利用近红外透射光谱技术测定小麦品质性状的研究

为了研究小麦品质性状的快速测试方法，本试验以2002年来自全国各地的426个小麦品种为材料，利用近红外光谱透射仪(NITS)分析了小麦籽粒水分、蛋白质含量、硬度和面粉的干、湿面筋含量、灰分含量、SDS及Zeleny沉淀值等8项指标，根据定标集样品化学分析数据和吸收光谱建立了定标模型，并获得了较高的预测集决定系数(O．70～O．97)和较低的标准误差(O.05～11．18)。同时，选用了一批有代表性的预测集样品对模型进行了预测，结果表明，近红外光谱技术用于测试小麦品质是可行的，能够用于育种的早代选择。     

Predicting and calibrating diameter distributions of Eucalyptus grandis (Hill) Maiden plantations in Zimbabwe

Diameter distribution models for even-aged Eucalyptus grandis plantations in Zimbabwe were developed using the two-parameter Weibull function. The analysis was based on data from Correlated Curve Trend (CCT) experiments replicated on four different sites. Parameters of the Weibull distribution were predicted using stand characteristics as regressors. Two sets of parameter models were estimated: a set with and one without stand basal area as a predictor. Stand variables such as dominant height, age, site index and number of stems were used in both sets. The models were further calibrated to result in a given number of stems and stand basal area simultaneously. The usability of constructed models was tested both in prediction of yield in a stand inventory situation and in simulation of growth in connection with different growth models. The results indicated that models not including stand basal area produce considerably less precise stand volume estimates compared to models including also stand basal area. Calibration improved the accuracy of diameter distribution models. In growth simulation diameter distribution models can be connected both to single tree growth models and to stand projection models. The usability of calibration in growth simulation depends on the accuracy of the prediction of stand characteristics.     

Evaluation of the modified olsen extracting reagent for Copper,Zinc and Manganese

Abstract

The Modified Olsen (MO) extracting reagent is used extensively as a soil test extractant in Latin America. Little correlation or calibration research hasbeenreportedonit, however, especially for the micronutrients. wheat, corn, and soybeans were grown successively in the greenhouse to evaluate Cu, Zn, and Mn, respectively. Lime and micronutrient variables (one micronutrient per crop) were imposed on six soils representing four orders. After each cropping the soils were extracted with MO and with three other extracting reagents for which there are referenced critical levels: Mehlich‐1 (Ml), Mehlich‐3 (M3) and Soltanpour‐Schwab (SS). The correlations between nutrient uptake and the concentrations extracted were fairly similar for the four solutions, but were better for Mn and Zn than Cu. The poor relationship for Cu occurred partly because a maximum wheat concentration of about 10 mg/kg was reached, creating a curvilinear function. The amounts of nutrients extracted by the four reagents were also well correlated except for that between MO and Ml for Cu. Using these relationships, along with critical levels previously determined with reference extractants, the MO critical levels for Cu, Zn, and Mn were estimated to be 0.3, 1.0, and 3.0 mg/L, respectively     

Influence of residual phosphate fertilizer on labile and extractable zinc in hawaii soils

Abstract

Zinc availability was studied using five soils from Hawaii which had histories of massive phosphorus applications. Heavy phosphate fertilization usually increased extractable Zn, irrespective of the extractant used. The extra extractable Zn associated with the added P probably came from Zn as an accessory element in the fertilizer. Treble superphosphate commonly used in Hawaii contains about 1400 ppm Zn. The Zn content of phosphate fertilizers must be considered before making statements about the effect of fertilizer P on Zn solubility and availability in soils.

Two solutions (0.1N HCl and 0.005M DTPA) were compared as Zn extractants for Hawaii soils. DTPA extracted less Zn than 0.1N HCl. Zinc extracted by repeated HCl treatment was more closely related to the labile Zn pool (E‐values and L‐values) than was DTPA‐extractable Zn. The results suggest that 0.1N HCl extractable Zn, Zn E‐value and Zn L‐value measured the quantity of a single fraction of soil Zn.

Repeated extraction of soil with 0.1N HCl seems to be a suitable procedure for evaluating the Zn status of acid, highly weathered soils of Hawaii.     

Soil and Plant Reference Norms for Evaluating Horn Plantain Nutritional Status

Abstract

The objective of this work was to calibrate, classify, and establish soil and plant reference norms for evaluating the nutritional status of the Horn plantain crop (Musa AAB, subgroup plantain cv. Horn). The sampling unit consisted of the “mother” plant and its corresponding soil at the fertilization band. Soil samples at depths of 0–20 cm and 21–40 cm were analyzed. A total of 221 sampling units were studied, hence, 442 soil and 221 leaf samples were used to develop the reference norms. A regression model with linear combinations of the soil and leaf variables for yield estimation was established by using the stepwise method. The model showed a high significant adjustment of 52% (R²) with normality of the standard residues. Four yield subclasses in kg cluster^?1 as 10.9–13.9 (60 units), 14.0–17.9 (92 units), 18.0–19.9 (47 units), and 20 or more (17 units) were defined. With the means of the soil and leaf data linearly related with yield, the reference norms for each subclass were developed. The method thereby established permits to develop reference norms that can be used for the simultaneous interpretation of soil and leaf analysis data and for yield estimation of the Horn plantain crop.     

宁夏自动土壤水分观测站标定的全过程分析

分析宁夏自动土壤水分观测站标定的全过程,阐明自动土壤水分站标定的全道工序,对关系标定成功与否的取土前对站址整改、土壤基本参数测定、人工取土对比观测和业务化检验审核这几个关键阶段需要注意的问题进行分析,提出对策措施。这对于今后的自动土壤水分站建设标定工作有一定的指导意义。     

带锯机切削力测定传感器

切削力传感器是木材机械加工研究领域的基本仪器之一。文中介绍了带锯切削力传感器的结构、制做方法。着重叙述了切削力传感器的校准方法及步骤,并通过试验介绍了切削力传感器的校准公式及如何建立标准F—H曲线。     

反应瓶与检压计作任意搭配使用的Warburg仪器标定方法

利用Warburg仪器的反应瓶与检压计互换结合可以不漏气这一特点,提出了反应瓶与检压计作任意搭配使用的定容方法,并对检压计容积测定方法进行改革。通过总体设计与局部改进,所提出的方法操作简便、容易掌握、节省时间、汞污染少,经过初步整理的实测数据输入计算机,便得到反应瓶与检压计作任意互换使用的打印标定结果。用本文方法对20支检压计98个反应瓶进行标定表明,在确保准确度情况下,操作工作量小于常用方法取得同样结果工作量的1/19,这种方法适于仪器用户及生产厂家采用。     

Visualizing certainty of extrapolations from models of land change

This article presents a method to estimate and to visualize the certainty of land change models as they extrapolate beyond the time interval for which empirical data exist. The method to project the certainty relies on measurements of model performance during a validation run with historic data and on the assumption that the model’s accuracy approaches randomness as it predicts farther into the future. A land change model typically predicts each pixel as exactly one category for each year. This article presents a technique to convert those predictions into conditional probabilities. As an example, we use the model Geomod to extrapolate forest change over a century for the Plum Island Ecosystems, which is a Long Term Ecological Research site of the United States’ National Science Foundation. Geomod uses calibration information between 1971 and 1985 in order to predict the changes from 1985 to 1999, at which point the validation procedure measures the model’s predictive accuracy. Then the model is re-calibrated with information from 1985 to 1999 in order to extrapolate into the future, assuming a business as usual scenario. As time progresses, the expected accuracy approaches 0.5, which is the probability at which the model’s prediction is as accurate as a random prediction, since the application involves two categories. The extrapolated accuracy of the prediction for the entire study area in the year 2097 is 68%. The method is designed to work with any number of categories so it can be used with a variety of land change models.     

Spatial occurrence of major tree species groups in Europe derived from multiple data sources

Pan-European distribution maps have been compiled for six main species groups in Europe. The aim was to combine detailed tree species information from plot data of the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) with other existing spatial and statistical information on forests. The applied method involves the interpolation of the plot data using the geo-statistical interpolation method kriging and a scaling and calibration procedure which makes the maps correspond both to the Forest map of Europe on pixel level and to national forest inventory statistics at regional or national level. Output is a set of European-wide maps with a resolution of 1 km, showing the proportion of the main tree species groups as a percent of the total land area. The maps are considered to be potentially valuable input for various applications in the forestry and biodiversity field at a pan-European scale.