Compatibility of root growth and tuber production of potato cultivars with dynamic and static water‐saving irrigation managements

The important root characteristics of root length density (RLD) and root mass density (RMD) generally differ among irrigation managements and potato cultivars. The objective of this study was to investigate the RLD and RMD variations and their functional relationships with gross potato tuber yield for two commercial potato cultivars, Agria and Sante, under different irrigation strategies. Full irrigation and water‐saving irrigation strategies, deficit and partial root drying irrigations, were applied statically (S) and dynamically (D) based on daily crop evapotranspiration. Results showed that SPRD had significantly greater RLD (3.64 cm/cm³) and RMD (132.7 μg/cm³) than other irrigation treatments. Between the potato cultivars, Agria had significantly larger values of RLD (3.50 cm/cm³) and RMD (138.7 μg/cm³) than Sante. The functional relationship between the root growth characteristics and tuber yield showed that under water‐saving irrigations, Agria increased root mass at the expense of gross tuber yield but Sante increased root mass to maintain larger gross tuber yields. However, Agria produced more roots and gross tuber yield than Sante, and it is concluded that Agria is a more drought‐tolerant potato cultivar, which is recommended for tuber production in regions where water might be scarce. It was shown that larger root production in potatoes was associated with improved tolerance to water stress.     

Boundary-fitted grid in landscape modeling

Landscape modeling requires the delineation of system boundaries and interior features. Quite often, these components are complex and difficult to accurately represent. A rectangular grid is used to represent the study and adjacent non-study areas in most cases. When the non-study area occupies a large portion of the grid, computer memory is wasted, and computational time increases. An elliptical grid generator for non-orthogonal curvilinear coordinates is used to generate a boundary-fitted grid for a landscape model. In a boundary-fitted grid coordinate system, one coordinate axis follows the landscape domain boundary and is non-orthogonal to the second axis. The boundary-fitted grid uses elliptic partial differential equations to distribute grid points inside the landscape domain. Although the boundary-fitted grid follows the domain boundary, the grid pattern and point allocation remain structured. Thus, a landscape model can use a boundary-fitted grid without changing the model’s data structure or the computational scheme. In this study, a boundary-fitted grid and a raster-based grid were applied to the Everglades Landscape Fire Model. Use of the boundary-fitted grid decreased model simulation time by about one fifth and computer storage by 58% relative to the raster-based grid. Also, the linear characteristics of interior geographical features such as rivers and airboat trails were preserved by the boundary-fitted grid, but not by the raster-based grid. This preservation provided a more reasonable base map for simulating ecological processes, such as fire across heterogenous landscapes.     

某类高阶非线性偏微分方程组弱解的正则性

本文研究一类2k阶非线性偏微分方程组之解的正则性,没有假定通常的椭圆性条件而只假定所谓"无穷远处"的椭圆性条件,证明了解的k-1阶导数为李普希兹连续的.     

苜蓿冠层温度与农艺性状的相关分析

对从国内外引进的31个苜蓿品种分枝期—结英期的冠层温度及其农艺性状指标进行了相关分析和偏相关分析。结果表明，苜蓿冠层温度与分枝期和现蕾期的茎叶比、开花期的叶面积和产量间存在显著的偏相关关系，可作为产量高低的间接或直接指标；由于农艺性状指标间互相关的影响，冠层温度与农艺性状指标间的单相关系数可靠性差，且与偏相关系数有明显的差异；排除农艺性状指标间互相关影响后，偏相关系数可靠性大，可作为变量间关系密切程度的量化指标。     

Feasibility analysis of NIR for detecting sweet corn seeds vigor

This paper explores the feasibility of particle-based detection and grading of seed vigor based on a self-built seed single-granulation device using near infrared spectroscopy (NIRS). Sweet corn with uniform kernel size was used for this study. The seed samples were divided into three types, they were normal seeds, artificially aged seeds and heat-damaged seeds. A 2-part spectral acquisition of each seed were performed, one for the collection of seeds that fall into the detection zone within the separation pipe, another was on the static platform, whose collection was performed on 5 faces of each seed. Partial least squares discriminant analysis (PLS-DA) was used to classify the original data of the seeds. In the 2 parts, the discriminant results of the unprocessed normal seeds and the artificial accelerated aging seeds, the untreated normal seeds and the heat-damaged seeds showed that classification accuracy was higher than 98%. The research indicates that the spectral data of different positions of seeds can reflect their activity information, and it is feasible to detect and classify seeds in real time in the detection area of the separation pipeline.     

宁夏玉米营养成分近红外分析模型建立与应用

研究采集宁夏区内各市县(固原、海原、同心、中卫、中宁、永宁、平罗)抽取玉米样品120批,用近红外分析仪扫描定标样品集获得玉米近红外光谱图,利用偏最小二乘法建立模型,并分别经过无预处理、均值中心化、标准正态变量转换、一阶导数、标准正态变量转换结合去趋势校正(SNV+D)预处理光谱,获得水分、粗蛋白、粗脂肪、粗纤维预测模型,分别是经过MC、SNV+D、SNV+D、SNV+D光谱预处理后效果最好。预测决定系数R² _p分别为0.951、0.976、0.728、0.897,相对分析误差RPD除粗脂肪为2.62外,其他均大于3的近红外预测模型,通过预测模型验证集验证后,并对模型预测值与实测值进行U检验,结果为差异不显著(P>0.05)。该近红外预测模型对玉米中水分、粗蛋白、粗纤维具有较佳预测效果,粗脂肪的预测精度有待进一步提高。     

Migration strategies of brown trout (Salmo trutta) in a subarctic river system as revealed by stable isotope analysis

We estimated the proportions of anadromous and freshwater‐resident brown trout (Salmo trutta) in different parts of the subarctic River Näätämöjoki/Neidenelva system (Finland and Norway) using carbon, nitrogen and hydrogen stable isotope analyses of archived scales as identifiers of migration strategy. Our results showed that carbon stable isotope values were the best predictor of migration strategy. Most individuals fell into two clearly distinct groups representing anadromous (47%) or freshwater‐resident (42%) individuals, but some fish had intermediate carbon values suggesting repeated movement between freshwater and the sea. The proportion of anadromous individuals decreased steadily with distance from the sea forming a spatial continuum in migration strategies which is probably maintained by the combination of several factors such as divergent availability of food resources, variable migration costs and genetic differences. These within‐catchment differences in migration strategies should be taken into account in fisheries management practices.     

蚯蚓粪缓解草莓连作土壤障碍的作用

【目的】土壤灭菌处理已成为草莓生产中土传病害综合管理的重要措施,但是土壤灭菌明显抑制了土壤微生物的活性,影响草莓植株的生长。有机肥中含有大量的生物活性物质,尤其是蚯蚓粪。本研究通过观测连作土壤灭菌后施用不同有机肥对草莓植株地上部和地下部的影响,为减缓草莓植株生长的连作障碍提供有机肥选择。【方法】采用温室盆栽草莓模拟试验,首先在去除土壤化感效应影响基础上设置土壤灭菌和正常土壤栽培两个处理,探讨土壤灭菌对草莓植株不同阶段地上部叶片及地下部根系生长影响,在此基础上以相同连作土壤进行另一个盆栽试验,设置不灭菌土壤加无机肥料(LW)、 加牛粪(LN)、 加蚯蚓粪(LQ)处理,灭菌土壤加无机肥料(LMW)、 加牛粪(LMN)、 加蚯蚓粪(LMQ)共6个处理。调查了不同处理开花前苗期草莓植株地上部叶片及地下部根系的生长状况。【结果】土壤灭菌处理较相应未灭菌处理显著抑制了草莓花前幼苗阶段植株地下部的生长(P＜0.05),在果实成熟期、 盛果期及盛果末期植株生长均存在补长效应。土壤灭菌改变了草莓植株地上部和地下部正常的生长发育进程,植株不同发育阶段根冠比发生变化。无论连作土壤灭菌与否,施用无机肥料处理较施用有机肥处理显著抑制了根系生长(P＜0.05)。在不灭菌土壤上,施用蚯蚓粪处理草莓植株根系总长、 根系总表面积、 根尖数及根叉数与施用牛粪处理差异不显著,但灭菌土壤上,施加蚯蚓粪与施加牛粪相比,显著增加了草莓植株根系总长、 根系表面积及根叉数(P＜0.05)。【结论】蚯蚓粪与牛粪和无机肥料相比具有显著的生物活性。在草莓连作土壤灭菌后施用具有生物活性的蚯蚓粪,可以促进根系生长,缓解土壤灭菌对草莓植株生长发育的影响,是值得推荐的有效措施。     

Influence of Soil Particle Size on the Measurement of Sodium by Near-Infrared Reflectance Spectroscopy

This study evaluates the effect of soil particle size (SPS) on the measurement of exchangeable sodium (Na) (EXC-Na) by near-infrared reflectance (NIR) spectroscopy. Three hundred thirty-two (n = 332) top soil samples (0–10 cm) were taken from different locations across Uruguay, analyzed by EXC-Na using emission spectrometry, and scanned in reflectance using a NIR spectrophotometer (1100–2500 nm). Partial least squares (PLS) and principal component regression (PCR) models between reference chemical data and NIR data were developed using cross validation (leaving one out). The coefficient of determination in calibration (R²) and the root mean square of the standard error of cross validation (RMSECV) for EXC-Na concentration were 0.44 (RMSECV: 0.12 mg kg^–1) for soil with small particle size (SPS-0.053) and 0.77 (RMSECV: 0.09 mg kg^–1) for soils with particle sizes greater than 0.212 mm (SPS-0.212), using the NIR region after second derivative as mathematical transformation. The R² and RMSECV for EXC-Na concentration using PCR were 0.54 (RMSECV: 0.07 mg kg^–1) and 0.80 (RMSECV: 0.03 mg kg^–1) for SPS-0.053 and SPS-0.212 samples, respectively.     

Effects of 2 concentrations of sodium citrate on coagulation test results, von Willebrand factor concentration, and platelet function in dogs

BACKGROUND: Blood collection tubes containing 3.2% (0.109 M) sodium citrate, instead of 3.8% (0.129 M) sodium citrate, have recently become available in the United States. These tubes are visually indistinguishable from the traditional 3.8% sodium citrate tubes, except for wording on the label. Consequently, samples for hemostatic evaluation are frequently collected in tubes containing the lower concentration of sodium citrate. HYPOTHESIS: Results of hemostasis assays are different in samples collected in 3.2% versus 3.8% sodium citrate. ANIMALS: Twenty healthy dogs. METHODS: This study aimed at determining whether results of standard coagulation tests, von Willebrand factor concentration (vWF:Ag), and platelet function with the platelet function analyzer PFA-100a were affected by the different concentrations of sodium citrate. Blood samples were collected in tubes containing either 3.2% or 3.8% sodium citrate concentrations and processed routinely for coagulation assays (one-stage prothrombin time [OSPT], activated partial thromboplastin time [aPTT], fibrinogen concentration, and platelet count), vWF:Ag, and platelet function assays with a PFA-100. RESULTS: There was no significant difference between samples collected in 3.2% versus those collected in 3.8% sodium citrate for OSPT, aPTT, fibrinogen concentration, platelet count, or vWF:Ag. The closure times with collagen/adenosine diphosphate were significantly shorter (66 +/- 8.1 versus 74.8 +/- 9.7 seconds; P < .0001) with the 3.2% than with 3.8% sodium citrate concentration, and the hematocrit was significantly higher (47.9 +/- 5.6 versus 46.0 +/- 4.7 seconds; P = .03) in samples collected in 3.2% than in those collected in 3.8% sodium citrate. CONCLUSIONS AND CLINICAL IMPORTANCE: There is no clinically relevant effect of collection of blood into 3.2% or 3.8% sodium citrate.