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  • temperature  (38)
  • wheat  (36)
  • Nitrogen fixation
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  • Springer  (114)
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  • 1989  (114)
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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
    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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  • 3
    ISSN: 1570-7458
    Keywords: European corn borer ; Ostrinia nubilalis ; maize ; water ; drought ; stress ; development ; models ; phytotron ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Des plants de maïs se développent dans un phytotron dans 4 conditions d'humidité du sol (de la saturation à la dessication) et à 3 températures constantes (20°, 25° & 30°C). Chaque pied est contaminé au moment de l'émission du pollen, par une ooplaque d'O. nubilalis Hübn. (ECB) de race européenne E. L'installation, la colonisation et le développement des chenilles sont notés lors de 12 périodes de prélèvements destructifs (4 par température). La vitesse de développement d'O. nubilalis est affectée par la température, main non par l'humidité du sol. Les 4 niveaux d'humidité du sol n'ont aucun effet sur la teneur en eau des tiges de maïs. En fait, les feuilles de maïs présentent une senescence précoce lorsqu'il y a déficit en eau dans le sol. La teneur en eau du sol agit sur l'installation, sur la distribution verticale, la dispersion et le lieu d'alimentation des chenilles; mais ces effets sont légers et ne modifient pas la vitesse de développement. L'environnement larvaire dans la tige de maïs est efficacement isolé des variations externes par l'aptitude de la plante à maintenir la teneur en eau des tiges relativement élevée et stable. Ainsi, des changements importants au niveau du sol n'ont pratiquement pas d'effets sur le développement d'O. nubilalis, malgré les conséquences brutales pour la plante. Cette étude montre que la vitesse de développement d'O. nubilalis est relativement insensible aux modifications de la teneur en eau du sol ainsi qu'aux effets de ce stress de sécheresse sévère sur le pied de maïs. La discussion porte sur l'importance de ces résultats pour la modélisation de la dynamique de l'insecte, la physiologie de la culture et les interactions entre insecte et plante.
    Notes: Abstract Maize plants were grown under four moisture regimes (wet to extreme deficit) and three constant temperatures (20°, 25° & 30°C) in a phytotron. Each plant was infested with one E-race European corn borer [Ostrinia nubilalis (Hubn.)] (ECB) egg mass at pollen shed. ECB development, location, and establishment were recorded over the course of 12 destructive sample dates (4/temperature). ECB developmental rates were not significantly affected by soil moisture treatments, but were significantly affected by temperature. In spite of successful establishment of four distinctly different soil moisture regimes, the maize stalk tissue water levels were not significantly different among soil water treatments. Instead, the maize plants exhibited accelerated leaf senescence in response to the water deficit conditions. Among the soil water treatments, differences were found in larval establishment, vertical distribution and dispersion, and feeding site selection; however, those effects were slight and could not explain the similarity in ECB developmental rates observed in these treatments. In maize, the larval environment within the stalk was effectively insulated from changes in the external environment by the plant's ability to maintain a relatively high and stable stalk tissue water content. Thus, large changes to the soil environment had essentially no effect on ECB development, though drastic consequences for the plant. This study indicates that ECB rates of development are relatively insensitive to changes in the soil water environment as well as the associated changes in the maize plant that accompany severe drought stress. The significance of these findings to insect modelling, crop physiology, and insect-crop interactions is discussed.
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  • 4
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    Journal of insect behavior 2 (1989), S. 849-852 
    ISSN: 1572-8889
    Keywords: alternative mating tactics ; temperature ; Stictia heros ; Sphecidae ; Costa Rica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 5
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    Cellular and molecular life sciences 45 (1989), S. 171-173 
    ISSN: 1420-9071
    Keywords: Estrogen receptor ; homogenization ; temperature ; nucleus ; uterus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Homogenization of rat uterus at elevated temperatures results in an increased nuclear localization of unoccupied estrogen receptor. This is a nonlinear effect which is accounted for by an increased population of KCl-resistant nuclear binding sites at the elevated homogenization temperatures.
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  • 6
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    Cellular and molecular life sciences 45 (1989), S. 349-351 
    ISSN: 1420-9071
    Keywords: Spermatogenesis ; temperature ; brain ; hibernation ; Helix aspersa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ablation of the brain from hibernatingHelix aspersa maintained at 25°C causes a significant increase in the proliferation of male cells in the gonad, whereas the ablation of the optic tentacles has no effect. The brain, therefore, produces a factor which specifically inhibits the multiplication of spermatogonia and spermatocytes.
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  • 7
    ISSN: 1570-7458
    Keywords: Coleoptera ; Cerambycidae ; Morimus funereus ; development ; laboratory conditions ; food quality ; temperature ; season
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé L'étude a porté sur les effets d'une température constante (23 °C), de la qualité de l'aliment,-B = aliment naturel, c'est-à-dire de l'écorce de chêne pulvérisée; B+C = aliment naturel enrichi avec de la poudre de biscuits sucrés-, et de la saison sur le développement larvaire de M. funereus L. La température de 23 °C a été défavorable aux larves récoltées en septembre dans des souches de chênes et élevées sur aliment B: les larves étaient mortes en 30 jours. Avec aliment B+C, l'effet défavorable a été neutralisé et le poids des larves augmenté de 543%, 897% et 1179% en 1, 2 et 3 mois. Des larves néonates d'été ou d'hiver se sont bien développées sur B+C, mais toutes les larves d'hiver étaient mortes sur B en 40 j. Des larves de mêmes parents, écloses à différentes époques de l'année, ont présenté des différences saisonnières du taux de survie et de la vitesse de développement lors de leur élevage à 23 °C sur B+C. Le développement le plus rapide et la meilleure survie ont été obtenus avec des larves écloses au début ou au milieu de l'été; tandis que le développement le plus lent et la plus mauvaise survie ont été obtenus avec les larves écloses à la fin de l'été. Les changements saisonniers synchrones des adultes et de leurs descendants, exprimés à différents niveaux d'organisation biologique, suggèrent l'existence d'un rythme annuel endogène qui dépend de l'expression de différents gènes au cours du cycle annuel.
    Notes: Abstract The effects of constant temperature (23 °C), food quality (B, natural diet i.e. powdered oak bark; B+C, natural diet enriched with powdered sweet crackers) and season on larval development of the cerambycid Morimus funereus L. were studied. The temperature of 23 °C exerted an unfavourable effect on larvae collected from oak stumps in September and bred on B; i.e. the larvae died within 30 days. When the larvae consumed B+C the unfavourable effect of temperature was abolished and the larvae increased their weight by 543%, 897% and 1179% in 1, 2 and 3 months, respectively. Newly hatched summerand winter-larvae developed successfully on B+C, while all the winter-larvae died within 40 days on B. Larvae of an identical parentage hatched in different phases of the annual cycle and showed seasonal differences in the rate of development and survival when reared on B+C at 23 °C. The fastest development and the highest survival rate were observed in larvae which emerged in early- and midsummer, whereas the slowest development and the lowest survival rate were in those hatched in late summer. The synchronized seasonal changes of adults and their offspring, as expressed at different levels of biological organization, suggest the existence of an endogenous annual rhythm which is dependent upon the expression of different genes in the course of the annual cycle.
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  • 8
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    Entomologia experimentalis et applicata 52 (1989), S. 185-188 
    ISSN: 1570-7458
    Keywords: Heteroptera ; Dolycoris baccarum ; S. Norwegian population ; adult hibernal diapause ; diapause completion ; diapause activation ; diapause induction ; diapause prevention ; photoperiod ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 9
    ISSN: 1570-7458
    Keywords: Developmental rates ; temperature ; parasitoid ; mealybug ; Hymenoptera ; Encyrtidae ; Epidinocarsis diversicornis ; Acerophagus coccois ; Homoptera ; Pseudococcidae ; Phenacoccus herreni ; cassava ; yucca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les vitesses de développement des oeufs et de tous les stades larvaires mâles et femelles de P. herreni Cox & Williams ont été déterminées à 18°, 20°, 22°, 25°, 30° et 35°C. La longévité des adultes mâles et femelles a été déterminée. Les vitesses de développement de la ponte à la formation du cocon et de celleci à l'émergence de E. diversicornis Howard, encyrtide parasite de P. herreni ont été déterminées à 18°, 20°, 25° et 30°C. Il en a été de même pour un second encyrtide parasite A. coccois Smith à 20°, 25° et 30°C. Les équations polynomiales des derniers carrés dérivés et les équations logistiques ont été ajustées pour chaque lot de données (à l'exception de A. coccois) de façon à ce qu'elles aient pu être interpolées pour analyser l'impact de ces parasites sur la dynamique de population de P. herreni. Les résultats de cette analyse sont présentés à part.
    Notes: Abstract Developmental rates for Phenacoccus herreni Cox & Williams were determined at 18°, 20°, 22°, 25°, 30° and 35°C for the egg, all juvenile male and all juvenile female stadia. Longevity was determined for adult females and adult males. Developmental rates for the P. herreni parasitoid Epidinocarsis diversicornis (Howard) were determined at 18°, 20°, 25° and 30°C for the oviposition-to-mummy-formation period and the mummy-formation-to-adult-eclosion period. Developmental rates were determined for the P. herreni parasitoid Acerophagus coccois Smith for the same two life stages at 20°, 25° and 30°C. Least-squares-derived polynomial equations or logistic equations were fitted to each data set (except for A. coccois) so that rates could be interpolated for temperatures between observed points for use in an analysis of the impact of these parasitoids on population dynamics of P. herreni. Results of this analysis are presented separately.
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  • 10
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    Entomologia experimentalis et applicata 50 (1989), S. 185-193 
    ISSN: 1570-7458
    Keywords: temperature ; development ; simulation ; phenology ; budmoth ; Zeiraphera canadensis ; Tortricidae ; degree-days
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé La diapause des oeufs de Zeiraphera canadensis Mutuura et Freeman (Lepidoptera: Tortricidae) a été complétée après 15 semaines d'élevage à 0,5°C. A ce stade de leur développement, une température supérieure à 30°C leur est létale. Les relations entre la température et le développement des larves sur l'épinette blanche, Picea glauca (Moench) Voss, et des pupes ont été observées au laboratoire. Les temps de développement les plus courts ont été observés à 28°C. Les larves sont tolérantes à la chaleur et se développent à 32 C, une température qui est létale aux pupes. II y a peu de variabilité des taux de développement de tous les stades immatures. Ceci explique le haut degré de synchronie observé au sein de populations de cet insecte. Un modèle simulant la phénologie a été mis au point et calibré pour prédire la fréquence des divers stades du cycle vital sous des conditions de terrain. La processus de calibration a révélé que la température dans le microhabitat des oeufs est très semblable à celle de l'air, mais que les larves, retrouvées sous l'enveloppe des bourgeons, sont exposées à des températures pouvant excéder celle-ci de plusieurs degrés. Pour des fins de planification du synchronisme entre le développement de l'insecte et des programmes de suivi et de lutte, le nombre de degré-jours nécessaires pour atteindre 10% d'éclosion des oeufs ou 75% d'émergence des adultes ont été estimés à partir d'une température seuil de 4,4°C.
    Notes: Abstract Diapause requirements of eggs of Zeiraphera canadensis Mutuura and Freeman (Lepidoptera: Tortricidae) are satisfied by 15 weeks of storage at 0.5°C. Temperatures above 30°C are lethal for this life stage. Temperature-dependent development of larvae fed on white spruce, Picea glauca (Moench) Voss, and of pupae was observed under laboratory conditions. The shortest development times were observed at 28°C. Larvae are tolerant to heat, and developed at 32°C, a lethal temperature for pupae. There was little variation of development rates in all stages of the life cycle, explaining the high degree of phenological synchrony reported in populations of this species. A phenological model was developed and calibrated to simulate the relative abundance of the various immature stages under field conditions. The calibration process suggested that temperature in the microhabitat of eggs may be very close to air temperature, but that temperatures under bud caps where larvae are feeding may rise several degrees above air temperature. For the purposes of planning the timing of survey and control practices, degree-day requirements for 10% egg hatch and 75% adult emergence were estimated based on a 4.4°C threshold temperature.
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  • 11
    ISSN: 1432-0789
    Keywords: Wheat ; Paddy straw compost ; N and P enrichment ; Rock phosphate ; Pyrite ; Triticum aestivum ; Nutrient uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A nutrient-rich compost from paddy straw was prepared using urea and Mussoorie rock phosphate for N and P enrichment respectively. Inorganic N was partly conserved in the compost by the addition of pyrite. Citric-acid-soluble P also increased with the addition of pyrite. Compost containing about 1.6% total N and 3.3% total P was found to be a good source of P for a wheat crop and also supplied a significant amount of N to the plants.
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  • 12
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    Biology and fertility of soils 8 (1989), S. 356-368 
    ISSN: 1432-0789
    Keywords: Plant-root associations ; Azospirillum spp ; Rhizosphere ; Nitrogen fixation ; Acetylene reduction assay (ARA) ; Phytohormones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Bacteria of the genus Azospirillum are extensively studied for their plant-growth promoting effect following inoculation. Physiological and biochemical studies of these diazotrophic bacteria are now benefiting from recent breakthroughs in the development of genetic tools for Azospirilum. Moreover, the identification and cloning of Azospirillum genes involved in N2 fixation, plant interaction, and phytohormone production have given new life to many research projects on Azospirillum. The finding that Azospirillum genes can complement specific mutations in other intensively studied rhizosphere bacteria like Rhizobia will certainly trigger the exploration of new areas in rhizosphere biology. Therefore a review of the Azospirillum-plant interactions is particularly timely.
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  • 13
    ISSN: 1432-0789
    Keywords: Nodule damage ; Rivellia angulata ; Nitrogen fixation ; Cajanus cajan ; Pigeonpea ; Vertisol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Damage caused by Rivellia angulata larvae to pigeonpea root nodules at the ICRISAT center in India was greater in the crop grown on Vertisols (up to 86%) compared to that on Alfisols (20%). Attempts to quantify the field effects of nodule damage on growth and yield of pigeonpea in a Vertisol, involving many heavy applications of soil insecticides (aldrin and hexachlorocyclohexane) failed because the insecticides did not control the pest and adversely affected the growth of the pigeonpea and the subsequent crop of sorghum (Sorgorum bicolor L. Moench). The impact of nodule damage on pigeonpea growth, yield and nutrient uptake was successfully studied in greenhouse-grown plants at three N levels. In this pot study, artificial inoculation with Rivellia sp. led to substantial nodule damage (70%). The results of this damage were a significant overall reduction in nodule dry weight (46%), acetylene reduction activity (31%), total leaf area (36%), chlorophyll content of leaves (39%) and shoot dry weight (23%) 68 days after sowing. At maturity, Rivellia sp. infestation caused significant reductions in top dry weight (22%), root and nodule dry weight (27%), seed dry weight (14%), and total N (29%) and P uptake (19%). The problems and prospects of manipulating nodule damage so as to reduce N losses in pigeonpea are discussed.
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  • 14
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    Biology and fertility of soils 7 (1989), S. 113-119 
    ISSN: 1432-0789
    Keywords: Vesicular-arbuscular mycorrhiza ; Herbicides ; Wheat ; Glomus spp. ; Spore germination ; Root infection ; Triticum aestivum L. ; Bifenox ; Mecoprop ; Difenzoquat methyl sulphate ; Chlortoluron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary We studied the effects of field application rates of four herbicides (Avenge, Ceridor, Dicurane, and Harrier) on spore germination and infection of wheat roots by three species of Glomus grown under conditions of low P availability. Low concentrations of Ceridor (bifenox, mecoprop) and Harrier (mecoprop, ioxynil, clopyralid) inhibited spore germination while higher concentrations were stimulatory. Avenge (difenzoquat methyl sulphate) prevented spore germination completely, while Dicurane (chlortoluron) had no effect. The herbicide applications had no significant effect on the infection rates of any of the three fungi except Harrier on G. geosporum. The herbicide treatments did, however, affect plant growth and ear yields. Ceridor and Harrier increased ear yields, while Dicurane showed marked phytotoxic effects.
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  • 15
    ISSN: 1432-0789
    Keywords: Dentrification ; Immobilization ; Tillage ; N leaching ; Wheat ; Wetland rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A field study was undertaken to examine the effects of various management strategies on wheat (Triticum aestivum L.) performance and N cycling in an intensively cropped soil. Microplots receiving 100 kg N ha−1 as15NH4 + 15NO3 − at sowing, tillering or stem elongation were compared with unfertilized microplots. Stubble from the previous rice crop was either incorporated, burnt without tillage, burnt then tilled or retained on the surface of untilled soil. Wheat grain yield ranged from 1.5 to 5.1 t ha− and was closely related to N uptake. Plant accumulation of soil N averaged 36 kg N ha−1 (LSD 5% = 10) on stubble-incorporation plots and 54 kg N ha−1 on stubble-retention plots. Fertilizer N accumulation averaged 18 kg N ha−1 (LSD 51% = 6) on stubble-incorporation plots and 50 kg N ha−1 on stubble-retention plots. Tillage had little effect on burnt plots. Delaying N application from sowing until stem elongation increased average fertilizer N uptake from 26 to 39 kg N ha−1 (LSD 5% = 6), but reduced soil N uptake from 50 to 37 kg N ha− (LSD 5% = 10). Immobilization and leaching did not vary greatly between treatments and approximately one-third of the fertilizer was immobilized. Less than 1% of the fertilizer was found below a depth of 300 mm. Incorporating 9 t ha−1 of rice stubble 13 days before wheat sowing reduced net apparent mineralization of native soil N from 37 to 3 kg ha−1 between tillering and maturity. It also increased apparent denitrification of fertilizer N from an average 34 to 53 kg N ha−1 (LSD 5% = 6). N loss occurred over several months, suggesting that denitrification was maintained by continued release of metabolizable carbohydrate from the decaying rice stubble. The results demonstrate that no-till systems increase crop yield and use of both fertilizer and soil N in intensive rice-based rotations.
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  • 16
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    Biology and fertility of soils 7 (1989), S. 269-274 
    ISSN: 1432-0789
    Keywords: Nitrogen fixation ; Frankia-Ceanothus spp. association ; Acetylene reduction assay (ARA) ; Microsymbiont population ; Nodules ; Actinomycetes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Wildland shrub improvement is needed for sound range and disturbed land revegetation practice. The possibility of selecting superior N2-fixingFrankia-Ceanothus spp. actinorhizal associations was examined. Greenhouse tests were used to expose various soil-borne microsymbiont andCeanothus sp. population accessions in reciprocal combination. The acetylene reduction rate was used as a measure of N2-fixation capacity. There was no significant interaction between host and microsymbiont regardless of source for all variables measured. The acetylene reduction rate, nodule number and mass, plant biomass, and root: shoot ratio were significantly different among soil sources. The acetylene reduction rate was not significantly different amongCeanothus sp. accessions. Neither was it strongly correlated with other variables. It was concluded that the N2-fixation rate is more a function ofFrankia sp. than the hostCeanothus sp. in actinorhizal associations. It appears possible to select soil sources with superior N2-fixing microsymbiont populations.
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  • 17
    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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  • 18
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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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  • 19
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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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  • 20
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    Biodegradation 7 (1989), S. 159-193 
    ISSN: 1572-9729
    Keywords: Brachiopod biogeochemistry ; diagenesis ; secular isotopic variations ; carbon isotopes ; oxygen isotopes ; Sr/Ca ; temperature ; Recent ; Late Paleozoic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Sr/Ca ratios in modern brachiopod shells reflect variations in ambient seawater, whereas their Na contents show no relationship with water depth or habitat. Their Mn and Fe contents are controlled, in part, by leaching of these elements from oxide coatings or the low input/sedimentation rate of detrital material into depositional areas such as Quatsino Sound. For most Carboniferous brachiopods from North America, the Mn and Fe contents are similar to those recorded by their Recent counterparts. The high Mn and Fe contents in the brachiopods from shales suggest several possibilities for these levels. One possibility is the leaching of Mn and Fe from oxide coatings/matrix which was not completely removed in the cleaning process, or the high levels in part reflect unusual depositional conditions (some degree of anoxia) for the local shaly environments. The Sr/Ca ratio of brachiopods and, by inference, complementary seawater, did not vary significantly during the Carboniferous. The Sr/Ca minimum observed in brachiopods of Mississippian age coincides with a dip in the 87Sr/86Sr curve and correlates with the Hercynian orogeny. This is attributed to the cycling of seawater through mid-ocean ridge basalts, and postulated exchange reactions account for variation in the composition of seawater-Ca. The unidirectional trend of heavier δ13C values from the Devonian to the Permian is intricately coupled with the evolution of the terrestrial biomass. In addition to expansion of terrestrial plants, burial of reduced carbon in the form of coal (organic matter) contributed to the observed shift. The start of the Permo-Pennsylvanian glaciation is marked by a negative excursion of the secular carbon trend, which is linked to weathering of reduced carbon and its return to the oceanic reservoir with its oxidized carbon. The oxygen isotope values reflect the unidirectional trend towards higher values of the carbon data with decreasing geologic age. Negative excursions of the trend may be related to extensive weathering of terrestrial and submarine rocks, whereas positive excursions may be related to hydrothermal alteration of submarine rocks and dehydration of oceanic crust during times of active sea-floor spreading. Oxygen-calculated water temperatures of unaltered brachiopod material are unrealistically high for all of the Devonian, and the Chesterian-Meramecian, Desmoinesian-Missourian, and Artinskian Epochs. During these times maximum water temperatures of 42° to 56°C are well above the thermal threshold of protein denaturation. This process, which is lethal to most higher organisms, demands an adjustment in oxygen of -2.5%. for samples older than Missourian, and of -1.250%. for samples spanning the Missourian-Artinskian interval. With these adjustments and salinity considerations made prior to calculations, water temperatures become reasonable for the Late Paleozoic epeiric, tropical seas of North America.
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  • 21
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    Cellular and molecular life sciences 45 (1989), S. 102-103 
    ISSN: 1420-9071
    Keywords: Djungarian hamster ; photoperiod ; temperature ; T3 ; T4 ; testosterone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of photoperiod, temperature and testosterone treatment on plasma T3 and T4 levels were investigated in the Djungarian hamster. Plasma T3 level was affected by temperature (25°C〈7°C) but not by photoperiod. Plasma T4 level was affected by photoperiod (short day 〈 long day) at 25°C. Administration of testosterone increased plasma T4 level under short photoperiod at 25°C. Thus, higher plasma T4 level under long photoperiod at 25°C might be induced by testosterone.
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  • 22
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    Oecologia 79 (1989), S. 566-568 
    ISSN: 1432-1939
    Keywords: Carbon dioxide ; Lichen ; Lobaria ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Thalli of Lobaria pulmonaria (L.) Hoffm., a nitrogen-fixing epiphyte common in mesic temperate forests, were collected in a Douglas-fir (Pseudotsuga menziesii Franco) forest near Corvallis, Oregon, and maintained for 20 to 40 days in controlled-environment chambers with atmospheric CO2 concentrations of 374 and 700 μll-1. Nitrogenase activity, which was assayed by the acetylene reduction method, was approximately doubled in the lichen maintained in elevated CO2. Increases in nitrogen fixation by lichens may be an important part of the integrated ecosystem response to rising CO2.
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  • 23
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    Archives of microbiology 151 (1989), S. 445-453 
    ISSN: 1432-072X
    Keywords: Denitrification ; Growth yield measurements ; Nitrate respiration ; Nitrogen fixation ; Proton translocations in respirations ; Azospirillum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract For Azospirillum brasilense Sp7, the energy transformation efficiencies were measured in anaerobic respirations with either nitrate, nitrite or nitrous oxide as respiratory electron acceptors by determining the maximal molar growth yields and the H+-translocations using the oxidant pulse method. In continuous cultures grown with malate limiting, the maximal molar growth yields (Y s max -values) were essentially the same with O2 or N2O but were 1/3 and 2/3 lower with NO 2 - or NO 3 - , respectively, as respiratory electron acceptors. Both the maximal molar growth yields and the maintenance energy coefficients were surprisingly high when Azospirillum was grown with nitrite as the sole electron acceptor and source for N-assimilation. Growth under N2-fixing conditions drastically reduced the Y s max -values in the N2O and O2-respiring cells. In the H+-translocation measurements, the $$\vec H^ + $$ /oxidant ratios were 5.6 for O2→H2O, 2.5–2.8 for NO 3 - →NO 2 - , 2.2 for NO 2 - →N2O and 3.1 for N2O→N2 respirations when the cells were preincubated with valinomycin and K+. All the values were enhanced when the experiments were performed with valinomycin plus methyltriphenylphosphonium (=TPMP+) cation. The uncoupler carbonyl cyanide-m-chlorophenyl-hydrazone diminished the H+-excretion indicating that this translocation was due to vectorial flow across the membrane. In the absence of any ionophore, nitrate and nitrite respirations were accompanied by a H+-uptake $$(NO_3^ - \to N_2 = - 2.9 \vec H^ + /NO_3^ - and NO_2^ - \to N_2 = - 2.5 \vec H^ + /NO_2^ - )$$ . Any significant H+-translocation could not be detected in N2O- and O2-respirations under these conditions. It is concluded that nitrate reduction proceeds inside the cytoplasmic membrane, whereas nitrite is reduced extramembraneously. The data are not conclusive for the location of nitrous oxide reductase. The maximal molar growth yield determinations and the absence of any H+-uptake in untreated cells indicate a cytoplasmic orientation of the enzyme similar to the terminal cytochrome oxidase of respiration. The low H+-extrusion values for N2O-respiration compared to O2-respiration in cells treated with valinomycin plus TPMP+ are, however, not in accord with such an interpretation.
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  • 24
    ISSN: 1432-072X
    Keywords: Bradyrhizobium ; Gene cloning ; Heme ; Marker exchange mutagenesis ; Nitrogen fixation ; Respiration ; Symbiosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Random and site-directed Tn5-induced mutagenesis of Bradyrhizobium japonicum yielded two mutations, one in strain 2960 and the other in strain 2606::Tn5-20, which mapped close to each other but in separate genes. The corresponding wild-type genes were cloned, and their approximate location on the cloned DNA was determined. Mutant 2960 was Fix- and formed green nodules on soybean, whereas strain 2606::Tn5-20 had ca. 4% of wild-type Fix activity and formed white nodules. Cytochrome oxidase assays (Nadi tests) showed a negative reaction with both mutants, indicating a functional deficiency of cytochrome c or its terminal oxidase or both. However, the mutants grew well under aerobic conditions on minimal media with different carbon sources. Furthermore, mutant 2960 had a reduced activity in hydrogen uptake, was unable to grow anaerobically with nitrate as the terminal electron acceptor and 2960-infected soybean nodules contained little, if any, functional leghemoglobin. Southern blot analysis showed that a B. japonicum heme biosynthesis mutant [strain LO505: O'Brian MR, Kirshbom PM, Maier RJ (1987) Proc Natl Acad Sci USA 84: 8390–8393] had its mutation close to the Tn5 insertion site of our mutant 2606::Tn5-20. This finding, combined with the observed phenotypes, suggested that the genes affected in mutants 2960 and 2606::Tn5-20 were involved in some steps of heme biosynthesis thus explaining the pleiotropic respiratory deficiencies of the mutants. Similar to strain LO505, the mutant 2606::Tn5-20 (but not 2960) was defective in the activity of protoporphyrinogen IX oxidase which catalyzes the penultimate step in the heme biosynthesis pathway. This suggests that one of the two cloned genes may code for this enzyme.
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  • 25
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    Archives of microbiology 151 (1989), S. 180-182 
    ISSN: 1432-072X
    Keywords: Klebsiella pneumoniae ; Nitrogen fixation ; nifL ; Regulation ; Oxygen control ; Nitrogen control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A number of in-frame deletions have been constructed in the Klebsiella pneumoniae regulatory gene nifL. The effects of each nifL mutation on NifA-mediated expression from the nifH promoter of K. pneumoniae have then been assessed with respect to both nitrogen and oxygen control. These experiments indicate that, in contrast to the situation with the homologous regulatory proteins NtrB and NtrC, NifA activity is not impaired in the absence of NifL. We conclude that the only function of NifL is to inactivate NifA in response to an increase in the nitrogen or oxygen status of the cell.
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  • 26
    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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  • 27
    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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  • 28
    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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  • 29
    ISSN: 1573-5028
    Keywords: F1F0 ATPase ; chloroplast coupling factor ; mitochondrial gene ; wheat
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  • 30
    ISSN: 1432-2048
    Keywords: Glutamate synthase ; Glutamine synthetase ; Nitrogen fixation ; Phaseolus (glutamate synthase) ; Plastid (glutamate synthase) ; Root nodule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The two isoenzymes of NADH-dependent glutamate synthase (NADH-GOGAT; EC 1.4.1.14), previously identified in root nodules of Phaseolus vulgaris L., have both been shown to be located in root-nodule plastids. The nodule specific NADH-GOGAT II accounts for the majority of the activity in root nodules, and is present almost exclusively in the central tissue of the nodule. However about 20% of NADH-GOGAT I activity is present in the nodule cortex, at about the same specific activity as this isoenzyme is found in the central tissue. Glutamine synthetase (GS; EC 6.3.1.2) occurs predominantly as the γ polypeptide in the central tissue, whereas in the cortex, the enzyme is represented mainly by the β polypeptide. Over 90% of both GS and NADH-GOGAT activities are located in the central tissue of the nodule and GS activity exceeds NADH-GOGAT activity by about twofold in this region. Using the above information, a model for the subcellular location and stoichiometry of nitrogen metabolism in the central tissue of P. vulgaris root nodules is presented.
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  • 31
    ISSN: 1432-203X
    Keywords: Wheat ; Maize ; Intergeneric cross-Embryo culture ; Haploid production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Four Japanese wheat varieties, three crossable and one non-crossable with Hordeum bulbosum, were pollinated with maize pollen of 5 genotypes. By the application of 2,4-dichlorophenoxyacetic acid after pollination, embryos kept developing on wheat plants until 14 days after pollination. The frequency of embryo formation was significantly different among the maize genotypes, varying from 18.0% to 31.9%, but not among the wheat varieties. By bagging spikes with flag leaves the frequency of embryo formation was increased by about 7%. Ten- to twelve-day-old embryos gave higher frequencies of plant formation (83.6%) than 14-day-old embryos(50.0%). All 6 regenerated plants investigated cytologically were found to be haploid. Twelve of the 14 colchicine-treated plants produced florets setting seeds. The overall efficiency of our procedure is considered to be higher than that reported by Laurie and Bennett (1988).
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  • 32
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    The journal of membrane biology 112 (1989), S. 277-289 
    ISSN: 1432-1424
    Keywords: myelinated nerve fiber ; gating current ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Asymmetrical displacement currents and Na currents of single myelinated nerve fibers ofXenopus laevis were studied in the temperature range from 5 to 24°C. The time constant of the on-response atE=4 mV,τ on, was strongly temperature dependent, whereas the amount of displaced charge atE=39 mV, Qon, was only slightly temperature dependent. The mean Q10 forτ on -1 was 2.54, the mean Q10 for Qon was 1.07. The time constant of charge immobilization,τ i , atE=4 mV varied significantly (α=0.001) with temperature. The mean Q10 forτ i -1 was 2.71±0.38. The time constants of immobilization of gating charge and of fast inactivation of Na permeability were similar in the temperature range from 6 to 22°C. The Qoff/Qon ratio forE=4 mV pulses of 0.5 msec duration decreased with increasing temperature. The temperature dependence of the time constant of the off-response could not be described by a single Q10 value, since the Q10 depended on the duration of the test pulse. Increasing temperature shifted Qon (E) curves to more negative potentials by 0.51 mVK −1, but shiftedP Na (E) curves andh ∞ (E) curves to more positive potentials by 0.43 and 0.57 mV K−1, respectively.h ∞ (E=−70 mV) increased monotonously with increasing temperature. The present data indicate that considerable entropy changes may occur when the Na channel molecule passes from closed through open to inactivated states.
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  • 33
    ISSN: 1432-2242
    Keywords: Mitochondrial DNA ; Chondriome variability ; In vitro culture ; Plant regeneration ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Plants have been regenerated from short-and long-term in vitro somatic tissue cultures made from immature embryos of the hexaploid wheat cultivar “Chinese Spring”. The mitochondrial genome organization of each regenerated plantlet was studied, after one selfing, by probing Sal I-restricted total DNA with cloned Sal I fragments of wheat mitochondrial DNA derived from a segment of the genome, which displays marked structural changes in response to in vitro culture. Short-term in vitro cultures give rise to regenerated plants whose mitochondrial genome organization is either close to that of the parental cultivar or to that of embryogenic callus cultures, except for a single plant which has an organization resembling that of short-term non-embryogenic cultures. In contrast, all but one of the plants regenerated from long-term cultures exhibited a mitochondrial genome organization similar to that of long-term nonembryogenic cultures. In addition, extra labelled bands were detected in some of the regenerated plants with two of the probes used. These results emphasize the importance of the duration of the in vitro step preceding the regeneration process: the longer it is, the higher the probability is of obtaining mitochondrial DNA variability in regenerated plants. Furthermore, since increasing the duration of the in vitro stetp results in the production of regenerated plants with a mitochondrial genome organization resembling that of non-embryogenic tissue cultures, the question is thus raised as to whether regeneration from long-term cultures is suitable for use in plant breeding.
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  • 34
    ISSN: 1432-2242
    Keywords: Wheat ; Aegilops ventricosa ; Powdery mildew resistance ; Biochemical markers ; Addition and transfer lines
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    Topics: Biology
    Notes: Summary The gene encoding a variant of alcohol dehydrogenase, Adh-μ, has been found to be associated with the chromosome of the Mv genome which is present in type 9 wheat/Aegilops ventricosa addition line, to which the genes for protein CM-4 and for a phosphatase variant, Aph-v, had been previously assigned. Transfer line H-93-33, which has 42 chromosomes and has been derived from the cross (Triticum turgidum x Ae. ventricosa) x T. aestivum, carries genes encoding all three biochemical markers. Linkage between these genes has been demonstrated by analysis of individual kernels of the F2 (H-93-33 x T. aestivum cv. “Almatense” H-10-15). A study of the hybrids of line H-93-33 with T. aestivum H-10-15 and with the 4DS ditelosomic line has confirmed that, as suspected, the linkage group corresponds to chromosome 4Mv from Ae. ventricosa. Additionally, it has been found that the previously reported resistance of line H-93-33 to powdery mildew (Erysiphe graminis) is also linked to the biochemical markers; this indicates that either the gene responsible for it is different from that in lines H-93-8 and H-93-35, or that a translocation between two different Mv chromosomes has occurred in line H-93-33.
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  • 35
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    Theoretical and applied genetics 77 (1989), S. 516-520 
    ISSN: 1432-2242
    Keywords: Wheat ; Single seed descent (SSD) ; Single plant selection (SPS) ; Bulk population (BP) ; Mechanical mass selection (MMS)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Four methods of generation advance (SPS, SSD, BP and MMS) were compared in F3 and F4 generations. In the F3 generation, the SPS and SSD methods of generation advance proved superior to the BP and MMS methods for grain yield per plant and for at least one of the yield component traits. The F3 SSD population did not differ significantly from the F3 SPS for any of the traits. However, the F3 SSD population retained more range and cv for different traits than with other methods of generation advance. F4 progenies derived from F3 SSD population were significantly superior for grain yield than lines derived from the other three F3 populations. The MMS method of generation advance proved useful for increasing the 1,000-grain weight for which initial selection was made.
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  • 36
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    Theoretical and applied genetics 77 (1989), S. 685-688 
    ISSN: 1432-2242
    Keywords: Wheat ; Triticale ; Cytoplasmic effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Thirteen wheat-like advanced-generation triticale x wheat derivatives, having tetraploid wheat cytoplasm from triticale, were reciprocally crossed with three improved bread wheats, and the resulting F1s were evaluated for determining the comparative performance of the bread wheat and triticale cytoplasms for different traits. Significant reciprocal differences in the mean performance were observed for days to heading, days to maturity, spikes/plant, flag-leaf area, peduncle length, plant height, spike length, grains/spike, 1,000-grain weight, grain yield and grain protein content, and most of them were in favour of hexaploid wheat cytoplasm. However, this superiority of the hexaploid cytoplasm was not universal for a particular trait, implying that the differences in the performance of the evaluated reciprocal crosses depended not solely on the cytoplasmic background, but also on the interplay of the specific genotype with the cytoplasm.
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  • 37
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    Theoretical and applied genetics 77 (1989), S. 809-814 
    ISSN: 1432-2242
    Keywords: Wheat ; Ribosomal DNA ; Tissue culture ; Somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In a previous study we observed extensive Nor region variability in tissue-culture derived plants of only one out of three tested wheat cultivars. This finding prompted us to further question whether or not this variability was invariably caused by in vitro culture. In the present study, the upper halves of spikes from four source plants of the inbred cultivar ‘ND7532’ were removed 12 days after anthesis. The immature embryos from these halves were cultured and regenerated into plants. The lower halves of the same spikes were retained on the plants to obtain mature caryopses. DNA was extracted from seedlings, cut with TaqI endonuclease, run on agarose gels, and the respective Southern blots were probed with the plasmid pTA71 to reveal the Nor region patterns. The sexual progeny of regenerants from three out of four source plants derived from the immature embryos provided Nor region patterns which were exactly identical to the patterns obtained from seedlings which germinated from the caryopses matured on the respective source spikes. The regenerants from the fourth source plant provided variable Nor region patterns. Analyses of the Nor region patterns of 21 individual seedlings germinated from caryopses of this source plant showed that 18 had a three-fragment pattern (consisting of 3.0, 2.7 and 1.9 kb fragments) while three seedlings lacked one (2.7 of 1.9 kb) fragment. Furthermore, the next sexual progeny of the regenerants which had a three-fragment pattern further segregated into three- and two-fragment patterns.These results, in conjunction with previous reports on Nor region variability among tissue-culture derived plants, suggest that this variability is not invariably related to in vitro culture.
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    Theoretical and applied genetics 78 (1989), S. 57-60 
    ISSN: 1432-2242
    Keywords: Hybrid necrosis ; Wheat ; Immature embryoculture ; Young ear culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Hybrid necrosis in wheat is a barrier to gene transfer in wheat breeding practice. It is based on two complementary genes, Ne1 and Ne2. Recovery mutants (Re1, Re2 and Re3) which can grow to maturity were recovered from immature embryo cultures of necrotic hybrids between T. aestivum and T. durum. Cytological observation demonstrated that Re1 had 34 chromosomes instead of 35. This indicated that one of the chromosomes carrying the Ne genes was lost. Genetic study suggested that for Re1, the lost chromosome was chromosome 5B of the durum parental line. Re mutants are male sterile but can be maintained through a young ear culture method. Re mutants could be successfully pollinated by either parental line and the BC1 progeny is partially fertile. Re mutants were repeatedly induced in about 1% of the regenerated plants from immature embryo culture. This technique provides a practical way to bypass hybrid necrosis.
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  • 39
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    Theoretical and applied genetics 78 (1989), S. 137-142 
    ISSN: 1432-2242
    Keywords: Wheat ; Diallel analysis ; Somatic embryogenesis ; Plant regeneration ; In vitro culture
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    Topics: Biology
    Notes: Summary Diallel analyses of F1 and reciprocal crosses among five winter wheat lines show that additive, non-additive, and cytoplasmic genetic effects were significant in the genetic control of somatic embryogenesis, shoot, and root induction frequencies as well as in numbers of somatic embryos, shoots, and roots. However, additive genetic effect appears to be most important since, in most cases a larger portion of the cross variation was accounted for by general combining ability. The results suggest that somatic embryogenesis and organ regeneration in winter wheat can be improved through genetic manipulation. Due to the presence of maternal effects, it may be critical to use a suitable genotype as a female parent in a selection program.
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  • 40
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    Theoretical and applied genetics 78 (1989), S. 783-787 
    ISSN: 1432-2242
    Keywords: Tissue culture ; Callus ; Wheat ; Ditelosomics ; Nullisomic-tetrasomics
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    Notes: Summary The ability of immature embryos of wheat (Triticum aestivum L.) to respond to tissue culture has been shown to involve the group 2 chromosomes. The available group 2 ditelosomic and nullisomic-tetrasomic lines of ‘Chinese Spring’ wheat were used to determine the chromosome arm location and chromosome dosage effect associated with the expression of tissue culture response (TCR). Significant differences were found between the aneuploid lines and the euploid control for the expression of both regenerable callus formation and callus growth rate. A model is proposed suggesting that a major TCR gene is located on 2DL and that 2AL and 2BS possess minor TCR genes. Furthermore, a major regulatory gene controlling the expression of TCR genes may be located on chromosome 2BL.
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  • 41
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    Theoretical and applied genetics 78 (1989), S. 867-872 
    ISSN: 1432-2242
    Keywords: Wheat ; Cytoplasm ; Anther culture ; Microspore embryogenesis
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    Topics: Biology
    Notes: Summary Anthers were cultured from two sets of seven lines of hexaploid wheat (Triticum aestivum L.) with different cytoplasms, the euplasmic nucleus donors, ‘Siete Cerros 66’ and ‘Penjamo 62’, as well as their six alloplasmic lines derived from wild relative species of the genera Triticum and Aegilops. Significant cytoplasmic and nuclear effects but no cytoplasmic-nuclear interaction were found for embryogenic anther response, with the best performance of ‘Penjamo 62’ in Ae. kotschyi cytoplasm. Plant regeneration was not affected significantly by the cytoplasmic background of the lines cultured. The possible genetic implications of the observed cytoplasmic and nuclear influences on the in vitro haploid induction of wheat are discussed.
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  • 42
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    Keywords: Wheat ; Anther culture ; Regeneration ability
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    Notes: Summary Marked effects of genotype on wheat anther culture response have been observed. Genetic factors have been recognised to be one of the major contributors to in vitro responses of cultured wheat tissues. In wheat anther culture, embryo induction, plant regeneration and albina/green ratio have been determined to be heritable traits. Using Chinese Spring (CS) monosomic 1D, single chromosome substitution lines of chromosome 5B or chromosome arm 5BL from Chinese Spring into six varieties, and F1 hybrids heterozygous for the 1B chromosome structure (1BL-1BS/1BL-1RS), the anther culture response was studied: genes on CS1D chromosome and 5BL chromosome arm increases the embryo frequency; gene(s) involved in regeneration ability are located on the 1RS chromosome arm; a gene increasing albina frequency is located on Chinese Spring 5B chromosome. Our results support the fact that without gametic selection, a differential development occurred from the particular classes of microspores carrying genes for higher regeneration ability. Moreover, in some crosses, a few genes with major effects were involved in determination of anther culture response.
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  • 43
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    Theoretical and applied genetics 78 (1989), S. 173-176 
    ISSN: 1432-2242
    Keywords: Wheat ; Tiller index ; Competitive ability ; Interplant competition ; Modified pedigree method of selection
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    Notes: Summary A dismal 81% failure of newly bulked lines against checks was observed in Indian wheat material evolved by the pedigree method. This is considered to be the consequence of selection in space planting in early generations followed by yield tests in a competitive environment which did not allow any scope of selection for competitive ability. Thus, most of the homozygous lines, which were until now raised and carried forward under space planting, failed to compete with the checks for yield in close planting. It is, therefore, necessary to modify the method to combine both the competitive ability and identity of selected plants. The proposed modified procedure involves raising the population under spaced planting as well as under drilling from F2 onwards. Evaluation for tiller index marks an important step. On the basis of tiller index, single plants are isolated from spaced populations. Steps of the modified procedure are outlined in detail. The modified method, which economises on breeders' workload and other physical inputs, besides having other advantages, can also be used for certain other grain crops. Preliminary results based on the modified method during the past two seasons have indicated its utility.
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  • 44
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    Theoretical and applied genetics 78 (1989), S. 349-352 
    ISSN: 1432-2242
    Keywords: Wheat ; Malate dehydrogenase ; Isozymes ; Triticeae
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    Notes: Summary A third set of malate dehydrogenase loci have been identified and located on the short arms of homoeologous group 5 chromosomes in wheat. Allelic differences have been found at each of the three Mdh-3 loci. However, Mdh-D3 appears to be least variable, with a second allele found only in Sears' ‘Synthetic’ among a survey of 42 varieties. Homoeoloci were identified on chromosome 7 (5H) of Hordeum vulgare, the short arm of 5E in Agropyron elongatum and 5U in Aegilops umbellulata.
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    Theoretical and applied genetics 78 (1989), S. 433-435 
    ISSN: 1432-2242
    Keywords: Rhizobium ; Irradiation ; Nitrogen fixation ; Vicia
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    Notes: Sumary The objective of this work was to know the behaviour and variability of Rhizobium leguminosarum after irradiation. The induced variation was tested under greenhouse conditions on the variety JV 3 of broad beans (Vicia faba) in six replications. Induced genetic variabilty was observed for strain, parent and mutant versus parent. Out of 24 irradiated strains, strain 93-32 performed better with a greater number of nodules and higher dry weight of nodules per plant and biological yield. Environment played an important role in the expression of characters observed. High heritability and genetic advance of these traits indicated that the nitrogen fixation ability of Rhizobium can easily be improved by selection.
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  • 46
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    Theoretical and applied genetics 78 (1989), S. 436-444 
    ISSN: 1432-2242
    Keywords: Intergeneric hybrids ; Wheat ; Leymus ; Chromosome pairing ; Meiosis
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    Notes: Summary Hybrid plants were obtained between Triticum aestivum (2n=6x=42, AABBDD) and Leymus innovatus (2n=4x=28, JJNN) at a frequency varying from 0.4% to 1.2% of the pollinated florets. Improvement of the embryo culture medium resulted in a higher frequency of embryo rescue. Eight of ten hybrids had the expected chromosome number of 35 (ABDJN). Meiotic analysis indicated that there was no homology between the genomes of the two species. Two hybrids had only 28 chromosomes. Comparison of chromosome pairing between the two types of hybrids suggested that Leymus innovatus carries genes that affect chromosome pairing and behavior. The relatively high occurrence of spontaneous doubling in the meiocytes of these hybrids may indicate that backcrossing of the hybrids to wheat should be possible, although frequent chromosome irregularities observed in the meiocytes of the hybrids may decrease the probability of success of this step, which is essential to the process of gene transfer from L. innovatus to wheat.
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  • 47
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    Theoretical and applied genetics 78 (1989), S. 495-504 
    ISSN: 1432-2242
    Keywords: Wheat ; Genetic mapping ; RFLPs ; Isozymes
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    Notes: Summary Restriction fragment length polymorphism (RFLP) mapping was attempted using 18 cDNA clones, 14 anonymous and 4 of known function, which had been shown to have homologous DNA sequences on the group 7 chromosomes of wheat. The loci identified by these probes have been mapped on one or more chromosomes in this homoeologous group using linkage data derived from various F2, random inbred, doubled haploid and single chromosome recombinant populations. The maps also include three isozyme loci, five disease resistance loci, two anthocyanin pigment loci and a vernalisation response locus. The mapping data have been used to determine the extent of map co-linearity over the A, B and D genomes, the degree of RFLP variability in the three genomes and the relative efficiency of various restriction enzymes in detecting RFLPs in wheat. The strategy for future mapping in wheat, particularly the use of “alien” genomes or segments, such as that from Aegilops ventricosa used here, is discussed.
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  • 48
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    Theoretical and applied genetics 78 (1989), S. 657-664 
    ISSN: 1432-2242
    Keywords: Aminopeptidase ; Wheat ; Isoelectric focussing ; Isozymes
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    Notes: Summary Isoelectric focussing was used to separate the isozymes of aminopeptidase of wheat and its relatives. Three distinct homoeoallelic sets of genes have been shown to be present. AMP-1, controlled by genes on the long arms of group 6, has previously been described, but two new systems, AMP-2 (group 4) and AMP-3 (group 7) are described here. The three systems are distinguished by their electrophoretic characteristics, by their genetic control and by their substrate specificity. Intervarietal, interspecific and intergeneric polymorphism has been observed at most of the loci. A further set of isozymes, AMP-4, was detected but the chromosomal control of these could not be determined.
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  • 49
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    Theoretical and applied genetics 78 (1989), S. 879-883 
    ISSN: 1432-2242
    Keywords: Wheat ; Anther culture ; Androgenetic responsiveness ; Albinism ; Genetic control
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    Notes: Summary Inheritance of the ability to respond in wheat anther culture was studied from 6×2 reciprocal crosses between six varieties with high and two varieties with low capacity for green plant formation and their parents, replicated in two environments. Effects of genotypes dominated embryo formation and percentages of green plants, accounting for 78.4% and 85.4% of total variation, respectively, while smaller genetic effects were indicated for regeneration. Nuclear genes could explain almost all the genotype effects in this material. Embryo formation showed heterosis over high parent for 5 of the 12 hybrids, while percentages of green plants from the hybrids were intermediate to the parents. General Combining Ability (GCA) could explain 78.8% of the variation for embryo formation among the hybrids, whereas differences in percentage of green plants were dominated by Specific Combining Ability (SCA), accounting for 67.9% of hybrid variation. A positive correlation (r=0.81**) was observed between the genetic capacity for regeneration and green plant formation. Analysis of covariance indicated that effects causing GCA for green plant formation were mainly responsible for this correlation. A regression model with two parallel lines divided the six parent lines with high green plant formation into three groups with respect to their reactions with the two testers. The results are discussed with regard to possible involvement of two sets of nuclear genes affecting the percentage of green plants obtained in wheat anther culture: one set consisting of mainly additive effects affecting green plant percentage through an initial effect on regeneration ability, and another set of two or a few more major genes with dominance or epistatic effects uncorrelated with regeneration.
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    Molecular genetics and genomics 216 (1989), S. 484-491 
    ISSN: 1617-4623
    Keywords: Nitrogen fixation ; nifL ; Repression ; Metal ions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ability of the Klebsiella pneumoniae nifL gene product to antagonise NIFA mediated transcriptional activation from the nifH promoter in vivo was inhibited either by metal deprivation, or by the presence of the iron chelators EDDA or Desferal in the growth medium. This inhibition of the repressive activity of NIFL was reversed by the addition of ferrous or manganous ions to the medium but was unaffected by other transition metals. The dependence on metal ions for NIFL activity was observed when NIFL was overexpressed and when cultures were exposed to oxygen or high levels of fixed nitrogen. Immunochemical evidence suggests that NIFL and NIFA associate to form a functional protein complex. Metal ions are apparently not required for the formation of this complex.
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  • 51
    ISSN: 1617-4623
    Keywords: glnB ; Klebsiella pneumoniae ; Nitrogen control ; Glutamine synthetase ; Nitrogen fixation
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    Notes: Summary The role of theKlebsiella pneumoniae PII protein (encoded byglnB) in nitrogen regulation has been studied using two classes ofglnB mutants. In Class I mutants PII appears not to be uridylylated in nitrogen-limiting conditions and in Class II mutants PII is not synthesised. The effects of these mutations on expression from nitrogen-regulated promoters indicate that PII is not absolutely required for nitrogen control. Furthermore the uridylylated form of PII(PII-UMP) plays a significant role in the response to changes in nitrogen status by counteracting the effect of PII on NtrB-mediated dephosphorylation of NtrC. PII is not involved in thenif-specific response to changes in nitrogen status mediated by NifL.
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  • 52
    ISSN: 1617-4623
    Keywords: LMW glutenin ; Seed storage protein ; Molecular evolution ; Tissue-specific expression ; Wheat
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    Notes: Summary The isolation and characterisation by DNA sequencing of a low molecular weight (LMW) glutenin gene from wheat is described. The deduced protein contains a signal peptide, a central repetitive region rich in proline and glutamine and N and C terminal non-repetitive domains, similar to other prolamins. A detailed comparison of the C terminal domain of 20 prolamin genes enabled us to divide them into 4 families. The LMW glutenin family is distinct from the α, β-and γ-gliadin families of wheat and is closest to the B hordein genes of barley. This and other comparisons were also used to assess the pattern of genetic variation among prolamin sequences and to provide a molecular basis for the interpretation of prolamin size polymorphism. The 5′ flanking fragment of the isolated gene was previously shown to direct endosperm-specific expression of a reporter gene in transgenic tobacco. Evidence is provided that the isolated gene is also active in wheat and its transcription initiation site was determined. Features of the gene which may be relevant to its activity are discussed.
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  • 53
    ISSN: 1617-4623
    Keywords: Rhodobacter capsulatus ; Nitrogen fixation ; DNA sequence analysis ; nifE, nifN, nifX genes ; Protein comparisons
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    Notes: Summary Rhodobacter capsulatus genes homologous to Klebsiella pneumoniae nifE, nifN and nifX were identified by DNA sequence analysis of a 4282 bp fragment of nif region A. Four open reading frames coding for a 51188 (NifE), a 49459 (NifN), a 17459 (NifX) and a 17472 (ORF4) dalton protein were detected. A typical NifA activated consensus promoter and two imperfect putative NifA binding sites were located in the 377 bp sequence in front of the nifE coding region. Comparison of the deduced amino acid sequences of R. capsulatus NifE and NifN revealed homologies not only to analogous gene products of other organisms but also to the α and β subunits of the nitrogenase iron-molybdenum protein. In addition, the R. capsulatus nifE and nifN proteins shared considerable homology with each other. The map position of nifX downstream of nifEN corresponded in R. capsulatus and K. pneumoniae and the deduced molecular weights of both proteins were nearly identical. Nevertheless, R. capsulatus NifX was more related to the C-terminal end of NifY from K. pneumoniae than to NifX. A small domain of approximately 33 amino acid residues showing the highest degree of homology between NifY and NifX was also present in all nifB proteins analyzed so far. This homology indicated an evolutionary relationship of nifX, nifY and nifB and also suggested that NifX and NifY might play a role in maturation and/or stability of the iron-molybdenum cofactor. The open reading rame (ORF4) downstream of nifX in R. capsulatus is also present in Azotobacter vinelandii but not in K. pneumoniae. Interposon-induced insertion and deletion mutants proved that nifE and nifN were necessary for nitrogen fixation in R. capsulatus. In contrast, no essential role could be demonstrated for nifX and ORF4 whereas at least one gene downstream of ORF4 appeared to be important for nitrogen fixation.
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    Protoplasma 150 (1989), S. 19-26 
    ISSN: 1615-6102
    Keywords: Nitrogen fixation ; Peanut ; Root nodules ; Dense body ; Microbody ; Oleosome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Nitrogen-fixing peanut root nodules are characterized by their unique structural organization, distinct from other legume nodules. The focus of this study has been in and around the hostsymbiont interface, where the bacterioid and the host cell surface (peribacteroid membrane envelope) interact during symbiosis. The infected nodule cells have revealed the presence of lipid bodies (oleosomes) in intimate association with the peribacteroid membrane, which encloses the large spherical bacteroids with a relatively narrow peribacteroid space. Electron dense structures, referred to as dense bodies have been found attached to the bacteroid outer membranes at the host-symbiont interface. The dense bodies are osmiophilic, amorphous and 3,3′-diaminobenzidine positive. The isolated intact bacteroids with dense bodies attached to their cell wall showed significant catalase activity. Many microbodies showing DAB-positive reaction have been found in the host cytoplasm, associated closely with the peribacteroid membrane. These ultrastructural and cytochemical characteristics of peanut root nodules suggest that lipids are utilized during symbiosis and the dense bodies and microbodies may be involved in the catabolic process.
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  • 55
    ISSN: 1615-6102
    Keywords: Plectonema boryanum ; Cyanobacteria ; Ultrastructure ; Nitrogen fixation ; Nitrogen starvation ; Immunogold localization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of fructose-supplemented and unsupplemented nitrogen-fixing (fix +) and nonfixing (fix −)Plectonema boryanum UTEX 581 cells was examined by transmission electron microscopy. The most prominent structural differences included the arrangement and morphology of the thylakoids and alterations in the appearance of the interthylakoidal spaces. These ultrastructural differences, together with other observations such as glycogen content and presence of nitrogenase (using acetylene reduction assay and immunogold localization), readily distinguished nonfixingP. boryanum from nitrogen-fixing cells.
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  • 56
    ISSN: 1615-6102
    Keywords: Legumes ; Nitrogen fixation ; Nodulation ; Rhizobium ; Symbiosis
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    Notes: Summary Two methods have been developed in order to discriminate between lateral roots, nodules and root-derived structures which exhibit both root and nodule histological features and which can develop on legumes inoculated with certainRhizobium mutants. The first method, known as the “clearing method”, allows the observation by light microscopy of cleared undissected root-structures. The second, known as the “slicing method”, is a complementary technique which provides a greater degree of structural information concerning such structures. The two methods have proved invaluable in defining unequivocally the nature of the interaction between a rhizobial strain and a legume host.
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    Journal of applied phycology 1 (1989), S. 59-65 
    ISSN: 1573-5176
    Keywords: temperature ; acclimation ; Eucheuma alvarezii ; Eucheuma isiforme
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    Topics: Biology
    Notes: Abstract Branch cultures ofEucheuma alvarezii Doty var.tambalang Doty, farmed in the Philippines, andE. isiforme (C. Agardh) J. Agardh var.denudatum Cheney, from the west coast of Florida, were gradually transferred through three temperature regimes over a 6-week period. Photosynthetic responses were measured under a series of irradiances (P-I curves) and temperatures to determine immediate responses of the plants before, during and after completion of the transfers. The Philippine variety did not show acclimation to 18 °C either after gradual transfer from the initial culture temperature of 25 °C or when abruptly transferred from 25 to 18 °C. The Florida variety did show acclimation to 25 °C when gradually transferred from 18 to 22 to 25 °C over the 6-week period, but not if abruptly transferred from 18 to 25 °C. The west coast variety ofE. isiforme from Florida shows a temperature acclimation ability that parallels the seasonal changes in water temperature of its habitat.
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    Plant and soil 119 (1989), S. 87-97 
    ISSN: 1573-5036
    Keywords: irradiance ; root development ; root growth ; shoot development ; shoot growth ; temperature ; thermal time ; winter wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Wheat plants were grown in columns of soil until early stem elongation at a wide range of constant root temperatures. Two light environments were imposed and three levels of nitrogen fertilizer added at sowing. Shoot and root development and growth were measured by destructive sampling to investigate the combined effects of temperature and changing nutrient and assimilate supply. Both mainstem leaf and root axis production were linearly related to thermal time above a base temperature of 0°C. Low irradiance affected the appearance of mainstem tillers and associated nodal root axes. Nitrogen had little effect on shoot or root development but increased shoot area between 6 and 8 mainstem leaves. Higher temperatures and supplementary light resulted in larger root systems when compared at equivalent times after sowing. Total root length and root dry weight increased exponentially with thermal time, based on the mean of 4 cm soil and 2 cm air temperatures, but no single relation existed for all temperature and light treatments. Total plant dry matter, root length and root dry weight increased linearly with accumulated, intercepted, photosynthetically active radiation. Root growth responded less than the shoot to supplementary light. Increasing temperature reduced the proportion of root weight to total plant weight.
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    Plant and soil 119 (1989), S. 99-110 
    ISSN: 1573-5036
    Keywords: Irradiance ; root development ; root growth ; temperature ; thermal time ; winter wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Winter wheat was sown on 2 dates with 3 levels of nitrogen fiertiliser (0, 50 and 200 kg N ha−1) in one year and on 2 sites in a followign season. Shoot and root development and growth were measured between emergence and anthesis in the first season and emergence and 7 mainstem leaves in the second. Differences in temperature and light regime led to significant differences in shoot and root development and growth between sowing dates. A thermal time-scale, based on soil surface or air temperatures, with a base of 0°C, adequately described the production of mainstem leaves and nodal root axes over all treatments. Autumn applied nitrogen had little effect on development. Shoot growth and green area index increased exponentially with thermal time prior to spring nitrogen application and the completion of canopy development. Early-sown crops had larger root systems than late-sown crops prior to winter and this divergence was retained until anthesis. The relationship between root growth and thermal time was little better than with days after sowing and was not improved by either varying the site of temperature measurement or the base temperature used for calculation. Differences in soil texture and drainage, between sites, led to significant changes in root length distribution. Although spring applied nitrogen generally increased root length, its effects were inconsistent. There was a curvilinear relation between root length and the amount of photosynthetically active radiation (PAR) intercepted; this relation was unaffected by sowing date or nitrogen treatment. The amount of root produced per unit PAR decreased as the season progressed, reflecting the decrease in the proportion of total dry matter partitioned to the root system.
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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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  • 61
    ISSN: 1573-5036
    Keywords: characterization ; deleterious rhizobacteria ; inhibitory bacteria ; pseudomonads ; toxin ; wheat
    Source: Springer Online Journal Archives 1860-2000
    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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  • 62
    ISSN: 1617-4623
    Keywords: Rhizobium leguminosarum ; Nitrogen fixation ; nif/fix genes ; Escherichia coli minicells ; Transcription regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary On the Rhizobium leguminosarum PRE sym plasmid, fixABC and a novel gene fixW were identified upstream of the regulatory gene nifA. The molecular masses of FixABC, 29, 44 and 50 kDa respectively, were estimated by polyacrylamide gel electrophoresis (PAGE) and of FixW, 25 kDa, by PAGE and nucleotide sequencing. Hybridization studies using bacteroid mRNA as a probe showed that fixABC is one operon which can be transcribed independently of fixW. Nucleotide sequencing revealed that both fixW and fixA are preceded by a nif consensus promoter. The fixA promoter partly overlaps the 3′-terminal coding region of fixW, indicating that readthrough from fixW into fixA is possible. Two open reading frames, ORF71 and ORF79, precede fixW and form one operon with fixW. ORF71 contains sequences homologous to the fixA promoter and 5′-terminal coding region. One more duplication of fixA sequences was detected, also located within the sym plasmid nif/fix clusters. One duplication of fixW sequences was found. No fixW homologue could be found in other nitrogen fixing organisms except in a number of R. leguminosarum strains.
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  • 63
    ISSN: 1617-4623
    Keywords: Nitrogen fixation ; draT ; draG ; TTG initiation codon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Nitrogen fixation activity in the photosynthetic bacterium Rhodospirillum rubrum is controlled by the reversible ADP-ribosylation of the dinitrogenase reductase component of the nitrogenase enzyme complex. This report describes the cloning and characterization of the genes encoding the ADP-ribosyltransferase (draT) and the ADP-ribosylglycohydrolase (draG) involved in this regulation. These genes are shown to be contiguous on the R. rubrum chromosome and highly linked to the nifHDK genes. Sequence analysis revealed the use of TTG as the initiation codon of the draT gene as well as a potential open reading frame immediately downstream of draG. The mono-ADP-ribosylation system in R. rubrum is the first in which both the target protein and modifying enzymes as well as their structural genes have been isolated, making it the model system of choice for analysis of this post-translational regulatory mechanism.
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  • 64
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    Molecular genetics and genomics 215 (1989), S. 507-516 
    ISSN: 1617-4623
    Keywords: Nitrogen fixation ; Regulation ; Rhodobacter capsulatus ; Gene sequences ; Transcription factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have determined the DNA sequence for the genes nifR1, nifR2 and nifR4 in the photosynthetic bacterium Rhodobacter capsulatus. These genes regulate transcription of the nifHDK operon and so limit the expression of nitrogen fixation activity to periods of low environmental concentrations of both oxygen and fixed nitrogen. The sequences of these three genes are similar to components of the ntr regulation system in Escherichia coli and Klebsiella pneumoniae. The two-component regulatory system of ntrB and ntrC in E. coli is represented by nifR2 and nifR1 in R. capsulatus and nifR4 in R. capsulatus is the equivalent of the E. coli ntr-related sigma factor ntrA.
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  • 65
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    Euphytica 41 (1989), S. 65-69 
    ISSN: 1573-5060
    Keywords: Fragaria ; Potentilla ; intergeneric hybrids ; pollen storage ; temperature ; relative humidity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Low temperature and humidity were used for the storage of pollen of four species of Fragaria (2n=14, 42 and 56) and two species of Potentilla (2n=14). The stainability of Fragaria pollen was assessed over a number of years by use of aceto-carmine stain and its viability by cross-pollinations; stainability of Potentilla pollen was assessed by acetocarmine. Fragaria pollen so stored remained stainable for seven years and showed the ability to set seed for three years. over the latter period, aceto-carmine staining gave a reasonable prediction of seed set produced by the stored pollen of Fragaria and so is of value in estimating pollen viability in that genus. Potentilla pollen remained stainable for three years.
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  • 66
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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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  • 67
    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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  • 68
    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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  • 69
    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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  • 70
    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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  • 71
    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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  • 72
    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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  • 73
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; herbicide binding ; photoinhibition ; photosynthesis ; photosystem II ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The time courses of some Photosystem II (PS II) parameters have been monitored during in-vivo and in-vitro photoinhibition of spinach chloroplasts, at room temperature and at 10 °C or 0 °C. Exposing leaf discs of low-light grown spinach at 25 °C to high light led to photoinhibition of chloroplasts in-vivo as manifested by a parallel decrease in the number of functional PS II centres, the variable chlorophyll fluorescence at 77K (F v /F m ), and the number of atrazine-binding sites. When the photoinhibitory treatment was given at 10 °C, the former two parameters declined in parallel but the loss of atrazine-binding sites occurred more slowly and to a lesser extent. During in-vitro photoinhibition of chloroplast thylakoids at 25 °C, the loss of functional PS II centres proceeded slightly more rapidly than the loss of atrazine-binding sites, and this difference in rate was further increased when the thylakoids were photoinhibited at 0 °C. During the recovery phase of leaf discs (up to 9 h) the increases in F v /F m preceded that of the number of functional PS II centres, while only a further decline in the number of atrazine-binding sites was observed. The recovery of variable chlorophyll fluorescence and the concentration of functional PS II centres occurred more rapidly at 25 °C than at 10 °C. These results suggest that the photoinhibition of PS II function is a relatively temperature-independent early photochemical event, whereas the changes in the concentration of herbicide-binding sites appear to be a more complex biochemical process which can occur with a delayed time course.
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  • 74
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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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  • 75
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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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  • 76
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    Euphytica 40 (1989), S. 121-126 
    ISSN: 1573-5060
    Keywords: Chrysanthemum morifolium ; chrysanthemum ; tolerance ; temperature ; days to flower ; breeding ; component analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Twenty seven clones of chrysanthemum, 19 of which were selected at low temperature, were flowered at 10, 14, 18 and 22°C. The number of days to flower in response to temperature could, for each genotype, be described by a parabola with the parameters: optimum temperature, days to flower at the optimum temperature and curvature which represents the sensitivity to temperature. The low-temperature selections did not have a reduced optimum temperature but reduced sensitivity to temperature accounted for most of the ability to flower at low temperature. The parameters may vary independently. Examples are given to show how these parameters can be combined to construct genotypes with a required temperature response.
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  • 77
    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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  • 78
    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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  • 79
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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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  • 80
    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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  • 81
    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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  • 82
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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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  • 83
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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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  • 85
    ISSN: 1573-5117
    Keywords: Acanthocyclops ; productivity ; temperature ; food limitation ; generation time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The generation time of the predatory cyclopoid copepod Acanthocyclops robustus was estimated on 11 occasions during the years 1980 to 1982 in Alderfen Broad. In a multiple regression model, generation time was found to be uncorrelated with temperature, positively correlated (p 〈 0.05) with the densities of Bosmina longirostris and rotifers, and negatively correlated (p 〈 0.001) with the density of nauplii of the calanoid copepod Eudiaptomus gracilis. It is suggested that generation time was determined largely by the availability of calanoid nauplii as prey, even though these constituted only 2% of zooplankton standing biomass.
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  • 86
    ISSN: 1573-5117
    Keywords: Cyclopoid copepods ; development times ; eggs ; instars ; temperature ; diapause
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The duration times of eggs, combined naupliar instars and of the different copepodite stages of five species of cyclopoid copepods — Acanthocyclops robustus, Cyclops vicinus, Diacyclops bicuspidatus, Mesocyclops leuckarti, and Thermocyclops crassus — were investigated at five different temperatures. The five species can be divided in two groups: two species, C. vicinus and D. bicuspidatus, adapted to cold water conditions and three species, A. robustus, M. leuckarti and T. crassus adapted to warm water conditions. The cold water species showed a faster egg development than M. leuckarti and T. crassus at 5–15 °C. The eggs and instars of the warm water species M. leuckarti tend to develop faster than those of the former two species at higher temperatures. A. robustus showed the shortest egg and instar development at 10–25 °C. The warm water species T. crassus produced no eggs at 10 °C and temperatures below. At higher temperatures (20, 25 °C) the egg and instar duration times were similar or longer than those of the other species. When cultured in total darkness a great part of the CIV respectively CV copepodites of the summer forms entered arrest and the percentage of copepodites that showed an arrest of development was highest at lowest temperatures. The present results are compared with data from literature and differences are discussed.
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  • 87
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    Hydrobiologia 186-187 (1989), S. 81-102 
    ISSN: 1573-5117
    Keywords: rotifers ; rate of population increase ; life span ; temperature ; salinity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A review of temperature and salinity effects on rotifer population dynamics is presented together with original data of these effects for three clones of Brachionus plicatilis. There is a clear relationship between temperature and the intrinsic rate of increase, r: an increase of temperature — within the natural environmental range — produces an exponential increase of r, and the slope of the response depends on the genotype. The effect of salinity is also genetically dependent; the highest r for each clone is observed at the salinity close to that of its environmental origin. The response of r to temperature is mainly a consequence of the response of the individual rates of development and reproductive timing. The effect of temperature on fecundity (number of descendents per individual life time) is negligible when temperature values are within the normal habitat ranges. On the other hand, salinity seems to affect primarily fecundity. The interaction salinity-temperature may be important in clones or species living in fluctuating environments with positive response to the more frequent combinations found in the corresponding habitats.
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  • 88
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    Hydrobiologia 186-187 (1989), S. 129-136 
    ISSN: 1573-5117
    Keywords: Hexarthra ; salinity ; alkalinity ; wind action ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Neusiedler See, a shallow alkaline lake with fluctuating water level and salinity, four species of Hexarthra occur: H. mira, H. fennica, H. jenkinae (occasional) and H. polyodonta. The analysis of longterm data reveals a general phenological pattern which does not change from year to year. They first occur in May, develop a maximum in June/July, sometimes a second one in August/September and disappear in October. But the species succession is different in the various years, occasionally only one species (H. mira or H. polyodonta) being present. There is a fairly consistent relation between the chemical conditions and the prevalent species; an increase in salinity favours the development of H. polyodonta. Low temperature and wind generated suspended particles have a negative influence on the development of the Hexarthra populations. Smaller populations of Hexarthra are in a relation to the occurrence of Leptodora indicating predation pressure of the latter species. In Neusiedler See the Hexarthra populations seem to be controlled to a great extent by abiotic factors, but predation by Leptodora and most probably by young fish seems to play an important role too.
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  • 89
    ISSN: 1573-5117
    Keywords: Rotifera ; resting eggs ; light ; temperature ; hatching ; mixis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The marine rotifer Brachionus plicatilis typicus (Clone 8105A, Univ. of Tokyo) was cultured in 500 ml beakers to form resting eggs. Tetraselmis tetrathele was used as a culture food. Just after formation, resting eggs were exposed to various temperature (5–25 °C) and light regimes (24L: OD and OL : 24D). When eggs were exposed to light just after formation, the eggs hatched sporadically over a month. No hatching was observed for six months when eggs were preserved under dark conditions regardless of the temperature. These eggs hatched simultaneously after being exposed to light and eggs preserved at 5 °C showed twice as high hatching rate (40%) as that of eggs preserved at 15–25 °C (24%). Clones from resting eggs that were kept under different temperature and light regimes were reared individually to the third generation. Incubation at 25 °C with lighting produced the highest (5.4% and 5.2 %) rate of mictic females during their 2nd and 3rd generations, respectively. The lowest rates (0 and 1.5%) were found when the eggs were kept at 5 °C in total darkness for six months. A lower rate of amictic female production was found in clones with higher rates of mixis.
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  • 90
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    Hydrobiologia 186-187 (1989), S. 209-214 
    ISSN: 1573-5117
    Keywords: rotifers ; distribution ; temperature ; oxygen content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lunzer Obersee, a small lake located at an altitude of 1100 m above sea level, was investigated from July 1985 to October 1987. The rotifer community consists of 7 dominant species, 7 subdominant species and 34 species which occasionally occurred in the plankton. The dominant species show rather different demands in relation to temperature and oxygen content; e.g.: Filinia hofmanni was found at a wide range of oxygen concentrations (0.6–13.3 mg O2l−1) and low temperatures (4–6 °O, living in the upper water layers (1–7 m) during spring and in the deeper, anoxic zone in summer. In contrast, Asplanchna priodonta was found at rather high oxygen contents (〉 9 mg O2 l−1), ), and showed a wide range of temperature tolerance (4–15 °C). On the basis of field data the temperature and oxygen requirements of several species are described and discussed.
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  • 91
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    Hydrobiologia 186-187 (1989), S. 363-369 
    ISSN: 1573-5117
    Keywords: rotifers ; temperature ; food concentration ; bioenergetic parameters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of temperature and food quality was studied on the following energy balance parameters of B. angularis: ingestion, production, growth and mortality. The ingestion rate rises to an optimum at 15 and 20 °C and decreases at 25 °C. The other rates increase continuously over the 5–25 °C range. The Q10-values of production rate are higher than those of ingestion rate. Temperature also modifies the relationship between food concentration and bioenergetic rates. They react according to a Monod function (production at all temperatures, growth at 10 °C) or decrease at high concentrations (growth at 15° and 20 °C.)
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  • 92
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    Hydrobiologia 186-187 (1989), S. 381-386 
    ISSN: 1573-5117
    Keywords: biometric analysis ; resting eggs ; rotifers ; salinity ; temperature ; genetic variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of temperature and salinity on resting egg size of two Brachionus plicatilis (Rotifers) clones was investigated. Clones were selected according to their different behaviour in laying resting eggs: one clone ejects them, whereas they remain inside the females body in the other clone. The difference in resting eggs size between the two clones is noticeable, although the difference is not as great as that between female body size. An important temperature-salinity interaction on resting egg size has been observed. The general inverse relationship between size and temperature is only true at lower temperatures. At high temperatures size varies around the mean although could be greater than at intermediate temperatures. This is more evident at the intermediate salinity tested which is considered to be the closest to the optimum in our experiments. This pattern of variation suggests that mean size is bigger than expected, in relation to temperature and salinity, when these factors have values close to the extremes of their range, normally found in nature, and to which adaptative mechanisms can evolve. Size is bigger at the salinity — temperature low - low and high - high combinations which are the most commonly found in the temperate environments.
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  • 93
    ISSN: 1573-5117
    Keywords: Antarctica ; bacteria ; biofilms ; cyanobacteria ; microbial mats ; Nostoc ; Phormidium ; photosynthesis ; respiration ; stream algae ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Water temperatures in southern Victoria Land streams fluctuated over the range 0 to 10 lay close to freezing. In a series of controlled assays at Fryxell Stream, Taylor Valley, the benthic microbial mats showed strongly positive metabolic responses to increases in temperature well above ambient. Rates of polysaccharide and lipid biosynthesis increased with temperature over the range 0 to 25 °C. Between 0 and 10 °C, Q10 values for the cyanobacterial mats were 1.7 to 3.2 for gross photosynthesis, 2.5 to 5.7 for respiration, 2.2 to 2.5 for acetate incorporation into lipid, 1.9 to 3.8 for glucose catabolism, and 1.9 to 2.8 for thymidine incorporation. Respiration accounted for a high percentage of gross photosynthesis, and a net respiratory loss of carbon from three communities was either induced or worsened by an increase in temperature from 0 to 10 °C. The chlorophyll a content of Nostoc disc incubated for one month in darkness decreased by 27% at 5 °C, but by 99% at 25 °C. This set of assays suggests that the cyanobacterial mats contained large amounts of chlorophyll a and carbon associated with inactive or senescing cells. This unusual standing stock could probably not persist under warmer conditions, which would promote both increased respiratory losses and faster rates of bacterial decomposition.
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  • 94
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    Hydrobiologia 173 (1989), S. 219-229 
    ISSN: 1573-5117
    Keywords: aquatic fungi ; temperature ; seasonal periodicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The occurrence, distribution and seasonal periodicity of 49 species of aquatic fungi belonging to the orders Chytridiales, Lagenidiales, Blastocladiales, Saprolegniales and Peronosporales from two tanks of Kurukshetra, India, is described. Seasonal periodicity was found to be governed by temperature.
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  • 95
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    Hydrobiologia 174 (1989), S. 89-97 
    ISSN: 1573-5117
    Keywords: carbon ; Illinois ; light ; nitrate ; nutrient limitation ; periphyton ; phosphate ; streams ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Factors limiting periphyton accrual in east-central Illinois agricultural streams were investigated. Nutrient-diffusing substrata were used to examine periphyton macronutrient limitation in streams in two agricultural watersheds. Substrata consisted of sand-agar mixtures with one of six experimental treatments. Macronutrients included carbon, nitrate, phosphate and combinations of the three. Substrata were collected after a 5 and 9 day period and analyzed for chlorophyll a. None of the treatments were significantly greater than the controls at any of the seven stations, thus we conclude that periphyton in these streams was not nutrient limited. Highest periphyton colonization/growth rates were associated with the smaller upstream reaches, while lower rates occurred in the larger downstream reaches. Multiple regression showed that most of the variance in the rate of chlorophyll a accrual after five days was explained through water temperature and turbidity (r2 = 0.91); whereas, stream nitrate and phosphate concentrations accounted for no significant portion of the variance. We conclude that instream primary production in agricultural streams of central Illinois is limited by temperature and light.
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  • 96
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    Hydrobiologia 179 (1989), S. 17-24 
    ISSN: 1573-5117
    Keywords: profiles ; resolution ; monitoring ; temperature ; oxygen ; spate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Longitudinal profiles of water quality along a well-mixed tidal river are, ideally, based on simultaneous measurements at fixed stations distributed along the river. The resolution of the profiles is limited by the density of the stations. However, for a given number of stations the resolution is greatly increased if water quality date can be extrapolated upstream and downstream of the stations, making use of velocity data; the resolution is then determined by the density of the extrapolated data points, which may be an order of magnitude higher than the density of the stations. A 15-km length of river was investigated using 5 current meters equipped to measure depth, temperature, conductivity and dissolved oxygen. Data were recorded simultaneously every 10 minutes. When the average cross-sectional speed was 0.25 ms−1 (typical of tidal conditions), the extrapolated data points were 150 m apart, so the resolution of the resulting profiles (7 per kilometre) was much higher than that of the stations alone (0.3 per kilometre). The extrapolation process required a means of deducing the average cross-sectional speed from the speed measured at a given station. The key to this was provided by temperature data recorded during the onset of a spate, when tidal flow was suspended and the average cross-sectional speed was uniformly about 0.75 ms −1 at four of the stations. Profiles of temperature and dissolved oxygen were generated by this method; the resolution was about 2 data points km−1 during the onset of the spate, and 6 points km−1 during tidal flow.
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  • 97
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    Hydrobiologia 175 (1989), S. 223-231 
    ISSN: 1573-5117
    Keywords: Rotifera ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Information on the distribution of 225 species of planktic, periphytic and benthic rotifers from diverse waters in south and central Sweden was analyzed for temperature preference and tolerance. Most rotifers have a very wide tolerance range. Certainly differences in temperature dependence exist between separate species. However, these differences are, in a regional material like this, generally less distinct than what has been found for the distribution within individual lakes.
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  • 98
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    Plant and soil 114 (1989), S. 269-278 
    ISSN: 1573-5036
    Keywords: deleterious ; inhibitory bacteria ; pseudomonads ; rhizobacteria ; toxin ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied the production of a toxin inhibitory to both winter wheat (Triticum aestivum L.) root growth andEscherichia coli that was produced by a rhizobacterial pseudomonad. Of several carbon sources tested, the most rapid growth and highest toxin concentrations were obtained with glucose, glycerol, or trehalose. Toxin production was repressed with L-cysteine as the nitrogen source. Toxin was produced during the late exponential and early stationary phase of growth by the bacterium and, contrary to studies with other toxins, was unaffected by Fe and P concentrations in the growth medium. Toxin production by the bacterium was the same at growth temperatures of 25 and 15°C while it produced less at 5°C. If the bacterium was able to grow, it produced toxin. No compound tested induced an increase in toxin production indicating toxin production is constitutive.
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    Plant and soil 115 (1989), S. 83-87 
    ISSN: 1573-5036
    Keywords: karnal funt ; Neovossia indica ; secondary spread ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Wheat-spikes inoculated withN. indica at the boot-leaf stage produced secondary sporidia when later incubated (intact/detached) under moist conditions in the laboratory. Sporidia were also released from inoculated spikes in the field where sporidial release exhibited diurnal periodicity. More sporidia were trapped between 5–6 o'clock than during the later parts of the day but no sporidia were trapped between 14–18 o'clock. However, they could be trapped at any time of the day from the detached spikes incubated under moist conditions in the laboratory. Sporidia trapped in different experiments were invariably of the allantoid type and they proved viable and infective. Maximum sporidia developed on the outer glumes of florets, and this observation was supported by scanning electron microcope studies. Sporidia developed at 15 and 20°C but not at 30°C. These findings indicated that repeated cycles of sporidial production in spikes provided more inoculum than expected from soil-borne teliospores ofN. indica.
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    Plant and soil 116 (1989), S. 29-36 
    ISSN: 1573-5036
    Keywords: cytokinins ; potassium ; seaweed concentrate ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of the seaweed concentrate “Kelpak’ on the growth and yield of wheat grown under conditions of varying K supply were investigated. Kelpak had no significant effect on the yield of wheat receiving an adequate K supply, but significantly increased the yield of K stressed plants. The increase in yield was caused by an increase in both grain number and individual grain weight. Although the beneficial effects of seaweed concentrates have often been attributed to their cytokinin content, several lines of evidence suggested that this group of plant growth regulators may not be solely responsible for the observed effects of Kelpak on wheat. Irrespective of the physiological mechanism of action, Kelpak would appear to have considerable potential for increasing yield in K stressed wheat and may therefore reduce the requirement of wheat for K fertilization.
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