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  • Author: H. Xue x
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Assessment of AFLP-Based Genetic Variation in the Populations of Picea asperata

Summary

Picea asperata Mast., which occurs in a restricted habitat in western China, has a wide ecological amplitude. In the present study, ten natural populations of P. asperata were studied using AFLP markers to investigate the population genetic structure and the level of genetic diversity. Of the 210 loci identified with two EcoRI/MseI primer combinations, 142 loci were found to be polymorphic. Yet, the level of genetic diversity observed within populations was quite low. The averages of NEI’s gene diversities (h) and Shannon's indices of diversity (I) calculated across populations equaled 0.156 and 0.227, respectively. The coefficient of gene differentiation among populations, based on the estimate GST and the unbiased estimate Φst, equaled 0.340 and 0.231, respectively. The mean genetic distance (D) between population pairs was 0.119 (range 0.050-0.156). Such high values indicate that there is significant differentiation among populations of P. asperata. Several factors could have contributed to the strong population differentiation, including relatively limited gene flow between populations (Nm = 0.968). Variation in environmental conditions and consequent selection pressures may be other factors attributing to the high level of genetic differentiation among populations. In addition, it was discovered that the geographic distances are not correlated with the genetic distances between the populations of P. asperata.

Open access
Impact of Different Irrigation Managements on Soil Water Consumption, Grain Yield, Seed Protein, Phosphorus and Potassium of Winter Wheat

Abstract

To evaluate soil water consumption, changes in quantity and quality of winter wheat seed and forage under different irrigation treatments, an experiment was conducted in Beijing, China, in the 2012-2013. Irrigation treatments were (I1): irrigation before sowing, (I2): irrigation before sowing + before freezing; (I3): irrigation before sowing + before freezing + irrigation in the beginning of erecting stage + irrigation at flowering stage; (I4): irrigation before sowing + irrigation before freezing + irrigation at the booting stage + irrigation at flowering stage. The laid out of experiment was randomized complete block design, repeated six times. The effect of irrigation on total biological yield, grain yield and harvest index is significant. The highest mean soil water consumption in Oct., Nov., Dec., Jan., Feb., Mar., Apr. and May was obtained for lysimeter 10 (I2), lysimeter 10 (I2), lysimeter 6 (I2), lysimeter 10 (I2), lysimeter 10 (I2), lysimeter 10 (I2), lysimeter 11 (I3), and lysimeter 10 (I2), respectively. The results from the study indicate that irrigation winter wheat throughout the booting stage and flowering stage increased grain yield, harvest index, potassium percentage, ash percentage of forage wheat at flowering stage, seed and forage protein percentage. Evapotranspiration trends increased steadily, especially in last three months, in which the lysimeter fields were covered by winter wheat completely.

Open access
Impact of Bio-Fertilizer or Nutrient Solution on Spinach (Spinacea oleracea) Growth and Yield in Some Province Soils of P.R. China

Abstract

A study was conducted to assess the effects of a bio-fertilizer and an inorganic fertilizer on growth, yield of spinach vegetable, on four cultivated soils, representing different agro-ecological zones of Chengdu, Hunan, Xiaotangshan and Shaanxi. Three replicates soil samples mixed with bio-fertilizer 100 g per pot and nutrient solution (MgSO4, Ca(NO)2, KNO3) 633 ml based on container volume. Spinach seeded directly ten per pot, thinned to five watered to plant water requirement until maturity. RCBD of three replication used, data for growth, yield and other agronomic characters and soil physicochemical properties evaluated. Soil results showed substantial differences in physicochemical properties from the four agro-ecological zones (Ferrod Arenosol, Entisol, Aridisol and Vertisol). Plant emergence percent were Xiaotangshan (74.8%), Chengdu (74.5%), Hunan (72.4%) and Shaanxi (70.7%), plant height at six week, Xiaotangshan (17.8 cm), Hunan (17.1 cm), Shaanxi (16.8 cm) and Chengdu (16.1 cm) the least, number of leaves at six weeks were Xiaotangshan (21), Hunan (19) and (16) Shaanxi, leaf area Hunan (89.5 cm2), Shaanxi (83.7 cm2), Chengdu (79.4 cm2) and Xiaotangshan (78.1 cm2), dry biomass of 4.88, 4.35, 3.83 and 3.03 g obtained for Hunan, Chengdu, Shaanxi and Xiaotangshan, respectively. Percentage plant emergence based on soil layers were 0-25 cm (75.8%), 25-50 cm (75.3%), 50-75 cm (71.6%) and 75-100 cm (69.6%), respectively; highest plant emergence percentage were obtained from top soil layer of Hunan, treated with biofertilizer. Substantial differences were observed for plant height, biomass and other agronomic characters in all the soils. The results show that Hunan soil is the most suitable for cultivation of spinach under biofertilizer treatment, compared to other types. The study underpins the importance soil types and fertilizer evaluation for a sustainable vegetable production in China.

Open access
Analysis of a Mechanistic Model for Non-invasive Bioimpedance of Intact Skin

Abstract

A mechanistic mathematical model for electrical impedance spectroscopy (EIS) measurements of human skin is analyzed, leading to a reduced model and approximate solutions. In essence, the model considers a complex-valued Laplace equation in the frequency domain for the alternating current from a circular EIS probe passing through the layers – stratum corneum, viable skin and adipose tissue – of human skin in the frequency range 1 kHz – 1 MHz. The reduced model, which only needs to be solved numerically for the viable skin with modified boundary conditions, is verified with the full set of equations (non-reduced model): good agreement is found with a maximum relative error of less than 3%. A Hankel transform of the reduced model allows for approximate solutions of not only the measured impedance but also the point-wise potential distribution in the skin. In addition, the dimensionless numbers governing the EIS are elucidated and discussed.

Open access
Dielectrical properties of living epidermis and dermis in the frequency range from 1 kHz to 1 MHz

Abstract

We determine the in-vivo dielectric properties—resistivity and relative permittivity—of living epidermis and dermis of human skin soaked with a physiological saline solution for one minute between 1 kHz and 1 MHz. This is done by fitting approximate analytical solutions of a mechanistic model for the transport of charges in these layers to a training set comprising impedance measurements at two depth settings on stripped skin on the volar forearm of 24 young subjects. Here, the depth settings are obtained by varying the voltage at a second inject on the electrical-impedance-spectroscopy probe. The model and the dielectric properties are validated with a test set for a third depth setting with overall good agreement. In addition, the means and standard deviations of the thicknesses of living epidermis and dermis are estimated from a literature review as 61±7 μm and 1.0±0.2 mm respectively. Furthermore, extensions to resolve the skin layers in more detail are suggested.

Open access