Wheat (Triticum aestivum L.)/faba bean (Vicia faba L.) intercropping shows significant overyielding and high nitrogen (N)-use efficiency, but the dynamics of plant interactions have rarely been ...estimated. The objective of the present study was to investigate the temporal dynamics of competitive N acquisition between intercropped wheat and faba bean with the logistic model. Wheat and faba bean were grown together or alone with limited N supply in pots. Data of shoot and root biomass and N content measured from 14 samplings were fitted to logistic models to determine instantaneous rates of growth and N uptake. The superiority of instantaneous biomass production and N uptake shifted from faba bean to wheat with their growth. Moreover, the shift of superiority on N uptake occurred 7-12 days earlier than that of biomass production. Interspecific competition stimulated intercropped wheat to have a much earlier and stronger superiority on instantaneous N uptake compared with isolated wheat. The modeling methodology characterized the temporal dynamics of biomass production and N uptake of intercropped wheat and faba bean in different planting systems, which helps to understand the underlying process of plant interaction for intercropping plants.
In this paper, we derive W~（1,∞） and piecewise C~（1,α） estimates for solutions, and their t-derivatives, of divergence form parabolic systems with coefficients piecewise H¨older continuous in space ...variables x and smooth in t. This is an extension to parabolic systems of results of Li and Nirenberg Comm Pure Appl Math, 2003, 56：892–925 on elliptic systems. These estimates depend on the shape and the size of the surfaces of discontinuity of the coefficients, but are independent of the distance between these surfaces.
Introduction
Quince A (
Cydonia oblonga
Mill.), a typical dwarfing rootstock in pear cultivation, is susceptible to iron (Fe) deficiency in calcareous soils. The aim of this study was to compare the ...strategies in Fe uptake and utilization in dwarfing rootstock quince A (low Fe efficiency) versus a typical vigorous rootstock
Pyrus betulifolia
(PB) with high Fe efficiency.
Methods
Quince A and PB were grown in nutrient solution (pH 6.3) for 4 weeks followed by three pH treatments: pH6.3, pH8.3a (adjusted with hydroxide) and pH8.3b (adjusted with bicarbonate). The Fe uptake and utilization indicators of the rootstocks were assessed at the onset of chlorosis symptoms (after 58 days of treatments).
Results and discussion
In contrast to PB, quince A exhibited Fe deficiency chlorosis under bicarbonate (pH8.3b). Bicarbonate stimulated the root proton secretion, inhibited root growth and ferric chelate reductase (FCR) activity in both PB and quince A, whereas high pH without bicarbonate (pH8.3a) stimulated only root proton release. Both species accumulated more Fe in roots under high pH treatments than under pH6.3, resulting in Fe sufficiency in leaves. Both high pH treatments increased the activity of leaf FCR in PB and quince A. However, extractable Fe(II) concentration in leaves was increased by high pH treatments in PB only. This study demonstrated that depressed Fe(III) reduction in leaves caused by bicarbonate rather than high pH explained Fe deficiency in quince A grown in bicarbonate-containing medium.
We used field experimental data to evaluate the ability of the agricultural production system model (APSIM) to simulate soil P availability, maize biomass and grain yield in response to P fertilizer ...applications on a fluvo-aquic soil in the North China Plain. Crop and soil data from a 2-year experiment with three P fertilizer application rates (0, 75 and 300 kg P2O5 ha−1) were used to calibrate the model. Sensitivity analysis was carried out to investigate the influence of APSIM SoilP parameters on the simulated P availability in soil and maize growth. Crop and soil P parameters were then derived by matching or relating the simulation results to observed crop biomass, yield, P uptake and Olsen-P in soil. The re-parameterized model was further validated against 2 years of independent data at the same sites. The re-parameterized model enabled good simulation of the maize leaf area index (LAI), biomass, grain yield, P uptake, and grain P content in response to different levels of P additions against both the calibration and validation datasets. Our results showed that APSIM needs to be re-parameterized for simulation of maize LAI dynamics through modification of leaf size curve and a reduction in the rate of leaf senescence for modern stay-green maize cultivars in China. The P concentration limits (maximum and minimum P concentrations in organs) at different stages also need to be adjusted. Our results further showed a curvilinear relationship between the measured Olsen-P concentration and simulated labile P content, which could facilitate the initialization of APSIM P pools in the NCP with Olsen-P measurements in future studies. It remains difficult to parameterize the APSIM SoilP module due to the conceptual nature of the pools and simplified conceptualization of key P transformation processes. A fundamental understanding still needs to be developed for modelling and predicting the fate of applied P fertilizers in soils with contrasting physical and chemical characteristics.
In composite materials, the stress may be arbitrarily large in the narrow region between two close-to-touching hard inclusions. The stress is represented by the gradient of a solution to the Lamé ...system of linear elasticity. The aim of this paper is to establish lower bounds of the gradients of solutions of the Lamé system with partially infinite coefficients as the distance between the surfaces of discontinuity of the coefficients of the system tends to zero. Combining it with the pointwise upper bounds obtained in our previous work, the optimality of the blow-up rate of gradients is proved for inclusions with arbitrary shape in dimensions two and three. The key to show this is that we find a blow-up factor, a linear functional of the boundary data, to determine whether the blow-up will occur or not.
Dans les matériaux composites, la contrainte peut être arbitrairement grande dans la région étroite entre deux inclusions dures proches de se toucher. La contrainte est représentée par le gradient d'une solution au système de Lamé d'élasticité linéaire. Le but de cet article est d'établir des bornes inférieures des gradients de solutions du système de Lamé avec des coefficients partiellement infinis car la distance entre les surfaces de discontinuité des coefficients du système tend vers zéro. En le combinant avec les limites supérieures ponctuelles obtenues dans nos travaux précédents, l'optimalité du taux de gonflement des gradients est prouvée pour des inclusions de forme arbitraire en dimensions deux et trois. La clé pour montrer cela est que nous trouvons un facteur d'explosion, une fonctionnelle linéaire des données de limite, à déterminer si l'explosion se produira ou non.
Little information is available on phosphorus (P) uptake and rhizosphere processes in maize (Zea mays L.), faba bean (Vicia faba L.), and white lupin (Lupinus albus L.) when intercropped or grown ...alone in acidic soil. We studied P uptake and soil pH, carboxylate concentration, and microbial community structure in the rhizosphere of maize, faba bean, and white lupin in an acidic soil with 0-250 mg P (kg⁻¹ soil) as KH₂PO₄ (KP) or FePO₄ (FeP) with species grown alone or intercropped. All plant species increased the pH compared to unplanted control, particularly faba bean. High KP supply (>100 mg P kg⁻¹) significantly increased carboxylate concentration in the rhizosphere of maize. The carboxylate composition of the rhizosphere soil of maize and white lupin was significantly affected by P form (KP or FeP), whereas, this was not the case for faba bean. In maize, the carboxylate composition of the rhizosphere soil differed significantly between intercropping and monocropping. Yield and P uptake were similar in monocropping and intercropping. Monocropped faba bean had a greater concentration of phospholipid fatty acids in the rhizosphere than that in intercropping. Intercropping changed the microbial community structure in faba bean but not in the other corps. The results show that P supply and P form, as well as intercropping can affect carboxylate concentration and microbial community composition in the rhizosphere, but that the effect is plant species-specific. In contrast to previous studies in alkaline soils, intercropping of maize with legumes did not result in increased maize growth suggesting that the legumes did not increase P availability to maize in this acidic soil.
In China, warfarin is usually prescribed with Chuanxiong Rhizoma for treating thromboembolism diseases. However, the reason for their combination is still being determined. The present study explored ...the pharmacokinetics interactions of warfarin, Chuanxiong Rhizoma, and gut microbiota in the rat model of middle cerebral artery occlusion (MCAO).
A total of 48 rats were randomly divided into six groups: MCAO rats orally administered warfarin (W group), pseudo germ-free MCAO rats orally administered warfarin (W-f group), MCAO rats co-administered Chuanxiong Rhizoma and warfarin (C + W group), pseudo germ-free MCAO rats co-administered Chuanxiong Rhizoma and warfarin (C + W-f group), MCAO rats co-administered warfarin and senkyunolide I (S + W group); pseudo germ-free MCAO rats co-administered warfarin and senkyunolide I (S + W-f group). After treatment, all animals' blood and stool samples were collected at different time points. The stool samples were used for 16S rRNA sequencing analysis. Ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) method was established to quantify warfarin, internal standards, and the main bioactive components of Chuanxiong in blood samples. The main pharmacokinetics parameters of warfarin were calculated by DAS 2.1.1 software.
The relative abundance of
and
in the pseudo germ-free groups (W-f, C + W-f, S + W-f) was lower than that in the other three groups (W, C + W, S + W). The relative abundance of
in the W-f group was higher than that of the W group, while the relative abundance of
decreased. The relative abundance of Ruminococcaceae
and Ruminococcaceae
in the S + W-f group was lower than in the S + W group. Compared to the W group, the AUC
and C
of warfarin in the W-f group increased significantly to 51.26% and 34.58%, respectively. The AUC
and C
in the C + W group promoted 71.20% and 65.75% more than the W group. Compared to the W group, the AUC
and C
increased to 64.98% and 64.39% in the S + W group.
Chuanxiong Rhizoma and senkyunolide I (the most abundant metabolites of Chuanxiong Rhizoma aqueous extract) might affect the pharmacokinetics features of warfarin in MCAO rats through, at least partly, gut microbiota.
The problem of coal spontaneous combustion prediction is very complex, and there are many factors that affect the prediction results. In order to solve the issues of high dimension and redundancy ...among features and limited samples in the prediction of coal spontaneous combustion, this paper proposes a prediction algorithm of coal spontaneous combustion based on least squares support vector machine and adaptive particle swarm optimization (APSO-LSSVM). The adaptive PSO algorithm is used to solve the problems such as high computational complexity and slow calculation speed of the LS-SVM model for large-scale samples, so that it can always obtain the optimal solution, and its training speed and accuracy are improved. This method adjusts the inertia weight based on the convergence degree of group and the adaptive value of an individual for accelerating the training speed of swarm. After that, the improved PSO is used to iteratively solve the matrix equations in LS-SVM. APSO-LSSVM avoids the matrix inversion, saves the internal memory and obtains the optimum solution. The experiment results show that this method simplifies the training sample, accelerates the training speed, and also offers superior classification accuracy, fast convergence speed and good generalization ability.
We study a class of second-order elliptic equations of divergence form, with discontinuous coefficients and data, which models the conductivity problem in composite materials. We establish optimal ...gradient estimates by showing the explicit dependence of the elliptic coefficients and the distance between interfacial boundaries of inclusions. These extend the known results in the literature and answer open problem (
b
) proposed by Li and Vogelius (2000) for the isotropic conductivity problem. We also obtain more interesting higher-order derivative estimates, which answers open problem (
c
) of Li and Vogelius (2000). It is worth pointing out that the equations under consideration in this paper are non-homogeneous.
Rhizosphere interactions between intercropping maize and alfalfa to increase phosphorus (P) acquisition remain largely unknown. This study aimed to investigate the mechanisms underlying niche ...complementarity to increase P acquisition in the maize/alfalfa mixture by influencing root/rhizosphere interactions. Maize was grown alone (single maize) or with maize (maize/maize) or alfalfa (maize/alfalfa) with low P (30 mg P kg−1 soil) and high P (150 mg P kg−1 soil) supplies. The target maize had greater shoot biomass and P content when grown with alfalfa than maize. Compared with maize, alfalfa had higher secretion of carboxylates and acid phosphatase, suggesting a stronger capacity to mobilize soil P. Phosphorus deficiency also increased the specific root length and the proportion of thin roots (diameter < 0.2 mm) in alfalfa, and intercropped alfalfa had higher carboxylates secretion than monocropped one, indicating that alfalfa root traits were modified by both soil P supply and the identity of neighbor. Increased soil P availability by alfalfa root exudation and improved rhizosphere environment by thin alfalfa roots promoted shoot growth and P acquisition of maize in the maize/alfalfa mixture. The presence of maize increased the secretion of carboxylates from alfalfa roots, suggesting that the root interactions between maize and alfalfa are crucial for improving P‐use efficiency and productivity in intercropping.
Phosphorus deficiency can inhibit maize growth and shoot P accumulation, but maize intercropping with alfalfa can effectively facilitate shoot growth and P uptake in maize. Alfalfa increased soil P availability through root exudation and enhanced growth of thin roots (diameter < 0.2 mm), resulting in improved P uptake and increased shoot growth of neighboring maize, suggesting that the complementarity of root/rhizosphere processes between maize and alfalfa contributes to improved maize P uptake and shoot growth. The complementarity of root/rhizosphere processes between maize and alfalfa was affected by soil P supply rate. The facilitation in P acquisition between maize and alfalfa was stronger at low P than high P supply.
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