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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 53 (1989), S. 17-29 
    ISSN: 1570-7458
    Keywords: Mayetiola destructor ; Cecidomyiidae ; oviposition ; host specificity ; wheat ; oats ; insect-plant interactions ; thresholds ; deprivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les réactions de femelles préalablement accouplées de Mouches de Hesse ont été examinées en analysant le comportement de femelles isolées sur blé et sur avoine. Le répertoire comportemental de ces femelles comprenait: le vol, l'atterrissage sur feuille, la flexion du corps de sorte que l'extrémité de l'abdomen touchât la surface de la feuille, l'antennation, les mouvements de l'extrémité de l'abdomen sur la feuille à angle droit des nervures, le repos avec la tarière droite et encore dévaginée, le repos avec la tarière télescopée à l'intérieur du corps. Sur blé plus que sur avoine, les femelles après atterrissage ont présenté une fréquence plus élevée de passage de la flexion à l'antennation que de la flexion à l'abdomen droit. Durant les 5 premières minutes d'observation, les individus libérés dans des enceintes avec blé fléchirent et ‘antennèrent’ 2 à 3 fois plus que ceux libérés sur avoine. Les durées des différentes séquences différaient aussi: sur blé, pendant les 5 premières minutes, les femelles passèrent plus de 50% du temps à fléchir, tandis que sur avoine elles passèrent plus de 50% du temps en repos. Les femelles restèrent aussi plus longtemps sur les feuilles de blé et y pondirent 4 fois plus d'oeufs que sur avoine. Les femelles de M. destructor ont montré une plasticité du seuil d'acceptation. Pendant les premières heures de ponte, elles ont été très sélectives et refusèrent, ou ne pondirent que quelques oeufs sur avoine, mais acceptèrent volontiers le blé. La discrimination s'est poursuivie tant que les femelles ont eu accès au blé en même temps qu'à l'avoine. Cependant, quand les femelles ont été privées de blé pendant plusieures heures, l'acceptation de l'avoine a augmenté. Cet accroissement de l'acceptation a eu lieu à peu près au moment où les femelles sur blé pondaient leurs derniers oeufs.
    Notes: Abstract Responses of mated female Hessian flies were investigated by analysing the behaviour of individual flies in wheat and oats. The behavioural repertoire of such females included: flying, alighting on leaves, arching of the body so that the tip of the abdomen touched the leaf surface, antennation, movements of the tip of the abdomen across the leaf at right angles to leaf veins, sitting with the ovipositor straight but still extended, and sitting with the ovipositor telescoped into the body. After alighting, females on wheat showed a higher frequency of transitions from arching to antennation and a lower frequency of transitions from arching to abdomen straight than females on oats. During the first 5 min of observations, individuals released into arenas with wheat arched and antennated 2–3 times more frequently than females released into oats. Time allotted to behaviours also differed; during the first 5 min, females in wheat spent 50 percent more time arching, whereas females in oats spent 50 percent more time sitting. Females in wheat also stayed longer and laid 4 times more eggs than females in oats. Temporal changes in egglaying were monitored by quantifying hourly rates of egglaying in no-choice assays for several hours following mating at 9:00 am. During the first and second hours post-mating, egglaying occurred infrequently. However, during the third hour post-mating (11:00 am to noon) females on wheat laid 5 times more eggs than females on oats. Rates of egglaying decreased on wheat but increased on oats during the fourth hour, and then during the fifth hour, decreased on both wheat and oats. Changes in egglaying responses were also evident when behaviours of individual females were measured 1–3 h vs. 3–7 h post-mating. Females deprived of host plants and released into wheat or oats later in the day showed higher frequencies of arching and antennation and laid more eggs before leaving the arena.
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  • 2
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    Entomologia experimentalis et applicata 93 (1999), S. 227-230 
    ISSN: 1570-7458
    Keywords: Rhopalosiphum padi ; cereal aphids ; wheat ; induced responses ; feeding site
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 3
    ISSN: 1570-7458
    Keywords: Coccinella septempunctata ; Coccinellidae ; wheat ; egg laying ; larva ; adult ; vertical distribution ; Coccinella septempunctata ; Coccinellidae ; blé ; ponte ; larve ; adulte ; répartition spatiale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary At the beginning of spring, post-hibernating adults of Coccinella septempunctata L. (Col., Coccinellidae), larvae and nymphs are found on the lower part of wheat plants. In June, adults born in the field as well as their progeny are dispersed all over the plant and a significant proportion of them is found on the apical parts of plants. Most of the egg clutches are layed on soil lumps, stones and small wild plants which represent preferential sites. Variations in coccinellid distribution may be influenced by climatic conditions, especially the temperature, by the thermophilic nature of this species and by the repartition of the three main aphid species on the plants. These results are relevant for the selection of a sampling methods.
    Notes: Résumé Au début du printemps les adultes de Coccinella septempunctata L. (Col., Coccinellidae) issus des sites d'hivernation, les larves et les nymphes qui en proviennent, fréquentent le sol et les parties basses du blé. En juin, les adultes nés dans le champ et leur descendance sont dispersés sur toute la hauteur des talles bien qu'une fraction non négligeable de leur population se rencontre à l'extrémité supérieure. La plupart des pontes sont déposées sous les mottes de terre, les pierres et les petites adventices qui constituent des sites privilégiés. Ces variations de la distribution de cette coccinelle peuvent être mises en relation avec le climat, en particulier la température, avec la thermophilie de cette espèce et avec la répartition sur les différentes parties des talles des 3 espèces de puceron qui se succèdent au cours de la saison. Ces observations sont importantes à considérer lors du choix ou de la mise au point d'une méthode d'échantillonnage.
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  • 4
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    Entomologia experimentalis et applicata 92 (1999), S. 157-164 
    ISSN: 1570-7458
    Keywords: plant resistance ; antibiosis ; tolerance ; antixenosis ; Russian wheat aphid ; wheat ; Homoptera ; Aphididae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Russian wheat aphid, Diuraphis noxia (Mordvilko), is one of the most important aphid pests of wheat, Triticum aestivum L., worldwide. Among the various pest management options, plant resistance is an economical management tactic to control D. noxia in cereal crops such as wheat. Researchers have identified D. noxia resistant germplasm and it has been incorporated into wheat. This study compared D. noxia resistance between the ‘Betta’ wheat isolines Betta-Dn1, Betta-Dn2, and Betta-Dn5 and their corresponding donor gene plant introduction (PI) lines PI 137739 (Dn1), PI 262660 (Dn2), and PI 294994 (Dn5). Although the Betta isolines and PI lines showed D. noxia resistance when compared with Betta wheat, the degree of resistance in the isolines to D. noxia was different from their corresponding PI donors. Aphid number, aphid fecundity, and biomass per aphid were not different between Betta-Dn1 and PI 137739 or Betta-Dn2 and PI 262660; however, the same parameters were significantly lower on PI 294994 compared with Betta-Dn5. This indicated that aphid resistance in PI 137739 and PI 262660 was probably governed by a single dominant gene, while the resistance in PI 294994 was controlled by more than one gene. Additionally, plant biomass reduction was aphid density dependent, which suggested that use of appropriate aphid infestation level is important when using plant biomass reduction as an indicator of resistance. Plant resistance categorization showed that there was no detectable difference in antixenosis among the seven lines evaluated. However, the higher aphid fecundity observed on PI 262660 compared with PI 137739 and PI 294994, in addition to no significant differences among the three PIs in plant biomass reduction, suggested PI 262660 was a tolerant line, while PI 137739 and PI 294994 were antibiotic lines. Plant tolerance could not be elucidated among the three Betta isolines using aphid fecundity and plant biomass reduction as indicators.
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  • 5
    ISSN: 1570-7458
    Keywords: sieve element ; salivation ; aphid ; plant resistance ; wheat ; Sitobion fragariae ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Extended sieve element salivation (E1 waveform in the electrical penetration graph) is a characteristic activity during early sieve element punctures, particularly in resistant plants. In order to explore a chemically-mediated mechanism of resistance associated with sieve element salivation, we compared the pattern of feeding behaviour of the aphid, Sitobion fragariae (Walker), on two cultivars of the wheat Triticum aestivum L., with different concentrations of hydroxamic acids (Hx). During 24 h of electronic monitoring, aphids dedicated over 50% of the total time to phloem ingestion from the sieve elements. Total time allocated to E1 in the experiment, time to first E1 within the experiment, time allocated to E1 before a sustained phloem ingestion (E2) and the contribution of sieve element salivation to the phloem phase (E1/[E1+E2]) were significantly higher in the high-Hx cultivar. The increased salivation in plants with higher contents of Hx suggests the existence, at least in this system, of a chemically-mediated sieve element constraint.
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  • 6
    ISSN: 1572-9397
    Keywords: evolutionary algorithms ; genetic algorithms ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This paper shows how evolutionary algorithms can be described in a concise, yet comprehensive and accurate way. A classification scheme is introduced and presented in a tabular form called TEA (Table of Evolutionary Algorithms). It distinguishes between different classes of evolutionary algorithms (e.g., genetic algorithms, ant systems) by enumerating the fundamental ingredients of each of these algorithms. At the end, possible uses of the TEA are illustrated on classical evolutionary algorithms.
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  • 7
    Electronic Resource
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    Plant molecular biology reporter 17 (1999), S. 323-331 
    ISSN: 1572-9818
    Keywords: Agrobacterium ; modular vector ; transformation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wheat (cv Chinese Spring) tissues were transformed using Agrobacterium tumefasciens and a new plasmid modular vector, pMVTBP. We constructed pMVTBP with unique restriction sites connecting (1) the CaMV 35S promoter, (2) a Kozak sequence, (3) the FLAG epitope, (4) the (His)6 epitope, (5) a coding region (for wheat TATA Binding Protein, wTBP) and (6) the CaMV 35S 3′UTR. This vector thus allows easy exchange of different regulatory or coding sequences. Explants of either germinating mature seeds, or immature embryos, were induced to callus for up to two weeks, treated with virulence-induced bacteria for one hour, then regenerated into plantlets. Transient expression of a GUS reporter gene, assayed at about one week, occurred in 10–12% of calluses. Expression of the FLAG-tagged wTBP was also detected, by immunostaining. Stable expression, by selective growth on geneticin, and by GUS expression at about six weeks, occurred in 1–2% of calluses, quite comparable to that achieved by other methods.
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  • 8
    ISSN: 1573-0867
    Keywords: Phosphorus ; lupin ; chickpea ; wheat ; nodulation ; dry matter production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A glasshouse experiment was conducted to examine the comparative growth and P uptake response following P fertilizer application in lupins (Lupinus angustifolius L. cv. Chittick) and chickpeas (Cicer arietinum cv. Tyson) compared to wheat (Triticum aestivum cv. Sunstar). Measurements of dry matter, phosphorus uptake and nodule numbers were made at 50 and 100 days after sowing. At the 50 day harvest, the two legume crops produced less dry matter and accumulated less plant P than wheat but no such species interactions were present at the 100 day harvest. Chickpeas showed strong positive responses in nodule numbers with increasing rates of P fertilizer while such effects were less and more variable with lupins.
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  • 9
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    Nutrient cycling in agroecosystems 20 (1989), S. 27-32 
    ISSN: 1573-0867
    Keywords: Cropping system ; phosphorus ; rice ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A long term field experiment was conducted on a sandy loam soil from 1983 to 1987 to determine how to best apply phosphorus fertilizer in a rice-wheat cropping system. The treatments included 9 combinations of phosphorus application either to both rice and wheat or to rice or wheat alone. Direct application of phosphorus at 13 kg/ha to both the crops resulted in significantly higher total productivity of the rice-wheat cropping system as compared with 26 kg P/ha applied either to rice or wheat alone. Phosphorus at 13 kg/ha for rice and 26 kg/ha for wheat was as efficient as 13 kg P/ha for rice and 13 kg P/ha for wheat. The higher rate of P (26 kg/ha) applied to both rice and wheat resulted a decline in the total productivity. The residual effects of phosphorus applied to either rice or wheat were significant to the succeeding crop but was inferior to its direct application. Phosphorus increased the leaf area index, chlorophyll content of leaves, and interception of more photosynthetically active radiation (PAR) which resulted in increased grain yield of rice and wheat. Phosphorus status of the surface soil declined markedly, in the absence of P application from 15.4 to 6.4 kg P/ha. Phosphorus applied at 26 kg P/ha to both the crops resulted a build up of the available P status of soil. Phosphorus application at 13 kg/ha to both rice and wheat maintained the phosphorus status of the soil at original level.
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  • 10
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    Nutrient cycling in agroecosystems 20 (1989), S. 59-66 
    ISSN: 1573-0867
    Keywords: Ammonia volatilization ; nitrogen leaching ; denitrification ; time of N application ; wheat ; Triticum aestivum ; Triticale ; irrigation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Grain yield, nitrogen (N) assimilation, ammonia (NH3) volatilization, denitrification and fertilizer N distribution were examined in three commercially grown cereal crops; two were sown into conventionally tilled fields, while the third was direct drilled into an untilled field. The crops were top dressed with urea at establishment, tillering or ear initiation. Crop yield and N assimilation were measured in 16 m by 2.5 m plots receiving 0, 35, 70, 105, 140 or 175 kg N ha−1. A mass balance micrometeorological technique was used to measure NH3 volatilization, and other fertilizer N transformations and transfers were studied using15N labelled urea in microplots. On the conventionally tilled sites application of urea increased the grain yield of wheat from 3.9 to 5.5 t ha−1, when averaged over the five application rates, three application times and two sites. There were no site or application time effects. However, on the direct drilled site, time of application had a significant effect on grain yield. When urea was applied at establishment, grain yield was not significantly increased and the mean yield (2.81 t ha−1) was less than that obtained from treatments fertilized at tillering or ear initiation (4.09 and 4.0 t ha−1, respectively). Much of the variation in grain yield at the no-till site could be ascribed to differences in NH3 volatilization. At the no-till site, NH3 losses were equivalent to 24, 12 and 1% of the N applied at establishment, tillering and ear initiation, respectively. Negligible volatilization of NH3 occurred at the other sites. The surface soil at the no-till site had the highest urease activity and the soil was covered with alkaline ash resulting from stubble burning. Plant recovery of fertilizer N did not vary with application time on conventionally tilled sites (mean 62%). However, plant recovery of15N applied to the no-till site at establishment (35% of the applied N) was significantly less than that from plots where the application was delayed (45% at tillering and 55% at ear initiation, respectively). Leaching of N to below 300 mm depth was minimal (0 to 5% of the applied N). The calculated denitrification losses ranged from 1% to 14% of the applied N. The results show that the relative importance of NH3 volatilization, leaching and denitrification varied with site and fertilization time. The importance of the various N loss mechanisms needs to be taken into account when N fertilization strategies are being developed.
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  • 11
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    Nutrient cycling in agroecosystems 53 (1999), S. 139-146 
    ISSN: 1573-0867
    Keywords: critical levels of Mn ; soil extractants ; Mn-deficiency ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seven chemical extractants were tested for their relative performance to predict the response of wheat to Mn application in coarse textured alkaline soils of semi-arid region. Five out of the seven extractants were found to be promising for the estimation of critical level of available Mn in these soils, as the amount of Mn extracted by these extractants was positively and significantly correlated with relative grain yield as well as Mn uptake. The critical deficiency level of soil available Mn with 0.005 M DTPA, 0.02% hydroquinone, 0.02 N sodium pyrophosphate, 0.1N H3PO4 and 0.05N HCl+0.025N H2SO4 was 3.1, 13.8, 23.5, 5.3 and 17.8 mg kg-1 soil, respectively. The 1N ammonium acetate and 0.01M CaCl2 were found to be unsuitable extractants for these soils. Further field trials at eight locations with varying levels of Mn deficiency showed successive increase in the grain yield of wheat with foliar Mn application, emphasizing the need for Mn fertilization when wheat is grown on Mn deficient soils.
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  • 12
    ISSN: 1572-9699
    Keywords: Sporobolomyces phylladus ; yeasts ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Six strains of an undescribed, leaf-borne species of the genus Sporobolomyces were recovered. A description of the new species, Sporobolomyces phylladus, is given.
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  • 13
    ISSN: 1572-9699
    Keywords: Zygozyma suomiensis ; Lipomycetaceae ; yeasts ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new species of the genus Zygozyma, Z. suomiensis, is described, based on the study of a single strain, derived from a bovine skin lesion.
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  • 14
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    Antonie van Leeuwenhoek 56 (1989), S. 349-356 
    ISSN: 1572-9699
    Keywords: coenzyme Q ; ubiquinones ; black yeasts ; Exophiala ; Aureobasidium ; Hormonema ; yeast-like fungi ; ascomycetes ; taxonomy ; chemotaxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 72 Strains belonging to 44 species of ascomycetous black yeasts were analyzed for their coenzyme Q systems. Prevalent were Q-10 and dihydrogenated Q-10 systems. Members of the Dothidealean suborder Dothideineae have Q-10 (H2), while those belonging to the suborder Pseudosphaeriineae mostly have Q-10. The anamorph genus Exophiala Carmichael and the teleomorph genus Capronia Sacc. seem to be heterogenous.
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  • 15
    ISSN: 1572-9761
    Keywords: Coccinellidae ; Aphididae ; wheat ; spatial scale ; species diversity ; numerical response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of prey density, within-field vegetation, and the composition and patchiness of the surrounding landscape on the abundance of insect predators of cereal aphids was studied in wheat fields in eastern South Dakota, USA. Cereal aphids, aphid predators, and within-field vegetation were sampled in 104 fields over a three year period (1988–1990). The composition and patchiness of the landscape surrounding each field were determined from high altitude aerial photographs. Five landscape variables, aggregated at three spatial scales ranging from 2.6 km2 to 581 km2, were measured from aerial photographs. Regression models incorporating within-field and landscape variables accounted for 27–49% of the variance in aphid predator abundance in wheat fields. Aphid predator species richness and species diversity were also related to within-field and landscape variables. Some predators were strongly influenced by variability in the composition and patchiness of the landscape surrounding a field at a particular spatial scale while others responded to variability at all scales. Overall, predator abundance, species richness, and species diversity increased with increasing vegetational diversity in wheat fields and with increasing amounts of non-cultivated lands and increasing patchiness in the surrounding landscape.
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  • 16
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    Integrated pest management reviews 4 (1999), S. 127-143 
    ISSN: 1572-9745
    Keywords: wheat ; stored-grain ; integrated pest management ; aeration ; biological control ; grain sampling ; insect monitoring ; modeling ; area-wide IPM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Management of stored-grain insect pests by farmers or elevator managers should be based upon a knowledge of the grain storage environment and the ecology of insect pests. Grain storage facilities and practices, geographical location, government policies, and marketing demands for grain quality are discussed as factors influencing stored-grain insect pest management decisions in the United States. Typical practices include a small number of grain samples designed to provide grain quality information for segregation, blending and marketing. This low sampling rate results in subjective evaluation and inconsistent penalties for insect-related quality factors. Information on the efficacy of insect pest management practices in the United States, mainly for farm-stored wheat, is discussed, and stored-grain integrated pest management (IPM) is compared to field-crop IPM. The transition from traditional stored-grain insect pest control to IPM will require greater emphasis on sampling to estimate insect densities, the development of sound economic thresholds and decision-making strategies, more selective use of pesticides, and greater use of nonchemical methods such as aeration. New developments in insect monitoring, predictive computer models, grain cooling by aeration, biological control, and fumigation are reviewed, their potential for improving insect pest management is discussed, and future research needs are examined.
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  • 17
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    Journal of the history of biology 32 (1999), S. 509-555 
    ISSN: 1573-0387
    Keywords: Louis Agassiz ; Spencer Baird ; Charles Girard ; reputation ; taxonomy ; ichthyology ; Museum of Comparative Zoology ; Smithsonian Institution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , History
    Notes: Abstract The reputations of scientists among their contemporaries depend not only on accomplishment, but also on interactions affected by influence and personality. The historical lore of most fields of scientific endeavor preserve these reputations, often through the identification of founders, innovators, and prolific workers whose contributions are considered fundamental to progress in the field. Historians frequently rely on the historical lore of scientists to guide their studies of the development of ideas, exhibiting justifiable caution in reassessing reputations in the light of current knowledge. However, the transmission of historical lore can obscure the relative importance of accomplishment, influence and personality in shaping contemporary reputations, leaving the historian to either accept reputations at face value or attempt to reconstruct the context in which they were created. The science of taxonomy, because of its rules of priority, leaves a relatively accurate record of historical accomplishment through the persistence of taxa in catalogues and faunal guides. These records allow the modern historian an unbiased means to assess the relative accomplishments of historical figures and therefore a means to critically reassess reputations independent of personality and influence. In the historical lore of North American ichthyology, Louis Agassiz at Harvard and Spencer Baird at the Smithsonian emerge as central figures in the early development of the field during the mid-1800s, contributing not only through the quality and quantity of their science, but also through their roles as institutional leaders and mentors to workers who followed. Charles Girard, originally a student of Agassiz's and later a coworker with Baird, receives little notice in the history of ichthyology, and his reputation is that of a minor player in the initial description of the North American fish fauna, and one whose work appears to have been flawed or even careless when compared to his contemporaries. However, a review of both contemporary and modern taxonomic works reveals that Girard's productivity far exceeded that of either Agassiz or Baird. Furthermore, an examination of the tendency of Girard and his contemporaries to introduce synonymous names into the literature, which might reflect careless or uncritical work, suggests that Girard was among the more accomplished workers of hisera, including Agassiz and Baird. Girard's low ranking in the folklore of North American ichthyology, therefore, can not be attributed to discernible shortcomings in his scientific work, but rather to a public and private campaign of criticism waged by Agassiz after Girard's departure from Harvard. While Agassiz's dispute with Girard stemmed from their personal interactions, he expressed them as criticisms of Girard's work, and thus helped shape Girard's scientific reputation as it has been transmitted through the lore of ichthyology. This case study reveals how scientific reputation may not always rest on accomplishment, but can be influenced by personal interactions obscured by time but nonetheless important to history.
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  • 18
    ISSN: 1573-5028
    Keywords: chloroplast DNA ; cytochrome b-559 ; photosystem II ; psbL ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The N-terminal amino acid sequence of a 3.2 kDa photosystem II polypeptide is shown to be identical to that of a polypeptide encoded by an open reading frame of 38 codons (orf38) in wheat chloroplast DNA. Orf38 is located just downstream of the psbE and psbF genes for the polypeptides of cytochrome b-559. Analysis of the transcription of this region of chloroplast DNA shows that psbE, psbF and orf38 are co-transcribed to give a 1.1 kb polycistronic transcript which also contains another open reading frame of 40 codons. The orf38 and orf40 products are hydrophobic polypeptides which are both predicted to span the thylakoid membrane once. Orf38 and orf40 are highly conserved, and map to similar locations adjacent to psbE and psbF, in all organisms from which this region of DNA has been sequenced. We propose that orf38 is named psbL.
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  • 19
    ISSN: 1573-5028
    Keywords: ADP-glucose pyrophosphorylase ; cDNAs ; gene organisation ; polypeptides ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA clone (WL : AGA.1) encoding wheat leaf ADP-glucose pyrophosphorylase has been isolated from a λgt11 expression library, by immunological screening with anti-spinach leaf ADP-glucose pyrophosphorylase serum. The WL : AGA.1 cDNA is 948 bp long and contains approximately 55% of the complete wheat leaf ADP-glucose pyrophosphorylase mRNA sequence, estimated from Northern blot experiments. A wheat endosperm cDNA library was subsequently constructed in λgt11 and six clones hybridising to the cDNA insert of clone WL : AGA.1 were isolated. The longest of these wheat endosperm ADP-glucose pyrophosphorylase cDNAs, clone WE : AGA.7, is nearly full-length (1798 bp), indicated by Northern blot analysis of wheat endosperm mRNA and nucleotide sequence analysis. Southern hybridisation analysis and restriction enzyme mapping indicated that the wheat leaf and wheat endosperm ADP-glucose pyrophosphorylase cDNAs and genes are members of two distinct gene families. In addition, restriction enzyme mapping revealed polymorphism in the wheat endosperm ADP-glucose pyrophosphorylase cDNAs, indicating the existence of at least two wheat endosperm ADP-glucose pyrophosphorylase gene sub-families. Subsequent nucleotide sequence analysis indicates that there is approximately 55% identity between wheat leaf and wheat endosperm ADP-glucose pyrophosphorylase cDNAs. In contrast, members of each sub-family of endosperm cDNA, represented by clones WE : AGA.3 and WE : AGA.7, are 96% identical.
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  • 20
    ISSN: 1573-5028
    Keywords: aleurone ; barley ; protoplasts ; transient expression ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Methods have been developed for the isolation of aleurone protoplasts from developing caryopses of Hordeum vulgare and Triticum aestivum in order to study transient expression of introduced genes. Chimaeric gene constructs were introduced into aleurone protoplasts by polyethylene glycol (PEG). Transient expression directed by the 35S promoter from cauliflower mosaic virus (CaMV) of the reporter gene encoding chloramphenicol acetyl transferase (CAT) was detected in aleurone protoplasts from developing barley and wheat grains. Using a similar construct, CAT activity increased when the alcohol dehydrogenase intron 1 fragment from maize was ligated between the 35S promoter and the CAT coding region. The demonstration of transient expression in protoplasts from developing aleurone layers indicates that they may be useful for investigating tissue and developmental control of genes coding for cereal seed proteins.
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  • 21
    ISSN: 1573-5028
    Keywords: F1F0 ATPase ; chloroplast coupling factor ; mitochondrial gene ; wheat
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  • 22
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    Mycoscience 40 (1999), S. 73-80 
    ISSN: 1618-2545
    Keywords: Mycena auricoma ; Mycena sect.Radiatae ; Mycena spinosissima ; taxonomy
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    Topics: Biology
    Notes: Abstract Two lignicolous species ofMycena (Agaricales, Basidiomycetes) are described and illustrated from eastern, Japan:Mycena auricoma sp. nov., forming ephemeral coprinoid basidiomata and belonging to sectionRadiatae, was found on a dead fallen twig ofQuercus serrata. It appears to close to a Malaysian species,“Trogia” crinipelliformis. Mycena spinosissima in sectionSacchariferae, new to Japan, was collected from dead bark ofAphananthe aspera, a dead fallen inflorescence ofCryptomeria japonica, and a dead fallen twig ofQuercus serrata.
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  • 23
    ISSN: 1618-2545
    Keywords: cellular slime molds ; dictyostelids ; macrocyst ; mating system ; taxonomy
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    Notes: Abstract Macrocyst formation in the sexual cycle was found in three dictyostelid species:Dictyostelium monochasioides, Polysphondylium candidum, andP. pseudo-candidum. Mating tests suggested thatD. monochasioides andP. pseudocandidum were heterothallic andP. candidum was homothallic. The primary walls of macrocysts had partially or fully degenerated, while the inner walls, believed to be tertiary walls, showed an undulate structure.
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  • 24
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    Mycoscience 40 (1999), S. 189-191 
    ISSN: 1618-2545
    Keywords: bamboo fungus ; hyperparasitism ; hyphomycetes ; mycoparasites ; taxonomy
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    Topics: Biology
    Notes: Abstract Cryptophiale sphaerospora sp. nov. is described and illustrated based on a single collection attached to a synnematous fungus,Janetia synnematosa, from a dead bamboo culm. It differs from other species ofCryptophiala in having spherical to subspherical conidia and a cerebroid layer of phialides. The overall morohology of this species is smaller than that of previously described species.
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  • 25
    ISSN: 1615-6110
    Keywords: Cyanophyta ; Cyanophyceae ; Nostocales ; Nostocaceae ; Aphanizomenon ; Anabaena ; Morphology ; morphometry ; variation ; trichome structure ; taxonomy
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    Topics: Biology
    Notes: Abstract The dimension and variation range of terminal and intercalary cells, heterocysts, and akinetes of fourAphanizomenon taxa occurring in Czechoslovakia were studied. Statistical and graphical procedures were used for evaluation. With regard toA. flos-aquae, the results support the distinction of two varieties (var.flos-aquae and var.klebahnii). In the samples determined asA. gracile two clearly distinguishable morphological types could be found; one of them is recognized as a new species:A. flexuosum. Its diacritical features are established and problems of the intrageneric taxonomy ofAphanizomenon and its demarcation from the genusAnabaena are discussed.
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  • 26
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    Plant systematics and evolution 168 (1989), S. 123-141 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Liliiflorae ; Liliales ; Dioscoreales ; Asparagales ; Cladistics ; relationships ; taxonomy
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    Topics: Biology
    Notes: Abstract Comparisons between previous intuitive or phenetic classifications of the netveinedLiliiflorae was used to determine a suitable group of taxa for cladistic analyses. The resultant 48 genera and generic groupings comprising 19 families from within theAsparagales, Liliales andDioscoreales were then analysed. The cladistics largely supported previous treatments, with theLiliales, Dioscoreales andAsparagales all monophyletic.
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  • 27
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    Plant systematics and evolution 163 (1989), S. 93-105 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Leguminosae (Fabaceae) ; Caesalpinioideae (Caesalpiniaceae) ; Cassia ; Chamaecrista ; Senna ; Stigma morphology ; taxonomy ; floral ecology
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    Notes: Abstract Two stigma forms occur inChamaecrista andSenna, but only one inCassia. In the common chambered form, a stigma pore is positioned on the reflexed style tip and is the entrance to a tapering chamber. The pore rim is fringed by hairs which vary in number, size, distribution and shape. In the alternative form the stigma is situated at the apex of the curved style and is crateriform. The crater rim is fringed by hairs of variable number and shape. The stigmatic hairs are predominantly unicellular and cutinized. Stigma and hair differences aid in the taxonomy of the genera. Their functions in pollination biology are discussed.
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  • 28
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    Plant systematics and evolution 163 (1989), S. 153-163 
    ISSN: 1615-6110
    Keywords: Algae ; Dinophyceae ; Gymnodiniales ; Gymnodiniaceae ; Symbiodinium ; S. microadriaticum subsp.condylactis ; subsp. nov. ; DNA ; hybridization ; karyotypes ; phenotypes ; symbiosis ; taxonomy ; zooxanthellae
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    Notes: Abstract Relationship among symbiotic dinoflagellates of the genusSymbiodinium derived from seven different host species has been studied by means of DNA/DNA hybridization. DNA homologies range from about 70 to 30%D. Highest homology is regarded as subspecific level. Based on the characteristics of DNA and phenotypes,Symbiodinium microadriaticum subsp.microadriaticum is separated fromSymbiodinium microadriaticum subsp.condylactis. Lowest homology occurs at the methodical background, and is similar to that obtained with DNA of algae belonging to different classes. The data are in excellent agreement with DNA base composition, karyotypes, and morpohological as well as biochemical markers, emphasizing speciation among these gymnodinioid zooxanthellae.
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  • 29
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    Plant systematics and evolution 163 (1989), S. 165-176 
    ISSN: 1615-6110
    Keywords: Algae ; Chlorarachniophyta ; Cryptochlora perforans ; Biology ; taxonomy ; phylogeny ; inter-specific relationships
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    Topics: Biology
    Notes: Abstract The life cycle ofCryptochlora perforans is described under culture conditions, including the following stages: Naked and walled amoebae, cysts, coccoid, palmelloid and flagellate stages. Phagotrophy of living diatoms, movement and reproduction are documented. Amoebae ofCryptochlora are chemotactically attracted by damaged algal filaments, perforate and penetrate such filaments, and subsequently engulf part of their contents. A comparison is made with a culture ofChlorarachnion reptans Geitler, according to earlier and own observations. Chloroplast structure as well as zoospore morphology confirm close affinities betweenCryptochlora andChlorarachnion. Generic characters as well as possible phylogenetic affinities with amoeboidXanthophyta andProtozoa are discussed.
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  • 30
    ISSN: 1615-6110
    Keywords: Bryophyta ; Mitochondria ; nad5 gene ; group I intron ; molecular phylogeny ; taxonomy
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    Topics: Biology
    Notes: Abstract In contrast to animals, the slowly evolving mitochondrial nucleotide sequences of plants appear well suited to investigate phylogenetic relations between old taxonomic groups. Analysis ofnad5 gene sequences in 47 bryophytes, the living representatives of very early land plants, confirm this assessment. Statistically reliable phylogenetic trees are obtained with different mathematical approaches. A group I intron sequence conserved in thenad5 gene of all 30 mosses and 15 liverworts investigated supports a sister group relationship of the two classes. The intron sequence adds phylogenetic information for fine resolution on top of the conserved exon sequences down to the level of classically defined orders or families, respectively. This intron is not present in the hornwortsAnthoceros husnotii andA. punctatus. The results allow statements on diverging taxonomic interpretations and support the monophyly of the liverworts, mosses, Jungermanniidae, Marchantiidae and Bryidae, and allow recognition of subclasses like Hypnanae and Dicrananae. Among the mosses, the derived orders (subclass Bryidae) are confidently set apart from the Sphagnales, Andreaeales, Polytrichales and Tetraphidales with Buxbaumiales occupying a mediating position. Among the liverworts, full support is found for the classic separation of simple (jungermanniid) and complex thalloid (marchantiid) species with a strikingly low mitochondrial sequence divergence among the latter.
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    Journal of applied phycology 11 (1999), S. 411-419 
    ISSN: 1573-5176
    Keywords: Bangiales ; Porphyra life history ; culture ; conchocelis ; conchosporangia ; spores ; neutral conchospores morphology ; taxonomy
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    Notes: Abstract Since 1992, as part of a study to circumscribe the genus Porphyra in New Zealand, an extensive culture programme has been developed at the Museum of New Zealand Te Papa Tongarewa. This collection currently houses more than 800 cultures and 150strains. We currently recognise at least 20 species in New Zealand, most of which are undescribed. Close observation of reproduction and the development of conchocelis-phase filaments grown in the laboratory, under controlled conditions of temperature, irradiance and photoperiod, has enabled the recognition of characters that can assist in species separation. The comparative taxonomic value of a range of such characters is discussed, including reporting a novel reproductive mode.
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  • 32
    ISSN: 1573-5176
    Keywords: distribution ; harvesting ; Porphyra ; recruitment ; seasonality ; South Africa ; taxonomy
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    Notes: Abstract Although Porphyra is commercially farmed in many countries, in South Africa only small harvests of wild populations for sale as nori have been carried out. The discovery that Porphyra improves growth of South African abalone (Haliotis midae) farmed inland-based tanks has led to increased pressure to harvest wild populations. This paper reports on a survey of the distribution and seasonality of Porphyra in the southern Western Cape. Porphyrawas present at all sites surveyed, and showed considerable temporal variation. A significant amount of the Porphyra present is in reserves and therefore protected from harvesting. Close rexamination of one site revealed seasonal populations of Porphyra that occupied different niches dependent on season. Recruitment peaked in spring and autumn, leading to dense summer and winter populations. Summer populations generally grew lower in the eulittoral than winter populations. No pattern in the mortality of larger thalli wasde tected, though sporeling mortality was high following recruitment peaks. Although it seems that most sites in the southern Western Cape are suitable for harvesting, the taxonomy of the genus in the region urgently needs revision if populations are to be appropriately managed.
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  • 33
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    Mycoscience 40 (1999), S. 165-183 
    ISSN: 1618-2545
    Keywords: freshwater fungi ; Halosphaeriaceae ; taxonomy ; tropics
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    Notes: Abstract The generic concepts inAniptodera, Halosarpheia, Nais andPhaeonectriella are discussed and those species occurring in freshwater are described, some with illustrations. Five new species:Aniptodera lignicola, A. mauritaniensis, A. megalospora, A. palmicola, Phaeonectriella appendiculata are also described. A key to the freshwater species in the above genera and a synoptic diagram of their ascospores are provided.
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  • 34
    ISSN: 1618-2545
    Keywords: Ascomycota ; marine fungi ; new species ; taxonomy
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    Notes: Abstract A new speciesDactylospora mangrovei is described and illustrated and compared withD. haliotrepha andD. canariensis, all marine inhabiting species.Dactylospora haliotrepha andD. mangrovei are tropical/sub-tropical mangrove species collected in Hong Kong, Malaysia, Taiwan and Thailand, whileD. canariensis was described from temperate waters. A map of the geographical distribution of the three marineDactylospora species is presented.
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    Mycoscience 40 (1999), S. 185-188 
    ISSN: 1618-2545
    Keywords: Amphisphaeria ; ascomycetes ; bamboo fungi ; taxonomy
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    Notes: Abstract A new species ofArecophila and a species previously known asAmphisphaeria coronata are described and illustrated from dead culms of bamboo.Arecophila bambusae sp. nov. is distinct in the genus in having ellipsoidal ascospores with slightly round ends, and asci with a narrow subapical ring.Arecophila coronata comb. nov. has asci with a wedgeshaped apical ring and weakly striated ascospores enclosed in wide mucilaginous sheath.
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    Molecular breeding 5 (1999), S. 561-568 
    ISSN: 1572-9788
    Keywords: wheat ; milling yield ; QTL mapping ; RFLP ; microsatellite
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A partial genetic linkage map constructed using 150 single seed descent (SSD) lines generated from a cross between the hexaploid wheat varieties ‘Schomburgk’ and ‘Yarralinka’ was used to identify loci controlling milling yield. Milling yield data were obtained using seed collected from field trials conducted at different sites over two seasons. The estimated broad-sense heritability of milling yield in this population was calculated as 0.48. In the preliminary analysis, two regions were identified on chromosomes 3A and 7D, which were significantly associated with milling yield and accounted for 22% and 19% of the genetic variation, respectively. Bulked segregant analysis in combination with AFLP identified other markers linked to these loci, as well as an additional region on chromosome 5A, which accounted for 19% of the genetic variation. The applicability of these markers as selection tools for breeding purposes is discussed.
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  • 37
    ISSN: 1572-9788
    Keywords: insect resistance ; aphids ; GNA ; lectins ; transgenic plants ; wheat
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Transgenic wheat plants containing the gene encoding snowdrop lectin (Galanthus nivalis agglutinin; GNA) under the control of constitutive and phloem-specific promoters were generated through the particle bombardment method. Thirty-two independently derived plants were subjected to molecular and biochemical analyses. Transgene integration varied from one to twelve estimated copies per haploid genome, and levels of GNA expression from 0 to ca. 0.2% of total soluble protein were observed in different transgenic plants. Seven transgenic plants were selected for further study. Progeny plants from these parental transformants were selected for transgene expression, and tested for enhanced resistance to the grain aphid (Sitobion avenae) by exposing the plants to nymphal insects under glasshouse conditions. Bioassay results show that transgenic wheat plants from lines expressing GNA at levels greater than ca. 0.04% of total soluble protein decrease the fecundity, but not the survival, of grain aphids. We propose that transgenic approaches using insecticidal genes such as gna in combination with integrated pest management present promising opportunities for the control of damaging wheat pests.
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  • 38
    ISSN: 1572-9788
    Keywords: wheat ; DNA markers ; yellow rust resistance ; Yr17
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The Yr17 gene, which is present in many European wheat cultivars, displays yellow rust resistance at the seedling stage. The gene introduced into chromosome 2A from Aegilops ventricosa was previously found to be closely linked (0.5 cM) to leaf and stem rust resistance genes Lr37 and Sr38, respectively. The objective of this study was to identify molecular markers linked to the Yr17 gene. We screened with RAPD primers, for polymorphism, the DNAs of cv. Thatcher and the leaf rust-resistant near-isogenic line (NIL) RL 6081 of cv. Thatcher carrying the Lr37 gene. Using a F2 progeny of the cross between VPM1 (resistant) and Thésée (susceptible), the RAPD marker OP-Y15580 was found to be closely linked to the Yr17 gene. We converted the OP- Y15580 RAPD marker into a sequence characterized amplified region (SCAR). This SCAR marker (SC-Y15) was linked at 0.8 ± 0.7 cM to the Yr17 resistance gene. We tested the SC-Y15 marker over a survey of 37 wheat cultivars in order to verify its consistency in different genetic backgrounds and to explain the resistance of some cultivars against yellow rust. Moreover, we showed that the Xpsr150-2Mv locus marker of Lr gene described by Bonhomme et al. [6] which possesses A. ventricosa introgression on the 2A chromosome was also closely linked to the Yr17 gene. Both the SCAR SC-Y15 and Xpsr150-2Mv markers should be used in breeding programmes in order to detect the cluster of the three genes Yr17, Lr37 and Sr38 in cross progenies.
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    Mathematical geology 21 (1989), S. 233-254 
    ISSN: 1573-8868
    Keywords: Compositional data ; locational data ; replicate data ; statistics ; taxonomy ; topography ; variance
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    Topics: Geosciences , Mathematics
    Notes: Abstract Diverse global and local measures of variability appear in the geological literature and, along with methods used to apply them, have been subject to some debate. Measures of variability for three data types—replicate, locational, and compositional—are considered; the source and nature of the variability determine the appropriate type of measure. To illustrate the effects of these measures and expose their inadequacy when improperly applied, the variability of a three-column data set is interpreted under three different suppositions. Geologists need to be aware of the confusion and misleading results that can develop from the use of variance as a measure of variability for locational or compositional data.
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    European journal of plant pathology 105 (1999), S. 629-641 
    ISSN: 1573-8469
    Keywords: wheat ; Triticum spp. ; Septoria tritici ; septoria tritici blotch of wheat Stagonospora nodorum ; stagonospora nodorum blotch of wheat
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 41
    ISSN: 1573-5036
    Keywords: alder ; Betulaceae ; birch ; in vitro clones ; cluster ; Frankia ; genetic divergence ; RFPs ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A study of restriction fragment polymorphisms of ribosomal DNA among seven actinorhizal species (Alnus spp.) and a non-actinorhizal species (Betula papyrifera Marsh.) of the Betulaceae was conducted, using a simple method for the extraction of high molecular weight restrictable nuclear DNA from leaf tissues of perennial angiosperms and nine restriction endonucleases. rDNA restriction fragments were variable within and among the species studied, and the variation noted was used to calculate the similarities and infer phenetic relationships among these members of the Betulaceae. The results confirmed the taxonomy of alder based on morphological characters, showing a clear clustering of the species ofAlnus sampled in each of the two different subgeneraAlnus andAlnobetula. Within each subgenus, the closely related taxa often classified as subspecies by their similar morphology and their ability to interhybridize, were similarly shown by restriction fragment polymorphisms to be more closely related to each other than to any other taxon. The analysis also suggested that some alder species may not be more divergent fromBetula papyrifera than from other alder species.
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    Plant and soil 120 (1989), S. 125-131 
    ISSN: 1573-5036
    Keywords: canola ; fallow ; N mineralization ; N immobilization ; organic matter ; rhizosphere ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A greenhouse experiment was conducted to determine the influence of cropping variables on nitrogen dynamics in a soil amended with green manure. Surface soil from various long-term spring wheat rotations was amended with15N-labelled legume green manure (Lathyrus tingitanus) and subsequently cropped (canola [Brassica napus] and spring wheat [Triticum aestivum]) or incubated without a crop for 56 days in a greenhouse. Nitrogen mineralization from both the indigenous soil N and from green manure was suppressed in cropped soil. Net N mineralization in the uncropped and cropped treatments averaged 73 and 43 mg kg−1, respectively. This difference was attributed, in part, to enhanced biological immobilization in the rhizosphere. Previous cropping practices also had significant effect on N mineralization, largely by their influence on indigenous organic matter quality. These observations suggest that short-term N mineralization is favored by fallowing soil after green manure application whereas N retention in organic matter is favored by immediate cropping.
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  • 43
    ISSN: 1573-5036
    Keywords: characterization ; deleterious rhizobacteria ; inhibitory bacteria ; pseudomonads ; toxin ; wheat
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A toxin produced by a deleterious rhizobacterial pseudomonad that inhibits both winter wheat (Triticum aestivum L.) root andEscherichia coli growth was characterized. The toxin was rapidly deactivated at pH 2 and 12 and by autoclaving (121°C, 15 minutes). Less toxin was destroyed as the temperature and time of exposure decreased, and at 40°C it was stable for at least 24 hours. The toxin was extremely polar and could not be extracted from culture filtrates with organic solvents. The compound eluted after the void volume from a Sephadex G-10 column indicating a molecular weight of less than 700. The toxin adsorbed to Dowex 50W strong cation exchange resin and eluted with 2M NH4OH. Numerous thin layer chromatography solvent systems were unsuccessful at purifying the toxin. The partially purified toxin inhibited several different microorganisms while the producing strains were resistant. The toxin appears unique to toxins produced by recognized plant pathogenic bacteria.
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    Journal of systems integration 9 (1999), S. 167-185 
    ISSN: 1573-8787
    Keywords: flexibility ; complexity ; systems approach ; taxonomy
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    Topics: Computer Science
    Notes: Abstract In this paper we present a taxonomy of manufacturing problems, labeled in a general sense as Design, Production, or Distribution problems. One or more basic systems concepts, such as complexity and adaptation, attach themselves to each such problems. By combining the hierarchical Design—Production—Distribution idea with system concepts, we establish the fact that there is, indeed, a significant systems component to most problems of modern manufacturing.
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    Plant systematics and evolution 164 (1989), S. 209-214 
    ISSN: 1615-6110
    Keywords: Algae ; Chrysophyceae (Synurophyceae) ; Mallomonadaceae ; Mallomonas alphaphora ; Electron microscopy ; phytoplankton ; scale-bearing flagellate ; taxonomy
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    Topics: Biology
    Notes: Abstract A new species ofMallomonas, M. alphaphora (Chrysophyceae), was found in freshwater ponds in the Perth region, Western Australia. It is distinguished from other species ofMallomonas by its very distinctive scale and bristle morphology and is placed in a new section,Alphaphorae, of the genusMallomonas.
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    Plant systematics and evolution 168 (1989), S. 109-121 
    ISSN: 1615-6110
    Keywords: Algae ; bacteria ; Mathematical phylogenetics ; biological relevance ; chemosystematics ; taxonomy ; graph theory ; algorithms ; Steiner problem ; parsimony ; dichotomy ; polytomy ; cytochrome c ; parallelism ; convergent evolution ; Wagner trees ; random distribution ; molecular clock ; identity matrix ; difference matrix ; homology ; analogy ; structural constraints ; comparability of sequences ; polyphyletic hypothesis
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    Topics: Biology
    Notes: Abstract Some basic problems of mathematical phylogenetics are discussed. While algorithms regularly depend on the principle of parsimony, some features of phylogenesis interfere with that principle. Nonrandomness of the distribution of mutations as well as the inconstancy of the molecular clock in time and within a given sequence can bias the calculated relationships of closely related taxa. True comparability of sequences is difficult to establish, since this requires defining of homology of positions and of functions of amino acids as well. Parallelism and convergence can give rise to errors in establishing homology. Furthermore, they are difficult to be integrated into a consistent mathematical approach. The asymmetry of identity versus difference matrices is discussed. Common mathematical procedures implicate the monophyletic hypothesis as well as strict dichotomy of the final tree. Real phylogeny demands to introduce more flexible approaches with respect to monophyly and dichotomy. Graph theory offers the possibility to prove the minimality of a given tree and to develop more flexible approaches. The consequences of altering the procedures to compare sequences can be tested. This is demonstrated by calculations with a set of 15 cytochromes from various taxa. To interpret a calculated tree requires a sharp distinction between taxonomy and phyletics. This is exemplified for the case of directly linked taxa. The limits of resolving uncertain relationships by accumulating more data are mentioned.
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    Plant systematics and evolution 214 (1999), S. 91-102 
    ISSN: 1615-6110
    Keywords: Asteraceae ; Lactuceae ; Aetheorhiza ; Launaea ; Reichardia ; Sonchus ; Pollen ; taxonomy ; harmomegathy
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    Topics: Biology
    Notes: Abstract The pollen morphology of the taxa belonging to the generaAetheorhiza Cass.,Launaea Cass.,Reichardia Roth andSonchus L. in the Iberian Peninsula has been studied with light and electron microscopy. The pollen is 3(-4)-zonocolporate and echinolophate (without polar lacunae, but in general with prelacunae), with equatorial ridges and 15–20 lacunae: 3–4 poral, 6–8 abporal and 6–8 paraporal. Small to medium size, P × E = 19−36 × 23–42 µm; sometimes two different sizes have been found. Exine 3–9 µm thick and ornamentation microreticulate and echinate. The results clearly show the relationships between genera.
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    Plant systematics and evolution 165 (1989), S. 55-69 
    ISSN: 1615-6110
    Keywords: Lichenes ; Umbilicariaceae ; Umbilicaria freyi spec. nova ; U. hirsuta ; U. grisea ; Thallus structure ; soredia ; parasoredia ; schizidia ; taxonomy ; distribution ; Lichenflora of Europe
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    Topics: Biology
    Notes: Abstract InUmbilicaria hirsuta andU. grisea the so-called soredia originate from structured plectenchyma of the upper thallus layer (thus contrasting with true soredia, which are pushed off from unstructured medullar plectenchyma), and, therefore, are termed parasoredia. Both species have been regarded to comprise (in western Europe) forms with relatively large thalli and a pale lower surface; rhizinomorphs may be present (with varying density) or absent; propagation is not by parasoredia, but by flattened diaspores (schizidia s. l.) These forms are united here and described as a separate species:U. freyi (syn.U. hirsuta var.pyrenaica Frey andU. grisea resp.murina f.subpapyria Frey). So far, the species is known to occur from the western Alps through C. France to the Pyrenees, C. Spain and Italy including Sardinia.
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  • 49
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    Plant systematics and evolution 164 (1989), S. 145-159 
    ISSN: 1615-6110
    Keywords: Algae ; Chlorophyta ; Trebouxia ; Pseudotrebouxia ; lichens ; Parmelia ; Hypogymnia ; Pyrenoid ; ultrastructure ; systematics ; taxonomy ; phycobionts ; freeze fixation ; freeze substitution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pyrenoid ultrastructure has been investigated from cultures of all 26 species ofTrebouxia with the aim of establishing pyrenoids as a taxonomic character. Different arrangements and forms of thylakoid lamellae within the pyrenoid matrix allow eight pyrenoid types to be distinguished. Each type is characteristic of a group of species. Thegigantea- andimpressa-type are similar, differing only in the form of the tubules: short, branched tubules mark thegigantea-type; ± long and straight invaginations theimpressa-type. Thearboricola-type is characterized by meandering pyrenoid membranes developing from lamellae parallel with each other in young autospores. Pyrenoids of thegelatinosa-type are traversed by thin parallel-arranged tubules. Few thylakoids with a curved profile are typical of theirregularis-type. Thecorticola-type is different from all others in having a distinct starch sheath closely connected with the pyrenoid matrix and no pyrenoglobuli being associated with the pyrenoid membranes. No true pyrenoids have been found inT. magna andT. erici. Within the chloroplast, they have indistinct areas with pyrenoglobuli, but without differentiated thylakoids. Pyrenoid morphology is stable in culture on different media as well as in phycobionts within lichen thalli. Comparing the pyrenoid of a lichenizedTrebouxia with that from cultured species, the identification of the phycobiont within the lichen thallus is possible, without the need of culturing the algae. This has been shown in species ofParmelia andHypogymnia. New aspects for the taxonomy and systematics ofTrebouxia are discussed.
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  • 50
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    Plant systematics and evolution 214 (1999), S. 161-186 
    ISSN: 1615-6110
    Keywords: Rubiaceae ; Rubioideae ; Angiosperms ; cladistics ; DNA sequences ; phylogeny ; rps16 intron ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phylogeny of the subfamilyRubioideae (Rubiaceae) was estimated from sequence variation in therps16 intron (cpDNA) in 143 ingroup and 5 outgroup taxa. The analysis largely confirms a recent one based onrbcL sequences, but branch support is often much stronger. Three of the traditional subfamilies are supported,Rubioideae, Cinchonoideae s. str., andIxoroideae s. l. while there is no support forAntirheoideae. TheRubioideae are the sister group of all otherRubiaceae and comprise the tribesAnthospermeae, Coccocypseleae, Cruckshanksieae, Coussareeae, Gaertnereae, Hedyotideae, Knoxieae, Morindeae, Ophiorrhizeae, Paederieae, Pauridiantheae, Perameae, Psychotrieae, Rubieae, Spermacoceae, Theligoneae, andUrophylleae. TheHamelieae andHillieae belong to theCinchonoideae. Rachicallis andSiemensia should be transferred from theHedyotideae to theCinchonoideae. ThePauridiantheae, Urophylleae, Ophiorrhizeae, andRaritebe form the basalmost subclade of theRubioideae. The second basalmost clade consists of the generaLasianthus andPerama. The third basalmost clade consists of the tribesCoussareeae, Coccocypseleae andCruckshanksieae, and the generaDeclieuxia andHindsia. The tribesKnoxieae, Anthospermeae, Argostemmateae, Paederieae, Theligoneae, Rubieae, Hedyotideae, andSpermacoceae are members of one clade. TheKnoxieae are monophyletic ifOtiophora, Otomeria, andPentas are included. The tribeAnthospermeae is supported as monophyletic, but its subtribes are not. ThePaederieae, together withTheligonum, form a paraphyletic grade basal to theRubieae. TheHedyotideae, includingSchismatoclada, form a grade at the base of theSpermacoceae. TheGaertnereae are monophyletic and distinct from thePsychotrieae. TheMorindeae are monophyletic and includeDamnacanthus andMitchella. Schradera is the sister group of theMorindeae. ThePsychotrieae are monophyletic when theGaertnereae, Lasianthus, andDeclieuxia are excluded. The recognition of a subtribeHydnophytineae leaves the rest of thePsychotrieae paraphyletic.Psychotria is paraphyletic with respect to all other genera of the tribe. Approximately 50 genera are here classified for the first time based on molecular data.
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  • 51
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    Plant systematics and evolution 219 (1999), S. 199-208 
    ISSN: 1615-6110
    Keywords: Brexioideae ; Brexia ; Ixerba ; Roussea ; Saxifragaceae s. l. ; 18S rDNA andrbcL sequence analysis ; molecular systematics ; phylogenetic analysis ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previous molecular phylogenetic analyses have demonstrated that Saxifragaceae sensu lato are polyphyletic, with component lineages scattered throughout the eudicots. As part of our effort to elucidate the relationships of members of Engler and Prantl's Saxifragaceae s. l., we undertook a molecular systematic study of subfamily Brexioideae, which comprises three genera:Brexia, Ixerba, andRoussea. Not all taxonomic treatments have concurred, however, in placing these genera together. To elucidate relationships among these three genera as well as their relationships to other angiosperms we constructed large data sets ofrbcL, 18S rDNA, andrbcL + 18S rDNA sequences. Our phylogenetic analyses indicate clearly that Brexioideae are polyphyletic.Brexia is part of a celastroid clade that also includesParnassia, Lepuropetalon, and Celastraceae.Ixerba appears as sister to a large eurosid I clade;Roussea appears as part of Asterales. Molecular data, therefore, indicate that Brexioideae are a polyphyletic assemblage and component genera should ultimately be incorporated into other groups. Our studies continue to demonstrate the polyphyly not only Saxifragaceae s. l., but also of its constituent subfamilies.
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  • 52
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    Plant molecular biology 39 (1999), S. 915-926 
    ISSN: 1573-5028
    Keywords: programmed cell death ; wheat ; endosperm ; ethylene ; nucleases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although maize endosperm undergoes programmed cell death during its development, it is not known whether this developmental feature is common to cereals or whether it arose inadvertently from the selection process that resulted in the enlarged endosperm of modern maize. Examination of wheat endosperm during its development revealed that this tissue undergoes a programmed cell death that shares features with the maize program but differs in some aspects of its execution. Cell death initiated and progressed stochastically in wheat endosperm in contrast to maize where cell death initiates within the upper central endosperm and expands outward. After a peak of ethylene production during early development, wheat endosperm DNA underwent internucleosomal fragmentation that was detectable from mid to late development. The developmental onset and progression of DNA degradation was regulated by the level of ethylene production and perception. These observations suggest that programmed cell death of the endosperm and regulation of this program by ethylene is not unique to maize but that differences in the execution of the program appear to exist among cereals.
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  • 53
    ISSN: 1573-5036
    Keywords: 2 ; 4-D ; germination ; growth ; salinity-tolerance ; seed treatment ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments were conducted under laboratory and greenhouse conditions to study the effect of 2,4-D on rooting and salinity tolerance of wheat. Seeds of one commercial wheat (Inqalab-91) and three salt-tolerant wheat lines (WL-41, WL-359, and WL-1073 developed through wide hybridization) were included in the study. Preliminary and short-term experiments were conducted to determine the level of 2,4-D (administered through seed soaking for 24.5 h. at 25 °C in the dark) at which the maximum number of roots emerged. Under hydroponic conditions, 2,4-D treatment of seeds caused an increase of 60 to 100% in the number of primary roots. The maximum increase in the number of roots was observed in one of the salt tolerant wheat lines (WL-41). The roots appeared in bunches but showed stunted growth at higher levels of 2,4-D. Dry matter accumulation decreased markedly; the effect was more pronounced in Inqalab-91 which is less tolerant to stress than other wheat lines. In all wheat types, allocation of dry matter to roots relative to shoot increased due to 2,4-D treatment. In soil, seeds treated with different levels of 2,4-D showed a germination delay of 1–3 days. Although the number of primary roots increased, 2,4-D treatment caused a decrease in total dry matter accumulation by plants grown for 40 days. In another experiment, conducted under greenhouse conditions, seed germination and growth of seedlings was significantly retarded in saline compared to that in non-saline (normal) soil. Initially, the pace of germination of treated seeds as well as seedling growth was slower in both soils, but after six weeks, the leaf area of seedlings raised from treated seeds was greater than those raised from untreated seeds. Towards maturity, plants arising from treated seeds developed wider and longer flag leaves leading to enhanced yield. Root biomass decreased in saline soil as compared to normal soil. However, 2,4-D treatment caused a substantial increase in root biomass in saline soil and the roots were harder in texture in wheats other than Inqalab-91. Seed treatment with 2,4-D led to a significant improvement in the number of productive tillers, yield of straw and grain, and grain protein content of all wheats grown in saline soil. Plants grown in normal soil did not show any marked effect of seed treatment on grain yield and other agronomic parameters. The four wheats showed substantial differences for different parameters but the salt tolerant wheat lines performed better compared to the commercial variety Inqalab-91.
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  • 54
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    Plant and soil 209 (1999), S. 283-295 
    ISSN: 1573-5036
    Keywords: leaf emergence ; phosphorus ; photosynthesis ; tillering ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus (P) deficiency limits the yield of wheat, particularly by reducing the number of ears per unit of area because of a poor tiller emergence. The objectives of this work were to (i) determine whether tiller emergence under low phosphorus availability is a function of the availability of assimilates for growth or a direct result of low P availability, (ii) attempt to establish a quantitative relation between an index of the availability of P in the plant and the effects of P deficiency on tiller emergence, and (iii) to provide a better understanding of the mechanisms involved in tiller emergence in field-grown wheat. Wheat (Triticum aestivum L., cv. INTA Oasis), was grown in the field under drip irrigation on a typic Argiudol, low in P (5.5 μg P g-1 soil Bray & Kurtz I) in Balcarce, Argentina. Treatments consisted of the combination of three levels of P fertilization 0, 60 and 200 kg P2O5 ha-1, and two levels of assimilate availability, a control (non-shaded) and 65% of reduction in incident irradiance from seedling emergence until the end of tillering (shaded). Phosphorus treatments significantly modified the pattern of growth and development of the plants. Shading reduced the growth and concentration of water-soluble carbohydrates in leaves and stems. Leaf photosynthetic rate at saturating irradiance was reduced by P deficiency, but was not affected by shading. At shoot P concentrations less than 4.2 g P kg-1 the heterogeneity in the plant population increased with respect to the number of plants bearing a certain tiller. At a shoot P concentration of 1.7 g P kg-1 tillering ceased completely. Phosphorus deficiency directly altered the normal pattern of tiller emergence by slowing the emergence of leaves on the main stem (i.e. increasing the phyllochron), and by reducing the maximum rate of tiller emergence for each tiller.
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  • 55
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    Euphytica 107 (1999), S. 51-59 
    ISSN: 1573-5060
    Keywords: wheat ; plant breeding ; yield stability ; environmental index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of plant breeding on yield and their physiological determinants has been widely studied in wheat. However, it is poorly understood how, and to what extent, yield stability has been modified. To attempt a direct analysis of changes in absolute and relative yield stability, data of yield of cultivars released in different eras in different environments were obtained from records from our lab and from the literature. Depending on the availability of data, effects of plant breeding on yield stability of cultivars released in Argentina, Australia, Italy and the United Kingdom were evaluated using a quantitative approach. In this paper it was assumed that the slope of yield vs. environmental index estimates the instability of the cultivars. In addition, a more qualitative approach for Mexico, and the former USSR complemented this analysis. There was a clear decrease in yield stability assessed in absolute terms as a consequence of wheat breeding. In Argentina, Australia, Italy and the UK this decrease was related to the magnitude of yield increases. However, the decrease in yield stability in Argentina and Australia was less than for Italy and the UK, particularly so during the last 30 years. Modern cultivars released in Argentina and Australia showed a trend to maintain yield stability as a percentage of their yield similar to that of their predecessors, while the two European countries analysed tended to a slight decrease in yield stability even in relative terms. The complementary, less quantitative evaluation of Mexico and the former USSR appeared to confirm the quantitative trends described for the other countries, i.e. a general decrease in yield stability (assessed in absolute terms) with genetic gains in yield potential.
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  • 56
    ISSN: 1573-5060
    Keywords: chromatin ; breeding ; gel electrophoresis ; in situ hybridization ; rye ; rye-specific probes ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Chromosome arm 1RS of rye ( Secale cereale L.), when transferred to wheat ( Triticum sp.), significantly influences variety performance, because it carries genes for resistance to disease and insect pathogens. Inserted into wheat, 1RS also promotes haploid production, affects end-product quality, and sometimes affects yield. Therefore, its detection by breeders and geneticists is important. The entire 1RS arm is present in chromosome substitutions and in Robertsonian translocations involving chromosomes 1A, 1B, or 1D of wheat. In recombinant lines, a segment of 1RS has been exchanged with a segment of a group-1 wheat chromosome. Determining the wheat chromosome arm involved in a translocation, the source of rye chromatin, and the amount of 1RS chromatin introduced is necessary for a complete characterization of the introgressed segment. Biochemical, molecular, and cytogenetic technologies are described which enable such a characterization of 1RS in wheat. Examples of using gel electrophoresis, high-performance liquid chromatography, monoclonal antibodies, rye-specific molecular probes, RFLP and PCR assays, chromosome banding, in situ hybridization, and flow cytometry are provided. A comparison of these technologies is made and the advantages and disadvantages of each technology are discussed relative to modern wheat breeding efforts.
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    Euphytica 42 (1989), S. 41-44 
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; frost resistance ; locus Fr1 ; recombinant lines ; chromosome 5A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A gene for frost resistance on chromosome 5A of wheat was located using single chromosome recombinant lines from the cross between the substitution line Hobbit (Triticum spelta 5A) and Hobbit. In this sample of recombinant lines the locus for frost resistance, designated Fr1, is completely linked to the locus Vrn1 controlling vernalisation requirement. The results can be explained by a pleiotropic action of the Vrn1 locus or close genetic linkage between Vrn1 and Fr1. Further detailed study is necessary to resolve these alternative hypotheses.
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  • 58
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; dwarfing genes ; drought stress ; yield ; yield components
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Near-isogenic tall (no dwarfing gene), semidwarf (Rht1 or Rht2) and dwarf (Rht1 + Rht2 or Rht3) spring wheat lines were evaluated for yield and yield components under irrigated and rainfed conditions. Under irrigated conditions, the dwarf and the semidwarf lines exhibited a significant yield advantage over the tall lines. Under rainfed conditions, the semidwarf lines outyielded the tall as well as the dwarf lines. Percent yield reduction in response to drought stress was highest with the dwarfs and lowest with the tall lines. Dry matter production of the tall lines and that of the semidwarf lines did not differ significantly and both produced significantly more dry matter than the dwarf lines under irrigated as well as rainfed conditions. Plant height and kernel weight decreased with increasing degree of dwarfness while number of kernels per spikelet, harvest index and days to heading increased under both moisture regimes. The dwarfing genes did not have any significant influence on number of tillers/m2 and spikelets per spike in either moisture regime.
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  • 59
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; chromosome substitution ; frost resistance ; hardening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The highly frost resistant wheat variety Cheyenne (donor) and the poorly frost resistant variety Chinese Spring (recipient) were frozen at −9° C and −11° C at various stages of hardening, as were a number of substitution lines of these two varieties (CS/Ch 3A, CS/Ch 5A, CS/Ch 7A, CS/Ch 2B, CS/Ch 4B, CS/Ch 5B, CS/Ch 4D, CS/Ch 5D). Chromosomes 5A, 5B, 5D, 4B and 7A of Cheyenne increased the frost resistance of the recipient variety to varying extents. However, the frost resistance changed not only as a function of the different chromosomes, but also as a function of the duration of hardening, indicating that genes responsible for frost resistance are expressed differently during different phases of the hardening process.
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    Euphytica 43 (1989), S. 223-232 
    ISSN: 1573-5060
    Keywords: Azolla ; classification ; fingerprinting ; isozymes ; taxonomy ; trichomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Azolla accessions (section Azolla) from the germplasm collections of the International Rice Research Institute and Washington State University were fingerprinted and classified by enzyme electrophoresis and leaf trichome morphology. A. filiculoides was enzymatically distinctive and also reliably identified by its prominent one-celled trichomes. Neotropical accessions labelled as A. filiculoides proved to be members of other species. Two groups of isolates were designated A. rubra, but those from Japan were identified as A. filiculoides. The A. rubra of Australia-New Zealand was biochemically unique and possessed less protuberant trichomes than A. filiculoides. A. microphylla, A. mexicana, and A. caroliniana were phenetically similar, but a. microphylla was identifiable from the others in the banding patterns of certain enzymes. A. mexicana and A. caroliniana were closely related enzymatically. The two-celled leaf trichomes of these three species were similar in size and shape.
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  • 61
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; Puccinia recondita ; leaf rust resistance ; alien gene transfers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Nine transfers of leaf rust (Puccinia recondita Rob. ex Desm.) resistance to wheat (Triticum aestivum L.) from Agropyron elongatum Host. Beauv., Triticum speltoides Tausch and rye (Secale cereale L.) were backcrossed up to 10 times to commercial wheat cultivars. The objective was to study the effect of the transfers on agronomic and quality characters and to make them available in desirable genetic backgrounds. The results varied greatly for different transfers. In four cases no promising material was obtained even after nine backcrosses. However, for the remaining five transfers material with potential as a new cultivar was obtained.
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  • 62
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; Puccinia recondita f. sp. tritici ; wheat leaf rust ; partial resistance ; latency period ; gene action ; oligogenic inheritance ; transgressive segregation ; number of genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Crosses were made between the highly susceptible Little Club and the partially resistant cultivars Westphal 12A, Akabozu and BH 1146 to obtain F1, F2 and backcross generations. Latency period (LP) was determined in plants inoculated at the young flag leaf stage with a monospore culture of race ‘Flamingo’ of wheat leaf rust. Broad sense heritability of LP in the F2 averaged 0.8. The genes showed partial to almost complete recessive inheritance. Scaling tests indicated that additive gene action was the most important factor in the inheritance of partial resistance. The tests showed that there were no indications for additive x additive, additive x dominance or dominance x dominance interactions. The number of effective factors was estimated as one or two for Akabozu, three or more for Westphal 12A, and two or three for BH 1146. BH 1146 also possessed a (semi-)dominant gene for a lower infection type which was temperature sensitive in its expression. The genes of the various parents had unequal effect on LP.
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  • 63
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; Puccinia recondita f. sp. tritici ; wheat leaf rust ; partial resistance ; latency period ; oligogenic inheritance ; transgressive segregation ; number of genes ; heritability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Three partially resistant spring wheat cultivars, with a long latency period were crossed among each other and with the highly susceptible Little Club, with a very short latency period. Parents, F3 and F5 plants have been inoculated with the leaf rust race Flamingo in the young flag leaf stage to determine the latency period. From the crosses with Little Club, it was concluded that Westphal 12A carries three, Akabozu two and BH 1146 two or three genes for a longer latency period. BH 1146 appears to carry also one hypersensitive resistance gene. Transgressive segregation occurred in crosses between partially resistant cultivars. From crosses between the partially resistant cultivars, it was concluded that the genes in Akabozu and Westphal 12A are different, while those in Akabozu and BH 1146 are at least partly different. The possibilities of accumulation of LP-prolonging genes are discussed.
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  • 64
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; anther culture ; callus initiation ; cytoplasm ; cytoplasmic male sterility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Nuclear and cytoplasmic factors affect tissue culture response in wheat (Triticum aestivum), and cytoplasmic male sterility may enhance callus initiation in anther culture. Three wheat nuclear genotypes, each in normal and two alien cytoplasms conferring cytoplasmic male sterility, were evaluated for callus initiation frequency in anther culture. Nuclear genotype had the greatest effect on callus initiation, but cytoplasm and nucleus X cytoplasm interaction also produced significant effects. The nuclear genotype of ‘Chris’ outperformed ‘Butte’ and ‘Coteau’ in all cytoplasms. Ordinary wheat and Triticum timopheevi cytoplasms outperformed Aegilops speltoides cytoplasm. Cytoplasmic male sterility did not increase callus initiation. This suggests manipulating the nuclear genotype is the best strategy for improving the capacity of wheat to initiate callus in anther culture.
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    Plant and soil 120 (1989), S. 273-282 
    ISSN: 1573-5036
    Keywords: aluminum toxicity ; biological tests ; calcium deficiency ; root growth ; sorghum ; subsurface soils ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two relatively simple procedures based on 4-day seedling growth were developed for identifying soil calcium (Ca) deficiency and/or aluminum (Al) toxicity. Test A uses any large-seeded cultivar that a farmer might consider planting and reveals whether the cultivar will suffer from Ca deficiency by comparing root growth in untreated soil to that in soil receiving a minimal Ca addition (0.1 meq.100mL−1 soil), sufficient to eliminate possible deficiency. Al toxicity is detected by comparing root growth in a sample receiving the minimal Ca treatment with growth in the soil treated with enough lime to neutralize exchangeable Al. In test B, potential Al toxicity problems are detected for any widely-grown standard crop by comparing its growth with that of a different, Al-tolerant variety on soil samples receiving 0.1 meq.100mL−1 Ca. With this test Ca deficiency in the untreated sample is detected by an increase in root growth of the Al-tolerant variety resulting from a small addition of Ca. The tests agreed with diagnoses made by standard chemical methods in about 84% of the cases examined. The proposed tests can be carried out using simple, easily-available materials without the necessity of sending soils to an analytical laboratory.
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    Plant molecular biology 40 (1999), S. 921-933 
    ISSN: 1573-5028
    Keywords: A23187 ; calcium ; elicitor ; MAP kinase ; Typhula ishikariensis ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wheat cultured cells were used to study the role of Ca2+ in regulating protein kinases during the induction of defense-related genes by fungal elicitor treatments. Manipulation of intracellular Ca2+ concentrations by treatment with calcium ionophore A23187 in the presence of high extracellular Ca2+ resulted in the induction of mRNA expression of WCK-1, a gene encoding mitogen-activated protein (MAP) kinase. The induction of WCK-1 mRNA by A23187 did not occur when extracellular Ca2+ was chelated by 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid (BAPTA). The WCK-1 mRNA was also induced by Typhula ishikariensis-derived elicitors, suggesting a possible involvement of WCK-1 in the plant defense response against pathogens. BAPTA and a calcium channel blocker, La3+, inhibited the elicitor-induced expression of the WCK-1 mRNA. A recombinant fusion protein of WCK-1 (GST-WCK-1) autophosphorylated at the Tyr residue and exhibited an autophosphorylation-dependent protein kinase activity towards myelin basic protein. Alteration of Tyr-196 in the conserved ‘TEY’ motif in GST-WCK-1 to Phe by site-directed mutagenesis abolished the autophosphorylation. The GST-WCK-1 protein was activated by elicitor-treated wheat cell extracts but not by the control extract. These results suggest that fungal elicitors activate WCK-1, a specific MAP kinase in wheat. Furthermore, the results suggest a possible involvement of Ca2+ in enhancing the MAP kinase signaling cascade in plants by controlling the levels of the MAP kinase transcripts.
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  • 67
    ISSN: 1573-5028
    Keywords: alternative splicing ; starch biosynthesis ; starch-branching enzyme ; transit peptide ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A wheat gene, denoted Sbe1, encoding a type I starch-branching enzyme (SBEI) was isolated from a genomic library and shown to comprise 14 exons distributed over a 5.7 kb DNA region. Analyses of kernel RNA by 5′ rapid amplification of cDNA ends (5′-RACE) and reverse transcription-polymerase chain reaction (RT-PCR) demonstrated a considerable sequence variation at the 5′ ends of SBEI gene transcripts. DNA sequence alignments between the 5′-RACE products and the Sbe1 genomic DNA indicated that the first two exons and first intron were differentially processed to generate three classes of the mature transcript. One form of the SBEI gene transcript in 12-day old kernels contained the exon I+II+III combination at the 5′ end, whereas other forms differed by inclusion of intron 1 or exclusion of exon II sequences. RT-PCR analysis of Sbe1-uidA::nptII chimeric mRNA produced in transgenic wheat cultured cells confirmed that the isolated Sbe1 was able to produce all three forms of SBEI gene transcripts by alternative splicing of the primary mRNA. The variants of processed Sbe1 mRNA were potentially translated into N-terminal variants of the SBEI precursor with different transit peptide sequences.
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    Plant and soil 208 (1999), S. 149-159 
    ISSN: 1573-5036
    Keywords: abscisic acid ; drought ; soil water content ; water potential ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to investigate the effects of soil texture on possible non-hydraulic signals under field conditions, spring wheat plants (Triticum aestivum L. cv. Cadensa) grown in sand and loam soils and with a well developed root system were exposed to slow soil drying in the late vegetative stage of growth. Soil water potential and content were measured daily at different depths and plant responses were measured in flag leaves. When the average soil water potential in the top soil layers (0–25 cm depth in sand and 0–45 cm depth in loam) dropped to –60 or –70 kPa and the lower soil layers were still at field capacity, morning xylem [ABA] (0.03–0.04 vs. 0.06–0.08 mmol m-3) and midday leaf ABA concentration increased (250–300 vs. 400–450 ng/g DW) and leaf conductance decreased relatively to well-watered (control) plants (0.75–0.88 vs. 0.64–0.70 mol m-2 s-1). These responses took place before any decrease in leaf water potential occurred as compared with control plants, indicating that they were triggered by root-borne signals due to reduced root water status in the top soil layers. At this stage the soil water content was as low as 6% by volume, the fraction of roots in ‘wet’ soil was 0.12 and relative available soil water was 45% in sand and still high 20%, 0.48 and 70%, respectively, in loam of the whole soil profile indicating that roots were responding to soil water availability and not soil water content at a certain evaporative demand. In addition, similar responses occurred at high and low evaporative demands (3.4–5.2 vs. 0.6–4.0 mm/day of potential evapotranspiration).
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  • 69
    ISSN: 1573-5036
    Keywords: macropores ; rhizosphere ; roots ; root-soil interplay ; soil properties ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Under certain soil conditions, e.g. hardsetting clay B-horizons of South-Eastern Australia, wheat plants do not perform as well as would be expected given measurements of bulk soil attributes. In such soils, measurement indicates that a large proportion (80%) of roots are preferentially located in the soil within 1 mm of macropores. This paper addresses the question of whether there are biological and soil chemical effects concomitant with this observed spatial relationship. The properties of soil manually dissected from the 1–3 mm wide region surrounding macropores, the macropore sheath, were compared to those that are measured in a conventional manner on the bulk soil. Field specimens of two different soil materials were dissected to examine biological differentiation. To ascertain whether the macropore sheath soil differs from rhizosphere soil, wheat was grown in structured and repacked cores under laboratory conditions. The macropore sheath soil contained more microbial biomass per unit mass than both the bulk soil and the rhizosphere. The bacterial population in the macropore sheath was able to utilise a wider range of carbon substrates and to a greater extent than the bacterial population in the corresponding bulk soil. These differences between the macropore sheath and bulk soil were almost non-existent in the repacked cores. Evidence for larger numbers of propagules of the broad host range fungus Pythium in the macropore sheath soil were also obtained.
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  • 70
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    Plant and soil 215 (1999), S. 65-72 
    ISSN: 1573-5036
    Keywords: barley ; boron deficiency ; Hordeum vulgare ; Triticum aestivum ; variation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Responses of a range of barley (Hordeum vulgare L.) genotypes to boron (B) deficiency were studied in two experiments carried out in sand culture and in the field at Chiang Mai, Thailand. In experiment 1, two barley genotypes, Stirling (two-row) and BRB 2 (six-row) and one wheat (Triticum aestivum L.) genotype, SW 41, were evaluated in sand culture with three levels of applied B (0, 0.1 and 1.0 μM B) to the nutrient solution. It was found that B deficiency depressed flag leaf B concentration at booting, grain number and grain yield of all genotypes. In barley Stirling, B deficiency also depressed number of spikes plant-1, spikelets spike-1 and straw yield. However, no significant difference between genotypes in flag leaf B concentration was found under low B treatments. Flag leaf B concentration below 4 mg kg-1 was associated with grain set reduction and could, therefore, be used as a general indicator for B status in barley. In experiment 2, nine barley and two wheat genotypes were evaluated in the field on a low B soil with three levels of B. Boron levels were varied by applying either 2 t of lime ha-1 (BL), no B (B0) or 10 kg Borax ha-1 (B+) to the soil prior to sowing. Genotypes differed in their B response for grain spike-1, grain spikelet-1 and grain set index (GSI). The GSI of the B efficient wheat, Fang 60, exceeded 90% in all B treatments. The B inefficient wheat SW 41 and most of the barley genotypes set grain normally (GSI 〉80%) only at the B+. In B0 GSI of the barley genotypes ranged from 23% to 84%, and in BL from 19% to 65%. Three of the barley with severely depressed GSI in B0 and BL also had a decreased number of spikelets spike-1. In experiment 3, 21 advanced barley lines from the Barley Thailand Yield Nursery 1997/98 (BTYN 1997/98) were screened for B response in sand culture with no added B. Grain Set Index of the Fang 60 and SW 41 checks were 98 and 65%, respectively, and GSI of barley lines ranged between 5 and 90%. One advanced line was identified as B efficient and two as moderately B efficient. The remaining lines ranked between moderately inefficient to inefficient. These experiments have established that there is a range of responses to B in barley genotypes. This variation in the B response was observed in vegetative as well as reproductive growth. Boron efficiency should be considered in breeding and selection of barley in low B soils.
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  • 71
    ISSN: 1573-5036
    Keywords: chelator ; genotypic differences ; HEDTA ; ion speciation ; micronutrient ; tolerance to zinc deficiency ; wheat ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The chelator-buffered nutrient solutions containing excess chelator have been used frequently in the micronutrient research, but potential toxicity of the excess chelator has not been ascertained. The present study was conducted to test effects of four concentrations of excess HEDTA [ N-(2-hydroxyethyl)ethylenedinitrilotriacetic acid] and two levels of total Zn on growth, root exudation, and nutrient uptake and transport by Triticum aestivum L. (cv. Aroona) and Triticum turgidum L. conv. durum (Desf.) MacKey (cv. Durati) genotypes differing in tolerance to Zn deficiency. Excess HEDTA at 50 μM reduced root and shoot growth and caused visual toxicity symptoms (necrotic lesions) on leaves; these effects were generally absent at lower concentrations of excess HEDTA. Root exudation of phytosiderophores increased with increasing concentrations of excess HEDTA at deficient and sufficient Zn levels, and was higher in Zn-deficiency-tolerant Aroona than in Zn-deficiency-sensitive Durati wheat. Shoot and root Zn concentrations showed a saturable response to increasing Zn2+ activities in solution. Excess HEDTA at 50 μM caused an increase in shoot concentrations of Fe and a decrease in concentrations of Mn and Cu. An average rate of Zn uptake increased with an increase in Zn2+ ionic activity in solution, with Zn-deficiency-tolerant Aroona having a higher rate of Zn uptake than Zn-deficiency-sensitive Durati in the deficiency range of Zn2+ activities. Average uptake rates of Mn and Cu decreased with an increase in concentration of excess HEDTA. Similar observations were noted for transport of Mn and Cu to shoots, while Zn transport to shoots was proportional to Zn2+ activities in solution. It was concluded that excess HEDTA at 50 μM adversely affects wheat growth and physiology, while excess of 25 μM or less does not cause measurable toxicity.
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  • 72
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    Plant molecular biology 40 (1999), S. 567-578 
    ISSN: 1573-5028
    Keywords: wheat ; mitochondria ; RNA polymerase ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using PCR-based methods, we assembled two wheat cDNA sequences, wheat-G and wheat-C, that encode T3/T7 bacteriophage-like RNA polymerases (RNAPs) sharing 45% amino acid identity. In phylogenetic analyses using maximum likelihood, parsimony and distance methods, the predicted protein sequence of wheat-G (1005 amino acids, 113 kDa) clusters with sequences of previously assigned mitochondrial RNAPs from dicotyledonous plants (Arabidopsis thaliana, Chenopodium album); likewise, in such analyses, the wheat-C sequence (949 amino acids, 107 kDa) affiliates specifically with the Arabidopsis sequence that encodes a phage-like RNAP thought to function in chloroplasts. To confirm biochemically the assignment of the gene encoding the putative wheat mitochondrial RNAP, we isolated a ca. 100 kDa wheat mitochondrial protein that is enriched in fractions displaying specific in vitro transcription activity and that reacts with an antibody raised against a recombinant maize phage-type RNAP. Internal peptide sequence information obtained from the 100-kDa polypeptide revealed that it corresponds to the predicted wheat-G cDNA sequence, providing direct evidence that the wheat-G gene (which we propose to call RpoTm) encodes the wheat mitochondrial RNAP.
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  • 73
    ISSN: 1573-5036
    Keywords: agriculture ; fertilisation ; nitric oxide flux ; nitrification ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The surface flux of nitric oxide from a wheat field was investigated from 23 March to 29 May 1997 in the Kerzersmoos, Switzerland. A plot fertilised with 19 kg N ha-1 in cattle slurry and 40 kg N ha-1 in mineral NH4NO3 fertiliser and a plot receiving no nitrogen containing fertiliser were compared. The flux was calculated based on hourly measurements of the NO soil–atmosphere concentration gradient using the one-dimensional soil diffusion model of Galbally and Johansson (1989). The soil bulk diffusion coefficient was determined from measurements of the 222Rn surface flux and the activity gradient between 10 cm depth and the surface. It ranged between 79% and 0.3% of the NO diffusion coefficient in air and was parameterised by air filled soil pore space. The indirectly determined NO flux agreed well with standard flux measurements using dynamic chambers. The largest NO emission was found following fertiliser application and irrigation. The emission occurred in pulses, which lasted for 4 days up to 3 weeks coinciding with elevated soil ammonium concentrations. Nitric oxide emission in 5 days following application of cattle slurry were 31 g NO-N ha-1 and 5 g NO-N ha-1 from the non-fertilised plot, respectively. Nitric oxide emission in 15 days following application of NH4NO3 was 95 g NO-N ha-1 and 10 g NO-N ha-1 from the non-fertilised plot, respectively. NO emission in 4 days following irrigation on 21 April were 36 g N ha-1 from the fertilised and 39 g N ha-1 from the non-fertilised plot. The daily NO emission before and after fertiliser and irrigation pulses was between 0.3 and 0.7 g NO-N ha-1 d-1. NO production and NO uptake of the soil was measured regularly. No systematic influence of management or climate on NO uptake was found. NO production was strongly stimulated by fertiliser input and soil moisture content. The simulation of NO production could be reproduced using a nitrification algorithm (Riedo et al., 1998) driven by soil temperature, moisture and ammonium concentration. A NO production rate constant of 1.1ċ10-3 h-1 at 15 °C was derived from a linear regression between nitrification and NO production. Introducing the parameterisation of NO production into the model of Galbally and Johansson (1989) the duration and the strength of the NO emission pulses could be reproduced and the total NO emission during the experiment was approximated within a factor of two.
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  • 74
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    Plant and soil 211 (1999), S. 223-230 
    ISSN: 1573-5036
    Keywords: silicon absorption ; transport ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Although silicon (Si) is a quantitatively major inorganic constituent of higher plants the element is not considered generally essential for them. Therefore it is not included in the formulation of any of the solution cultures widely used in plant physiological research. One consequence of this state of affairs is that the absorption and transport of Si have not been investigated nearly as much as those of the elements accorded 'essential' status. In this paper we report experiments showing that Si is rapidly absorbed by wheat (Triticum aestivum L.) plants from solution cultures initially containing Si at 0.5 mM, a concentration realistic in terms of the concentrations of the element in soil solutions. Nearly mature plants (headed out) 'preloaded' with Si absorbed it at virtually the same rate as did plants grown previously in solutions to which Si had not been added. The rate of Si absorption increased by more than an order of magnitude between the 2-leaf and the 7-8 leaf stage, with little change thereafter.
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  • 75
    ISSN: 1573-5060
    Keywords: barley ; embryogenesis ; medium ; regeneration ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Media have been developed for somatic embryogenesis and plant regeneration from immature inflorescences and immature scutella of elite cultivars of wheat, barley and tritordeum. For wheat and tritordeum inflorescences, regeneration from embryogenic calluses induced on medium with picloram was almost twice as efficient as regeneration from cultures induced on 2,4-dichlorophenoxyacetic acid (2,4-D). The addition of zeatin at 5 or 10 mg l−1 to regeneration media had a positive effect on regeneration. For scutella, the highest frequencies of embryogenesis (85%) and regeneration (50%) was obtained using an induction medium containing 2 mg l−1 of 2,4-D and half concentration of aminoacids. The morphogenetic capacities of 19 different cultivars of wheat, barley and tritordeum were compared, and clear differences were found both between explants and genotypes. In wheat, embryogenic capacity from inflorescences (average of 92%) was higher than from immature scutella (average of 62%). However, shoot regeneration from scutella was clearly higher than from inflorescences (averages of 63%, and 18% respectively). Frequencies of regeneration in wheat and barley varied widely among the cultivars tested and in both species no difference was found between spring and winter varieties.
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  • 76
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    Euphytica 108 (1999), S. 193-198 
    ISSN: 1573-5060
    Keywords: K+/Na+ selectivity ; Lophopyrum elongatum ; salt-stress ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Accumulation of potassium ions (K+) in expanding or most recently expanded leaves and exclusion of sodium ions (Na+) from them (K+/Na+ selectivity) have been shown to be associated with salt stress tolerance in wheat and Lophopyrum elongatum, a highly salt stress tolerant relative of wheat. This physiological trait is expressed in an amphiploid from the cross of wheat (cv. Chinese Spring) × L. elongatum and the chromosomes controlling it have been identified in field studies employing Chinese Spring disomic substitution lines with individual L. elongatum chromosomes. In this paper the arm location of these genes was investigated by assessing K+/Na+ selectivity in lines harboring individual chromosomes and chromosome arms of L. elongatum. Lophopyrum elongatum chromosome arms 1ES, 7ES, and 7EL, were shown to enhance K+/Na+ selectivity in wheat.
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  • 77
    ISSN: 1573-5060
    Keywords: diallel analysis ; Fusarium culmorum ; heterosis ; resistance ; scab ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Fusarium head blight (FHB, scab) caused by Fusarium spp. is a widespread disease of cereals causing relevant yield and quality losses and contaminating cereal products with mycotoxins. Breeding resistant cultivars is the method of choice for controlling the disease. Resistance to FHB is a quantitative trait and is most likely governed by several genes. We present the results of an F1 diallel analysis of FHB resistance involving six resistant and one susceptible European winter wheat genotypes of diverse origin in order to identify promising combinations for the selection of improved cultivars. Parents and F1s including reciprocals were evaluated for FHB resistance in an artificially inoculated field trial. Two traits were assessed: visual disease symptoms on the heads and the percentage of Fusarium damaged kernels in a harvested sample. General combining ability (GCA) and specific combining ability (SCA) effects were statistically significant for visual symptoms and kernel damage, whereas reciprocal effects were small or not significant. Heterosis for resistance was common, indicating that the parental genotypes possess different resistance genes. Selection of transgressive segregates should be feasible from such heterotic combinations.
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  • 78
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    Euphytica 40 (1989), S. 103-109 
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; triticale ; wheat-triticale hybrids ; Secale cereale ; rye ; Gaeumannomyces graminis ; take-all ; resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Fifteen triticale and wheat-triticale hybrid lines were evaluated for resistance to the take-all fungus Gaeumannomyces graminis var. tritici and compared with five wheat and two rye lines in inoculated field and pot trials. The triticale and wheat-triticale hybrid lines varied in rye chromosome number and degree of resistance expressed. One line, Venus with seven pairs of rye chromosomes consistently showed levels of resistance intermediate between wheat and rye. A trend was observed where increasing rye chromosome content led to greater resistance but exceptions showed that variation within triticales could not be ascribed to rye chromosome content alone.
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  • 79
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; gliadins ; electrophoresis ; cultivar identification ; breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The process of the separation of gliadin proteins of wheat, using polyacrylamide gel electrophoresis, was studied in detail. It was shown that electrophoresis is a dynamic process during which the pH of the gel changes together with the potassium ion concentration. The most positive effect on the separation of the gliadins was generated by a moving front, which is a boundary between regions with a low concentration of K+ ions and a low pH, and region with a high concentration of K+ ions and a high pH, after optimization of the concentrations of the cations and anions in the electrode solutions. The finding was exploited for the development of an extremely simple electrophoresis system, in which buffers were not needed for obtaining a high resolution. The system was further improved by applying a stacking gel. The advantages of this system are discussed. This new approach may be useful for improving electrophoresis systems for other applications.
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    Euphytica 41 (1989), S. 191-197 
    ISSN: 1573-5060
    Keywords: Triticeae grasses ; taxonomy ; nomenclature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The two causes of destabilization of names in the tribe Triticeae are discussed in detail. These include changes in names due to changing classifications and changes in names due to application of nomenclatural rules. We favour the opinion that a classification should be based on maximum information and not on one single character like the genome as suggested in a recent classification of Dewey and that of Löve. The problem of changes in names is discussed using two examples-Triticum-Aegilops group and Agropyron-Elytrigia-Leymus group. The users of Triticeae grasses, should always authenticate the material they are using and specify the scheme or reference of classification they follow in naming their material, even though one would have the freedom to use a particular classification and thus the names given in this classification. The problem of instability in the names of Triticeae grasses due to nomenclatural rules are discussed using the examples of bread wheat (T. aestivum) and of Haynaldia villosa. A list of recommended names of World's flora for preservation as suggested by Brummitt recently has also been examined.
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  • 81
    ISSN: 1573-5060
    Keywords: alloplasmic line ; breeding ; chromosome ; eyespot resistance ; substitution line ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The variety Roazon possesses genes for resistance to eyespot including that on the 7D chromosome transferred from Aegilops ventricosa. In order to assess the level of resistance due to the latter, we developed the intervarietal substitution for the 7D chromosome of ‘Roazon’ into ‘Courtot’ which is very susceptible to eyespot. As ‘Roazon’ contains Aegilops ventricosa cytoplasm, the substitution lines were produced both with wheat and Aegilops cytoplasm. Resistance was assessed at the seedling and the adult plant stage. No cytoplasmic effect was observed. The substitution lines were as resistant as ‘Roazon’. This shows that the chromosome 7D genes for resistance introduced from Aegilops ventricosa result in a high level of resistance in wheat.
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  • 82
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    Euphytica 44 (1989), S. 143-150 
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; Triticum durum ; durum ; environmental correlations ; grain yield ; plant height ; tiller number ; grain size
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Environmental correlation coefficients were computed among all pairs of five traits, namely grain yield, heading date, number of tillers per m2, plant height and 1000-grain weight (grain size) using 30 Triticum durum and 30 Triticum aestivum varieties grown in 18 environments. Grain yield was significantly correlated with the other four traits in almost all of the varieties. The mean correlation coefficient over all varieties ranged from 0.58 to −0.83 for durum wheat and 0.66 to 0.88 for aestivum wheat. The correlation coefficients between heading date and the other traits were also significant, ranging from −0.45 to −0.79 in durum wheat and −0.61 to −0.85 in aestivum wheat. The correlation coefficient between number of tillers with plant height and 1000-grain weight were the smallest, 0.19−0.32 in durum wheat and 0.39−0.60 in aestivum wheat. It was concluded that agronomic practices favouring early and good stand establishment in the dry regions will favour the yield components and important adaptive traits, which contribute towards larger yields. Significant differences were found among genotypes in the environmental correlation coefficients and the associated changes in one trait as a result of changes in other traits.
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  • 83
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; Puccinia recondita f. sp. tritici ; wheat leaf rust ; partial resistance ; latency period ; infection frequency ; urediosorus size ; growth stage ; component analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Latency period (LP), infection frequency (IF) and urediosorus size (US) of leaf rust were determined on primary leaves and young flag leaves of 18 spring wheat cultivars. A large growth stage effect and a large cultivar effect on all three components were observed. Partial resistance as measured by the three components was generally better expressed in the adult plant stage than in the seedling stage. Associated variation of the components was observed: long LP, low IF and small US tended to go together. The association was not complete, cultivars with clear deviations of this association for one of the components were found suggesting the existence of at least partly different genetic factors controlling the respective components. LP measured on flag leaves gave the most reliable results and, therefore, could best be used as a selection criterion in breeding programs for partial resistance.
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  • 84
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; Puccinia recondita f.sp. tritici ; leaf rust ; temperature sensitivity ; latency period ; infection frequency ; urediosorus size ; growth stage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Three components of partial resistance (PR) were studied at three post-infection temperatures using seven spring wheat genotypes differing in level of PR and two different wheat leaf rust races. The components were latency period (LP), infection frequency (IF) and urediosorus size (US). The expression of LP was more sensitive to temperature than the expression of the other two components. LP-prolonging genes were better expressed at low temperatures than at high temperatures and cultivar differences tended to increase with decreasing temperature in both seedling and adult plant stages. The reaction of IF to temperature differed from that of LP and US, probably because IF is regulated by another mechanism than LP and US. It is recommended to perform PR-screening tests at low rather than at high temperatures. If temperatures are maintained at about 8–13°C (night-day), seedlings can be used to screen for PR instead of the more expensive adult plant tests. The effectiveness of PR in seedling stage at low temperatures suggests that the seedling stage may have epidemiological significance as the low temperatures (8–13°C) are relevant for seedlings in the field.
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    Euphytica 44 (1989), S. 273-282 
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; race-specificity ; Puccinia recondita f.sp. tritici ; wheat leaf rust ; partial resistance ; hypersensitive resistance ; latency period ; disease severity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Partial resistance (PR) in wheat to wheat leaf rust (Puccinia recondita f.sp. tritici) is characterized by a slow epidemic build-up despite a susceptible infection type. Two greenhouse tests and two field tests, in which 11 spring wheat cultivars were exposed to five wheat leaf rust races, revealed some indication for race-specificity of PR. In the greenhouse, the expression of PR was highly dependent on the environment. Significant cultivar-race interactions in the first experiment were lost in the second experiment probably due to cultivar-environment and cultivar-race-environment interactions. In the polycyclic field tests several factors played a role in explaining the inconsistency of the cultivar-race interactions, such as differences in initial inoculum, genotypic differences in earliness, interplot interference or environmental conditions. One cultivar-race combination showed a significant but small interaction towards susceptibility in both field experiments. The interaction was probably too small to detect in the monocyclic greenhouse tests. The results do not conflict with the idea that a gene-for-gene relationship could exist between PR-genes in the host and genes in the pathogen. Some problems with regard to the selection of PR in wheat to wheat leaf rust are discussed.
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    Euphytica 44 (1989), S. 241-245 
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; Puccinia recondita f.sp. tritici ; leaf rust ; partial resistance ; environmental stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Five spring wheat cultivars differing in partial resistance (PR) to wheat leaf rust were tested at Wageningen (the Netherlands) on a sandy and a clay site, El Batan (CIMMYT, Mexico) and Ponta Grossa (Brazil) over two years. The cultivars were Skalavatis 56, Little Club (both very susceptible), Westphal 12A, Akabozu and BH 1146 (all three with high levels of PR). The results showed that PR was expressed at all four locations in both years. The level of expression was influenced by the environment but the cultivar ranking was hardly affected. Selection for PR in the field can therefore be carried out over a wide range of environments.
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    Euphytica 44 (1989), S. 247-258 
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; Puccinia recondita f.sp. tritici ; leaf rust ; epidemiological parameters ; microfield ; race nursery ; partial resistance ; components of resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Eighteen spring wheat cultivars were tested in microfields and race nurseries for their partial resistance PR to wheat leaf rust under low and high disease pressure respectively. Large differences existed between the 18 cultivars, Skalavatis 56 being the most susceptible and Ponta Grossa 1 being the most resistant cultivar. Of the three epidemic parameters, disease severity (DS) at the time that the susceptible check was severely diseased and area under the transformed disease severity curve (AUTC) and the logistic growth rate (r), AUTC and DS were highly correlated. Both seemed to be reliable estimators of PR but DS should be preferred for economical reasons. The logistic growth rate seemed to be unsuitable as an estimator of partial resistance. High and low disease pressure gave similar cultivar ranking. PR can be screened and selected equally well in race nurseries with low space, low time and low cost input as in microfields with high space, time and cost input. Cultivar differences in development rate had a large impact on the cultivar differences for amount of disease and can therefore greatly bias the estimation of cultivar resistance. The resistance of early cultivars tended to be underestimated whereas the resistance of late cultivars tended to be overestimated. The effect of differences in developmental rate was most pronounced in the flag leaf. It is advisable to avoid the assessment of disease levels on the flag leaf only and to incorporate in the tests several susceptible and resistant checks that cover the range of development rates in the material to be selected, because otherwise selection for resistance will tend to select also for lateness. Regression of the epidemiological parameters on three components of partial resistance revealed that latency period (LP) is an important factor in determining the resistance observed in the field explaining on average 67% of the observed variation. Adding infection frequency (IF) and urediosorus size (US) to the linear model increased the proportion of the observed variation in the field explained by the components to 80%. This result supports the idea that the components of PR inherit independently, at least, in part.
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    Plant growth regulation 28 (1999), S. 187-197 
    ISSN: 1573-5087
    Keywords: ABA ; grain filling ; water stress ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of in situ water stress on the endogenous abscisic acid (ABA) content of the endosperm and the in vitro application of ABA on some important yield regulating processes in wheat have been studied. Water stress resulted in a marked increase in the ABA content of the endosperm at the time close to cessation of growth. Application of ABA to the culture medium of detached ears reduced grain weight. Exogenously applied ABA, at the highest concentration (0.1 mM) reduced transport of sucrose into the grains and lowered the starch synthesis ability of intact grains. In vitro sucrose uptake and conversion by isolated grains was stimulated by low ABA concentrations (0.001 mM) in the medium but was inhibited by higher concentrations. ABA application had no effect on sucrose synthase (SS) and uridine diphosphate glucose pyrophosphorylase (UDP-Gppase) activities, whereas adenosine diphosphate glucose pyrophosphorylase (ADP-Gppase), soluble starch synthase (SSS), and granule-bound starch synthase (GBSS) activities were reduced. These results raise the possibility that water stress-induced elevated levels of endogenous ABA contribute to reduced grain growth.
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  • 89
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    Plant growth regulation 29 (1999), S. 1-21 
    ISSN: 1573-5087
    Keywords: drought resistance ; wheat ; small grains ; genetic analysis ; yield stability ; traits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Drought is a serious problem in many parts of the world where wheat, barley and other small-grained cereals are part of the staple diets. Even in parts of South-eastern Europe, seasonal rainfall for winter cereals has been falling gradually for many years. Thus, since 1981 across three sites in Yugoslavia (Novi Sad, Kragujevac and Zaječar), rainfall fell from a mean of 511 mm for October to July in 1981--1982 to about 453 mm during the same period for the 1995--1996 season. Nevertheless, average wheat yields for new varieties in Yugoslav Commission trials during this period have shown a steady increase from 7.6 to 8.8 t ha−1. This is due to increasing the yield potential of the new varieties, even in trials giving low average yields, caused largely by drought. Thus, breeders in Yugoslavia are succeeding in improving drought resistance in new wheat varieties. However, future progress in improving drought resistance may be helped by focusing on specific traits which will help to improve either crop water use, water-use efficiency or harvest index. Thus, for example, rapid early leaf area development not only improves subsequent crop growth rates, but increases competition with weeds for water and nutrients. The rate of leaf area development is closely associated with embryo size, so selection for large embryo size should improve early growth rates. Osmotic adjustment in wheat in response to drought appears to be important for maintaining yields, and selection for high osmotic adjustment has improved drought yields. Carbon 13 discrimination (Δ) is an integral measure of plant water-use efficiency. Selecting for low Δ has also resulted in increased yield under drought conditions. Other constitutive and induced traits, such as phenology, leaf xeromorphy, excised-leaf water loss, rooting behaviour, senescence and stored assimilates are also discussed in relation to improving yields in small-grain crops. Opportunities for marker-assisted selection are also considered. Incorporating specific drought resistance traits in breeding programmes should facilitate more rapid improvement in the drought resistance of wheat and other small-grained cereals.
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    Genetic resources and crop evolution 46 (1999), S. 81-85 
    ISSN: 1573-5109
    Keywords: aluminum tolerance ; germplasm ; rye ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Regional rye populations and wheat cultivars/lines were screened for aluminum tolerance using the hematoxylin staining method. Portuguese regional rye populations showed better tolerance than the Polish cv. Dank. Zlote, used as tolerant tester. In the group of bread wheats, EPM 305/81, a Barbela reselection, was the most tolerant genotype with the same behaviour as the cv. BH 1146, a tolerant tester. In a study with lines selected from a local Barbela landrace, aluminum tolerance variability was detected. Some lines were as tolerant, or higher, as wheat tester. As Portuguese rye populations and the Barbela wheat landrace have grown for centuries on an acid soil region, the data supports the idea that natural biotic or abiotic stresses associated to man selection, lead to the adaptation of genotypes to specific regional conditions and, in this case, to acid soils where aluminum toxicity occurs.
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    Genetic resources and crop evolution 46 (1999), S. 143-147 
    ISSN: 1573-5109
    Keywords: Amygdalus ; distribution ; domestication ; taxonomy ; wild relatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Almond, Amygdalus communis L., is an ancient crop of south west Asia. Selection of the sweet type marks the beginning of almond domestication. Wild almonds are bitter and eating even a relatively small number of nuts can be fatal. How man selected the sweet type remains a riddle. Also, the wild ancestor of almond has not been properly identified among the many wild almond species. Breeding experiment, which is the most critical test for identifying the wild progenitors of other crops, is ineffective in almond, because it is interfertile with many wild taxa. The so-called wild A. communis of central Asia cannot be regarded as a genuine wild form, but as a feral form, or remains of old afforestation. The wild taxa morphologically akin to almond, A. korshinskyi (H.-M.) Bomm. and A. webbii Spach, are also feral types occurring in the Middle East and southern Europe, respectively. The taxon A. fenzliana (Fritsch) Lipsky is the most likely wild ancestor of almond for three reasons: 1. It is a genuine wild type forming extensive thickets of large trees young seedlings and all the intergradations between them in nature; 2. Its morphology, and particularly the partially pitted grooved nut-shell are within the range of variation of almond, and 3. A. fenzliana is native of Armenia and western Azerbaijan in the Middle East where almond was apparently domesticated.
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  • 92
    ISSN: 1573-5109
    Keywords: evolution ; genetic resources ; PCR-RFLP ; RAPDs ; Vicia ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We report the results of two methods of DNA analysis to elucidate phylogenetic relationships among 29 Vicia subgen. Vicia species in comparison with two species of subgenus Vicilla sect. Vicilla. The methods employed were RAPD analysis of total genomic DNA and PCR-RFLP analysis of five chloroplast genes, rbcL, rpoB, 16S, psaA and trnK. The results of each method were similar and complementary, and support the current taxonomic systems of subsp. Vicia. According to RAPD and PCR-RFLP analysis the Narbonensis complex can be considered a well separated section, which may be related to section Vicia. Sections Vicia, Atossa and Wiggersia are separate, but closely related sections. Species of the section Hypechusa form a single monophyletic section, where V. lutea, V. anatolica and V. hyrcanica are quite remote from other species. Our results suggest that within the subgenus Vicia, V. faba is more closely related to V. bithynica and that these two species are most closely related to section Peregrinae. We found that PCR-RFLP of cp DNA provided more precise information concerning relationships between Vicia sections than RAPD analysis. However, RAPD analysis was more informative concerning diversity of closely related Vicia taxa, such as the variable groups, section Narbonensis and V. sativa aggregate.
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    Hydrobiologia 180 (1989), S. 83-89 
    ISSN: 1573-5117
    Keywords: enchytraeids ; muscles ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The muscle organization of the body wall in some species of oligochaetes belonging to the Enchytraeus genus is described. No differences have been detected in their circular muscles, whereas longitudinal muscles show significant differences, allowing an easy identification of the various worm species. In particular, differences are noticeable in the external longitudinal layer. These observations suggest that structural and ultrastructural muscle fiber organizations can be used as a taxonomic tool.
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  • 94
    ISSN: 1573-5117
    Keywords: Protozoa Ciliophora ; Colpidium ; Dexiostoma ; Paracolpidium ; revision ; taxonomy ; saprobic system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genera Colpidium Stein, 1860 and Dexiostoma Jankowski, 1967 are revised. Our monographic treatment is based on a morphologic and biometric reinvestigation of the main species of these genera and on an evaluation of data from the literature. Colpidium comprises four species, namely C. colpoda (Losana, 1829), C. singulare Vuxanovici, 1961, C. acuminatum Vuxanovici, 1962, and C. kleini Foissner, 1969. The monotypic genus Dexiostoma contains D. campyla (Stokes, 1886) and is distinguished from Colpidium by a different oral infraciliature and the position and shape of the preoral suture. A new genus, Paracolpidium nov. gen., is suggested for Colpidium truncatum Stokes, 1885 because its oral infraciliature deviates from both Colpidium and Dexiostoma. Contrary to Colpidium and Dexiostoma, the silverline system of Paracolpidium truncatum lacks secondary meridians but shows short projections to the left of the primary meridians indicating a phylogenetic relationship to Tetrahymena.
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  • 95
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    Hydrobiologia 184 (1989), S. 153-164 
    ISSN: 1573-5117
    Keywords: Batracobdelloides tricarinata ; Hirudinea ; African fish leech ; taxonomy ; morphology ; bionomics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A study of well over one thousand specimens provided proof to put the conspecifity of the two supposed species originally described asHelobdella tricarinata andClepsine nilotica beyond all doubt. Evidence is presented which indicates that the striking changes in body-shape and drastic alteration in the appearance of the tuberculation at different stages of reproduction and nutrition combined with individual variation in tuberculation, annulation, and in the arrangement and pigmentation of the eyes were responsible for earlier confusion as to the identity of this species. Since the early accounts were incomplete and contained some important errorsBatracobdelloides tricarinata is redescribed and, for the first time, comprehensively figured.
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  • 96
    ISSN: 1573-5117
    Keywords: Rotifera ; Notholca ; fine structure ; Andes ; South America ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rotifers described from the Andes by Murray (1913) and De Beauchamp (1939) as Notholca foliacea (Ehrenberg) are reviewed and re-assessed as Notholca walterkostei De Paggi, 1982. They are compared with N. foliacea and details of the lorica of this species seen with the scanning electron microscope are presented.
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    Genetic resources and crop evolution 46 (1999), S. 207-211 
    ISSN: 1573-5109
    Keywords: introduced species ; karyotypes ; taxonomy ; Vicia sativa agg
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract V. sativa L. sensu strictu was introduced in Rio Grande do Sul (Southern Brazil) by Italian settlers and is nowadays cultivated for forage in backyards and fields. V. angustifolia L. is a widespread highly polymorphic naturalized ruderal. Both taxa grow sympatrically and morphologically transitional types are often found. We analyzed 37 accessions of V. sativa, V. angustifolia, intermediate types, and V. cordata Wulf. ex. Hoppe from Rio Grande do Sul, for karyotypes, corolla and legume color, seed color pattern, pod constrictions and phenological development. Karyotypes allowed a clear distinction between the taxa: V. sativa (2n=12) had a metacentric marker chromosome, V. angustifolia and intermediate types (2n=12) only acrocentric chromosomes and V. cordata presented 2n=10. Flowering and fruiting periods were shorter for V. sativa than for V. angustifolia, which was separated into early and late flowering groups. Qualitative characters separated the taxa by Jaccard coefficients into three groups: V. sativa at 0.5 similarity level, V. angustifolia and intermediate types at 0.6 and V. cordata joined V. sativa at 0.12. Our results show that karyotypes and a range of qualitative characters are diagnostic for the aggregate represented in Southern Brazil.
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  • 98
    ISSN: 1573-5117
    Keywords: Anheteromeyenia ryderi ; taxonomy ; freshwater sponge ; Porifera ; Norway ; amphiatlantic distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The freshwater sponge Anheteromeyenia ryderi (Potts) ( = Heteromeyenia ryderi Potts) has its main range in the eastern parts of North America, with one record from Central America. It is also represented in western parts of the British Islands, on the Faroes, and is now reported from three lakes in western South Norway. A description is given of some ecological factors in the Norwegian habitats such as the low calcium content and low pH. With the use of scanning electron microscopy details of the spicules appeared which were useful in species determination. These findings support the view that Anheteromeyenia pictovensis Potts cannot be ranked as a distinct species, but should be considered as a variety of A. ryderi. If A. ryderi is a very old species, its amphiatlantic distribution pattern may be explained by continental drift and/or Pre-Pleistocene land bridges. The species is probably easily transported by birds. There are arguments in favour of a more recent colonization of Europe by such transport, the European populations possibly having their origin in populations adapted to an oceanic climate in North America.
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    Hydrobiologia 178 (1989), S. 113-134 
    ISSN: 1573-5117
    Keywords: tropical zooplankton ; crustacea ; copepoda ; taxonomy ; Andes ; Colombia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Calanoid copepods belonging to four species and one subspecies from lakes and ponds mainly from the Cordillera Oriental (22) and Cordillera Central (1) of the Colombian Andes are recorded. Most of the water bodies studied are located in the ‘páramo’ region, between 2996 and 4085 m altitude. The family Boeckellidae is recorded for the first time from Colombia. Taxonomic characteristics of Boeckella occidentalis Marsh, 1906, Boeckella gracilis (Daday,1902) and the diaptomid Prionodiaptomus colombiensis (Thiébaud, 1914) are discussed. A new diaptomid genus, Colombodiaptomus, with one species and one subspecies are established.
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    Genetic resources and crop evolution 46 (1999), S. 469-475 
    ISSN: 1573-5109
    Keywords: foliar blight ; germplasm ; resistance ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract One thousand three hundred and eighty-seven spring wheat germplasm (Triticum aestivum L.) lines belonging to the Indian and CIMMYT wheat programmes were evaluated for their tolerance to foliar blight disease for three consecutive years i.e., from 1994 to 1997. Disease severity at six different growth stages, beginning from tillering to late milk stage, was recorded. None of the genotypes showed immunity to the disease. Of 43 lines showing resistant reaction, a major proportion (25) was represented by CIMMYT material. Comparatively, Indian germplasm lines tended to be more susceptible at more advanced growth stages. Area Under Disease Progress Curve (AUDPC) and Apparent Infection Rate (r) values of resistant lines were much lower than those of susceptible ones, but lower AUDPC in some of the resistant lines did not correspond to a lower 'r' value. Most of the resistant lines were derived from Seri, Myna, Bau, kauz, Hork 's' and Aegilops tauschii Coss.
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