Intestinal absorption of forsythoside A in different compositions of Shuang-Huang-Lian

Shuang-Huang-Lian (SHL), a traditional Chinese formula containing Lonicerae japonicae flos (LJF), Scutellariae radix (SR) and Forsythiae fructus (FF), is commonly used to treat acute upper respiratory tract infection, acute bronchitis and light pneumonia. Forsythoside A is one of the main active ingredients in Forsythiae fructus, a key herb in SHL. In the present study, effects of different compositions in SHL on the intestinal absorption of forsythoside A were investigated. The observations from in situ intestinal circulation model showed that A/%(h^− 1) of forsythoside A in FF + LSF, FF + SR and SHL were all reduced greatly compared with that in FF. However, in pharmacokinetics study, C_max and AUC_0 → 1440 of forsythoside A all increased and T_1/2 prolonged in SHL, FF + LJF and FF + SR compared with FF. The results indicated that the different compositions of SHL decreased absorption but increased bioavailability of forsythoside A, which may be related to its metabolism inhibited in intestine or liver.     

电导率法测定榛子枝条抗寒性

试验测定了10个榛子品种(系)1年生枝条在不同温度处理下电解质渗出率的变化情况。结果表明,随着低温胁迫的加强,枝条组织的电解质渗出率明显上升,其中,85-51,81-14,84-1与84-48,84-545,82-11和达维间存在极显著差异。由此推测,10个榛子品种(系)的抗寒性强弱顺序为:达维>82-11>84-545>84-48>84-402>82-8>84-508>84-1>81-14>85-51,与田间调查基本吻合。     

典型草原建群种长芒草(Stipa bungeana)在中国的潜在分布范围预测及主要影响因子分析

以广泛分布在中国北方典型草原的建群种长芒草为研究对象,利用Maxent模型对长芒草在中国当前及未来气候变化下的潜在分布区进行预测并对主要影响其分布的环境变量进行分析,结果表明,采用受试者工作特征曲线(receiver operating characteristic curve,ROC)对模型精度进行检验所得到的训练数据与测试数据的受试者工作特征曲线面积(areaunder ROC curve,AUC)分别为0.962和0.950,表明模型预测结果可靠,当前中国长芒草高适宜性分布区主要有5个,分别为黄土高原分布区、泰山-沂蒙山分布区、横断山分布区、藏南谷地分布区及天山分布区。在RCP2.6(representative concentration pathways 2.6)和RCP8.5(representative concentration pathways 8.5)两种气候情景模式下预测得到的2070年长芒草最适宜的潜在分布区有逐渐缩小的趋势。Jackknife检验对主导环境变量的筛选结果显示,影响长芒草分布的主要环境变量有地形粗糙度指数(terrain roughness index,tri)、9月降水量(precipitation 09,prec09)、气候湿度指数(climatic moisture index,topowi)、2月最高温度(maximum temperature 02,tmax02)、12月降水量(precipitation 12,prec12)和12月平均温度(average temperature 12,tavg12)。结果可为气候变化背景下中国典型草原的可持续管理提供科学依据。     

基于无人机遥感影像的覆膜农田面积及分布提取方法

针对基于无人机遥感的覆膜农田识别研究甚少的现状,该文以云南省昭通市鲁甸县为研究区,获取了研究区中地表类型复杂程度不同的2幅航空影像(复杂区影像和简单区影像)作为试验数据,利用灰度共生矩阵对原始航片影像进行纹理特征提取并选择纹理特征最佳提取参数;然后基于随机森林算法进行纹理特征重要性评价,优选纹理特征,结合原始数据进行最大似然初步分类;运用众数分析进行分类后处理;最后结合图像形态学算法与面积阈值分割法提取出了最终的覆膜农田面积及分布。通过试验结果发现,依据该文提出的方法,复杂区和简单区覆膜农田识别的总体精度、Kappa系数、产品精度、用户精度和面积误差分别达到了94.84%、0.89、92.48%、93.39%、0.38%和96.74%、0.93、97.39%、94.63%、1.95%。该文提出的融合监督分类和图像形态学算法的覆膜农田提取方法可以简单、快速的将地膜连成块,形成覆膜农田对象,进而通过面积阈值分割法获取高精度的覆膜农田分布信息。该方法可以为精准覆膜农田识别算法的发展提供参考。     

Nitrogen application affects maize grain filling by regulating grain water relations

Grain water relations play an important role in grain filling in maize. The study aimed to gain a clear understanding of the changes in grain dry weight and water relations in maize grains by using hybrids with contrasting nitrogen efficiencies under differing nitrogen levels. The objectives were: 1) to understand the changes in dry matter and percent moisture content(MC) during grain development in response to different nitrogen application rates and 2) to determine whether nitrogen application...     

荔枝生产相关的水分生理指标远程监测研究

利用植物远程监测系统对荔枝园中的大气温湿度、土壤湿度、光照强度、大气蒸汽压差(VPD)等环境因子和茎干直径微变化、果实生长、叶片温度等树体生理指标进行了监测,发现该系统能准确及时并无伤害地记录他们的实时和周期性变化。据获得的数据初步表明,当果实处于快速膨大期,主茎的加粗生长明显缓慢,一旦果实采收后,茎干加粗生长则有一个迅速上升的变化;当土壤湿度高于33%(v/v)时,主茎的生长受到明显的抑制;VPD白天上升,夜间下降,当夜间VPD始终高于0,就形成所谓的“夜间干燥”,VPD的这种变化对荔枝主茎和果实的生长以及叶气温差(LATD)都有较大的影响,如主茎和果实的日间收缩量随VPD的增大而增大,夜间空气干燥不但抑制了主茎生长,也使日最大LATD下降。据此认为,果实和茎干的生长之间存在竞争关系,土壤湿度过高或者夜间空气干燥对荔枝的生长不利。     

Simple method for extracting the seasonal signals of photochemical reflectance index and normalized difference vegetation index measured using a spectral reflectance sensor

A spectral reflectance sensor(SRS) fixed on the near-surface ground was developed to support the continuous monitoring of vegetation indices such as the normalized difference vegetation index(NDVI) and photochemical reflectance index(PRI). NDVI is useful for indicating crop growth/phenology, whereas PRI was developed for observing physiological conditions. Thus, the seasonal change patterns of NDVI and PRI are two valuable pieces of information in a crop-monitoring system. However, capturing the seasonal patterns is considered challenging because the vegetation index values estimated by the reflection from vegetation are often governed by meteorological conditions, such as solar irradiance and precipitation. Further, unlike growth/phenology, the physiological condition has diurnal changes as well as seasonal characteristics. This study proposed a novel filtering method for extracting the seasonal signals of SRS-based NDVI and PRI in paddy rice, barley, and garlic. First, the measurement accuracy of SRSs was compared with handheld spectrometers, and the R~2 values between the two devices were 0.96 and 0.81 for NDVI and PRI, respectively. Second, the experimental study of threshold criteria with respect to meteorological variables(i.e., insolation, cloudiness, sunshine duration, and precipitation) was conducted, and sunshine duration was the most useful one for excluding distorted values of the vegetation indices. After data processing based on sunshine duration, the R2 values between the measured vegetation indices and the extracted seasonal signals of vegetation indices increased by approximately 0.002–0.004(NDVI) and 0.065–0.298(PRI) on the three crops, and the seasonal signals of vegetation indices became noticeably improved. This method will contribute to an agricultural monitoring system by identifying the seasonal changes in crop growth and physiological conditions.     

基于MaxEnt模型的新疆红枣生态适宜性与区划分析

【目的】 结合种植区资源分布现状,利用最大熵模型(MaxEnt)预测新疆红枣潜在适生区,为新疆红枣区域布局和种植结构调整提供有效的理论指导和依据。【方法】 以年降水量、花期降水量(5~6月)、成熟期降水量(9~10月)、年有效积温(≥10℃)、年极端最低气温和平均气温6个气候因子和绿洲灌溉区、沙漠敏感区2个土地因子及高程因子为环境变量,利用GIS空间分析技术获取新疆红枣地理分布数据,采用MaxEnt模型进行建模并预测新疆红枣潜在适生区,使用百分比贡献率分析其主要环境因子及生态位参数。【结果】 (1)ROC评价(Receiver Operating Characteristic,ROC)显示MaxEnt模型预测新疆红枣潜在适生区的训练数据集和测试数据集的AUC值分别为0.921和0.904,模拟效果优秀。(2)新疆红枣潜在适生区总面积2 365.939 7×10⁴ hm²,其中最适生区429.350 1×10⁴ hm²,主要分布于新疆南疆的喀什地区、阿克苏地区、和田地区、克孜勒苏柯尔克孜自治州和巴音郭楞蒙古自治州,东疆的吐鲁番市、哈密市。(3)影响新疆红枣生长的主要环境因子是年极端最低气温(35.15%)、绿洲灌溉区(20.77%)、年有效积温(19%)和成熟期降水量(13.27%)。新疆红枣适宜生长在年极端最低气温≥-24.65℃,年有效积温≥3 595℃,成熟期降水量为0.54~7.64 mm,且绿洲灌溉区有助于提高其适生程度。【结论】 新疆红枣潜在适生区呈现环塔里木盆地聚集,低温是其最主要的影响因子。     

差高机构对微型履带山地拖拉机稳定性的影响

为使微型履带山地拖拉机更好地适应丘陵、山地等地带作业,在现有履带拖拉机的基础上,对其行走系统进行了改进,增加了液压差高机构。根据差高机构的工作原理,运用矢量矩阵理论,建立了差高机构工作时整机质心位置变化的数学模型,并进一步给出了在坡道行驶时允许的最大坡度角。实例分析表明,差高机构使微型履带山地拖拉机纵向稳定性有所降低,但可提高其横向稳定性。     

Regulation of root-to-leaf Na and Cl transport and its association with photosynthetic activity in salt-tolerant soybean genotypes

ABSTRACT

Soil salinity is a major constraint to sustainable crop production. Genetic improvements are needed for growing soybean in salinity-prone environments. Salt-tolerant soybean genotypes alleviate a reduction in photosynthesis and growth under saline conditions; however, the detailed mechanisms involved remain unclear. Here, we aimed to clarify how Na and Cl root-to-leaf transport is quantitatively regulated, and to identify whether photosynthetic tolerance depends on traits associated with either stomata or with mesophyll tissues. Two pairs of pot-grown soybean near-isogenic lines (NILs) consisting of tolerant and susceptible counterparts, derived from a cross between salt-tolerant FT-Abyara and salt-sensitive C01, were subjected to salinity treatment in a rainout greenhouse. Comparison of photosynthetic responses between genotypes indicated that genotypic differences in salinity tolerance depended on the ability for sustained CO₂ assimilation in mesophyll tissues, rather than stomatal conductance. The ratio of photosynthetic rate to intercellular CO₂ concentration (A/Ci) declined exponentially with increasing Na and Cl concentration regardless of genotype, but tolerant genotypes effectively kept both elements at significantly low levels. Under saline conditions, tolerant genotypes reduced Na and Cl content at the two transport pathways: from root to stem, and from stem to leaf, but the reduction of Cl at each pathway was only minor. These results suggest that integrating genetic capacity for Cl transport regulation and osmotic adjustment should be an important target in salinity-tolerance soybean breeding.