reproductive stage of pearl millet in the semi-arid African country, Namibia.  相似文献   

12.
《Plant Production Science》2013,16(3):338-341
Abstract

The mobility in phloem of boron (B) has been reported to vary among plant species. Boron is phloem immobile in many species and completely mobile in others. Recent reports regarding phloem B mobility or immobility only considered temperate plants, and there is no information on tropical species. Information of phloem B mobility is useful for improving the diagnosis of B deficiency and management of B status in crop production. This study aimed to survey tropical species for their B mobility. Leaf samples of 17 species, including cashew (Anacardium occidentale L.), mango (Mangifera indica L.), custard apple (Annona squamosa L.), papaya (Carica papaya L.), cassava (Manihot esculenta Crantz.), Indian walnut (Samanea samen (Jacq.) Marrill.), cork wood tree (Sesbania grandiflora (L.) Pers.), tamarind (Tamarindus indica L.), jackfruit (Artocarpus heterophyllus Lamk.), guava (Psidium guajava L.), star fruit (Averrhoa carambola L.), passion fruit (Passiflora edulis Sims.), coffee (Coffea arabica L.), lime (Citrus aurantifolia Swingle.), longan (Euphoria longana Lam.), lychee (Lychi chinensis Sonn.) and teak (Tectona grandis L.) were collected in the position of the youngest fully expanded leaf (YFEL), the middle leaf age of a branch (ML) and the oldest leaf (OL). Based on a premise that the nutrient concentration gradient between young and old leaves will be steeper in those species in which B is immobile, B concentration in the different leaf positions was examined in comparison with calcium (Ca is phloem immobile) and potassium (K is phloem mobile). Concentrations of K in all leaf types were not significantly different or decreased with leaf age, while Ca concentrations were always higher in the older leaves. Three species; tamarind, guava and teak, showed concentration gradients of B that were similar to K. The results suggested that B may be retranslocated from older to younger leaves of these species, hence indicating that B may be phloem mobile in these species. However, this hypothesis needs confirmation through studies examining retranslocation of B using 10B isotope or identification of B-complexing molecules in the phloem, e.g. sugar alcohols.  相似文献   

13.
Summary Recurrent backcrosses (BC) were used to introduce nuclear factors ofS. tuberosum L. ssp.tuberosum into the cytoplasm of Andean potatoesS. tuberosum ssp.andigena (Juz. and Buk.) Hawkes andS. phureja Juz. and Buk. Each generation BC was produced in reciprocal directions to test the effect of cytoplasmic substitution on yield. This report analyses tuber number, tuber weight, and tuber length of BC2 and BC3 substitution into ssp.andigena cytoplasm and BC2 and BC2 substitutions intoS. phureja cytoplasm. Direction of cross had no consistent significant effect on yield components of ssp.andigena substitution lines. InS. phureja reciprocal progenies direction of cross was responsible for significant differences of some reciprocal sets. When there were significant differences the higher yield usually occurred when ssp.tuberosum was the pistillate parent, but in some progenies when ssp.tuberosum was the pistillate parent the yield was significantly lower than in the reciprocals. It is suggested that differences between reciprocals resulted from chromosomally encoded gene action, resulting from maternal and/or paternal effects, rather than cytoplasmic factors. Authorized for publication as paper No. 7494 in the Journal Series of The Pennsylvania Agriculture Experiment Station.  相似文献   

14.
Porophyllum tagetoides is an annual warm-weather herb that has an intense typical smell. Its leaves are commonly used in soup preparation and traditional medicine for treatment of inflammatory diseases. Its volatile compounds and antioxidant properties were evaluated in crude, aqueous and ethanol leaf extract and an oil emulsion using different antioxidant assays in vitro, such as: DPPH radical scavenging activity, redox potential, polyphenol content, reducing power and optical density. A high antioxidative activity was found when comparing leaves with stems. The crude extract from leaves showed a very high reducing power (2.88 ± 0.20 O.D.) and DPPH radical-scavenging activity (54.63 ± 4.80%), in concordance with a major concentration of vitamin C (23.97 ± 0.36 mg/100 g). Instead, the highest polyphenol content (264.54 ± 2.17 mg GAE/g of sample) and redox potential (561.23 ± 0.15 mV) were found by the ethanol and aqueous extract, respectively. Aldehydes and terpenes such as nonanal, decanal, trans-pineno, β-myrcene and D-limonene were the major volatiles found. This study suggests that Porophyllum tagetoides extracts could be used as antioxidants.  相似文献   

15.
BES1基因是植物体内一类重要的转录因子。本研究利用基因组测序数据,在小麦基因组中鉴定到20个 BES1基因家族成员,它们分布在14条染色体上。为进一步研究 BES1基因在小麦以及其他禾本科作物(水稻、玉米、高梁、谷子和大麦)中的功能和进化关系,对小麦等6种禾本科作物以及十字花科模式植物拟南芥的 BES1基因家族进行系统发育关系、结构特性和共线性关系分析,结果发现,系统发育分析将该家族成员分为Group A、Group B、Group C和Group D四类,大部分小麦 BES1基因集中在Group A;大部分小麦 BES1基因家族成员有2个外显子,最多有10个外显子;小麦与水稻 BES1基因之间存在更多的共线性关系。此外,在小麦根和穗中还鉴定到3个具有较高表达水平的 BES1基因( TaBES1-3A-2 TaBES1-3B-2 TaBES1-3D-2),表明 BES1基因在小麦生长发育过程中发挥着重要作用。  相似文献   

16.
17.
Non‐systemic endophytes coexist with grasses and produce positive or negative effects for the host. In agricultural grasses, endophytes such as Epichloë spp. (formerly: Neotyphodium spp.) enhance the biometric parameters and agricultural value of grass biomass and seeds. Some endophytic fungi produce active substances that exert a negative influence on grass‐fed livestock. There is a general scarcity of studies investigating other endophytic fungi, the species composition of fungal communities, fungal species capable of colonizing different grasses and endophyte transfer between grass taxa. This study aims to fill in the existing knowledge gap by describing the relationships between fungal species and grass species. Timothy grass (Phleum pratense L.) is more readily colonized by endophytic fungi than perennial ryegrass (Lolium perenne L.), and the ratio of fungi isolated from the above species was determined at 3:1. Ecological indicators, especially diversity, were also higher in the fungal community colonizing timothy grass. The vast majority of the isolated fungi were ascomycetes. In addition, two Basidiomycota isolates and three Oomycota isolates (Phythium acanthicum) were also obtained from timothy grass. The most prevalent fungal species were Alternaria alternata, Microdochium bolleyi and Epicoccum nigrum. An analysis of minisatellite DNA regions revealed high levels of genetic polymorphism in A. alternata, whereas the remaining isolates were characterized by low levels of genetic variation or genetic homogeneity. The transfer of endophytic fungi between grass species was determined, which was one of the most important observations made in the study. The Sørensen–Dice coefficient reached 50%, which indicates that all fungal species isolated from perennial ryegrass are capable of colonizing timothy grass.  相似文献   

18.
Applications of either sewage sludge or N as ammonium nitrate were made to a 15-year-old hayfield over a 2-year period. The original seeding mixture was unknown but was believed to be timothy (Phleum pratense L.) and red clover (Trifolium pratense L.). During the second year, botanical separations indicated that applications of both N and sewage sludge resulted in reduced proportions of red and volunteer white clover (Trifolium repens L.) as well as volunteer Kentucky bluegrass (Poa pratensis L.). During the growing season a decline in proportion of timothy (Phleum pratense L.) was observed for the control as well as for the N and sludge treatments. In contrast, quackgrass (Agropyron repens (L.) Beauv.) was markedly stimulated by the treatments and the proportion of it in the hay increased during the growing season.  相似文献   

19.
Serradella (Ornithopus) species are high‐quality pasture legumes that originate from the Mediterranean basin and have been increasingly used in southern Australian temperate grazing systems. They are generally regarded as tolerant of soils with low pH and, by inference, elemental toxicities such as aluminium (Al). No studies have examined the effect of high Al concentrations on the growth of French serradella (Ornithopus sativus Brot.) or newly developed cultivars of yellow serradella (O. compressus L.). Several cultivars/accessions of each species were grown in low ionic‐strength nutrient solutions at pHCa 4.5 containing a range of Al concentrations. Their susceptibility to root growth inhibition by Al was benchmarked against reference species ranging from Al‐sensitive to Al‐tolerant. Most serradella cultivars had moderate‐to‐high Al tolerance in solution culture but one yellow and two French serradella cultivars ranked alongside the Al‐sensitive reference species. A subset of cultivars and reference species were then grown in an Al‐toxic soil to test the validity of the solution culture results; these cultivars spanned the apparent range in Al sensitivity/tolerance indicated by the solution culture experiment. Variation in the relative root length achieved in Al‐toxic solution culture explained ~59% of the variation in the relative root length achieved in the acidic Al‐toxic soil. This result supports the conclusion that Al tolerance varies among serradella and that some cultivars may not thrive in soils with pHCa < 4.5 and elevated extractable Al concentrations.  相似文献   

20.
A 2-year field experiment was conducted in northern Greece to study the mulch effects of seven annual [anise (Pimpinella anisum L.), sweet fennel (Foeniculum vulgare P. Mill.), sweet basil (Ocimum basilicum L.), dill (Anethum graveolens L.), coriander (Coriandrum sativum L.), parsley (Petroselinum crispum (P. Mill.) Nyman ex A.W. Hill) and lacy phacelia (Phacelia tanacetifolia Benth.)] and three perennial [mint (Mentha X verticillata L.), oregano (Origanum vulgare L.) and common balm (Melissa officinalis L.)] aromatic plants, used as incorporated green manure, on the emergence and growth of barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.], common purslane (Portulaca oleracea L.), puncturevine (Tribulus terrestris L.), common lambsquarters (Chenopodium album L.) and maize (Zea mays L.). In addition, the phytotoxic potential of the abovementioned aromatic plants extracts was determined in the laboratory using a perlite-based bioassay with maize and barnyardgrass. The bioassays indicated that germination, root elongation and fresh weight of barnyardgrass were reduced by the most aromatic plant extracts. However, maize growth parameters were only affected by the extracts of anise, sweet fennel, coriander, common balm and oregano. In the field, emergence of barnyardgrass, common purslane, puncturevine or common lambsquarters was reduced by 11–50%, 12–59%, 26–79% or 58–83% in green manure-treatment plots, respectively, as compared with green manure-free plots (control). On the contrary, maize emergence was not affected by any green manure. At harvest, maize grain yield in green manure-herbicide untreated plots was 10–43% greater than that in the corresponding green manure-free plots. In particular, maize grain yield in anise, dill, oregano or lacy phacelia green manure-herbicide untreated plots was 27–43% greater than that in the green manure-free-herbicide untreated and slightly lower than that obtained in the corresponding herbicide treated plots. These results indicated that green manure of aromatic plants, such as anise, dill, oregano or lacy phacelia could be used for the suppression of barnyardgrass and some broadleaf weeds in maize and consequently to minimize herbicide usage.  相似文献   

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