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991.
Protein content, which represents rice taste quality, must be estimated in order to create a harvesting plan as well as next year’s basal dressing fertilizer application plan. Ground-based hyperspectral imaging with high resolution (1 × 1 mm per pixel) was used for estimating the protein content of brown rice before harvest. This paper compares the estimation accuracy of rice protein content estimation models generated from the mean reflectances of five regions of interest (ROIs): the overall target area, dark area (less illuminated parts of the rice plants), canopy area (leaves, yellow leaves, and ears), leaf area, and ear and yellow leaf area. The size of the target sampling area was 0.85 × 0.85 m. An R + G + B histogram and a GNDVI–NDVI image were used to separate the target area into the individual ROIs. The values of the coefficient of determination R 2 and the root mean square error of prediction (RMSE) were similar for each model: R 2 ranged from 0.83 to 0.86 and RMSE ranged from 0.27 to 0.30% for all models except for the dark area model, where R 2 = 0.76 and RMSE = 0.35%. There were no significant differences in the magnitude of the estimation error among all models. This result indicates that it is not necessary to obtain an image with a ground resolution that is greater than 0.85 × 0.85 m per pixel to estimate rice protein content before harvest. This result should provide useful information when deciding the altitude of platforms for imaging rice fields.  相似文献   
992.
993.
中亚热带不同植被恢复阶段林地土壤磷库特征   总被引:1,自引:1,他引:0  
以湘中丘陵区檵木—南烛—杜鹃灌草丛(LVR)、檵木—杉木—白栎灌木林(LCQ)、马尾松—柯(又名石栎)—檵木针阔混交林(PLL)、柯—红淡比—青冈常绿阔叶林(LAG)4种林地为对象,采用Tiessen和Moir修正后的Hedley磷(P)分级方法,研究不同植被恢复阶段林地土壤P各分级组分含量及其组成比例。结果表明:随着植被恢复,同一土层全磷(TP)、总无机磷(Pi)、总有机磷(Po)含量增加,NaHCO_3-Pi、NaOH-Pi、HCl-Pi和NaHCO_3-Po、NaOH-Po属于快速积累型,Residual-P属于缓慢积累型,Resin-Pi属于稳定型;不同植被恢复阶段林地土壤Pi以NaOH-Pi为主,Po以NaOH-Po为主,土壤P以Residual-P和Po为主;随着植被恢复,同一土层Po含量占TP的百分比增加,Pi先增加后减少,而Residual-P逐渐下降;不同林地土壤TP及P各分级组分含量均随着土壤深度增加而降低;随着植被恢复,群落植物多样性、群落生物量和凋落物层养分含量及质量的变化显著影响着土壤P各分级组分的含量及其组成比例。  相似文献   
994.
研究甘南高寒草甸退化草地土壤理化性质和微生物数量动态变化特征,为退化草地改良修复提供理论依据。于2017年5,7,10月分别采集极度(ED)、中度(MD)和轻度(LD)退化草地,以及未退化的对照草地(CK)土壤,测定其理化特性及微生物数量特征。结果表明:CK的土壤含水量在5,7月均显著小于LD、MD和ED的土壤含水量,而在10月显著大于LD、MD和ED的土壤含水量;随着退化程度的加剧,土壤pH逐渐增大,有机碳、全氮和全磷含量逐渐减小;土壤细菌数量对草地的退化反映更敏感,放线菌次之,真菌最小;CK和LD的土壤微生物数量随土层深度下降更为明显;冗余分析结合蒙特卡罗置换检验结果发现,各月份影响微生物数量的环境因子不同,显著影响5月微生物数量的是土壤全磷和土壤含水量,而7月除土壤pH外,其余指标均有显著影响,10月除土壤pH和土壤碳氮比外,植被盖度和生物量等均有显著影响。可见,甘南高寒草甸土壤理化特征和三大微生物数量对退化程度的响应具有季节差异,不同时期影响因素和权重需在草地管理中予以重视。  相似文献   
995.
利用开发的13对楸树SSR引物,对其在近缘物种滇楸中的可转移性与应用进行研究。将13对楸树SSR引物对75份滇楸无性系进行PCR扩增,所使用的引物对滇楸的扩增成功率与引物多态性比例均为100%,表明楸树SSR标记对近缘种滇楸具有较高的可转移性和多态性。共检测到76个多态位点,平均有效等位基因数(Ne)为2.364 4个,平均期望杂合度(He)为0.550 2,Nei’s基因多样性指数(H)为0.013 2~0.833 5,平均值0.446 8,结果显示滇楸无性系中遗传差异处于中间水平,各无性系之间亲缘关系较近。UPGMA聚类将75个无性系划分为5个类群,类群中地域性聚集不明显、亚群地域性聚集较明显。  相似文献   
996.
The aim of this study was to use the natural dietary markers (stable isotopes and fatty acids) during grow‐out in a biofloc system and for the egg production of Farfantepenaeus brasiliensis shrimp. Egg production was compared for two broodstock origins: biofloc and a wild origin. To delineate the relative contribution to shrimp muscle and eggs, IsoSource software was used. The most important source that contributed to grow‐out shrimp was biofloc ≥250 μm. According to the principal component analysis (PCA) applied to the fatty acid profile of food sources, the first component explains 84.4% of the variability, and the most important source of fatty acids for this component was biofloc ≥250 μm. The most important fresh food sources that contributed to egg production were Artemia biomass, polychaetes and semi‐moist feed for both broodstock origins. According to a PCA analysis of the fatty acid profiles, the most important fresh foods were polychaetes and semi‐moist feed. In conclusion, both isotopic signature and fatty acid profile of the food sources can be used successfully to determine the integration of carbon in the diets of shrimp.  相似文献   
997.
在退化草地上建造人工湖泊,可以使人工湖泊与毗邻退化草地形成近湿地生态系统,从而可能改善毗邻退化草地的生态环境,积极影响退化草地土壤中养分的流动,加快退化草地的修复。本研究分析了人为建造人工湖泊后3年内(2014年、2015年、2016年)湖泊毗邻的退化草地土壤碳氮磷在离湖距离(10 m、60 m、100 m、150 m、250 m、600 m)上的时空动态变化。结果如下:距离上,土壤有机碳、全氮、全磷在上层土壤(0~10 cm和10~20 cm)中与距离有显著(P<0.05)的线性关系,呈逐渐降低的趋势,说明在建湖3年这个短时期内,土壤养分(有机碳、全氮、全磷)形成了一个近湖效应,即靠近湖的养分含量高。年际间,自建湖后土壤全磷随着年数的增加在各个土层均显著降低。土壤养分(有机碳、全氮、全磷)在建湖初期2014年在距离上特异性较大,经过建湖3年后,2016年时在距离上的特异性减弱。这些结果表明,人工湖影响毗邻退化草地土壤中养分流动,尤其在距离上有显著的影响并表现出一定的规律性。建湖对毗邻退化草地的养分产生一定的影响,表明人工湖对放牧草地产生一定的积极效应。  相似文献   
998.
999.
We report the preparation of polybenzoxazole (PBO) fiber from polyhydroxyamide (PHA) precursor fiber which is free from strong acid such as polyphosphoric acid. We prepared the PHA fibers with different spin-draw ratios (SDRs) using a wet-spinning method and the PBO fibers with an SDR of 3.5 (SDR-3.5 PBO fibers) were prepared by various heat-treatment temperatures, and investigated their morphology, crystalline structure, and mechanical properties. The simultaneous thermogravimetric analysis-mass spectrometry (STA-MS) and field-emission scanning electron microscopy (FE-SEM) results confirmed that the diameter of the SDR-3.5 PBO fiber was much smaller than that of the SDR-3.5 PHA fiber, due to the release of water during the thermal cyclization reaction which forms the PBO structure. The wide-angle Xray diffraction (WAXD) pattern of the SDR-3.5 PBO fiber heat-treated at 350 °C (SDR-3.5 PBO 350 fiber) showed two peaks, at 2θ=14.83 ° and 24.38 °, and the diffraction angles dropped with increasing heat-treatment temperature. In addition, the initial modulus and tensile strength of the SDR-3.5 PBO fiber heat-treated at 550 °C (SDR-3.5 PBO 550 fiber) were found to be 19.1 GPa and 449.2 MPa, which were much higher than those of the SDR-3.5 PHA fiber, 9.3 GPa and 227.0 MPa, respectively.  相似文献   
1000.
Electro-spun silk web has attracted attention for biomedical applications because of its excellent bio-compatibility and facile fabrication method. Because biomedical applications require various performances of silk web, many studies have been conducted on the effect of the variables associated with their preparation on the structure and properties of silk web. In the present study, the effect of residual sericin content on the morphology, structural characteristics, and properties of electrospun regenerated silk web was examined. The regenerated silk without sericin (i.e., silk with 100 wt% fibroin) did not show good electro-spinnability. However, the electro-spinnability improved remarkably above a sericin content of 0.6 wt%. The crystallinity index of the electro-spun silk increased at 0.6 wt% sericin content and decreased above 8.2 wt% sericin. The mechanical properties of the electro-spun silk webs showed a similar trend as their crystallinity indices. The breaking strength and elongation improved significantly at 0.6 wt% sericin content and both parameters gradually decreased above this value. The thermal stability of the silk web decreased slightly upon increasing the sericin content.  相似文献   
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