Focus Issue: Imprint of Environmental Change on Paleosols (J. Plant Nutr. Soil Sci. 4/2008)     

Daniela Sauer  Reinhold Jahn  Karl‐Heinz Feger  Edoardo A. C. Costantini  Alexander Makeev  Peter Felix‐Henningsen 《植物养料与土壤学杂志》2008,171(4):482-482

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Podzol development with time in sandy beach deposits in southern Norway     

Daniela Sauer  Isabelle Schülli‐Maurer  Ragnhild Sperstad  Rolf Sørensen  Karl Stahr 《植物养料与土壤学杂志》2008,171(4):483-497

The coastal areas of SE Norway provide suitable conditions for studying soil development with time, because unweathered land surfaces have continuously been raised above sea level by glacio‐isostatic uplift since the termination of the last ice age. We investigated Podzol development in a chronosequence of six soils on sandy beach deposits with ages ranging from 2,300 to 9,650 y at the W coast of the Oslofjord. The climate in this area is rather mild with a mean annual temperature of 6°C and an annual precipitation of 975 mm (Sandefjord). The youngest soil showed no evidence of podzolization, while slight lightening of the A horizon of the second soil (3,800 years) indicated initial leaching of organic matter (OM). In the 4,300 y–old soil also Fe and humus accumulation in the B horizon were perceptible, but only the 6,600 y–old and older soils exhibited spodic horizons. Accumulation of OM in the A horizons reached a steady state in <2,300 y, while in the B horizons OM accumulated at increasing rates. pH dropped from 6.6 (H₂O)/5.9 (KCl) in the recent beach sand to 4.5 (H₂O)/3.8 (KCl) within approx. 4,500 y (pH_H2O)/2,500 y (pH_KCl) and stayed constant thereafter, which was attributed to sesquioxide buffering. Base saturation showed an exponential decrease with time. Progressive weathering was reflected by increasing Fe_d and Al_d contents, and proceeding podzolization by increasing amounts of pyrophophate‐ and oxalate‐soluble Fe and Al with soil age. These increases could be best described for most Fe and Al fractions by exponential models. Only the increasing amounts of Fe_p could be better described by a power function and those of Fe_o by a linear model.  相似文献   

Selection of cowpea genotypes based on grain mineral and total protein content     

Abe Shegro Gerrano  Willem S. Jansen van Rensburg  Sonja L. Venter  Nemera G. Shargie  Beyene A. Amelework  Hussein A. Shimelis 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2019,69(2):155-166

Grain legumes, including cowpea, are the cheapest sources of minerals and protein to enhance human nutrition. Cultivar development and deployment of cowpea with increased grain mineral content and protein composition rely on selection of genetically unique and complementary breeding lines. The objective of this study was to assess the grain minerals and protein composition of diverse cowpea collections of eastern, southern and western Africa to select promising parents to develop a breeding population. Twenty-two genetically diverse cowpea genotypes were field evaluated using a randomised complete block design with three replications in two locations in South Africa. The dried grain mineral contents were determined using an Atomic Absorption Spectrophotometre, while the protein content was determined by the combustion method. Analyses of variance showed significant (P?<?0.05) effects of genotypes, locations and their interactions. The test genotypes showed considerable variation for the following nine mineral contents: calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorus (P), and zinc (Zn) varying from 0.07 to 0.12?mg?kg^?1; 4.46 to 7.81?mg?kg^?1; 0.06 to 0.11?g; 11.82 to 14.45?g; 1.86 to 2.27?g; 9.24 to 13.30?mg?kg^?1; 0.26 to 0.80?g; 4.63 to 5.92?g and 0.03.00 to 0.05?g, respectively. Further, the total protein content varied from 23.16 to 28.13%. Significant correlations were detected among some mineral elements and total protein content, suggesting the possibility of simultaneous selection for these traits. The principal component analysis (PCA) identified four principal components (PCs) contributing to 70.93% of the total explained variation amongst genotypes. Overall the following genotypes with desirable grain mineral and protein attributes were selected: IT90K-59 (Ca), 98K-5301 (Ca and protein), ITOOK-1060 (Cu), ITOOK-1217 and IT845-2246 (Fe), Bensogla (K, Na, and P), TVU11424 and ITOOK-1217 (Mg), CH14 (Mn and Na), TVU12637 (Mn) and Glenda and Vuli (Zn). The selected cowpea genotypes are useful genetic resources for population and cultivar development for grain nutrients composition.  相似文献   

A Laboratory Assay for Phytophthora infestans Resistance in Various Solanum Species Reflects the Field Situation   总被引：4，自引：0，他引：4  

Vivianne G.A.A. Vleeshouwers  Willem van Dooijeweert  L.C. Paul Keizer  Luc Sijpkes  Francine Govers  Leontine T. Colon 《European journal of plant pathology / European Foundation for Plant Pathology》1999,105(3):241-250

Physiological and molecular research on resistance responses of Solanum tuberosum cultivars and partially resistant Solanum species to Phytophthora infestans requires a reliable resistance test that can be used in the laboratory. Laboratory tests performed on detached leaves and intact plants were compared with field tests for similarity of late blight reactions. Detached leaves from field-grown plants were as resistant as detached leaves from climate chamber-grown plants when challenged with P. infestans. However, detached leaves incubated in covered trays at high relative humidity were more susceptible than detached leaves kept in open trays or leaves on intact plants. The incubation conditions of detached leaves in covered trays rather than detachment itself appeared to affect the resistance expression. Detached leaves of some wild Solanum genotypes became partially infected, whereas intact plants were completely resistant when inoculated. Inoculation of leaves on intact plants, however, resulted in lower infection efficiencies. These limitations should be taken into account when choosing the appropriate inoculation method for specific purposes. For resistance screening, laboratory tests proved to be a good alternative for field tests. The ranking of resistance levels for twenty plant genotypes was similar under laboratory and field conditions.  相似文献   

Potentials and Limitations of Existing Forecasting Models for <Emphasis Type="Italic">Alternaria</Emphasis> on Potatoes: Challenges for Model Improvement     

Sofie Landschoot  Jolien De Reu  Kris Audenaert  Pieter Vanhaverbeke  Geert Haesaert  Bernard De Baets  Willem Waegeman 《Potato Research》2017,60(1):61-76

Alternaria species, including A. solani and A. alternata, are a serious threat to potato cultivation and cause necrotic leaf spots, leading to premature defoliation and yield losses. To reduce the impact of the disease, a timely prediction of a disease outbreak is important. Worldwide, modelling attempts have been made to predict the occurrence of Alternaria in order to take adequate measures. In the present paper, we made an effort to classify the existing prediction models and subdivided them into three categories: plant-based, pathogen-based and plant-pathogen-based models. Plant-based models predict the susceptibility of the host crop and presume that Alternaria inoculum is abundantly present and not the restrictive factor, whereas pathogen-based models consider one or more stages of the Alternaria life cycle and suppose that the host crop is always susceptible. The plant-pathogen-based models try to take into account the complete plant-pathogen-environment relationship. In this paper, a critical review of the described models for Alternaria leaf spot is presented. To illustrate the discrepancy between the predicted and the observed dates of the first Alternaria symptoms or the discrepancy between the suggested first treatment and necessity to treat Alternaria, the existing models were subjected to the Belgian weather conditions. It turns out that these models are not applicable in Belgium or similar regions. This can be partially attributed to the fact that most of the currently available models are too simplistic (only plant- or pathogen-based) for regions where the disease pressure highly fluctuates between growing seasons and between locations within one season. Finally, perspectives for model improvement are given taking into account both plant, pathogen and environment.  相似文献   

Endangered plant life     

Willem Meijer 《Biological conservation》1973,5(3):163-167

This paper discusses ways and means of more effective action, on an international scale, for the protection of endangered plant life, and shows how, in places where people have become aware of possessing spectacular or unique examples of plant life, they have often added to amenities around sacred places and created inviolate parts of the world's heritage. Good results for conservation of representative areas have been reached locally through improved attitudes towards rational land-use planning, great caution in the employment of herbicides and pesticides, recognition in forestry of the need for a systems planning for natural areas, and awareness that the great diversity of the green plant cover, of flowers and trees, is among the most delightful features helping to keep the Earth as a livable and beautiful environment. Plant protection can be a very good and profitable way to promote local tourism.  相似文献   

土壤旋切振动减阻的有限元分析   总被引：8，自引：0，他引：8  

蒋建东  高洁  赵颖娣  Willem Hoogmoe  张宪 《农业机械学报》2012,43(1):58-62

提出了一种对旋耕机具施加振动载荷进行压实土壤切削减阻的方法。对板结土壤参数进行土壤三轴测试试验,结合LS—DYNA的MAT147材料模型,测试土壤材料模型参数,并建立了南方丘陵地带板结土壤本构模型及土壤振动旋切过程的有限元数值模型。通过三维数值模拟和计算,分析了外加激励的振型、频率及振幅等因素对土壤切削阻力的影响及变化规律,并得到实现最优减阻效果的各项参数组合。研究结果表明,采用振动旋耕机具进行土壤作业过程中,选择合适振动频率、幅值以及振动类型的外加刀具振动能实现土壤耕作减阻,有效降低机具的土壤切削功率。  相似文献   

15N-leucine and 15N-isoleucine isotope dilution techniques versus the 15N-isotope dilution technique for determining the recovery of endogenous protein and amino acids in digesta collected from the distal ileum in pigs.   总被引：2，自引：0，他引：2  

C F de Lange  W C Sauer  W B Souffrant  K A Lien 《Journal of animal science》1992,70(6):1848-1856

Twelve gilts, with an average initial BW of 38 kg, were fitted with simple T-cannulas at the distal ileum and two catheters in the external jugular veins. The animals were fed twice daily (0800 and 2000) 700 g of one of four diets containing either soybean meal, canola meal, wheat, or barley as the sole protein source. 15N-leucine was infused continuously for 9 d at a rate of 40 mg/kg of BW daily via one of the jugular catheters. Blood samples were taken during feeding. Ileal digesta samples were collected continuously for 24 h on d 7 and 9 of the infusion period. 15N-enrichment excess in leucine and isoleucine in the trichloroacetic acid (TCA)-soluble fraction of blood and in digesta were measured using single-ion monitoring gas chromatography-mass spectrometry. Assuming that the 15N-enrichment excess in leucine and isoleucine in the TCA-soluble fraction of the blood is similar to that in endogenous protein secreted into the digestive tract and that the amino acid composition of endogenous protein is constant, the contribution of endogenous to total protein in ileal digesta was calculated using the 15N-isotope dilution technique for leucine and isoleucine, respectively. These contributions were much smaller for the 15N-leucine than for the 15N-isoleucine isotope dilution technique: 7.1 to 11.0 vs 21.8 to 24.9 g of protein/kg of DM intake. The values obtained with the 15N-isoleucine isotope dilution technique were close to those obtained with the 15N-isotope dilution technique as described in a previous publication.  相似文献   

Tracer studies of urea kinetics in growing pigs: II. The effect of starch infusion at the distal ileum on urea recycling and bacterial nitrogen excretion.     

R Mosenthin  W C Sauer  H Henkel  F Ahrens  C F de Lange 《Journal of animal science》1992,70(11):3467-3472

Six gilts, with an average BW of 70 kg, were fitted with a simple T-cannula at the distal ileum to study the effect of continuous starch infusion on urea kinetics by means of a radioisotope dilution technique. The pigs were fed twice daily 600 g of a cornstarch-based diet formulated to contain 16% CP by supplementation with isolated soy protein. Infusion of starch, compared with water, decreased (P < .05) plasma urea concentration, urea pool size, and entry, excretion, and degradation rates; urea turnover rate and urea space were not affected (P > .05). Expressed as a percentage of total entry rate, approximately 40% of urea was recycled into the digestive tract in both infusion treatments. The stimulation of microbial fermentation in the large intestine resulted in an increase (P < .05) in fecal N excretion, which was mainly due to an increased excretion of bacterial N. This increase could not be attributed to a greater secretion of urea into the large intestine and its subsequent utilization by the intestinal microflora. The increased bacterial N assimilation after starch infusion led to a reduction in ammonia absorption from the large intestine, which in turn was reflected by a reduced urinary N excretion. As a result, the overall N balance was not affected. In a second experiment, two barrows, with an average BW of 80 kg, were fed twice daily 1.4 kg of a cereal-based diet. The body urea pool of both pigs was labeled with a single injection of 1 g and 2 g of [15N]urea, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Tracer studies of urea kinetics in growing pigs: I. The effect of intravenous infusion of urea on urea recycling and the site of urea secretion into the gastrointestinal tract.     

R Mosenthin  W C Sauer  C F de Lange 《Journal of animal science》1992,70(11):3458-3466

Four gilts (average BW 80 kg) were used in the first experiment to study the effect of i.v. infusion of urea on urea kinetics by means of a radioisotope dilution technique. The pigs were fed twice daily 600 g of a cornstarch-based diet formulated to contain 16% CP by supplementation with isolated soy protein. Infusion of urea, compared with saline, increased (P < .05) plasma urea concentration, urea pool size, urea entry, urea excretion, and urea degradation rates; urea turnover rate and urea space were not affected (P > .05). Expressed as a percentage of the total entry rate, a lower (P < .05) percentage of urea was recycled in pigs infused with urea. The urea infused was almost completely excreted in urine, so there were no differences (P > .05) in N balance. In the second experiment, four gilts (average BW 40 kg), fitted with ileocecal reentrant cannulas, were used to determine whether the upper or the lower digestive tract represents the preferential site of urea secretion in pigs. Two pigs were fed twice daily 600 g of a cornstarch-based diet, formulated to contain 16% CP from soybean meal. The other two pigs were fed the same diet in which 15% cornstarch was replaced by beet pulp. After labeling the body urea pool of one pig on each treatment with [15N]urea, the reentrant cannulas were disconnected to prevent the flow of digesta from the small into the large intestine.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献