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161.
The effects of an increase in the absolute environmental pressure (air, N2 , O2 or hydrostatic), up to 1 MPa, on the germination of wheat seeds and the survival of wheat seedlings were studied. Seeds were exposed to saline and non-saline media, in Petri dishes, on a double layer of filter paper. They were then introduced for different time periods into a pressure chamber and pressurized by the addition of N2 to the chamber in the range of ambient to 1 MPa. Subsequently the seeds were left to germinate under normal atmospheric conditions. Seed germination and subsequent growth decreased during the first 6 h and then regained the control levels. Nevertheless, application of similar pressures to seeds which had been submerged under water was highly inhibitory. Such effects of pressure seem to be the result of flooding with water of some crucial intercellular spaces and a consequent disturbance of O2 supply to the germinating embryo. The additional flood-water comprised only 1–3% of the total water content of 24-h-old seedlings. Sensitivity of the submerged seeds and the germinating seedlings to pressure varied with age and developmental stage. Highest sensitivity to pressure was obtained with 12 to 72-h-old submerged seedlings. Removal of the excess water after the pressure treatment restored the germinability of the seeds. 相似文献
162.
Forrest L. Tittle 《Physiologia plantarum》1987,70(3):499-502
The auxins indole-3-acetic acid (IAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) stimulated ethylene production from gametophytes of the fern Pteridium aquilinum (L.) Kuhn. var. latiusculum (Desv) underw. ex Heller and sporophytes of the ferns Matteuccia struthiopteris (L.)Todaro and Polystichum munitum (Kaulf.) Presl. Treatment with Co2+ or l -α -(2-aminoethoxyvinyl)-glycine (AVG) eleminated or significantly reduced the stimulatory effects of IAA. Treatment with 1-aminocyclopropane-1-carboxylic acid (ACC) resulted in significantly greater rates of ethylene production from all tissues tested. Based on their response to auxin, ACC, AVG and Co2+ , the ethylene biosynthetic pathway in these three lower vascular plants appears similar to that existing in angiosperms. 相似文献
163.
I. Papastylianou 《Plant and Soil》1987,104(1):23-29
The increasing need for protein at low cost has created a need to evaluate the biological nitrogen fixing potential of legumes
in Cyprus. In field studies which were conducted over the growing years of 1982–3 and 1983–4, legumes which are traditionally
grown in the country were evaluated for dry matter and nitrogen yield and biological nitrogen fixation (BNF). The legumes
studied were medic (Medicago truncatula Gearth), ochrus vetch (Lathyrus ochrus L.), bitter vetch (Vicia ervilia L.) and faba bean (Vicia faba L. var major) in the first year and in addition chickpea (Cicer arietinum L.), woollypod vetch (Vicia dasycarpa Ten.) and tickbean (Vicia faba L. var minor) in the second year.
Using the A-value method with barley and oats as reference crops, nitrogen (N) fixed by the various legumes in the first year
was 30–50% and from 55–67% of total N yield for the two reference crops, respectively. In the second year the estimates of
N fixed ranged from 70 to 80% with similar results obtained for the two reference crops barley and ryegrass. However, in the
second year chickpea, which had limited nodulation, fixed only 40% of its N yield.
Estimates of nitrogen from the atmosphere (Ndfa) obtained by the difference method (DM) were 10 to 14% lower than those from
the A-value method. These results were obtained after correcting for the amount of N derived from the applied fertilizer.
The two methods were highly correlated (r=0.98) for estimates of amount of BNF. The rates of N2 fixation of uninoculated legumes which are nodulated by the indigenous populations of Rhizobium in Cyprus are comparable
to those of legumes inoculated with selected strains of Rhizobium in other countries. An exception was the amount of N fixed
by chickpea. The appearance of the first nodules at late stages of growth may be the reason for the low BNF of this crop. 相似文献
164.
Evaluation of N2-fixation and nitrogen economy of a maize/cowpea intercrop system using15N dilution methods 总被引:2,自引:0,他引:2
Yields of above ground biomass and total N were determined in summer-grown maize and cowpea as sole crops or intercrops, with
or without supplementary N fertilizer (25 kg N ha−1, urea) at an irrigated site in Waroona, Western Australia over the period 1982–1985. Good agreement was obtained between
estimates of N2 fixation of sole or intercrop cowpea (1984/85 season) based on the15N natural abundance and15N fertilizer dilution techniques, both in the field and in a glasshouse pot study. Field-grown cowpea was estimated to have
received 53–69% of its N supply from N2-fixation, with N2-fixation onlyslightly affected by intercropping or N fertilizer application. Proportional reliance on N2-fixation of cowpea in glasshouse culture was lower (36–66%) than in the field study and more affected by applied N. Budgets
for N were drawn up for the field intercrops, based on above-ground seed yields, return of crop residues, inputs of fixed
N and fertilizer N. No account was taken of possible losses of N through volatilization, denitrification and leaching or gains
of N in the soil from root biomass. N2-fixation was estimated tobe 59 kg N ha−1 in the plots receiving no fertilizer N, and 73 kg N ha−1 in plots receiving 25 kg N ha−1 as urea. Comparable fixation by sole cowpea was higher (87 and 82 kg N ha−1 respectively) but this advantage was outweighed by greater land use efficiency by the intercrop than sole crops. 相似文献
165.
The N2O flux from the surface of grass-covered pots was only significant following grass maturing. Removal of the above-ground plant
material resulted in an immediate and long-lasting increase in N2O production in the soil. The results suggest that easily available organic matter from the roots stimulates the denitrification
when the plants are damaged. Grass cutting might therefore result in a marked nitrogen loss through denitrification. The quantitative
effect was equal in soil with and without succinate added. The size of the anaerobic zone around the roots is therefore sufficient
to allow for denitrification activity mediated by increased organic matter availability because of plant cutting. 相似文献
166.
Martin Wood 《Plant and Soil》1987,97(3):303-314
Summary Laboratory data for the loss of root material by barley and field data for the growth of barley plants in Syria and in England
have been combined to predict the amount of material lost by barley roots during a season, and to predict the resulting microbial
biomass in the rhizosphere. The predicted microbial biomass C in the rhizosphere ranged from 10–34% of the total plant biomass
C depending mainly upon the value used for rate of loss of root material. Total loss of root material predicted during a season
in England constituted 7.7–25.4 percent of C fixed by photosynthesis. The major assumptions made in these calculations are
considered, and the predicted values discussed in relation to reported values for soil microbial biomass, CO2 fluxes from soil and associative nitrogen fixation. 相似文献
167.
Summary Inoculation of water fernAzolla pinnata R. Brown (Bangkok isolate) at the rate of 500kg fresh weight ha−1 in rice fields at weekly intervals after planting in addition to 30 kg N ha−1 as urea showed a decrease in its growth and N2-fixation with delay in application. Use of Azolla up to 3 weeks after planting (WAP) during wet and 4 WAP during dry season
produced significantly more grain yield than 30 kg N ha−1, whereas its application upto one WAP produced more grain yield than 60 kg N ha−1. Grain yield with Azolla applied at the time of planting was similar to that of 60 kg N treatment during the wet season.
Higher grain yields in zero and one WAP Azolla treatments resulted due to increase in both number of panicles m−2 and number of grains/panicle while the subsequent Azolla inoculations increased grain yield mainly by producing more number
of grains/panicle.
Dry matter and total N yields at maturity of rice crop were more with Azolla application upto 3 WAP during wet and 2 WAP during
dry season while the reduction in sterility (%) was observed upto one WAP over 30 kg N ha−1 during both seasons. Number of tillers m−2 and dry matter production at maximum tillering and flowering were more than 30 kg N ha−1 with the use of Azolla upto one WAP. Increased grain N yield was observed with the use of Azolla upto 4 WAP during two seasons
whereas straw N yield increased upto one WAP during wet and 2 WAP during dry season. 相似文献
168.
Spinach-leaf ferredoxin was identified as a calcium-binding protein by 45Ca autoradiography on nitrocellulose membranes and with the cationic carbocyanine dye 1-ethyl-2-[3-(1-ethylnaphtho[1,2-d]thiazolin-2-ylidene)-2-methylpropenyl] naphtho[1,2-d]thiazolium bromide (stains-all). Binding of 45Ca was observed at pH 6.8 and pH 7.8 and in the presence of 5 mM and 20 mM MgCl2. At the higher MgCl2 concentration the Ca2+-binding capacity is reduced. Only micromolar concentrations of LaCl3, however, are required to achieve a similar effect. Both the oxidized and reduced forms of ferredoxin bind calcium.Abbreviations PAGE
polyacrylamide gel electrophoresis
- SDS
sodium dodecyl sulfate
- stains-all
1-ethyl-2-[3-(1-ethylnaphtho[1,2-d]thiazolin-2-ylidene)-2-methylpropenyl] naptho[1,2-d]thiazolium bromide 相似文献
169.
B. Friebe M. C. Cermeño F. J. Zeller 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1987,73(3):337-342
Summary C-banding patterns and nucleolar activity were analyzed in Dasypyrum villosum, its added chromosomes to hexaploid wheat and the hexaploid amphiploid Triticum dicoccum-D. villosum. Two different populations of the allogamous species D. villosum (2n= 14, VV) from Greece and Italy were analyzed showing a similar polymorphism for C-banding pattern. Six of the seven addition lines were identified by their characteristic C-banding pattern. No polymorphism between both members of each added alien chromosome was found. Furthermore, nucleolar activity and competition were studied by using silver staining procedure. In D. villosum only one chromosome pair, A, was found to be responsible for organizing nucleoli. The results obtained in the amphiploid and in the addition lines demonstrate that nucleolar activity is restricted to SAT-chromosomes 1B and 6B of wheat, while those of D. villosum remain inactive. 相似文献
170.
M. M. Kyle R. Provvidenti 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1987,74(5):595-600
Summary Resistance to watermelon mosaic virus-2 in Phaseolus vulgaris L. is conferred by two distinct dominant alleles at independent loci. Based on segregation data one locus is designated Wmv, the other, Hsw. The dominant allele Wmv from cv. Great Northern 1140 prevents systemic spread of the virus but viral replication occurs in inoculated tissue. In contrast, Hsw confers both local and systemic resistance to WMV-2 below 30C. At higher temperatures, plants that carry this allele in the absence of modifying or epistatic factors develop systemic veinal necrosis upon inoculation with the virus that results in rapid death. Patho-type specificity has not been demonstrated for either allele; both factors confer resistance to every isolate tested. A temperature-sensitive shift in epistasis is apparent between dominant alleles at these loci. Because Hsw is very tightly linked if not identical to the following genes for hypersensitivity to potyviruses I, (bean common mosaic virus), Bcm, (blackeye cowpea mosaic virus), Cam, (cowpea aphid-borne mosaic virus) and Hss (soybean mosaic virus), parental, reciprocal dihybrid F1 populations, and selected F3 families were inoculated with each of these viruses and held at 35 C. F1 populations developed vascular necrosis completely or primarily limited to inoculated tissue, while F3 families from WMV-2-susceptible segregates were uniformly susceptible to these viruses. The relationship between Hsw, Wmv and other genes for potyvirus resistance suggest patterns in the evolution of resistance and viral pathogenicity. Characterization of the resistance spectrum associated with each factor provides an additional criterion to distinguish genes for plant virus resistance. 相似文献