Showing papers in "Acta Agriculturae Scandinavica Section B-soil and Plant Science in 2000"
TL;DR: The design of a rather complex experiment to explore the possibilities for both short-term and long-term increases in organic cereal production through manipulation of crop-rotation design on different soil types is described.
Abstract: A field experiment is being conducted which focuses on crop rotations for cereal production in organic farming. The objective of the experiment is to explore the possibilities for both short-term and long-term increases in organic cereal production through manipulation of crop-rotation design on different soil types. This paper describes the design of a rather complex experiment, and later papers will describe and discuss the results. Three factors are included in the experiment in a factorial design with two replicates: (1) fraction of grass-clover and pulses in the rotation (crop rotation); (2) catch crop (with or without catch crop or bi-cropped clover); and (3) manure (with or without animal manure applied as slurry). All fields in all rotations are represented in each year. The experimental factors are defined to allow management to be adjusted for optimization of the individual treatment combinations. This makes the systems more realistic and the results more applicable in practical farming. The exp...
115 citations
TL;DR: The result showed that P has a direct effect on the N2-fixation parameters, rather than an indirect effect via increased plant growth, which indicates the importance to studying the effects of more than one nutrient at a time.
Abstract: Red clover (Trifolium pratense L.) is one of the most important plants in forage production, especially in northern areas. Fertilisation practices are focused on high yield and forage quality but effects of nutrients on nodulation and N2 fixation are poorly understood. The aim of this work was to study how nitrogen (N) and phosphorus (P) separately as well as in combination affected nodulation. Red clover plants were grown in pots with gravel in a greenhouse for 11 weeks. To resemble field conditions the root temperature was kept lower than the shoot temperature. Plants were given five different combinations of N and P concentrations during growth. The result showed that at high N concentrations P had a counteracting effect on the N inhibition. The N2-fixation parameters, nodule number, nodule dry matter and specific nitrogenase activity, were six times higher in plants grown with high N and high P than in plants with high N and low P. When the N2-fixation parameters and the dry matter of roots and shoots...
61 citations
TL;DR: In a six-year crop rotation trial organically and integrated grown vegetables were produced according to current good agricultural practices, taking quality and quantity aspects into consideration as mentioned in this paper, and the results showed that the vegetables were harvested according to good practices.
Abstract: In a six-year crop rotation trial organically and integrated grown vegetables were produced according to current good agricultural practices, taking quality and quantity aspects into consideration....
55 citations
TL;DR: In this article, the authors developed pedotransfer functions for Danish soils by multiple linear regression analysis of 1643 samples from a nation-wide 7 km grid survey, and the average soil organic matter-CEC is 284-291 cmolc kg.
Abstract: The soil cation-exchange capacity (CEC) has edaphological, pedological and environmental importance. CEC pedotransfer functions were developed for Danish soils by multiple linear regression analysis of 1643 samples from a nation-wide 7 km grid survey. By partitioning the data into four groups [podzolic B-horizons, organic soils (>10% soil organic matter), calcareous soils (>0.1% CaCO3), and a 'normal data set'], four separate functions were developed. Without further partitioning of the normal data, 90% of the variability in CEC values can be modelled by using clay and organic matter content as independent variables. This yields a standard error of the estimate of 1.99. The average soil organic matter-CEC is 284-291 cmolc kg
51 citations
TL;DR: Farm-related determinants for the adoption of short-rotation willow coppice production among Swedish farmers are identified and estimated and a Tobit model is applied to cross-sectional data on farmers in 1995.
Abstract: The area of short-rotation willow coppice energy plantations on Swedish farmland increased quickly in the early 1990s because of subsidies for energy crop production, an increased CO2 tax on fossil fuel and an already existing biofuel market in the country. In this study farm-related determinants for the adoption of short-rotation willow coppice production among Swedish farmers are identified and estimated. A Tobit model is applied to cross-sectional data on Swedish farmers in 1995. The results show that the decision to plant willow and the areas planted depend positively on arable land area, forest land area, the area of other land types, leasing out of arable land and tractor ownership. Negative factors are pasture area, tenancy and animal production. Differences in willow growing between ownership types, age groups and geographical regions are also important. The policy implications of the results are discussed.
32 citations
TL;DR: Surprisingly, a high formation of tetraploid shoots (10-25%) was, moreover, obtained from the APM studies, and a clear positive chromosome-doubling effect was indicated with prolonged preculture of the ovules before theAPM treatment.
Abstract: Chromosome doubling in vitro of sugar beet (Beta ulgaris L.) ovules precultured for 0-10 days was studied with the antimicrotubule herbicide amiprophos-methyl (APM) in 20, 150, 300 mM concentrations and with 2, 5 or 18 h of treatment. Efficient chromosome-doubling results were obtained at 150 mM APM for 5 h, which produced 56-64% diploid regenerants from B. ulgaris ovule culture. APM was found to possess chromosome-doubling effects in combination with toxic effects on embryo formation. A clear positive chromosome-doubling effect was indicated with prolonged preculture of the ovules before the APM treatment. The percentage of diploid shoots increased from 31 to 56 when prolonging the preculture from 0 to 10 days. Surprisingly, a high formation of tetraploid shoots (10-25%) was, moreover, obtained from the APM studies.
20 citations
TL;DR: In this paper, the variations in carrot cadmium (Cd) concentration and determine how they are influenced by soil factors were collected over a 2-year period, and the Cd content of carrots averaged 0.30 mg kg-1 dry matter (DM).
Abstract: Over a 2-year period, carrots and surface soil samples (0-25 cm) from commercial fields in Sweden were collected in order to determine the variations in carrot cadmium (Cd) concentration and determine how they are influenced by soil factors. Differences between varieties with respect to Cd concentration were also determined in two field trials. The Cd content of carrots averaged 0.30 mg kg-1 dry matter (DM), but the range was large (0.06-0.85 mg kg-1
18 citations
TL;DR: In this article, the major extractable organic compounds were identified in the biologically degradable fraction of fresh, composted and anaerobically digested household waste and isolated by supercritical fluid extraction using carbon dioxide.
Abstract: The recirculation of plant nutrients from urban areas to agriculture and horticulture and a need to reduce waste disposal by landfilling and incineration are the main reasons for recycling the biologically degradable fraction of household waste. However, before using the recycled material in agricultural and horticultural production it is necessary to make sure that the material does not contain any unwanted contaminants. In general, there is a lack of knowledge about organic contaminants in the degradable fraction of household waste and its compost and anaerobic digestion products. As a first step in a study of organic contaminants in household waste, and as part of the characterization of the degradation processes during composting and anaerobic digestion, the major extractable organic compounds were identified in the biologically degradable fraction of fresh, composted and anaerobically digested household waste. The organic compounds were isolated by supercritical fluid extraction using carbon dioxide ...
17 citations
TL;DR: Because the samples analysed were representative of grain produced for the market in seasons with normal weather, trichothecene contamination of grain from large family farms and partnerships would not be expected to be a problem in most years.
Abstract: Samples of winter wheat (n =84), winter rye (46) and barley (29) were collected from the larger family farms and from partnerships in Lithuania just after the 1998 harvest. The number of samples collected from each region was proportional to the amount of grain produced in it. The levels of the Fusarium toxins deoxynivalenol (DON), 3-acetyl-DON, 15-acetyl-DON, nivalenol (NIV), fusarenon-X (4-acetyl-NIV), T-2 toxin, HT-2 toxin, 4,5-diacetoxyscirpenol (DAS), 1,5-monoacetoxyscirpenol (MAS) and scirpentriol in the grain were determined by gas chromatography with mass-selective detection (GC-MS). DON was most often detected in the wheat and rye samples and NIV in the barley samples. The concentrations found were lower than those causing acute or chronic toxic effects in livestock or humans. No fusarenon-X or 15-acetyl-DON was detected, and only small amounts of other trichothecenes were present. Climatic conditions in Lithuania in the summer of 1998 were slightly cooler and wetter than the average for the 1992...
14 citations
TL;DR: Dolly, Queen Elizabeth and Friesia were used as pistillate parents and the resistant germplasm L83 (derived from the amphidiploid R) was used as fertiliser for Rosa species exhibiting high level of resistance to blackspot.
Abstract: Blackspot is a serious disease on cultivated roses and resistance is rare; however, some wild Rosa species exhibit a high level of resistance. Disease incidence in field-grown offspring from three seedling families was evaluated as percentage of infected leaves (regardless of the size and number of spots) on each plant. Dolly, Queen Elizabeth and Friesia were used as pistillate parents and the resistant germplasm L83 (derived from the amphidiploid R
13 citations
TL;DR: The results showed that bees still chose and utilized plant species with a small number of open flowers in the density-reduced plots, and in plantspecies with a larger number of flowers, bees often chose the dense plots or did not visit as many flowers on plants in thedensity-red reduced plots.
Abstract: This investigation tested how a reduction in plant density affected the willingness of bees to visit a number of palaearctic plant species. Pairwise comparisons were made between the first bee visits to control and manipulated plots. The results showed that bees still chose and utilized plant species with a small number of open flowers in the density-reduced plots. In plant species with a larger number of flowers, bees often chose the dense plots or did not visit as many flowers on plants in the density-reduced plots. Multiflowered plants may produce only small amounts of nectar in order to discourage pollinators from foraging too long in the inflorescences. This would result in a decrease in the number of self-pollination events and an increase in pollen export.
TL;DR: The objective of this research was to select an appropriate secondary crop that could be grown with maize in an intercropping system to control weeds while maintaining maize yields, and a negative relation was found between theield of secondary crop plus weeds in August and October and the yield of maize in October.
Abstract: Intercropping and bicropping are common cultivation systems in many countries. Maize (Zea mays L.) as a main crop combined with a legume as secondary crop is in general use in many countries. These systems may contribute to a higher biodiversity, and reduced import of fertilizer, concentrates and agrochemicals. The objective of this research was to select an appropriate secondary crop that could be grown with maize in an intercropping system to control weeds while maintaining maize yields. Field beans (Vicia faba L.), crimson clover (Trifolium incarnatum L.), phacelia (Phacelia tanacetifolia Benth.) and thyphon [Brassica rapa L. ar. rapa (L.) Thell] were selected as secondary crops. Acceptable yields of dry matter in maize were obtained regardless of secondary crop. Different yield levels were obtained depending on the morphology of the secondary crop. Thyphon, a high, dense secondary crop with large leaves, shaded the lower maize canopy, and thereby reduced the yield of maize. In contrast, field bean, wh...
TL;DR: The relationship between regrowth rates and the content of water-soluble carbohydrates in stubble (WSC) and percentage of non-elongated tillers (PNT) was studied in timothy and meadow fescue cut at different phenological stages.
Abstract: The relationship between regrowth rates and the content of water-soluble carbohydrates in stubble (WSC) and percentage of non-elongated tillers (PNT) was studied in timothy (Phleum pratense L.) and meadow fescue (Festuca pratensis Huds.) cut at different phenological stages. Single plants were grown in pots and cut outdoors and then regrown under controlled climatic conditions. The data for the dry matter production during the following 3 weeks were fitted to an expolinear growth equation to determine an initial maximum relative regrowth rate (R m) and a daily maximum regrowth rate (C m). C m appeared to be positively correlated to PNT in both species, whereas R m was increased with increasing WSC. For regrowth after later cuts of meadow fescue there was a positive contribution to R m by PNT.
TL;DR: Estimates of broad sense heritability (h2 b) for winter hardiness in white clover (Trifolium repens L.) based on an experiment in the field, and freezing hardiness based on a laboratory test are compared.
Abstract: For testing of winter hardiness and to obtain estimates of heritability (h2) for this character, field experiments are the most common method. In order to develop a supplement to the field method, artificial freezing to test for freezing hardiness in the laboratory has been carried out. The purpose of the present study was to compare estimates of broad sense heritability (h2 b) for winter hardiness in white clover (Trifolium repens L.) based on an experiment in the field, and freezing hardiness based on a laboratory test. The plant material consisted of six local populations with origins between ca. 61°- and 70° northern Latitude. The northern related populations Nos. 06 and 22 showed the best winter hardiness in the field, while the more southern related population No. 38 showed the best freezing hardiness in the laboratory. The field data was generally more variable than the laboratory data. In the field, h2 b
TL;DR: Occurrence and amounts of some Fusarium toxins in Finnish cereal samples in 1998 and in 1998 are shown.
Abstract: Eskola, M., Rizzo, A., and Soupas, L. (Department of Chemistry, National Veterinary and Food Research Institute (EELA), P.O. Box 368 (Hämeentie 57), FI-00231 Helsinki, Finland, and Department of Applied Chemistry and Microbiology, Faculty of Agriculture and Forestry, University of Helsinki, P.O. Box 27 (Latokartanonkaar i 11, Building D), FI-00014, Finland). Occurrence and amounts of some Fusarium toxins in Finnish cereal samples in 1998. Accepted April 2, 2001. Acta Agric. Scand., Sect. B, Soil and Plant Sci. 50, 183–186, 2000. © 2000 Taylor & Francis. Mari Eskola Aldo Rizzo and Laura Soupas Department of Chemistry, National Veterinary and Food Research Institute (EELA), P.O. Box 368 (Hämeentie 57), FI-00231 and Department of Applied Chemistry and Microbiology, Faculty of Agriculture and Forestry, University of Helsinki, P.O. Box 27 (Latokartanonkaari 11, Building D), FI-00014, Helsinki, Finland
TL;DR: Tuber quality was lowered by the use of excess N fertilizer, particularly in the case of earlies and the quantity of mineralised N present in the soil after harvest rose sharply with above optimum fertilizer use, and the amount ofN present in crop residues also increased.
Abstract: Trials were performed with early and semi-early potatoes to test the effects of nitrogen (N) fertilizer level (0-160 kg N ha-1) and timing (all at planting versus half then and half either soon after emergence or 3 weeks later). All seven trials with earlies were irrigated as required, whilst different irrigation regimes (moderate versus intensive) were compared in two trials with semi-earlies. No benefit was derived from splitting the N application. Haulm growth and N uptake increased in all cases almost linearly up to the highest N level, but tuber yield did not respond in the same way. The optimum N level was 80 kg N ha-1 for a yield of 15 Mg ha-1, rising to 120 kg N ha-1 for a yield of 40 Mg ha-1. Tuber quality was lowered by the use of excess N fertilizer, particularly in the case of earlies. The quantity of mineralised N present in the soil after harvest rose sharply with above optimum fertilizer use, and the amount of N present in crop residues also increased. The likely leaching after early potato...
TL;DR: In this article, solid phase microextraction (SPME) is used to detect quality impact compounds from the p-menthane group (menthol, menthone, neomenthol, isomenthone, and menthyl acetate).
Abstract: Essential oils (EO) are plant secondary metabolites that are known for their fragrance and food flavour properties. They consist of a complex mixture of mono- and sesquiterpenes, phenyl propanoids and oxygenated compounds. EOs can be present in different plant organs and materials, and their storage is related to specialised secretory structures. The yield of EOs from plant raw materials by distillation or pressing may on average vary from 0.1 – 1%, thus restricting the major EO production to the plant group of aromatic plants. Due to their function as signalling compounds between different types of organisms and diverse biological systems, their general antimicrobial and antioxidative effects and medicinal activity, EOs offer a promising potential for future applications within the fields of agriculture, medicine, pharmaceutical industry and biotechnology.Changed consumer demands and raised interest in natural product compounds, especially essential oils, have formed the basis for initiating the research project “Norwegian Herb Production (Norsk Urteproduksjon NUP)” to encourage the cultivation, processing, marketing and distribution of aromatic and medicinal plants. The production, composition and quality characteristics of EOs (yield and terpene composition) from chamomile, lemon balm, oregano, peppermint, sachalinmint, thyme and yarrow have been investigated in the project period between 1994-1998.Much focus has been put on the application of solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) for the analysis of EO volatiles from various aromatic and medicinal plants. SPME is a fast, solvent-free and non- destructive sample preparation technique where the analytes are extracted from fluid or solid matrices by headspace (HS) or direct immersion sampling (DI). Apart from EO isolation by common distillation, the applicability and sensitivity of the SPME fibre has made it feasible to carry out qualitative and semi-quantitative HS analyses of aromatic plants with regard to changes of EO metabolism during ontogenesis and plant development.Based on NUP-results from field trials in the period between 1995-1996, the mint species peppermint (Mentha × piperita L.) and sachalinmint (Mentha sachalinensis (Briq.) Kudo) have been studied in detail (Papers B, D and E). Comparative analyses by applying distillation sampling and SPME have been carried out in order to study the advantages and disadvantages of both techniques (Papers B and E). It could be shown, that SPME offers a fast and reliable method for detecting quality-impact compounds from the p-menthane group (menthol, menthone, neomenthol, isomenthone and menthyl acetate). A distinct increase in the menthol/menthone ratio in the basipetal direction could be detected for peppermint and sachalinmint by applying SPME, thus revealing within-plant quality differences according to pharmacopeial requirements. Taking the increase of EO production from the vegetative to the generative growth stage into account, the harvest of mint plants in bloom will result in better EO yield and quality with regard to higher amounts of menthol.When applying HS-SPME on complex EO volatile matrices such as known for yarrow (Achillea millefolium L.; Paper C), one might deal with fibre-partitioning effects of the different mono- and sesquiterpenes due to their physical and chemical properties. Despite these disadvantages, HS-SPME appears to be a sensitive extraction method for the screening of EO volatiles from complex sample matrices. Comparative analyses of volatiles from rose root rhizomes (Rhodiola rosea L.) have been carried out in order to characterize the rose-like odour compounds (Paper F). A total of 75 and 59 compounds have been identified by distillation sampling and HS-SPME, respectively, thus underscoring the excellent extraction properties and applicability of the SPME fibre.Paper A gives a brief overview of EO biosynthesis and chemical structures, plant sources and methods of EO production. Before leading over to the main topic of HS-SPME applications by referring to numerous examples from the research work at The Plant Biocenter in the past 5 years, an introduction of solid-phase microextraction with regard to devices, procedures and extraction parameters is given.The advantages and disadvantages of distillation vs. SPME are outlined on the background of comparative analyses of peppermint, chamomile, basil and dill. Furthermore, the utilization of HS-SPME for quantitative studies with regard to extraction time and analyte concentration is being highlighted. Examples for the screening of chemotypes (hops −Humulus lupulus L.) and cultivars (dill – Anethum graveolens L.) and ontogenetic studies are given (Mentha species; arnica −Arnica montana L.). Finally, the applicability of HS-SPME for the quality assessment of processed herbs (sweet basil −Ocimum basilicum L.) and phytomedicinal preparations (red coneflower – Echinacea purpurea L.) is being discussed.The advantages of HS-SPME over classical distillation and headspace applications are impressive due to drastically reduced analysis time and will introduce new frontiers in plant volatile research with regard to secondary metabolism, plant-insect interactions and in vivo studies. The user-friendliness of operating SPME will initiate the development of future applications and equipment for the monitoring of volatiles for plant biological and environmental studies, extraction automation, on-site sampling and on-fibre storage of analytes.
TL;DR: While the total content of DIBOA and the total biomass in the shoot varied at similar rates in the first GS evaluated, a substantially greater relative increase in biomass occurred in the last two GS.
Abstract: The allocation of a hydroxamic acid (DIBOA) and biomass was evaluated in vegetative growth stages (GS) of rye. Allocation to the shoot, root/shoot ratio of allocation, and the effect of reduced pot volume on such patterns of allocation were evaluated. Higher allocation of biomass to the shoot relative to the root as the plant aged was observed. No significant differences in allocation of DIBOA were found at different plant GS. Reducing pot volume decreased final shoot biomass. The effect at an early GS was marginally non-significant, while it was highly significant at a late GS. The effect of reduced pot volume on DIBOA accumulation differed between the GS. At the early stage the DIBOA content per unit of biomass in the shoot increased significantly with reduced pot volume, whereas at the late stage it was not significantly different. The effects of reduced pot volume on the shoot were not a consequence of a significant shift in the corresponding root/shoot ratios. While the total content of DIBOA (nmol) ...
TL;DR: Prebreeding of red clover (Trifolium pratense L.) for northern areas.. Accepted October 4, 2000.
Abstract: Helgadóttir, Á., Larsen, A., Marum, P., Fritsen, H., Lindvall, E. and Miettinen E. (The Agricultural Research Institute, IS-112 Reykjav ṍ k, Iceland, The Norwegian Institute of Crop Research, VaÊ gønes Experimental Station, NO-8010 Bodø, Norway, The Norwegian Institute of Crop Research, Løken Experimental Station, NO-2940 Heggenes, Norway, DLF-Trifolium, Danish Plant Breeding, Box 19, DK-4660 Store Heddinge, Denmark, Svalöf Weibull AB, Northern Branch, Box 4097, SE-904 03 UmeaÊ , Sweden, and The Agricultural Research Centre, Kainuu Experimental Station, Kipinäntie 16, FI-88600 Sotkamo, Finland). Prebreeding of red clover (Trifolium pratense L.) for northern areas.. Accepted October 4, 2000. Acta Agric. Scand., Sect. B, Soil and Plant Sci. 50: 187–190, 2000. © 2000 Taylor & Francis. Áslaug Helgadóttir1,Ì, Arild Larsen, Petter Marum, Hugo Fritsen, Eva Lindvall and Eero Miettinen The Agricultural Research Institute, IS-112 Reykjav õ ́k, Iceland, The Norwegian Institute of Crop Research, VaÊ gønes Experimental Station, NO-8010 Bodø, Norway, The Norwegian Institute of Crop Research, Løken Experimental Station, NO-2940 Heggenes, Norway, DLF-Trifolium, Danish Plant Breeding, Box 19, DK-4660 Store Heddinge, Denmark, Svalöf Weibull AB, Northern Branch, Box 4097, SE-904 03 UmeaÊ , Sweden, and The Agricultural Research Centre, Kainuu Experimental Station, Kipinäntie 16, FI-88600 Sotkamo, Finland
TL;DR: Changes in grain production, mechanisms for sale of grain and possible effects on grain quality in Lithuania in the period 1990–1999 are studied.
Abstract: Keblys, M., FlaÊ øyen, A. and Langseth, W. (Lithuanian Veterinary Academy, Tilzes 18, Kaunas, Lithuania, National Veterinary Institute, P.O. Box 8156 Dep., NO-0033, Norway, and Department of Large Animal Clinical Sciences, Norwegian School of Veterinary Medicine, P.O. Box 8146 Dep., NO-0033 Olso, Norway). Changes in grain production, mechanisms for sale of grain and possible effects on grain quality in Lithuania in the period 1990–1999. Accepted March 9, 2001. Acta Agric. Scand., Sect. B, Soil and Plant Sci. 50: 97–101, 2000. © 2000 Taylor & Francis.
TL;DR: The results of this study indicated a high potential for use of perennial forage legumes at some locations in Alaska and the lack of large differences in most soil parameters indicates slow responsiveness to management by some commonly used soilquality indicators under subarctic conditions.
Abstract: Forage crops and soil attributes were evaluated for 4 years at three sites in Alaska. Annual herbage yields usually exceeded 5 Mg ha-1 on neutral soils at Fairbanks (64°52' W) and on moderately acidic soils at Point MacKenzie (61°24' N, 150°3' W). Strongly acidic, droughty soils at Delta Junction (63°55' N, 145°20' W) produced low yields for all crops. Soil pH decreased significantly over 4 years under N-fertilized grasses at Delta Junction and under alfalfa and N-fertilized barley at Fairbanks. Soil organic C and N and microbial biomass C showed no differences among treatments at the end of the study. Wet aggregate stability did not vary significantly among crops but was lower for fallow. The results of this study indicated a high potential for use of perennial forage legumes at some locations in Alaska. The lack of large differences in most soil parameters indicates slow responsiveness to management by some commonly used soilquality indicators under subarctic conditions.
TL;DR: The rate of vegetative development during the firstgrowth season was reflected in the yields in both the first and the second harvest year; the greater the plant diameter after the first growth season, the higher the yield.
Abstract: The effect of different factors on plant diameter and yield in hybrid arctic bramble (Rubus arcticus nothosubsp. stellarcticus) was examined in two field experiments with a factorial design. The studied factors included planting time (August, September, May or June), plant type (bare-rooted or potted plants) and ground cover (no ground cover or mulching with a dark plastic film). Development of bare-rooted and potted plants did not differ when transplanted in the autumn and in May. Potted plants developed better than bare-rooted plants when transplanted in June. In one year, plants transplanted in May developed best, while in another, plants transplanted in the autumn developed best. Mulching with a dark plastic film improved plant development. The rate of vegetative development during the first growth season was reflected in the yields in both the first and the second harvest year; the greater the plant diameter after the first growth season, the higher the yield.
TL;DR: Growth and carbon dioxide (CO2) assimilation responses of winter wheat (Triticum aestivum) are studied to study the response of wheat to carbon dioxide in the environment.
Abstract: Growth and carbon dioxide (CO2) assimilation responses of winter wheat (Triticum aestivum
TL;DR: Leaf area and shoot dry weight were lower outdoors than in growth chambers at similar irradiance and temperature and a simulation model with temperature and irradiance responses derived from growth-chamber experiments was used to test whether outdoor growth could be estimated properly.
Abstract: The early growth of spring barley (Hordeum ulgare L.), Brassica rapa L. ssp. oleifera (DC.) Metzger, Stellaria media (L.) Vill. and Viola arvensis Murray in growth chambers and in shading cages outdoors at different irradiance levels was compared. Leaf area and shoot dry weight were lower outdoors than in growth chambers at similar irradiance and temperature. A simulation model with temperature and irradiance responses derived from growth-chamber experiments was used to test whether outdoor growth could be estimated properly. The correlations of the regressions between simulated and measured values of leaf area index (LAI) and shoot dry weight were high. However, with some exceptions, overestimations occurred, more for shoot dry weight than for LAI, and more for 100% daylight than for lower irradiance. The reasons for this are discussed.
TL;DR: In this paper, the importance of a firm seedbed bottom was evaluated, where germination of spring barley (Hordeum vulgare L.) under dry weather conditions was studied on a clay, a silty clay loam and a sandy loam.
Abstract: Placement of seeds on a firm, moist seedbed bottom has proved important for crop establishment in spring in Sweden. However, most modern seed drills can place the seed at the desired depth independent of a firm seedbed bottom. This was not the case with older equipment. In this work, the importance of a firm seedbed bottom was evaluated, where germination of spring barley (Hordeum vulgare L.) under dry weather conditions was studied on a clay, a silty clay loam and a sandy loam with or without a firm seedbed bottom. The experiments were carried out in lysimeters protected from precipitation. Time-domain reflectometry was used for soil water content measurements, and thermocouples to monitor soil temperature. A firm seedbed bottom greatly improved seed germination on the clay soil with a small content of plant available water, but not on the other soils. On all soils, a loose seedbed bottom increased maximum surface soil temperature.