不同液土比和温度条件下塿土铵离子吸附

Effects of NH₄⁺ concentration, solution/soil ratio and temperature on NH₄⁺ adsorption were studied in a Eum-Orthic Anthrosol. The slopes of the soil NH₄⁺ adsorption isotherms and the fitted n, the coefficient for the adsorption intensity, and k, the coefficient related to adsorption capacity, of the Freundlich equation increased with increasing solution/soil ratio (SSR) and with decreasing temperature (T). For the range of experimental conditions, the value of ∂q/∂c, the rate of change of the amount of NH₄⁺ adsorbed in the soil solid phase (q) with respect to the equilibrium concentration of NH₄⁺ in soil solution (c), was 0.840, indicating that q increased with increasing c. From 2 to 45 ℃, ∂q/∂SSR, the rate of change of q with respect to SSR, decreased from 2.598 to 1.996, showing that q increased with increasing SSR, while its increasing rate decreased with temperature. From SSR 1:1 to 20:1, ∂q/∂T, the rate of change of q with respect to T, decreased from -0.095 to -0.361, indicating that q decreased with increasing temperature, and at the same time the negative effect of temperature became larger as SSR increased. Thus under the experimental conditions the order of importance in determining the amount of NH₄⁺ adsorbed in the soil solid phase was ∂q/∂SSR > ∂q/∂c > |∂q/∂T|, indicating that the greatest effect on the amount of NH₄⁺ adsorbed was with the solution/soil ratio; the equilibrium concentration of NH₄⁺ had a lesser effect; and temperature had the least effect.     

金沙江干热河谷退耕还林与生态问题的研究

通过对金沙江干热河谷生态环境和经营条件详细分析，具体提出适合金沙江流域不同海拔和立地条件的退耕还林的技术模式，论述了经济林模式、生态林模式、用材林模式和林草混交立体模式的适用立地条件、造林树种、经营技术及经济效益。     

Aluminum-induced decrease in CO2 assimilation in citrus seedlings is unaccompanied by decreased activities of key enzymes involved in CO2 assimilation

'Cleopatra' tangerine (Citrus reshni Hort. ex Tanaka) seedlings were irrigated daily for 8 weeks with 1/4 strength Hoagland's nutrient solution containing 0 (control) or 2 mM aluminum (Al). Leaves from Al-treated plants had decreased CO2 assimilation and stomatal conductance, but increased intercellular CO2 concentrations compared with control leaves. On a leaf area basis, 2 mM Al increased activities of key enzymes in the Calvin cycle, including ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), NADP-glyceraldehyde-3-phosphate dehydrogenase (GAPDH), phosphoribulokinase (PRK), stromal fructose-1,6-bisphosphatase (FBPase), and a key enzyme in starch synthesis, ADP-glucose pyrophosphorylase (AGPase), compared with control leaves. Aluminum had no effect on cytosolic FBPase activity, but it decreased sucrose phosphate synthase (SPS) activity. Aluminum had no effect on area-based concentrations of carbohydrates, glucose-6-phosphate (G6P) and fructose 6-phosphate (F6P) or the G6P:F6P ratio, but it decreased the area-based concentration of 3-phosphoglycerate (PGA). Photochemical quenching coefficient (qP) and electron transport rate through PSII were greatly reduced by Al. Non-photochemical quenching coefficient (NPQ) was less affected by Al than qP and electron transport rate through PSII. We conclude that the reduced rate of CO2 assimilation in Al-treated leaves was probably caused by a combination of factors such as reduced electron transport rate through PSII, increased closure of PSII reaction centers and increased photorespiration.     

Estimation of nitrogen status of paddy rice at vegetative phase using unmanned aerial vehicle based multispectral imagery

Precision Agriculture - Precision nitrogen fertilizer application depends on accurate estimation of plant nitrogen content. However, the assessment of plant nitrogen content at early growth stages...     

Integration of independent component analysis with near infrared spectroscopy for evaluation of rice freshness

The storage time and conditions of rice has an enormous effect on its appearance, flavor, and quality of the nutrients; and the acidity of rice usually increases with prolonged storage. Therefore, evaluation of freshness is an important issue for rice quality. In this study, the NIR (near infrared) spectra combined with independent component analysis (ICA) technique was used to evaluate the rice freshness. A total of 180 white rice samples were collected from 6 crop seasons for the purpose of developing an ICA-NIR based procedure for rice freshness as quantified by pH values. Values of pH were determined by a BTB-MR (bromothymol blue – methyl red) method. The best calibration model of white rice was developed using the smoothed first derivative spectra, five ICs and cross-validation; the results indicated that r² (coefficient of determination) = 0.924, and in units of pH, SEC (standard error of calibration) = 0.145, SEP (standard error of prediction) = 0.146, bias = 0.001, and RPD (residual predictive deviation) = 3.65. Freshness of white rice could be distinguished either visually by a 3-dimensional diagram composed from ICs 2, 3 and 4, or statistically by a calibration model. The results show that ICA with NIR has the potential to be adopted as an effective method for evaluating rice freshness.     

土壤结构组成对K+运移障碍因子的定量研究

With six packed columns composed of <1 μm and 5 μm~0.25 mm fractions from an Eum-Orthic Anthrosol (Columns 1~6) and one column of the Eum-Orthic Anthrosol (Column 7), K⁺ transport experiments under the condition of saturated steady water flow were conducted to qualify the effects of soil texture composition on the retardation factor (R) of K⁺ transport. The results showed that the retardation factor of K⁺ transport in the tested soil columns greatly increased with increasing clay contents. In an attempt to use pedo-transfer function (PTF) approach in the solute transport study, a preliminary PTF was established through the six packed columns (Columns 1~6) with soil basic data including soil bulk density, volumetric water content and clay content to predict the retardation factor, and proved valid by the satisfactory prediction of R in Column 7.     

中国陕西省施有机肥黄土NH4+固定的热力学性质

Some thermodynamic properties of NH₄⁺ fixation by loess soil in plowing and clay layers are discussed. The results indicate that the four ion adsorption equations commonly used can describe the properties of NH₄⁺ fixation in these soils under constant temperature. Among the four adsorption equations, the single-surface Langmuir equation is the best. When the concentration of NH₄Cl solution is 10^-1 mol below, the Freundlich equation can be used. The changes of apparent standard free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) illustrate that NH₄⁺ fixation in soil is an endothermic adsorption and spontaneous reaction, and the process can be enhanced by a higher temperature and clay content in soil. The "proper value of NH₄⁺ fixation by soil (K₁ × q_m) increased with increasing clay content and temperature. The heat of NH₄⁺ fixation in soil (Q_m) confirms the conclusions made in this paper.     

根－土界面区域磷酸盐的分布和移动: Ⅱ. 土壤水分含量和磷酸盐施用量的影响

The phosphate in the soil-root interface zone under various soil water contents and application rates of phosphate was still of depletion distribution which could be described by a power function in the form of C/Co= ax^b(C/Co is the relative content of fertilized phosphate in a distance from the root surface x, a and b are the regression constants). The depletion rate of phosphate in soil near the root surface was higher and the depletion range was narrower under lower soil moisture. On the contrary, at higher soil water content the depletion range was wider, generally. The application rate of phosphate led to the greater depletion intensity of phosphorus was higher in the heavier texture soils. In general, the depletion intensity in the soils, which decreased with increasing clay content or increasing buffering power of soil, decreased in the order as loessal soil and black lou soil > lou soil > yellow cinnamon soil when 50 or 100 mg of phosphorus were applied in the form of KH₂PO₄. This result indicated that the phosphate distribution and its movement in the soil-root interface zone closely related with the buffering capacity of soil.     

Identifying and characterizing yield limiting factors in paddy rice using remote sensing yield maps

Identification and characterization of yield limiting factors based on multi-year yield maps is important for delineating field management zones. Multi-year yield maps were derived from satellite images of a paddy-rice (Oryza sativa L.) study site with a conventional two-cropping system in central Taiwan. Spatiotemporal yield-trend maps with consistently high, average and low yields, and inconsistent yield areas were delineated based on temporal variation and the means of the normalized yields on a per pixel basis. Soil and plant samples were collected and grouped for statistical analysis based on the derived yield-trend maps. Comparison of soil properties and rice yield components among yield classes indicated that differences in leaching loss of basal and top-dressed N fertilizers were the likely limiting factor affecting the spatial variation of yield within the study site.     

鸡FATP1基因多态性与屠体性状的相关分析

 【目的】研究FATP1基因多态性与优质肉鸡屠体性状的相关性,为进一步加快育种进程提供参考依据。【方法】利用PCR-SSCP技术对381只大恒优质鸡FATP1基因的部分外显子进行群体遗传学检测,计算基因频率和基因型频率,对多态性与屠体性状进行相关分析。【结果】在FATP1 P3和P4两个位点上分别存在3种多态以及9种单倍型组合。P3位点不同基因型对活重、屠体重、半净膛、全净膛、胸肌重和腿肌重有显著影响,P4位点不同基因型对腿肌重和腹脂率有显著影响。9种单倍型组合AAMM、AAMN、AGMM、AGMN、AANN、AGNN、GGMM、GGMN和GGNN的频率分别为0.538、0.052、0.265、0.029、0.045、0.037、0.024、0.005和0.005,不同单倍型与腹脂重、胸肌重和胸肌率存在相关性。【结论】鸡FATP1不同基因型和单倍型组合与部分屠体性状和腹脂率存在相关性。