摘要:

The changes caused by 30 years of potassium (K) depletion in a Danish, neutral Alfisol formed on glacial till were studied by comparing K pools and mineralogy of samples from the Ap horizon of a fertilized plot (100 kg ha−1year−1) and a non‐fertilized plot. The two soils have almost identical particle size distributions and contained similar amounts of total K, but the sample from the fertilized plot is richer in water‐soluble K, exchangeable K and HNO3‐extractable K. The difference between the sums of these pools could, however, only account for 30% of the K added to the fertilized plot. Despite the long period of K depletion, the soil still seems able to release substantial amounts of K to the plants. According to X‐ray diffraction analysis, the clay and silt fractions contained the same layer silicates including kaolinite, illite or mica, chlorite, vermiculite and a component considered to be a vermiculite‐illite intergrade. The main effect induced by K depletion as shown by the diffractograms of these fractions was a decrease in the intensity of a peak at 1.34 nm and a corresponding increase in a peak at 1.43 nm. This change, which does not seem to have been reported before, is interpreted as a transformation of a vermiculite‐illite intergrade (peak at 1.34 nm) into vermiculite (peak at 1.43 nm) by K depletion.

ISSN:0906-4710    

DOI:10.1080/09064719709362431

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Micronutrients can be limiting for crop production and quality in fine sandy loam Podzolic soils in the cool, humid climate of Atlantic Canada. This study was conducted to determine the effect of mimimum tillage practices, in three long‐term animal feed crop rotations, on micronutrient (B, Cu, Zn, Mn, Fe and Mo) content and grain quality of spring barley(Hordeum vulgareL.) and soybean (Glycine maxL. Merrill). Reductions in soil tillage had various effects on micronutrient concentration in plant parts, especially for Cu, Zn, Mn, and Mo, which were probably related to pH changes at the soil surface. Grain micronutrient concentrations, however, for crop yield potential tended to be in the sufficiency range and were not limiting for crop growth or feed quality. Evidence suggesting a decline in Mo concentration over time underlines the need for periodic assessment of micronutrient assimilation in conservation tillage systems.

ISSN:0906-4710    

DOI:10.1080/09064719709362432

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A seed mixture ofPhleum pratenseL.,Lolium perenneL. andFestuca pratensisHuds. was grown in spaghnum peat or sandy soil in six growth chambers placed in a greenhouse compartment. Two different experiments were performed. Increasing the CO2concentration from 375 to 740 μmol mol−1increased the total dry weight of the grass mixture by about 30%, while an increase in the O3concentration from < 10 to 50 nmol mol−1decreased the dry weight by 18% as a mean in both experiments. The relative dry weights of the three species were not significantly affected by elevated CO2concentrations at low O3, whileLoliumincreased its relative dry weight at high O3concentrations at low CO2on the expenditure ofPhleumdry weight. CO2enrichment counteracted some of this O3effect. No significant interaction between CO2concentration and temperature (14 and 19°C mean temperature) was found with respect to the dry weights of the three species. The soil type had generally no influence on the effect of CO2and O3. However, plant growth was significantly slower in sandy soil than in peat.

ISSN:0906-4710    

DOI:10.1080/09064719709362433

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Eight Nordic open‐top chamber experiments with field‐grown spring wheat were combined to obtain relationships between ozone exposure and yield loss. Two exposure indices, AOT30 and AOT40 (AOT = accumulated exposure over threshold), were tested. Strongly significant linear regressions between relative yield and exposure were obtained with both indices. The coefficient of determination(r2)was higher and the model assumptions of linear regression were satisfied to a larger extent with AOT30 than with AOT40. The exclusion of charcoal‐filtered treatments from the analysis made little difference to the regressions. The AOT30 regression model predicted larger yield loss than the AOT40 regression model, especially for the range of exposures, which is likely to occur in the Nordic countries. The protein content of the grain increased with increasing ozone exposure in all eight experiments, but to a varying degree.

ISSN:0906-4710    

DOI:10.1080/09064719709362434

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Seven samples of rye with a wide variation in origin were collected from Finland and Sweden. Starch (57–66%), dietary fibre (15–17%) and crude protein (7–13%) were found to be the principal chemical constituents. The arabinoxylan content varied between 8 and 10%, of which 20–38% was water‐extractable. Of the chemical constituents analysed the highest coefficients of variation were found for crude protein, water‐extractable xylose residues and lignan (matairesinol and secoisolariciresinol) content. No correlation was found between the two lignans but a negative correlation was found between mixed‐linked ß‐glucans and secoisolariciresinol. Large variations were also found in the flour, dough and bread parameters measured, especially for parameters which could be related to the arabinoxylan content and arabinoxylan degrading enzymes. Correlations were found between the falling number of the flours, viscosity decrease during the swelling curve test, softening factor of the doughs and percentage decrease of the dough storage modulus, all related to the activity of endogenous hydrolytic enzymes. Notable differences in crumb properties (firmness, elasticity and stickiness) were found in the breads baked from five different whole‐meal flours. No correlation could be found between the dough and bread parameters and the content of lignans measured.

ISSN:0906-4710    

DOI:10.1080/09064719709362435

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Data describing white flour composition, dough properties and baking performance of both spring and winter wheat treated with different fertilizer strategies including meat bone meal, slurry manure and urea, were analyzed by principal component analysis and variance analysis. No significant differences in the analyzed variables were found between flour from wheat fertilized with organic fertilizers or urea at different N rates, irrespective of experiment. The differences mainly reflected variation between experiments. Higher N application rates significantly increased flour protein content and dough development time but decreased dough softening. Protein content was positively correlated to wet gluten content and dough stability, development time, resistance, extensibility as well as bread yield. The correlation between protein content and dough softening was negative and the correlation to farinograph water absorption was poor. The bread yield response to increasing protein content, obtained by increasing the N fertilizer rate, was lower in the spring wheat than in the winter wheat.

ISSN:0906-4710    

DOI:10.1080/09064719709362436

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A three‐step digestion simulation model was used to study the effects of monogastric digestive enzymes and exogenous microbial enzymes on the microstructure of wheat. Sections were stained for cell wall polysaccharides, protein, starch and phytate. Bright field and fluorescence microscopy was used to study the microstructural changes following each step of the digestion process. Starchy endosperm protein was not detected after the pepsin step, although aleurone protein was largely unaffected. After pancreatin treatment, starch had also disappeared. Xylanase decreased the fluorescence of the aleurone protein and collapsed the cell walls in the subaleurone. Unbroken cell walls of the aleurone and endosperm were not influenced by any of the treatments.

ISSN:0906-4710    

DOI:10.1080/09064719709362437

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Hexaploid and tetraploid wheats were pollinated by the wild perennial wheat relativesLeymus arenarius, L. mollis, L. racemosusandThinopyrum junceiforme.Hybrids were obtained from all attempted cross combinations, two of which are reported here for the first time. They are tall and perennial and have the expected chromosome numbers. Strategies for the future use of these hybrids in wheat improvement are discussed and outlined.

ISSN:0906-4710    

DOI:10.1080/09064719709362438

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Lingonberry(Vaccinium vitis‐idaeaL.) cvs “Sussi”; and “Sanna”; were cultivated on mineral soil with four different soil surface treatments(Sphagnumpeat mulch, sand mulch, plastic mulch and herbicide 3‐syclohexyl‐5, 6‐trimethylenurasil (lenasil)). Amount of annual weeds, plant coverage and yield were observed over five years. Weeds were most abundant in the first two observation years. Sand mulch was the least efficient for the control of annual weeds for both cultivars, whereas lenasil was the most efficient for “Sussi”;, and peat mulch for “Sanna”;. The plant coverage increased steadily throughout the years in the “Sussi”; plots, especially in plots mulched with peat. The spreading of “Sanna”; was slower in all treatments. It was best in plots mulched with peat or sand. Overall, “Sanna”; was more productive, with the highest yield on sand mulch and the lowest on lenasil‐treated plots. “Sussi”;, instead, yielded best on lenasil plots and poorest on sand.

ISSN:0906-4710    

DOI:10.1080/09064719709362439

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The frost hardiness of clones of two ornamental shrubs, hydrangea(Hydrangea paniculataSieb. ‘Grandiflora') and mock orange(Philadelphus lewisiiPursh. var.lewisii’Waterton'), was measured after completion of endodormancy. In addition to actual hardiness, minimum and potential hardiness were examined with the aid of four artificial hardening and dehardening treatments. Logit models were used for determining the lethal temperature. Artificial dehardening at 12°C (3 or 7 days) diminished the hardiness ofPhiladelphusfrom ‐38 to ‐22°C and that ofHydrangeafrom ‐37 to 26 ‐ ‐28°C. Hardening at ‐ 15°C (3 or 7 days) had no effect on hardiness. Visual assessment of injuries revealed no differences between clones of different origin, whereas electrolyte leakage tests indicated slight interclonal variation, especially after dehardening treatments.

ISSN:0906-4710    

DOI:10.1080/09064719709362440

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor