Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Considerations on the shuttle mechanism of FeEDDHA chelates at the soil-root interface in case of Fe deficiency
    Schenkeveld, W.D.C. ; Reichwein, A.M. ; Temminghoff, E.J.M. ; Riemsdijk, W.H. van - \ 2014
    Plant and Soil 379 (2014)1-2. - ISSN 0032-079X - p. 373 - 387.
    strategy i plants - calcareous soil - lolium-perenne - metal uptake - iron uptake - complexes - eddha - chlorosis - isomers - montmorillonite
    A mechanism of action for the performance of Fe chelates as soil-applied fertilizer has been hypothesized by Lindsay and Schwab (J Plant Nutr 5:821-840, 1982), in which the ligand participates in a cyclic process of delivering Fe at the root surface and mobilizing Fe from the soil. This "shuttle mechanism" seems appealing in view of fertilizer efficiency, but little is known about its performance. The chelate FeEDDHA is a commonly used Fe fertilizer on calcareous soils. In this study, the performance of the shuttle mechanism has been examined for FeEDDHA chelates in soil interaction and pot trial experiments. The specificity of EDDHA ligands for chelating Fe from soils of low Fe availability is limited. Experimental support for a shuttle mechanism in soil-plant systems with FeEDDHA was found: specific metal mobilization only occurred upon FeEDDHA-facilitated Fe uptake. The mobilized metals originated at least in part from the root surface instead of the soil. The results from this study support the existence of a shuttle mechanism with FeEDDHA in soil application. If the efficiency of the shuttle mechanism is however largely controlled by metal availability in the bulk soil, it is heavily compromised by complexation of competing cations: Al, Mn and particularly Cu.
    Urban agriculture in Portugal: Availability of potentially toxic elements for plant uptake
    Cruz, N. ; Rodriguez, S.M. ; Coelho, C. ; Carvalho, L. ; Duarte, A.C. ; Pereira, E. ; Romkens, P.F.A.M. - \ 2014
    Applied Geochemistry 44 (2014). - ISSN 0883-2927 - p. 27 - 37.
    halimione-portulacoides - contaminated soils - european cities - trace-elements - lolium-perenne - heavy-metals - part i - vegetables - cadmium - mercury
    Soils from urban areas often contain enhanced pseudo-total levels of potentially toxic elements (PTEs). Considering the expanding tendency of urban agricultural practices it is necessary to understand if these contaminants are available for plant uptake and if they pose risks to animal and human health. This study showed that estimates of Daily Intakes (DIs) of Cu, Pb and Zn for grazing animals were above animal Acceptable Daily Intakes (ADIs) at specific sites under the influence of an airport, an oil refinery and near highways with high traffic rates in the "Grande Porto" urban area (Portugal). These results suggest that there is a potential for dietary transfer of contaminants associated with the ingestion of both contaminated soil and feed by cows and sheep at unacceptably high concentrations.Furthermore, results showed that 40% of variability of ryegrass shoot contents of Cu, Pb and Ni; 60% for Ba; 70% for Zn; and 80% for Cd can be significantly (p
    Intermediate herbivory intensity of an aboveground pest promotes soil labile resources and microbial biomass via modifying rice growth
    Huang, J. ; Liu, M. ; Chen, X. ; Chen, J. ; Chen, F. ; Li, H. ; Hu, F. - \ 2013
    Plant and Soil 367 (2013). - ISSN 0032-079X - p. 437 - 447.
    nilaparvata-lugens stal - below-ground communities - inner-mongolia grassland - animal trophic groups - brown planthopper - lolium-perenne - nitrogen availability - plant performance - grazing intensity - carbon allocation
    The importance of aboveground herbivores for modifying belowground ecosystems has prompted numerous studies; however, studies can be biased by context dependent conditions which lead to extremely inconsistent results. So far, the impacts of herbivory inte
    Determination of free Zn2+ concentration in synthetic and natural samples with AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) and DMT (Donnan Membrane Techniques)
    Chito, D. ; Weng, L.P. ; Galceran, J. ; Companys, E. ; Puy, J. ; Riemsdijk, W.H. van; Leeuwen, H.P. van - \ 2012
    Science of the Total Environment 421-422 (2012). - ISSN 0048-9697 - p. 238 - 244.
    dissolved organic-matter - metal-ion concentrations - humic-acid - electroanalytical technique - lolium-perenne - soil solution - trace-metals - speciation - binding - waters
    The determination of free Zn2+ ion concentration is a key in the study of environmental systems like river water and soils, due to its impact on bioavailability and toxicity. AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) and DMT (Donnan Membrane Technique) are emerging techniques suited for the determination of free heavy metal concentrations, especially in the case of Zn2+, given that there is no commercial Ion Selective Electrode. In this work, both techniques have been applied to synthetic samples (containing Zn and NTA) and natural samples (Rhine river water and soils), showing good agreement. pH fluctuations in DMT and N2/CO2 purging system used in AGNES did not affect considerably the measurements done in Rhine river water and soil samples. Results of DMT in situ of Rhine river water are comparable to those of AGNES in the lab. The comparison of this work provides a cross-validation for both techniques.
    Green biorefinery (GBR) scenarios for a two-cut silage system: Investigating the impacts of sward botanical composition, N fertilisation rate and biomass availability on GBR profitability and price offered to farmers
    O'Keeffe, S. ; Schulte, R.P.O. ; Lalor, S.T.J. ; O'Kiely, P. ; Struik, P.C. - \ 2011
    Biomass and Bioenergy 35 (2011)11. - ISSN 0961-9534 - p. 4699 - 4711.
    old permanent grassland - lolium-perenne - herbage productivity - quality - grasses - nitrogen - forages - range
    In Ireland, grass is a readily available bioresource. It has previously been established that Green biorefinery (GBR) could become a potential use of Irish grasslands, and a blueprint for a sustainable GBR industry in Ireland has been developed. The objective of this paper is to use scenario analysis to investigate the sensitivity of the profitability of the GBR blueprint to variations in grass quantity and quality as a function of botanical composition, fertiliser application, and biomass availability. As an outcome of these scenario analyses, the price the GBR can offer to farmers above their production costs (€ t-1 dry matter) was calculated. Results of the scenario analyses determined that GBR systems located in a catchment area of permanent pasture (Lolium perenne > 60%) with annual grass yields in the range of 9–12 t dry matter (DM) ha-1, and supplied with grass biomass with a fibre content of 500–555 g kg-1 DM and a protein content of 110–130 g kg-1 DM, were viable. The most profitable scenarios were generated when nitrogen fertiliser application was greater than 90 kg ha-1 a-1. Biomass availability of less than 30% resulted in reduced profitability and for some scenarios resulted in a loss for both the GBR and farmer due to increased transport costs. Within the scenario assumptions of this study, grass feedstock was valued at €4–€56 t-1 dry matter above production costs. However, this value depended on the yields and biomass availability of the GBR catchment area.
    Modeling the surface-atmosphere exchange of ammonia
    Wichink Kruit, R.J. ; Pul, W.A.J. van; Slauter, F.J. ; Broek, M. van den; Nemitz, E. ; Sutton, M.A. ; Krol, M.C. ; Holtslag, A.A.M. - \ 2010
    Atmospheric Environment 44 (2010)7. - ISSN 1352-2310 - p. 945 - 957.
    intensively managed grassland - nh3 deposition processes - oilseed rape plants - compensation point - dry deposition - seminatural vegetation - agricultural grassland - gradient measurements - apoplastic nh4+ - lolium-perenne
    New parameterizations for surfaceeatmosphere exchange of ammonia are presented for application in atmospheric transport models and compared with parameterizations of the literature. The new parameterizations are based on a combination of the results of three years of ammonia flux measurements over a grassland canopy (dominated by Lolium perenne and Poa trivialis) near Wageningen, the Netherlands and existing parameterizations from literature. First, a model for the surfaceeatmosphere exchange of ammonia that includes the concentration at the external leaf surface is derived and validated. Second, a parameterization for the stomatal compensation point (expressed as Gs, the ratio of [NH4+]/[H+] in the leaf apoplast) that accounts for the observed seasonal variation is derived from the measurements. The new, temperature-dependent Gs describes the observed seasonal behavior very well. It is noted, however, that senescence of plants and field management practices will also influence the seasonal variation of Gs on a shorter timescale. Finally, a relation that links Gs to the atmospheric pollution level of the location through the ‘long-term’ NH3 concentration in the air is proposed.
    Relationship between metal speciation in soil solution and metal adsorption at the root surface of ryegrass
    Kalis, E.J.J. ; Temminghoff, E.J.M. ; Town, R.M. ; Unsworth, E.R. ; Riemsdijk, W.H. van - \ 2008
    Journal of Environmental Quality 37 (2008). - ISSN 0047-2425 - p. 2221 - 2231.
    donnan membrane technique - deposition potential sscp - stripping chronopotentiometry - contaminated soils - diffusive gradients - organic-matter - natural-waters - lolium-perenne - heavy-metals - trace-metals
    Received for publication October 12, 2007. The total metal content of the soil or total metal concentration in the soil solution is not always a good indicator for metal availability to plants. Therefore, several speciation techniques have been developed that measure a defined fraction of the total metal concentration in the soil solution. In this study the Donnan Membrane Technique (DMT) was used to measure free metal ion concentrations in CaCl2 extractions (to mimic the soil solution, and to work under standardized conditions) of 10 different soils, whereas diffusive gradients in thin-films (DGT) and scanning chronopotentiometry (SCP) were used to measure the sum of free and labile metal concentrations in the CaCl2 extracts. The DGT device was also exposed directly to the (wetted) soil (soil-DGT). The metal concentrations measured with the speciation techniques are related to the metal adsorption at the root surface of ryegrass (Lolium perenne L.), to be able to subsequently predict metal uptake. In most cases the metal adsorption related pH-dependently to the metal concentrations measured by DMT, SCP, and DGT in the CaCl2 extract. However, the relationship between metal adsorption at the root surface and the metal concentrations measured by the soil-DGT was not¿or only slightly¿pH dependent. The correlations between metal adsorption at the root surface and metal speciation detected by different speciation techniques allow discussion about rate limiting steps in biouptake and the contribution of metal complexes to metal bioavailability.
    Comparison of energy evaluation systems and a mechanistic model for milk production by dairy cattle offered fresh grass-based diets.
    Dijkstra, J. ; Kebreab, E. ; Bannink, A. ; Crompton, L.A. ; Lopez, S. ; Abrahamse, P.A. ; Chilibroste, P. ; Mills, J.A.N. ; France, J. - \ 2008
    Animal Feed Science and Technology 143 (2008)1-4. - ISSN 0377-8401 - p. 203 - 219.
    perennial ryegrass cultivars - locally available supplements - neutral detergent fiber - rumen function - degradation characteristics - nitrogen-fertilizer - grazing behavior - lolium-perenne - fed sugarcane - cows
    Grass-based diets are of increasing social-economic importance in dairy cattle farming, but their low supply of glucogenic nutrients may limit the production of milk. Current evaluation systems that assess the energy supply and requirements are based on metabolisable energy (ME) or net energy (NE). These systems do not consider the characteristics of the energy delivering nutrients. In contrast, mechanistic models take into account the site of digestion, the type of nutrient absorbed and the type of nutrient required for production of milk constituents, and may therefore give a better prediction of supply and requirement of nutrients. The objective of the present study is to compare the ability of three energy evaluation systems, viz. the Dutch NE system, the agricultural and food research council (AFRC) ME system, and the feed into milk (FIM) ME system, and of a mechanistic model based on Dijkstra et al. [Simulation of digestion in cattle fed sugar cane: prediction of nutrient supply for milk production with locally available supplements. J. Agric. Sci., Cambridge 127, 247¿60] and Mills et al. [A mechanistic model of whole-tract digestion and methanogenesis in the lactating dairy cow: model development, evaluation and application. J. Anim. Sci. 79, 1584¿97] to predict the feed value of grass-based diets for milk production. The dataset for evaluation consists of 41 treatments of grass-based diets (at least 0.75 g ryegrass/g diet on DM basis). For each model, the predicted energy or nutrient supply, based on observed intake, was compared with predicted requirement based on observed performance. Assessment of the error of energy or nutrient supply relative to requirement is made by calculation of mean square prediction error (MSPE) and by concordance correlation coefficient (CCC). All energy evaluation systems predicted energy requirement to be lower (6¿11%) than energy supply. The root MSPE (expressed as a proportion of the supply) was lowest for the mechanistic model (0.061), followed by the Dutch NE system (0.082), FIM ME system (0.097) and AFRC ME system (0.118). For the energy evaluation systems, the error due to overall bias of prediction dominated the MSPE, whereas for the mechanistic model, proportionally 0.76 of MSPE was due to random variation. CCC analysis confirmed the higher accuracy and precision of the mechanistic model compared with energy evaluation systems. The error of prediction was positively related to grass protein content for the Dutch NE system, and was also positively related to grass DMI level for all models. In conclusion, current energy evaluation systems overestimate energy supply relative to energy requirement on grass-based diets for dairy cattle. The mechanistic model predicted glucogenic nutrients to limit performance of dairy cattle on grass-based diets, and proved to be more accurate and precise than the energy systems. The mechanistic model could be improved by allowing glucose maintenance and utilization requirements parameters to be variable.
    A new member of the LIR gene family form perennial ryegrass is cold-resposive, and promotes vegetative growth in Arabidopsis
    Ciannamea, S. ; Jensen, C.S. ; Agerskov, H. ; Petersen, K. ; Lenk, I. ; Didion, T. ; Immink, R.G.H. ; Angenent, G.C. ; Nielsen, K.K. - \ 2007
    Plant Science 172 (2007)2. - ISSN 0168-9452 - p. 221 - 227.
    mads-box genes - vernalization response - lolium-perenne - floral transition - flowering time - messenger-rnas - expression - thaliana - rice - tolerance
    A cold-regulated gene Lolium perenne LIR1 (LpLIR1) was isolated from perennial ryegrass using a subtractive approach. The gene has strong homology to the Light Induced Rice1 (LIR1) gene and is regulated at the transcriptional level by cold, and by a diurnal rhythm. Expression of LpLIR1 in perennial ryegrass was upregulated by vernalization but did not follow a standard vernalization-responsive expression pattern. LpLIR1 expression was restricted to vegetative tissues and absent in apices during floral induction and in flowers. LpLIR1 mRNA levels displayed diurnal fluctuations, which peaked before dusk and declined during the night. Heterologous expression of LpLIR1 in Arabidopsis led to a significant increase in leaf formation under short days (SD) conditions but only when plants had received a preceding vernalization treatment. Furthermore, dissection of plant development under SD revealed a minor but significant delay of flowering in the transgenic lines compared to wildtype plants
    Variation in effective pollination rates in relation to the spatial and temporal distribution of pollen release in rejuvenated perennial ryegrass
    Treuren, R. van; Goossens, P.J. ; Sevcikova, M. - \ 2006
    Euphytica 147 (2006)3. - ISSN 0014-2336 - p. 367 - 382.
    genetically-modified grasses - effective population-size - lolium-perenne - ssr markers - l. - diversity - cultivars - dna - dispersal - repeats
    Genebank accessions stored as seed populations require periodic rejuvenation in order to maintain sufficient numbers of viable seeds. During rejuvenation the genetic composition of accessions may be altered for a variety of reasons, of which variation in pollination rates between plants is the least understood. In the present study, a paternity exclusion analysis was performed on a rejuvenated accession of perennial ryegrass. In addition, flowering data of the 49 parental plants were collected during the flowering season. The aim of the study was to determine how accurate variation in pollination rates between plants can be predicted from data on the spatial and temporal distribution of pollen release. The parental population and a total of 551 offspring from 12 progeny arrays were genotyped by means of molecular analysis. Using 25 microsatellites, paternity was identified for 81.9% of the offspring, while remaining ambiguities were resolved by AFLP analysis, except in four cases. Within the total sample 9 cases of contamination were observed. Mating within the study population was clearly non-random, as 61.9% of the identified pollen donors were located within I m distance from the mother plant. Observed pollination rates were very well described by an inverse quadratic function of inter-plant distance between potential mating pairs. Incorporation of the recorded flowering data in the calculation of expected pollination rates improved the goodness of fit with observed values by only 0.77%. Suggestions to reduce the variance in paternal contributions were presented. However, contamination was considered more threatening to the genetic integrity of perennial ryegrass germplasm than variation in pollination rates between plants, and indicated the need for improved measures to avoid gene flow from other germplasm.
    Total soil C and N sequestration in a grassland following 10 years of free air CO2 enrichment
    Kessel, C. van; Boots, B. ; Graaff, M.A. de; Harris, D. ; Blum, H. ; Six, J. - \ 2006
    Global Change Biology 12 (2006)11. - ISSN 1354-1013 - p. 2187 - 2199.
    elevated atmospheric co2 - trifolium-repens l - organic-matter - carbon-dioxide - lolium-perenne - n-15-labeled fertilizer - litter quality - nitrogen pools - forest soils - plant
    Soil C sequestration may mitigate rising levels of atmospheric CO2. However, it has yet to be determined whether net soil C sequestration occurs in N-rich grasslands exposed to long-term elevated CO2. This study examined whether N-fertilized grasslands exposed to elevated CO2 sequestered additional C. For 10 years, Lolium perenne, Trifolium repens, and the mixture of L. perenne/T. repens grasslands were exposed to ambient and elevated CO2 concentrations (35 and 60 Pa pCO(2)). The applied CO2 was depleted in delta C-13 and the grasslands received low (140 kg ha(-1)) and high (560 kg ha(-1)) rates of N-15-labeled fertilizer. Annually collected soil samples from the top 10 cm of the grassland soils allowed us to follow the sequestration of new C in the surface soil layer. For the first time, we were able to collect dual-labeled soil samples to a depth of 75 cm after 10 years of elevated CO2 and determine the total amount of new soil C and N sequestered in the whole soil profile. Elevated CO2, N-fertilization rate, and species had no significant effect on total soil C. On average 9.4 Mg new C ha(-1) was sequestered, which corresponds to 26.5% of the total C. The mean residence time of the C present in the 0-10 cm soil depth was calculated at 4.6 +/- 1.5 and 3.1 +/- 1.1 years for L. perenne and T. repens soil, respectively. After 10 years, total soil N and C in the 0-75 cm soil depth was unaffected by CO2 concentration, N-fertilization rate and plant species. The total amount of N-15-fertilizer sequestered in the 0-75 cm soil depth was also unaffected by CO2 concentration, but significantly more N-15 was sequestered in the L. perenne compared with the T. repens swards: 620 vs. 452 kg ha(-1) at the high rate and 234 vs. 133 kg ha(-1) at the low rate of N fertilization. Intermediate values of N-15 recovery were found in the mixture. The fertilizer derived N amounted to 2.8% of total N for the low rate and increased to 8.6% for the high rate of N application. On average, 13.9% of the applied N-15-fertilizer was recovered in the 0-75 cm soil depth in soil organic matter in the L. perenne sward, whereas 8.8% was recovered under the T. repens swards, indicating that the N-2-fixing T. repens system was less effective in sequestering applied N than the non-N-2-fixing L. perenne system. Prolonged elevated CO2 did not lead to an increase in whole soil profile C and N in these fertilized pastures. The potential use of fertilized and regular cut pastures as a net soil C sink under long-term elevated CO2 appears to be limited and will likely not significantly contribute to the mitigation of anthropogenic C emissions.
    Effects of perennial ryegrass cultivars on milk yield and nitrogen utilization in grazing dairy cows
    Tas, B.M. ; Taweel, H.Z. ; Smit, H.J. ; Elgersma, A. ; Dijkstra, J. ; Tamminga, S. - \ 2006
    Journal of Dairy Science 89 (2006). - ISSN 0022-0302 - p. 3494 - 3500.
    water-soluble carbohydrate - lolium-perenne - herbage intake - nutritive-value - l. cultivars - performance - metabolism - lactation - pasture - quality
    The effects of 4 diploid perennial ryegrass cultivars that differed in water-soluble carbohydrate (WSC) concentrations on milk yield and nitrogen (N) utilization in dairy cows were evaluated in a 2-yr grazing experiment. Twelve lactating dairy cows were assigned to 1 cultivar for a 2-wk period in a 4 x 4 Latin square design with 3 replicates. Each year, the experiment lasted 8 wk. Swards were in a vegetative stage throughout the experiment. Herbage constituents were determined, and DM intake was estimated with the n-alkane technique. Nitrogen utilization was calculated as N excreted in milk divided by N intake, assuming a zero N retention. Two cultivars had consistently higher WSC concentrations and slightly lower neutral detergent fiber concentrations than the other 2 cultivars. The ranking of the cultivars in chemical composition traits in both years was rather consistent. Cows grazing the cultivar with the lowest concentration of WSC had the lowest herbage DM intake, N intake, milk yield, and milk N yield in 2002, but with a similar difference in WSC concentration, no differences among cultivars were found in 2003. In both years, milk urea N concentration was slightly higher for cows grazing the cultivar with the lowest WSC concentration, although it was significant only in 2003. Nitrogen utilization (N milk:N intake, g/g) varied between 0.241 and 0.246 in 2002 and between 0.190 and 0.209 in 2003, and in both years there was no effect of cultivar. At relatively high N concentrations in grass and only small differences among cultivars in neutral detergent fiber concentrations, cultivars with an elevated WSC concentration did not increase N utilization in grazing dairy cows
    Utilisation of N in perennial ryegrass cultivars by stall-fed lactating dairy cows
    Tas, B.M. ; Taweel, H.Z. ; Smit, H.J. ; Elgersma, A. ; Dijkstra, J. ; Tamminga, S. - \ 2006
    Livestock Science 100 (2006)2-3. - ISSN 1871-1413 - p. 159 - 168.
    water-soluble carbohydrate - lolium-perenne - intracellular constituents - rumen fermentation - milk-production - nitrogen - digestion - protein - l. - nutrition
    In the summers of 2000 and 2001, the effect of six diploid perennial ryegrass (Lolium perenne L.) cultivars on the N utilisation by 12 high productive dairy cows was determined. Experiments were conducted according to a double 3 × 3 Latin square design; within each Latin square, three cultivars were fed to six cows during three periods of 2 weeks each. Two cultivars had a higher water-soluble carbohydrate (WSC) content than the other cultivars in both years. A higher WSC content was more compensated by a lower neutral detergent fibre (NDF) content than by a lower crude protein content. In both years, dry matter intake (DMI) and milk production (MP) varied only slightly among cultivars and no differences among cultivars were found in the excretion of N in milk (in g/day and as % of N intake). Furthermore, cows fed the two cultivars with elevated WSC content had a lower N intake and this was associated with a lower milk urea N content and urinary N excretion. The small differences in chemical composition among cultivars did not result in significant differences in DMI, MP and N utilisation in dairy cows fed indoors. The results suggest that there is little scope to improve N utilisation of dairy cows at high N fertilization levels by breeding new cultivars
    Genetic diversity in perennial ryegrass and white clover among old Dutch grasslands as compared to cultivars and nature reserves
    Treuren, R. van; Bas, N. ; Goossens, P. ; Jansen, J. ; Soest, L.J.M. van - \ 2005
    Molecular Ecology 14 (2005)1. - ISSN 0962-1083 - p. 39 - 52.
    trifolium-repens l. - lolium-perenne - aflp analysis - populations - markers - plant - differentiation - polymorphisms - mixtures - nitrogen
    To support conservation policies for old Dutch grasslands that are still in agricultural use, morphological variation and AFLP-based (amplified fragment length polymorphism-based) genetic diversity was studied in perennial ryegrass and white clover populations and compared with the diversity in reference varieties. In addition, AFLP variation was also studied in grasslands located in nature reserves. From principal component analysis (PCA), it appeared that date of ear emergence in perennial ryegrass and characters related to plant vigour in white clover were the main morphological characters separating the reference varieties from the old Dutch grassland populations, and some of the grassland populations from each other. In both species, intrapopulation variation was lower for the reference varieties. Lower heterogeneity within the reference varieties was also found in the AFLP analysis. All common AFLP's observed in old Dutch grasslands could also be found in the reference varieties and nature reserves. Only a small number of low-frequency alleles found in old Dutch grasslands were absent from the other two groups. However, band frequencies of markers could vary considerably between populations, which may have been caused by selection. Analysis of the AFLP data by PCA distinguished the majority of reference varieties from the old Dutch grasslands, and showed genetic differentiation only between some grasslands. Comparison of old Dutch grasslands with grasslands in nature reserves indicated that basically the same range of genetic variation is covered by the two groups. Our study indicates that the Netherlands harbour a more or less continuous population for major parts of the diversity of perennial ryegrass and white clover. It was concluded that no specific conservation measures are presently needed to maintain genetic diversity of perennial ryegrass and white clover occurring in old Dutch grasslands
    Effects of perennial ryegrass cultivars on intake, digestibility, and milk yield in dairy cows
    Tas, B.M. ; Taweel, H.Z. ; Smit, H.J. ; Elgersma, A. ; Dijkstra, J. ; Tamminga, S. - \ 2005
    Journal of Dairy Science 88 (2005)9. - ISSN 0022-0302 - p. 3240 - 3248.
    water-soluble carbohydrate - lolium-perenne - rumen fermentation - white clover - nitrogen - ruminants
    The effects of 8 diploid perennial ryegrass (Lolium perenne L.) cultivars on dry matter (DM) intake, DM digestibility, and milk yield (MY) of dairy cows were evaluated in the summer of 2000 and 2001. Each summer, herbage was harvested daily and stall-fed to 12 dairy cows during six 2-wk periods. Six cultivars were fed in 3 periods (1, 3, and 5) according to a double 3 x 3 Latin square design. In the other periods (2, 4, and 6), 2 cultivars were fed in a repeated measurement design. Herbage mass and leaf blades in the sward canopy varied among cultivars, but differences were not consistent between years. The largest differences in herbage composition were found in water-soluble carbohydrate content, followed by crude protein content. only small differences were found in the neutral detergent fiber (NDF) content. A higher water-soluble carbohydrate content was found in 2 cultivars in both years, whereas ranking of cultivars in crude protein and NDF content was not consistent with years. Dry matter intake and MY were not affected by cultivar. In both years, DM digestiblity was high (>77%), with very small differences among cultivars in 2000 (
    Effects of feeding perennial ryegrass with an elevated concentration of water-soluble carbohydrates on intake, rumen function and performance of dairy cows
    Taweel, H.Z. ; Tas, B.M. ; Smit, H.J. ; Elgersma, A. ; Dijkstra, J. ; Tamminga, S. - \ 2005
    Animal Feed Science and Technology 121 (2005)3-4. - ISSN 0377-8401 - p. 243 - 256.
    dry-matter intake - lolium-perenne - milk-production - detergent fiber - external water - nitrogen - digestion - protein - digestibility - nutrition
    This study investigated effects of feeding perennial ryegrass with an elevated concentration of water-soluble carbohydrates (WSC) on dry matter intake (DMI), rumen function, milk production and composition of dairy cows. Twelve Holstein-Friesian dairy cows in mid lactation were stall-fed with fresh herbage of six varieties of perennial ryegrass during three 2-week periods, using a double 3 × 3 Latin square design. In each Latin square, three varieties were fed, one of which was characterised by a higher level of WSC (HSV) of 24 and 31 g/kg DM, respectively, than the lower WSC varieties (LSV). Other chemical components were similar or differed marginally and digestibility was similar. The results prove that it is possible to select for grass varieties with an elevated level of WSC. The DMI was not positively influenced by the increased WSC content, as cows fed HSV had similar DMI to cows fed the LSV (16.2 kg/day versus 16.6 kg/day). Rumen pH, neutral detergent fibre fractional clearance (KclNDF) and fractional degradation (kdNDF) rates were not reduced as a result of feeding HSV. Total VFA concentrations were not changed, nor were the proportions of acetate:propionate:butyrate. Milk urea concentration was reduced (P <0.05) as a result of feeding HSV. Milk yield and concentrations of milk fat, crude protein and lactose were not influenced. At the level of difference in WSC between grasses in this experiment, feeding HSV was not beneficial in improving DMI and milk production, or in altering the composition of milk. The hypothesis that feeding high WSC grasses increases DMI and milk production was, therefore not confirmed
    Decomposition of 14C-labeled roots in a pasture soil exposed to 10 years of elevated CO2
    Groenigen, C.J. van; Gorissen, A. ; Six, J. ; Harris, D. ; Kuikman, P.J. ; Groenigen, J.W. van; Kessel, C. van - \ 2005
    Soil Biology and Biochemistry 37 (2005)3. - ISSN 0038-0717 - p. 497 - 506.
    atmospheric carbon-dioxide - organic-matter dynamics - trifolium-repens l - microbial biomass - lolium-perenne - forest soils - tallgrass prairie - litter quality - fine roots - turnover
    The net flux of soil C is determined by the balance between soil C input and microbial decomposition, both of which might be altered under prolonged elevated atmospheric CO2. In this study, we determined the effect of elevated CO2 on decomposition of grass root material (Lolium perenne L.). 14C-labeled root material, produced under ambient (35 Pa pCO2) or elevated CO2 (70 Pa pCO2) was incubated in soil for 64 days. The soils were taken from a pasture ecosystem which had been exposed to ambient (35 Pa pCO2) or elevated CO2 (60 Pa pCO2) under FACE-conditions for 10 years and two fertilizer N rates: 140 and 560 kg N ha¿1 year¿1. In soil exposed to elevated CO2, decomposition rates of root material grown at either ambient or elevated CO2 were always lower than in the control soil exposed to ambient CO2, demonstrating a change in microbial activity. In the soil that received the high rate of N fertilizer, decomposition of root material grown at elevated CO2 decreased by approximately 17% after incubation for 64 days compared to root material grown at ambient CO2. The amount of 14CO2 respired per amount of 14C incorporated in the microbial biomass (q14CO2) was significantly lower when roots were grown under high CO2 compared to roots grown under low CO2. We hypothesize that this decrease is the result of a shift in the microbial community, causing an increase in metabolic efficiency. Soils exposed to elevated CO2 tended to respire more native SOC, both with and without the addition of the root material, probably resulting from a higher C supply to the soil during the 10 years of treatment with elevated CO2. The results show the importance of using soils adapted to elevated CO2 in studies of decomposition of roots grown under elevated CO2. Our results further suggest that negative priming effects may obscure CO2 data in incubation experiments with unlabeled substrates. From the results obtained, we conclude that a slower turnover of root material grown in an `elevated-CO2 world¿ may result in a limited net increase in C storage in ryegrass swards.
    Climate change affects carbon allocation to the soil in shrublands
    Gorissen, A. ; Tietema, A. ; Joosten, N.N. ; Estiarte, M. ; Peñuelas, J. ; Sowerby, A. ; Emmett, B. ; Beier, J.C. - \ 2004
    Ecosystems 7 (2004)6. - ISSN 1432-9840 - p. 650 - 661.
    lolium-perenne - calluna-vulgaris - plant - temperature - rhizosphere - decomposition - photosynthesis - translocation - respiration - dioxide
    Climate change may affect ecosystem functioning through increased temperatures or changes in precipitation patterns. Temperature and water availability are important drivers for ecosystem processes such as photosynthesis, carbon translocation, and organic matter decomposition. These climate changes may affect the supply of carbon and energy to the soil microbial population and subsequently alter decomposition and mineralization, important ecosystem processes in carbon and nutrient cycling. In this study, carried out within the cross-European research project CLIMOOR, the effect of climate change, resulting from imposed manipulations, on carbon dynamics in shrubland ecosystems was examined. We performed a 14C-labeling experiment to probe changes in net carbon uptake and allocation to the roots and soil compartments as affected by a higher temperature during the year and a drought period in the growing season. Differences in climate, soil, and plant characteristics resulted in a gradient in the severity of the drought effects on net carbon uptake by plants with the impact being most severe in Spain, followed by Denmark, with the UK showing few negative effects at significance levels of p 0.10. Drought clearly reduced carbon flow from the roots to the soil compartments. The fraction of the 14C fixed by the plants and allocated into the soluble carbon fraction in the soil and to soil microbial biomass in Denmark and the UK decreased by more than 60%. The effects of warming were not significant, but, as with the drought treatment, a negative effect on carbon allocation to soil microbial biomass was found. The changes in carbon allocation to soil microbial biomass at the northern sites in this study indicate that soil microbial biomass is a sensitive, early indicator of drought- or temperature-initiated changes in these shrubland ecosystems. The reduced supply of substrate to the soil and the response of the soil microbial biomass may help to explain the observed acclimation of CO2 exchange in other ecosystems.
    An object-oriented model of the morphological development and digestibility of perennial ryegrass
    Groot, J.C.J. ; Lantinga, E.A. - \ 2004
    Ecological Modelling 177 (2004)3-4. - ISSN 0304-3800 - p. 297 - 312.
    chemical-composition - seasonal-changes - lolium-perenne - plant-growth - leaf growth - grasses - crop - architecture - temperature - simulation
    An object-oriented simulation model was developed to integrate detailed analyses of perennial ryegrass (Lolium perenne) plant part dimensions, and their mass, cell wall content (CWC) and cell wall digestibility (CWD). The model was validated against data from two field experiments, carried out in The Netherlands (52degreesN) and Norway (67degreesN). In the experiments, the effects of temperature x daylength interactions on development, growth and digestibility were determined. Three cultivars differing in heading date were used, and undisturbed growth and regrowth after early (only in The Netherlands) and late cutting were studied. The sensitivity of the model was tested for changes in parameters determining morphological development. A grass plant was modelled as an aggregation of shoot objects. A shoot is an aggregation of phytomers, plus an inflorescence in the reproductive development stage. A phytomer consists of a leaf blade, a leaf sheath, a stem internode and a root. Each phytomer has an axillary bud, which can develop into a new shoot. Morphological development, organic matter (OM) growth and composition were simulated well by the model. Only for regrowing crops in The Netherlands CWC was lower and CWD was higher in the simulations than observed in the field, whereas the differences increased when stem development was more advanced at the moment of cutting. This was attributed to residual stems in the stubble after cutting due to difficulties with machine cutting of lodged crops on the experimental plots. The model can be considered as sufficiently accurate to simulate OM yield and composition of grass cultivars differing in heading date and growing under strongly contrasting temperature and daylength conditions. When the leaf appearance rate, width or length of the leaf blade were increased in the sensitivity analysis, OM yield enhanced, but composition and digestibility of the reproductive grass crops were not systematically affected. (C) 2004 Elsevier B.V. All rights reserved.
    Evaluation of BC2 progenies derived from 3x-2x and 3x-4x crosses of Lilium hybrids : a GISH analysis
    Lim, K.B. ; Ramanna, M.S. ; Jacobsen, E. ; Tuyl, J.M. van - \ 2003
    Theoretical and Applied Genetics 106 (2003)3. - ISSN 0040-5752 - p. 568 - 574.
    in-situ hybridization - lolium-perenne - introgression - derivatives - chromosomes - fertility - behavior - grasses - genome
    An allotriploid (ALA, 2n=3x=36) BC1 plant was obtained by backcrossing a diploid F1 interspecific hybrid (LA, 2n=2x=24), derived from a Lilium longiflorum (L genome) and an Asiatic hybrid (A genome), to the latter parent. This allotriploid was backcrossed to a diploid Asiatic hybrid (2n=2x=24) and to an allotetraploid (LLAA, 2n=4x=48) LA hybrid. A total of 25 plants of these crosses were examined for ploidy level, and 12 individuals were analyzed for their genome constitution through genomic in situ hybridization (GISH). In most cases the progenies from the triploid-diploid (3x-2x) crosses consisted of aneuploids. Further more, there was evidence for the formation of near-haploid (x=12+2) to triploid (3x=36) gametes in the allotriploid BC1 plant. The progenies of triploid-tetraploid (3x-4x) cross also consisted of mostly aneuploids but in this case the triploid female parent had contributed predominantly near-triploid (2n) gametes for the origin of BC2 progenies. The different ploidy levels observed between 3x-2x and 3x-4x crosses are possibly caused by preferential fertilization or survival resulting in a different ratio of chromosome numbers between the embryo and endosperm. Though Lilium has a tetrasporic, eight-nucleate type of embryo sac formation (Fritillaria type), the observed difference between the progeny types in 3x-2x and 3x-4x crosses is comparable to that of observed in monosporic eight nucleate types (Polygonum type) that predominate in most genera of Angiosperms. An important feature of the genome constitution of the progenies was that the homoeologous recombinant chromosomes were transmitted intact from BC1 to BC2 progenies in variable numbers. In addition, there was evidence for the occurrence of new homoeologous recombinations in the triploid BC1. Of the two euploid BC2 plants one had originated through the parthenogenetic development of a 2n egg and the other had originated through indeterminate meiotic restitution (IMR).
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