Zusammenfassung Die Fremdbefruchtungsrate bei Kulturgerste ist in der Regel sehr gering. Einige Anemophiliemerkmale sind aber gut ausgebildet, und unter besonderen Bedingungen kann das Ausmaß der Allogamie recht hoch sein. Aus den blütenbiologischen Merkmalen Antherenejektion (AE), Antherenlänge (AL), und Stigmatafläche (SF) wurden nach zwei verschiedenen Methoden Indices der Allogamieneigung (AN) kalkuliert, mit denen die potentielle Neigung der Gerste zur Allogamie geschätzt werden kann: AN=3,33 (AL·AE)+2,22 (SF·AE) und AN=–3,5+3,58 (AL·AE)+2,29 (SF·AE)Indices der Allogamieneigung werden für ausgewähltes Material des Gaterslebener Gerstensortiments angeführt (Tabellen 1 und 2).
Proposal for an index of the tendency to allogamy in barley (Hordeum vulgare L. s. l.)
Summary Outcrossing in cultivated barley can be observed relatively seldom. There are some well developed characters of anemophily in barley, however, and under certain conditions a tendency to allogamy can be found. From the flower characters anther extrusion (AE), anther length (AL), and stigma size (SF) in two different manners the following indexes were calculated: AN=3,33 (AL·AE)+2,22 (SF·AE) and AN=–3,5+3,58 (AL·AE)+2,29 (SF·AE)By using these indexes it is possible to demostrate the actual tendency to allogamy in barley. Some results from the barley collection in Gatersleben are shown in tables 1 and 2.
This study investigated the effects of mineral-N addition and intensive mixing (analogous to disturbance by plowing) on decomposition of 14C-labelled maize (Zea mays L.) residue and soil organic matter (SOM). Soils were collected from the upper 5 cm of three land use types at Edelweiler, Germany: plow tillage (PT), reduced tillage (RT), and grassland (GL). Soils were incubated for 112 days at 20 °C, with or without 14C-labelled maize residue (4 g DM kg−1 soil), with or without nitrogen (100 mg N kg−1 soil as NH4NO3) and with or without intensive mixing.
The effect of mineral-N on maize residue decomposition differed depending on the stage of decomposition and land use type. Nitrogen accelerated residue decomposition rates in the first 5 days in RT and GL soils, but not in PT soil, and decreased residue decomposition rate in all three land use types after 11 days. At the end of the incubation, N suppressed 14CO2 efflux in RT and PT soils, but not in GL soil. Mineral-N did not increase SOM decomposition independently on the land use types.
Intensive mixing stimulated decomposition of both plant residue and SOM in all three land use types. However, effects were smaller in GL soil than in RT or PT soil, presumably because stronger soil aggregates in GL would have been less affected by mixing and allowed greater protection of SOM and plant residue against decomposition. 相似文献
Soils are structurally heterogeneous across a wide range of spatio-temporal scales. Consequently, external environmental conditions do not have a uniform effect throughout the soil, resulting in a large diversity of micro-habitats. It has been suggested that soil function can be studied without explicit consideration of such fine detail, but recent research has indicated that the micro-scale distribution of organisms may be of importance for a mechanistic understanding of many soil functions. Current techniques still lack the adequate sensitivity and resolution for data collection at the micro-scale, and the question ‘How important are various soil processes acting at different scales for ecological function?’ is therefore challenging to answer. The nano-scale secondary ion mass spectrometer (NanoSIMS) represents the latest generation of ion microprobes, which link high-resolution microscopy with isotopic analysis. The main advantage of NanoSIMS over other secondary ion mass spectrometers is its ability to operate at high mass resolution, whilst maintaining both excellent signal transmission and spatial resolution (down to 50 nm). NanoSIMS has been used previously in studies focussing on presolar materials from meteorites, in material science, biology, geology and mineralogy. Recently, the potential of NanoSIMS as a new tool in the study of biophysical interfaces in soils has been demonstrated. This paper describes the principles of NanoSIMS and discusses the potential of this tool to contribute to the field of biogeochemistry and soil ecology. Practical considerations (sample size and preparation, simultaneous collection of isotopes, mass resolution, isobaric interference and quantification of the isotopes of interest) are discussed. Adequate sample preparation, avoiding bias due to artefacts, and identification of regions-of-interest will be critical concerns if NanoSIMS is used as a new tool in biogeochemistry and soil ecology. Finally, we review the areas of research most likely to benefit from the high spatial and high mass resolution attainable with this new approach. 相似文献
Italy has been used as a country for estimating genetic erosion in crops. It was possible to compare early surveys (from the
1920s to the 1950s), especially on wheats, with results of later missions in the 1980s and 1990s. In the early years, a relatively
high genetic erosion was observed (13.2% p.a.). From the 1950s until the 1980s erosion rates between 0.48 and 4% p.a. were
estimated. In the little island of Favignana there was an erosion rate of 12.2% p.a. leading to the extinction of the last
wheat landraces of this island. There have been no significant differences in erosion rates between field- and garden-crops
though there has been the impression that garden crops are better preserved over the long run. Interestingly extinction rates
of wild plants (0.13% in the Mediterranean) come close to the average erosion rates of crop plants in the area.
1Dedicated to Erna Bennett on the occasion of her 80th birthday
2Lecture presented during the XVIIth Congress of EUCARPIA in Tulln, Austria, 2004 相似文献
New Potentilla synonyms of the Fragaria species names are discussed and considered to be dispensable. Further unnecessary nomenclatural changes based on the argument to recognize monophyletic but not paraphyletic taxa should be avoided to maintain nomenclatural stability for global communication about plant genetic resources. The new combination Fragaria×rosea (Mabb.) K. Hammer et Pistrick is presented for the hybrid Potentilla palustris (L.) Scop. ×Fragaria×ananassa Duchesne ex Rozier. 相似文献
Summary Important papers on taxonomy and evolution of cultivated plants published in 1985 and 1986 were compiled and briefly discussed.
Taxonomie und Evolution der Kulturpflanzen: Literaturübersicht 1985/1986
Zusammenfassung Wichtige Arbeiten über Taxonomie und Evolution der Kulturpflanzen aus den Jahren 1985 und 1986 wurden zusammengestellt und kurz kommentiert.
A Spatially Differenciating Method for Computing High Resolution Maps of Soil Loss by Rain Wash - Fundamental Principles of the dUSLE The theoretical basis of a procedure to compute maps of the soil loss is presented. This procedure allows to estimate soil loss on a large scale (1:5000) for planning specific protection measures. The procedure uses the Universal Soil Loss Equation combined with a digital terrain model that consists of a triangulated, irregular network. In this way not only slope but also the influence of increasing soil loss down slope and the slope morphology are taken into account. Also, slope morphology is considered along the slope as well as across the slope. Therefore the procedure is called differentiating Universal Soil Loss Equation dUSLE. With the dUSLE it is possible to combine high resolution with high automatisation and reasonable computation time. The application of the USLE has the advantage of easy use and availability of data. Furthermore, most parts of the USLE have been adapted to and verified for German conditions in recent years. In part 2 the integration of the equations presented in the digital terrain model will be described. In a third part the application of the dUSLE in land reconsolidation and farmers extension service will be presented. 相似文献
Physicochemical and functional properties of proteins were modeled as a function of the contributions of each of the 20 coded amino acids to three (z-scores) or five (extended z-scores) amino acid principal properties using partial least squares regression. The five term models were in all cases stronger in both fit and prediction than the three term models, indicating that useful information is contained in the fourth and fifth property scores. Models predicting protein hydrophobicity (R = 0.932), viscosity (R = 0.737), and foam capacity (R = 0.880) from amino acid composition rather than sequence were obtained. It is likely that additional functional and physicochemical properties of proteins can be modeled in this way. 相似文献