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1.
Modelling crop growth and biomass partitioning to shoots and roots in relation to nitrogen and water availability,using a maximization principle 总被引:1,自引:0,他引:1
Many crop models relate the allocation of dry matter between shoots and roots exclusively to the crop development stage. Such models may not take into account the effects of changes in environment on allocation, unless the allocation parameters are altered. In this paper a crop model with a dynamic allocation parameter for dry matter between shoots and roots is described. The basis of the model is that a plant allocates dry matter such that its growth is maximized. Consequently, the demand and supply of carbon, nitrogen, and water is maintained in balance. This model supports the hypothesis that a functional equilibrium exists between shoots and roots.This paper explains the mathematical computation procedure of the crop model. Moreover, an analysis was made of the ability of a crop model to simulate plant dry matter production and allocation of dry matter between plant organs. The model was tested using data from a greenhouse experiment in which spring wheat (Triticum aestivum L.) was grown under different soil moisture and nitrogen (N) levels.Generally, the model simulations agreed well with data recorded for total plant dry matter. For validation data the coefficient of determination (r2) between simulated and measured shoot dry weight was 0.96. For the validation treatments r2 was slightly lower, 0.94. In addition to dry matter production the model succeeded satisfactorily in simulating the dry weight of different plant organs. The response of simulated root to shoot ratio to the level of soil moisture was mainly in accordance with the measured data. In contrast, the simulated ratio seemed to be insensitive to the changes in the levels soil N concentration used in the experiment.The data used in the present study were not extensive, and more data are needed to validate the model. However, the results showed that the model responses to the changes in soil N and water level were realistic and mostly agreed with the data. Thus, we suggest that the model and the method employed to allocate dry matter between roots and shoots are useful when modelling the growth of crops under N and water limited conditions. 相似文献
2.
The estimation of parameters in several dynamic models, which describe growth and substrate consumption, has been carried out using a modified Gauss-Newton-type method. The four models considered are Monod, Contois, linear specific growth rate, and an enzyme kinetic model. The initial values of the differential equations are included in the parameter vector which will be estimated. The efficiency of the method and the confidence limits of the parameters were studied using simulated measurement noise. The experimental results describe Trichoderma viride growing on glucose as the main carbon source. 相似文献
3.
4.
Juha Karjalainen Olli Urpanen Tapio Keskinen Hannu Huuskonen Jouko Sarvala Pentti Valkeajrvi Timo J. Marjomki 《Ecology and evolution》2016,6(3):779-790
Fish are known for their high phenotypic plasticity in life‐history traits in relation to environmental variability, and this is particularly pronounced among salmonids in the Northern Hemisphere. Resource limitation leads to trade‐offs in phenotypic plasticity between life‐history traits related to the reproduction, growth, and survival of individual fish, which have consequences for the age and size distributions of populations, as well as their dynamics and productivity. We studied the effect of plasticity in growth and fecundity of vendace females on their reproductive traits using a series of long‐term incubation experiments. The wild parental fish originated from four separate populations with markedly different densities, and hence naturally induced differences in their growth and fecundity. The energy allocation to somatic tissues and eggs prior to spawning served as a proxy for total resource availability to individual females, and its effects on offspring survival and growth were analyzed. Vendace females allocated a rather constant proportion of available energy to eggs (per body mass) despite different growth patterns depending on the total resources in the different lakes; investment into eggs thus dictated the share remaining for growth. The energy allocation to eggs per mass was higher in young than in old spawners and the egg size and the relative fecundity differed between them: Young females produced more and smaller eggs and larvae than old spawners. In contrast to earlier observations of salmonids, a shortage of maternal food resources did not increase offspring size and survival. Vendace females in sparse populations with ample resources and high growth produced larger eggs and larvae. Vendace accommodate strong population fluctuations by their high plasticity in growth and fecundity, which affect their offspring size and consequently their recruitment and productivity, and account for their persistence and resilience in the face of high fishing mortality. 相似文献
5.
A polyamine analogue prevents acute pancreatitis and restores early liver regeneration in transgenic rats with activated polyamine catabolism 总被引:4,自引:0,他引:4
Rasanen TL Alhonen L Sinervirta R Keinanen T Herzig KH Suppola S Khomutov AR Vepsalainen J Janne J 《The Journal of biological chemistry》2002,277(42):39867-39872
We recently generated a transgenic rat model for acute pancreatitis, which was apparently caused by a massive depletion of pancreatic polyamines spermidine and spermine due to inducible activation of their catabolism (Alhonen, L., Parkkinen, J. J., Kein?nen, T., Sinervirta, R., Herzig, K. H., and J?nne, J. (2000) Proc. Natl. Acad. Sci. U. S. A. 97, 8290-8295). When subjected to partial hepatectomy, these animals showed striking activation of polyamine catabolism at 24 h postoperatively with a profound decrease in hepatic spermidine and spermine pools and failure to initiate liver regeneration. Here we show that pancreatitis in this model could be totally prevented, as judged by histopathology and plasma alpha-amylase activity, by administration of 1-methylspermidine, a metabolically stable analogue of spermidine. Similarly, the analogue, given prior to partial hepatectomy, restored early liver regeneration in the transgenic rats, as indicated by a dramatic increase in the number of proliferating cell nuclear antigen-positive hepatocytes from about 1% to more than 40% in response to the drug. The present results suggest that the extremely high concentration of spermidine in the pancreas, in fact the highest in the mammalian body, may have a critical role in maintaining organ integrity. The failure to initiate liver regeneration in the absence of sufficient hepatic polyamine pools similarly indicates that polyamines are required for proper commencement of the regenerative process. 相似文献
6.
An instrumentation and automation system for a side-vented pan coater with a novel air-flow rate measurement system for monitoring
the film-coating process of tablets was designed and tested. The instrumented coating system was tested and validated by film-coating
over 20 pilot-scale batches of tablets with aqueous-based hydroxypropyl methylcellulose (HPMC). Thirteen different process
parameters were continuously measured and monitored, and the most significant ones were logged for analysis. Laser profilometry
was used to measure the surface roughness of the coated tablets. The instrumentation system provided comprehensive and quantitative
information on the process parameters monitored. The measured process parameters and the responses of the film-coated tablet
batches showed that the coating process is reproducible. The inlet air-flow rate influenced the coating process and the subsequent
quality of the coated tablets. Increasing the inlet flow rate accelerated the drying of the tablet surface. At high inlet
flow rate, obvious film-coating defects (ie, unacceptable surface roughness of the coated tablets) were observed and the loss
of coating material increased. The instrumented and automated pancoating system described, including historical data storage
capability and a novel air-flow measurement system, is a useful tool for controlling and characterizing the tablet film-coating
process. Monitoring of critical process parameters increases the overall coating process efficiency and predictability. 相似文献
7.
Lampinen M Bondesson U Fredriksson E Hedeland M 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2003,789(2):347-354
A liquid chromatography tandem mass spectrometry (LC-MS-MS) method for determination of the analgesic aminophenol ketobemidone in human plasma is presented. Two preparation methods for plasma samples containing ketobemidone were compared, liquid-liquid extraction (LLE) and solid-phase extraction (SPE). Both methods showed good precision (n=10), 1.7% and 2.9%, respectively (0.04 micro M) and 1.1% and 2.5%, respectively (0.14 micro M). The accuracy was 98% and 103%, respectively (0.04 micro M) and 105% and 99%, respectively (0.14 micro M). Ketobemidone could be quantified at 0.43 nM, with a relative standard deviation of 17.5% (n=19) using LLE and 18.6% (n=10) using SPE. This level was an order of magnitude lower than earlier reported quantification limits. Quantitative data from plasma samples analyzed with LC-MS-MS were in good agreement with those obtained by gas chromatography with chemical ionization mass spectrometry (GC-CI/MS). This indicates that LC-MS-MS is a good alternative method to GC-MS as it is more sensitive and time-consuming derivatization can be avoided. 相似文献
8.
9.
Sanna Saarnio Jukka Alm Pertti J. Martikainen & Jouko Silvola 《Journal of Ecology》1998,86(2):261-268
1 In a glasshouse experiment we studied the effect of raised CO2 concentration (720 p.p.m.) on CH4 emission at natural boreal peat temperatures using intact cores of boreal peat with living vascular plants and Sphagnum mosses. After the end of the growing season half of the cores were kept unnaturally warm (17–20 °C). The potential for CH4 production and oxidation was measured at the end of the emission experiment.
2 The vascular cores ('Sedge') consisted of a moss layer with sedges, and the moss cores (' Sphagnum ') of Sphagnum mosses (some sedge seedlings were removed by cutting). Methane efflux was 6–12 times higher from the Sedge cores than from the Sphagnum cores. The release of CH 4 from Sedge cores increased with increasing temperature of the peat and decreased with decreasing temperature. Methane efflux from Sphagnum cores was quite stable independent of the peat temperatures.
3 In both Sedge and Sphagnum samples, CO2 treatment doubled the potential CH4 production but had no effect on the potential CH4 oxidation. A raised concentration of CO2 increased CH4 efflux weakly and only at the highest peat temperatures (17–20 °C).
4 The results suggest that in cool regions, such as boreal wetlands, temperature would restrict decomposition of the extra substrates probably derived from enhanced primary production of mire vegetation under raised CO2 concentrations, and would thus retard any consequent increase in CH4 emission. 相似文献
2 The vascular cores ('Sedge') consisted of a moss layer with sedges, and the moss cores (' Sphagnum ') of Sphagnum mosses (some sedge seedlings were removed by cutting). Methane efflux was 6–12 times higher from the Sedge cores than from the Sphagnum cores. The release of CH
3 In both Sedge and Sphagnum samples, CO
4 The results suggest that in cool regions, such as boreal wetlands, temperature would restrict decomposition of the extra substrates probably derived from enhanced primary production of mire vegetation under raised CO
10.
Nutrient concentration in shape Sphagna at increased N-deposition rates and raised atmospheric CO2 concentrations 总被引:1,自引:0,他引:1
Sphagnum fuscum, S. magellanicum, S. angustifolium and S. warnstorfii were treated with N deposition rates (0, 10, 30 and 100 kg ha-1 a-1) and with four atmospheric CO2 concentrations (350, 700, 1000 and 2000 ppm) in greenhouse for 71–120 days. Thereafter, concentrations of total N, P, K, Ca and Mg in the capitulae of the Sphagna were determined. The response of each species to N deposition was related to ecological differences. With increasing N deposition treatments, moss N concentrations increased and higher N:P-ratios were found, the increase being especially clear at the highest N load. Sphagnum fuscum, which occupies ombrotrophic habitats, was the most affected by the increased nitrogen load and as a consequence the other elements were decreased. Oligotrophic S. magellanicum, wide nutrient status tolerant S. angustifolium and meso-eutrophic S. warnstorfii tolerated better increased N deposition, though there were increased concentrations of Ca and Mg in S. warnstorfii and Mg in S. magellanicum. Nitrogen and P concentrations decreased with raised CO2 concentrations, except for S. magellanicum. This seems to be the first time this kind of response in nutrient concentrations to enhanced CO2 concentration has been shown to exist in bryophytes. The concentration of K clearly decreased in S. fuscum as did the concentration of Mg in the other Sphagna with increasing CO2. Sphagnum angustifolium and S. magellanicum, which are the less specialized species, were the least affected by the CO2 treatments. 相似文献