棉花冠层对不同灌水量的反应及其产量形成研究   总被引：1，自引：0，他引：1  

张伟  吕新 《干旱区研究》2004,21(4):425-429

通过探讨新疆北部棉区推广棉种新陆早6号与新陆早8号,在不同灌水量条件下冠层结构特征的差异性,得出新陆早6号对限量滴灌反应不敏感,而新陆早8号对限量滴灌反应较敏感。因此,在限量滴灌条件下,选择新陆早6号种植较适宜。叶面积指数低,叶片平均倾斜角度大,群体散射辐射透过系数和群体直射辐射透过系数增加,光能的截获率降低,由此得出,不同品种对灌水量的反应表现及理想群体冠层结构的合理指标,为增加棉花产量和提高水分利用效率提供了理论依据。  相似文献   

Evaluation of Transmittance and Reflectance Pulse Oximetry in a Canine Model of Hypotension and Desaturation     

Linda J. Barton DVM  Jennifer J. Devey DVM  Steven Gorski BSt  Louis Mainiero MSt  Daniel DeBehnke MD  FACEP 《Journal of Veterinary Emergency and Critical Care》1996,6(1):21-28

Ten, anesthetized dogs were instrumented with three pulse oximeter probes; two lingual transmittance probes and one rectal reflective probe. Arterial oxygen desaturation was produced by decreasing the inspired oxygen concentration. Hypotension was produced with an infusion of nitroprusside. Simultaneous pulse oximeter readings (SpO₂) were compared to co-oximeter measured arterial saturation (SaO₂) collected over a range of SaO₂ (50–100%) and mean arterial pressures (40–100mmHg). Each of the monitors and means of evaluating SpO₂ studied provided accurate SpO₂ measurements over a range of mean arterial pressure from 40–100mmHg. All of the monitors tested tended to overestimate the SaO₂ when the arterial saturation was less than 70%.  相似文献   

苜蓿冠层温度与农艺性状的相关分析     

蒋骏  贾志宽  徐春明  刘玉华 《干旱地区农业研究》2003,21(4):20-22

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。  相似文献   

科尔沁草原主要草地植物传播生物学简析   总被引：11，自引：4，他引：11  

刘志民  蒋德明  阎巧玲  李雪华  李荣平  骆永明  王红梅 《草业学报》2005,14(6):23-33

本研究论述了科尔沁草原主要草地植物的传播生物学特性.在141种植物中,44种以种子作为传播体,97种以果实作为传播体;传播体重量< 0.1 mg的植物12种,重量0.1～0.999 9 mg的植物61种,重量1～9.999 9 mg的植物55种,重量10～99.999 9 mg的植物12种,重量100～999.999 9 mg的植物1种;具有典型聚合传播体的植物4种;具有典型多态传播体的植物1种;传播体具附属物的植物66种(占总数的46%),其中19种带冠毛,10种带绢毛或丝毛,15种带芒或刚毛,6种带翅,6种带钩或刺,10种带其他附属物(花柱、花萼、结块和喙等).在124种植物中,11种植物(7种蒿属植物、2种车前、百里香1种和野亚麻1种)种子具有粘液,其种子或果实的干重＜1 mg.已发现23种植物具有明显的植冠种子库(植冠种子库种子达到总结种量的5%).8种植物植冠种子库种子超过结种量的30%,7种植物达到结种量的20%～30%,8种植物少于结种量的20%.具有植冠种子库的植物以菊科(尤其蒿属)、禾本科和藜科植物为多.具有较强或相对较强沙生适应性的植物多数具有植冠种子库.探讨了传播体类型和重量、利于(或阻滞)传播的传播体特征、传播体多态性与传播适应的多面性、延缓传播与植冠种子库等方面的问题.  相似文献   

Prediction of chemical composition and peroxide value in unground pet foods by near‐infrared spectroscopy          下载免费PDF全文

M. De Marchi  F. Righi  M. Meneghesso  D. Manfrin  R. Ricci 《Journal of animal physiology and animal nutrition》2018,102(1):337-342

The massive development of the pet food industry in recent years has lead to the formulation of hundreds of canine and feline complete extruded foods with the objective of meeting both the needs of the animals and numerous demands from pet owners. In the meantime, highly variable raw material compositions and the industry's new production techniques oblige manufacturers to monitor all phases of the extrusion process closely in order to ensure the targeted composition and quality of the products. This study aimed at evaluating the potential of infrared technology (visible and near‐infrared spectrophotometer; 570–1842 nm) in predicting the chemical composition and peroxide value (PV) of unground commercial extruded dog foods. Six hundred and forty‐nine commercial extruded dog foods were collected. For each product, an unground aliquot was analysed by infrared instrument while a second aliquot was sent to a laboratory for proximate analysis and PV quantification. The wide range of extruded dog food typologies included in the study was responsible for the wide variability observed within each nutritional trait, especially crude fibre and ash. The mean value of the 208 pet foods sampled for PV quantification was 17.49 mEq O₂/kg fat (min 2.2 and max 94.10 mEq O₂/kg fat). The coefficients of determination in cross‐validation of NIRS prediction models were 0.77, 0.97, 0.83, 0.86, 0.78 and 0.94 for moisture, crude protein, crude fat, crude fibre, ash and nitrogen‐free extract (NFE) respectively. PV prediction was less precise, as demonstrated by the coefficient of determination in cross‐validation (0.66). The results demonstrated the potential of NIRS in predicting chemical composition in unground samples, with lower accuracy for moisture and ash, while PV prediction models suggest use for screening purposes only.  相似文献   

A Comparison of Two Herbaceous Cover Sampling Methods to Assess Ecosystem Services in High-Shrub Rangelands: Photography-Based Grid Point Intercept (GPI) Versus Quadrat Sampling     

Kristin B. Hulvey  Katherine Thomas  Eric Thacker 《Herpetological Monographs》2018,40(5):152-159

  相似文献   

Pedotransfer functions to assess adsorbed phosphate using iron oxide content and magnetic susceptibility in an Oxisol          下载免费PDF全文

L. A. Camargo  J. Marques Jr.  G. T. Pereira  L. R. F. Alleoni  A. S. R. de S. Bahia  D. De B. Teixeira 《Soil Use and Management》2016,32(2):172-182

Adsorbed phosphate in soils can be chemically extracted; however, this process is both time‐consuming and not cost‐effective if large numbers of samples have to be analysed. Indirect assessment of adsorbed phosphate by pedotransfer functions (PTFs) can help optimize fertilizer strategies. This study aimed to evaluate the spatial variability of adsorbed phosphate (P_ads), iron oxides and magnetic susceptibility (MS) in oxisols and to calibrate PTFs to predict P_ads. A total of 308 soil samples were collected from Hapludox and Eutrudox soils formed from sandstone in Brazil. The contents of clay (196–607 g/kg), iron oxides (40–165 g/kg), MS (1.2–29 × 10^?6 m³/kg) and P_ads (327–842 mg/kg) were in the range of typical values for these highly weathered soils. This study showed that the attributes studied were spatially dependent. Geomorphic surfaces enabled understanding of spatial variability and helped to develop a more efficient sampling scheme to calibrate PTFs. Moreover, the adsorbed phosphate in these oxisols could be predicted by a PTF using iron oxides and MS as predictors. The MS attribute enabled the most accurate prediction (concordance coefficient = 0.95, root‐mean‐square error = 46 mg/kg and relative improvement in root‐mean‐square error = ?4.12) of spatial variability through PTF compared to other predictors.  相似文献   

东京野茉莉花色成分的初步研究     

徐丽萍  喻方圆 《江西农业大学学报》2016,(5):935-939

对东京野茉莉花色成分进行了初步的探究。结果表明:通过特征颜色反应和光谱扫描说明了其花瓣细胞内有异黄酮、儿茶精类,还有叶绿素a、b,可能含有胡萝卜素、黄酮类化合物,以及无色花色素,可能不含查耳酮或橙酮。  相似文献   

Estimation of litchi (Litchi chinensis Sonn.) leaf nitrogen content at different growth stages using canopy reflectance spectra     

《European Journal of Agronomy》2016

The estimation of crop nitrogen status in fresh vegetation leaf using field spectroscopy is challenging due to the weak responses on leaf/canopy reflectance and the overlapping with the absorption features of other compounds. Although the spectral indices were proposed in the literature to predict leaf nitrogen content (LNC), the performance of selected spectral indices to estimate the LNC is often inconsistent. Moreover, the models for nitrogen content estimation changed with the growth stage. The goal of this study was to evaluate the performance of published indices, ratio of data difference index (RDDI) and ratio of data index (RDI) developed by band iterative-optimization algorithm in LNC estimation. The correlation analysis, linear regression and cross validation were used to analyze the relationship between spectral data and LNC and construct the best performed estimation model. The study was conducted by the data of five growing seasons of litchi from the orchards in Guangdong Province of China. Results showed that the relationship between chlorophyll (Chl) related spectral indices and LNC varied with the growth stage. Even in flower bud morphological differentiation stage and autumn shoot maturation stage, there were not significant correlations between the proposed spectral indices and LNC. Besides it is difficult to estimate the LNC by the general model across the growth stages due to the integrated effects of cultivar, biochemical, canopy structure, etc. The band iterative-optimization algorithm can improve the sensitivity of spectral data to LNC to some extent. The optimal RDDI performed better than other indices for the synthetic dataset and the dataset in each growth stage. And the sensitive bands selected in the optimal indices at each growth stage are not consistent, which are not only related to the Chl absorption but also other biochemical components, such as starch, lignin, cellulose, protein, etc. In general, the LNC can be estimated by the optimized CR-based RDDI indices in autumn shoot maturation stage, flower spike stage, fruit maturation stage, and flowering stage with the R² > 0.50 and RMSE < 0.14. Although there were the significant relationship between RDIs and RDDIs in flower bud morphological differentiation stage, the highest R²s of the model developed by RDDIs and RDIs were less than 0.50 in cross validation. This study indicated that the applicability of canopy reflectance to estimate litchi LNC was closely related to the growth stage of litchi. Growth stage-specific models will be preferred for estimating litchi LNC estimation.  相似文献