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21.
Leaf and root tissues of Poa pratensis L. showing distinct morphological changes associated with infection by Ustilago striiformis (West.) Niessl var. poae (stripe smut) or Urocystis agropyri (Pruess) Schroet. (flag smut) were analyzed for total soluble sugars and free amino acids. Decreases in the quantity of soluble sugars in stripe-smutted plants were not significant, indicating that the presence of U. striiformis sori in leaf tissue does not interfere with photosynthesis of the host. Severe decreases in the quantity of soluble sugars in flag-smutted plants suggest that U. agropyri either directly impairs photosynthesis or effectively metabolizes the photosynthate. Both pathogens caused significant decreases in total free amino acids in leaf and root tissues. The negligible decrease in soluble sugars in stripe-smutted plants was associated with a disproportionate decrease in free amino acids, suggesting that the pathogen either metabolizes amino acids or inhibits their synthesis. The severe decrease in amino acids in leaves and roots of U. agropyri-infected plants is believed due to carbohydrate starvation. It is probable that morphological changes in U. agropyri-infected plants, including reduced branching, dwarfed leaves and root systems, and the inability to produce inflorescences, are probably the direct result of severely reduced levels of sugars and amino acids. The reduced branching, somewhat smaller root systems, and inhibition of inflorescence production on plants infected by U. striiformis probably are associated to some extent with decreases in amino acids. The upright elongated leaves of U. striiformis-infected plants, however, cannot be attributed to the decrease in amino acid content and are suggestive of hyperauxiny. 相似文献
22.
Rates of Leaf and Tiller Production in Young Spaced Perennial Ryegrass Plants in Relation to Soil Temperature and Solar Radiation 总被引:5,自引:2,他引:3
In an experiment designed to investigate the rate of leaf appearanceand tiller production in young spaced plants of three clonesof perennial ryegrass grown in the field, it was found thatthe rate of leaf appearance per tiller increased linearly withmean soil temperature up to approx. 14 °C. The rate of productionof tillers in relation to the rate of leaf appearance (sitefilling) appeared to be virtually independent of weather conditions.In plants which were adequately established, but still relativelysmall, site filling was equal to or exceeded the theoreticalsteady state; all the tiller buds which were being formed weredeveloping into visible tillers. Thus the relative rate of tillerproduction was controlled by the rate of leaf appearance. Inlarger plants site filling was less complete, and site redundancieswere probably caused by within-plant competition for light atthe tiller bases. Lolium perenne L., perennial ryegrass, tillering, leaf production, solar radiation, soil temperature 相似文献
23.
Expression of Characteristics of Ammonium Nutrition as Affected by pH of the Root Medium 总被引:6,自引:1,他引:5
CHAILLOU S.; VESSEY J. K.; MOROT-GAUDRY J. F.; RAPER C. D. JR; HENRY L. T.; BOUTIN J. P 《Journal of experimental botany》1991,42(2):189-196
To study the effect of root-zone pH on characteristic responsesof -fed plants, soybeans (Glycine max {L.}Merr. cv. Ransom) were grown in flowing solution culture for21 d on four sources of N (1.0 mol m3 , 0.67 mol m3 plus 0.33 mol m3, 0.33 mol m3 plus 0.67 mol m3 , and 1.0 mol m3) with nutrient solutions maintained at pH 6.0, 5.5, 5.0, and 4.5. Amino acid concentration increased inplants grown with as the sole source of N at all pH levels. Total amino acid concentration in the rootsof -fed plants was 8 to 10 times higher than in -fed plants, with asparagine accounting for more than 70% of the total in the roots of these plants.The concentration of soluble carbohydrates in the leaves of-fed plants was greater than that of -fed plants, but was lower in roots of -fed plants, regardless of pH. Starch concentration was only slightlyaffected by N source or root-zone pH. At all levels of pH tested,organic acid concentration in leaves was much lower when was the sole N source than when all or part of theN was supplied as . Plants grown with mixed plus N sources were generally intermediate between - and -fed plants. Thus, changes in tissue compositioncharacteristic of nutrition when root-zone pH was maintained at 4.5 and growth was reduced, still occurredwhen pH was maintained at 5.0 or above, where growth was notaffected. The changes were slightly greater at pH 4.5 than athigher pH levels. Key words: Ammonium, nitrogen nutrition, root-zone pH, soybean, tissue composition 相似文献
24.
Bayesian analyses for a multiple capture-recapture model 总被引:3,自引:0,他引:3
25.
The present study investigates the effects of triacontanol (CH3(CH2)28CH2OH),on plant growth (root and stem), peroxidase activity (apicalmeristem tissue), and auxin destruction (apical meristem tissue)in Little Marvel dwarf (LM) and Alaskapeas (AP). Triacontanol inhibited root growth in LM comparedto untreated controls. However, root growth in AP tissue wasenhanced by 1.0 mg I1 triacontanol and inhibited by allother treatments, in comparison to untreated controls. Wateruptake in triacontanol-treated AP plants was greater than inuntreated controls, with the converse being the case for LM.Triacontanol treatment caused an increase in peroxidase activityin both LM and AP plants compared to untreated controls. Interms of (114C)IAA destruction, GA3 + 0.01 mg 11triacontanol caused appreciable auxin breakdown (40%) in LMtissue, with GA3 + 0.1 mg 11 triacontanol giving a 43%decrease compared to untreated controls. In AP tissue, 10 µMGA3 increased auxin destruction by 188% whereas 0.1 mg I1triacontanol caused a 20% decrease compared to untreated controls.The effects of triacontanol on root and stem growth, peroxidaseactivity, and auxin destruction appear to be cultivar-specific,with respect to LM and AP varieties of peas. 相似文献
26.
The internal phylogeny of ants (Hymenoptera: Formicidae) 总被引:5,自引:0,他引:5
Abstract. The higher phylogeny of the Formicidae was analysed using 68 characters and 19 taxa: the 14 currently recognized ant subfamilies plus 5 potentially critical infrasubfamilial taxa. The results justified the recognition of 3 additional subfamilies: Aenictogitoninae Ashmead (new status), Apomyrminae Dlussky & Fedoseeva (new status), and Leptanilloidinae Bolton (new subfamily). A second analysis on these better delimited 17 subfamilies resulted in 24 equally most parsimonious trees. All trees showed a basal division of extant Formicidae into two groups, the first containing (Myrmicinae, Pseudomyrmecinae, Nothomyrmeciinae, Myrmeciinae, Formicinae, Dolichoderinae, Aneuretinae) and the second the remaining subfamilies. Clades appearing within these groups included the Cerapachyinae plus 'army ants', the Nothomyrmeciinae plus Myrmeciinae, the 'formicoid' subfamilies (Aneuretinae + Dolichoderinae + Formicinae), and the Old World army ants (Aenictinae + Aenictogitoninae + Doryline), but relationships within the last two groups were not resolved, and the relative positions of the Apomyrminae, Leptanillinae and Ponerinae remained ambiguous. Moreover, a bootstrap analysis produced a consensus tree in which all branches were represented in proportions much lower than 95%. A reconstruction of the ground plan of the Formicidae indicated that the most specialized of all recent ants are the members of the subfamily Dorylinae and the least specialized ones are the monotypic Apomyrminae. 相似文献
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29.
PHILIP D. RABINOWITZ MEHDI Z. YUSIFOV JESSICA ARNOLDI EYAL HAKIM 《Ocean Development & International Law》2013,44(1):19-40
The Caspian Sea region contains oil and gas reserves that are comparable to those of other of the world's fossil-fuel-producing regions, excluding the Middle East. We review here the economic, environmental, and complicated geopolitical concerns with respect to exploration and recovery of the region's fossil fuels. These include mud volcanoes, gas hydrates, earthquakes, pollution, rapid changes in sea level, desertification, ownership of resources, and the transportation routes of fossil fuels. Significant advances have been made concerning these problems in the short time since the breakup of the Soviet Union, fueling optimism for the future of the region.- 相似文献
30.
PHILIP S WANG MATTHIAS ANGERMEYER GUILHERME BORGES RONNY BRUFFAERTS WAI TAT CHIU GIOVANNI DE GIROLAMO JOHN FAYYAD OYE GUREJE JOSEP MARIA HARO YUEQIN HUANG RONALD C KESSLER VIVIANE KOVESS DAPHNA LEVINSON YOSHIBUMI NAKANE MARK A OAKLEY BROWN JOHAN H ORMEL JOSé POSADA-VILLA SERGIO AGUILAR-GAXIOLA JORDI ALONSO SING LEE STEVEN HEERINGA BETH-ELLEN PENNELL SOMNATH CHATTERJI T. BEDIRHAN üSTüN 《World psychiatry》2007,6(3):177-185
Data are presented on patterns of failure and delay in making initial treatment
contact after first onset of a mental disorder in 15 countries in the World
Health Organization (WHO)''s World Mental Health (WMH) Surveys. Representative
face-to-face household surveys were conducted among 76,012 respondents aged
18 and older in Belgium, Colombia, France, Germany, Israel, Italy, Japan,
Lebanon, Mexico, the Netherlands, New Zealand, Nigeria, People''s Republic
of China (Beijing and Shanghai), Spain, and the United States. The WHO Composite
International Diagnostic Interview (CIDI) was used to assess lifetime DSM-IV
anxiety, mood, and substance use disorders. Ages of onset for individual disorders
and ages of first treatment contact for each disorder were used to calculate
the extent of failure and delay in initial help seeking. The proportion of
lifetime cases making treatment contact in the year of disorder onset ranged
from 0.8 to 36.4% for anxiety disorders, from 6.0 to 52.1% for mood disorders,
and from 0.9 to 18.6% for substance use disorders. By 50 years, the proportion
of lifetime cases making treatment contact ranged from 15.2 to 95.0% for anxiety
disorders, from 7.9 to 98.6% for mood disorders, and from 19.8 to 86.1% for
substance use disorders. Median delays among cases eventually making contact
ranged from 3.0 to 30.0 years for anxiety disorders, from 1.0 to 14.0 years
for mood disorders, and from 6.0 to 18.0 years for substance use disorders.
Failure and delays in treatment seeking were generally greater in developing
countries, older cohorts, men, and cases with earlier ages of onset. These
results show that failure and delays in initial help seeking are pervasive
problems worldwide. Interventions to ensure prompt initial treatment contacts
are needed to reduce the global burdens and hazards of untreated mental disorders. 相似文献