Relationship Between Spectral Data from an Aerial Image and Soil Organic Matter and Phosphorus Levels     

Varvel  Gary E.  Schlemmer  Michael R.  Schepers  James S. 《Precision Agriculture》1999,1(3):291-300

Early ventures into site-specific management involved fertilizer management decisions based on soil chemical properties characterized by some form of grid sampling. This is both labor and capital intensive and practitioners quickly began investigating other methods to get a measure of spatial variability. Aerial photographs, which were mainly used to evaluate and assess crop status, allow for the collection of whole-field data at relatively low cost. Our objective is to determine what relationships exist between aerial spectral data and intensive grid soil test results and whether this information can be used to improve future soil sampling strategies. Soil-test organic matter (OM) and Bray-1 P concentrations were measured on soil samples taken using an alternating 12.2- by 24.4-m grid in late March 1994 from a quarter section under center pivot irrigation. Spectral data were collected in the spring of 1996 prior to planting using a multispectral network of digital cameras. Correlations of brightness values from the blue, green, and NIR bands with both OM and Bray-1 P were significant, but relatively low. Normality tests revealed that brightness values for the spectral data sets were generally evenly distributed while those of the soil test OM and Bray-1 P were positively skewed. Many of the very high soil-test data values were due to past management. When those values were removed from the database, greater correlations between spectral data and soil test data were obtained. These results substantiated that aerial imagery can be used to improve sampling strategies, but it must be used in conjunction with existing knowledge and past management histories.  相似文献   

Appraisal and standardization of curvilinear velocity (VCL) cut‐off values for CASA analysis of Japanese quail (Coturnix japonica) sperm          下载免费PDF全文

U Farooq  IA Malecki  M Mahmood  GB Martin 《Reproduction in domestic animals》2017,52(3):389-396

One of the basic steps in objective analysis of sperm motility is the subdivision of a motile sperm population into slow, medium and rapid categories based on their velocity. However, for CASA analysis of quail sperm, the velocity values for categorization of slow, medium and rapid sperm have not yet been standardized. To identify the cut‐off values of “velocity curvilinear” (VCL) for quail sperm categorization, we captured and analysed 22,300 tracks of quail sperm using SCA^®‐CASA. The median and mean VCL values were 85 and 97 μm/s. To define the VCL cut‐off values, we used two methods. In the first, we identified the upper (rapid sperm) and lower (slow sperm) cut‐off values using: (i) median VCL ± 25% or ± 50% or ± 75% of median VCL value; (ii) first and third quartile values of VCL data (i.e. 25% cut‐off setting); and (iii) 33% and 66% of VCL data. Among these settings, sperm categories and their corresponding motility characteristics recorded using the “25%” setting (i.e. slow ≤36 ≤ medium ≤154 ≤ rapid) were found the most realistic and coherent with male ranking by fertility. In the second method, we calculated heteroscedasticity in the total VCL data using PCA and the two‐step clustering method. With this approach, the mean of the high and low clusters was 165 and 51 μm/s, respectively. Together, the mean from two methods suggested that, for SCA^®‐CASA categorization of quail sperm, sperm should be classed as “rapid” at VCL ≥160 μm/s and “slow” at VCL ≤45 μm/s.  相似文献   

单胞藻饵料强化对太平洋纺锤水蚤营养成分的影响     

景斐  朱爱意  李彬  夏灵敏  张建设 《中国水产科学》2017,24(6):1354-1362

采用生化手段对舟山附近海域中浮游桡足类夏季优势种—太平洋纺锤水蚤(Acartia pacifica)进行营养成分测定,比较分析两种单胞藻饵料小球藻(Chlorella sp.)和三角褐指藻(Phaeodactylum tricornutum)对其营养价值的影响。结果表明,太平洋纺锤水蚤在投喂三角褐指藻和投喂小球藻后,其体内粗蛋白湿重含量分别为(6.51±0.46)%和(5.21±0.98)%,比对照组(2.44±0.63)%显著上升(P0.05);投喂三角褐指藻后太平洋纺锤水蚤粗脂肪湿重含量(0.25±0.03)%显著上升(P0.05),投喂小球藻后粗脂肪湿重含量(0.15±0.03)%显著下降(P0.05);但总糖和灰分湿重含量变化不明显(P0.05)。本研究检测出太平洋纺锤水蚤体内共含17种氨基酸,其中鱼类必需氨基酸(EAA)9种,非必需氨基酸(NEAA)8种,对照组与投喂两种饵料后太平洋纺锤水蚤中EAA含量均较高,干重含量为(47.56±0.04)%~(49.84±0.07)%;检测出太平洋纺锤水蚤共含21种脂肪酸,投喂三角褐指藻后太平洋纺锤水蚤的DHA和EPA干重含量之和最高(28.00%),其次为投喂小球藻(21.51%),均高于对照组(9.77%),而对照组干重(9.77%)也仍高于强化后轮虫DHA和EPA干重含量(0.8%)和强化后卤虫DHA和EPA干重含量(8.40%)。通过本实验发现,自然状态下的太平洋纺锤水蚤DHA和EPA含量较高,营养价值高,而投喂后三角褐指藻后太平洋纺锤水蚤营养价值明显增加,表明人工培养条件下太平洋纺锤水蚤具有作为水产经济动物活体开口饵料的潜在开发价值。  相似文献   

基于生态价值的玉田县适生植物资源实地调查与评价          下载免费PDF全文

董国明  于帅 《林业调查规划》2024,49(1):133-139

为探索玉田县适生植物资源,进行实地调查,立足于植物资源的生态价值,运用生态服务价值评价与当量因子法研究不同区域的适生植物。结果表明,玉田县北部褐土丘陵地带应多种植榆树、黄栌、油松等植物;中部平原草甸地带应种植紫穗槐、栾树与侧柏等,植物与园林观赏植物交叉种植;南部脱沼泽化潮土区域应多种植油松、栾树、臭椿等植物,补充种植牡荆等观赏植物。  相似文献   

基于遥感的生态服务价值测算与土地利用动态变化     

王世东  贾策 《水土保持研究》2018,25(3):258-264

生态服务价值是反映一个区域生态环境状况的优劣和整体生态效益大小的重要概念与指标。根据研究区土地利用特点和生态系统类型特征,选取适合研究区的植被净初级生产力、植被覆盖度等生态参数,利用Landsat TM遥感影像、地面观测、气象数据、统计资料等数据,建立了基于遥感定量测算的生态服务价值评估指标与评估模型,对研究区单项和单位面积生态服务价值进行了定量计算。结果表明:研究区在2000-2010年10年间,随着不同土地利用类型之间的相互转换,研究区生态服务价值总量呈逐渐减少的趋势。其中,耕地生态服务价值减少了11.92%,湿地减少了11.75%,总价值减少了5.74%,虽然林地、水域和滩涂的生态服务价值有一定程度的增加,但是未能改变研究区总体生态服务价值不断减少的趋势。在此基础上分析了研究区生态服务价值时空变化规律,揭示了其土地利用与生态服务价值变化之间的内在关系。  相似文献   

Genome‐wide association analysis of salmon lice (Lepeophtheirus salmonis) resistance in a North American Atlantic salmon population          下载免费PDF全文

Christina M Rochus  Melissa K Holborn  Keng P Ang  J A K Elliott  Brian D Glebe  Steven Leadbeater  J J Tosh  Elizabeth G Boulding 《Aquaculture Research》2018,49(3):1329-1338

Our objective was to detect single nucleotide polymorphisms (SNPs) associated with resistance to the salmon louse in the Saint John River aquacultural population of North American Atlantic salmon using estimated breeding values (EBVs) and 6K genotypes from the parent‐generation and lice count phenotypes from the challenged, but ungenotyped, offspring‐generation. In 2011 and 2012, we challenged recent smolts with approximately 100 copepodids each. Fish were euthanized once the lice reached the chalimus stages and lice count, sex, tank and salt water weight were recorded. We used a multiple trait model to estimate breeding values for the parent‐generation using their own fresh water weights and the salt water weights and lice counts of the offspring‐generation. Salmon lice count heritability for untransformed and transformed data was 0.17 and 0.29 respectively. Two different genome‐wide association study methods were compared: (i) forward multiple linear regression and (ii) a mixed linear model using principal components to correct for population stratification as implemented in the egscore function of GenABEL. The two methods detected different SNPs located on different chromosomes. The multiple regression method incorporated 70 SNPs found on chromosomes 2, 7, 9, 12, 14, 15, 21, 22, 1p/23, 24. Many SNPs entered into the forward multiple regression are likely to be false positives from not correcting for the observed population stratification and cryptic relatedness. In contrast, the mixed linear model identified only two SNPs, one on chromosome 1p/23 (6.9%) and one on chromosome 1q (6.1%) consistent with louse‐resistance being a quantitative trait.  相似文献   

不同滴灌春小麦品种的氮素吸收规律和氮营养指数     

史力超  翟勇  侯振安  冶军 《麦类作物学报》2016,36(3):302-307

为探究滴灌春小麦氮素吸收规律和不同生育时期氮营养状况的基因型差异,以新春6号和新春35号为供试材料,设置0、75、150、225、300、375kg·hm-26个施氮水平,分析滴灌条件下不同春小麦品种在生育期内的氮素吸收曲线、临界值曲线及氮营养指数。结果表明,两个春小麦品种氮素吸收量均随施氮量的增加而增加,新春6号的氮素快速积累期早于新春35号。植株吸氮量的临界值与出苗后天数均呈极显著的二次函数关系(新春6号:y=-0.174 6x2+22.528x+414.02,R2=0.998**;新春35号:y=-0.169 9x2+20.832x+357.13,R2=0.993**)。依据氮营养指数计算,两个春小麦品种的适宜施氮量均在225~300kg·hm-2范围,且应适当降低出苗后25d之前和提高出苗后35d的施氮量。  相似文献   

1976-2011年博斯腾湖小湖区湿地生态系统服务价值变化分析   总被引：1，自引：0，他引：1  

祖皮艳木·买买提  赛迪古丽·哈西木  玉米提·哈力克  肉孜·阿吉 《水土保持研究》2016,(3)

以1976年、1990年、2002年和2011年4期的遥感影像资料为基础,结合野外实地调查及其他相关资料,研究了1976-2011年博斯腾湖小湖区湿地面积和生态系统服务价值变化及其影响因素.结果表明:(1)近40年间小湖区湿地面积变化呈波动性趋势.其中1976年湿地面积最大为3 813.12 hm2;2002年和2011年湿地面积分别减少为3 138.12,2 285.53 hm2.(2)在整个研究时段博斯腾湖小湖区湿地生态系统服务价值的变化整体上呈减少趋势:其中在1976 1990年,年平均减少2.67％;而在1990-2002年,年平均增长2.63％;2002年以后不断减少,减少速度比前15年明显加快.从研究区各生态功能服务价值对总的生态系统服务功能价值的贡献来看,废弃物处理、水涵养和气候调节功能服务价值的贡献率较大,且在整个研究时段呈增加的趋势.在研究期间,博斯腾湖小湖区湿地面积和生态系统服务价值的变化与流域自然和人为因素密切相关,应重视近年来人类活动的负面影响,对绿洲经济活动进行合理规划和控制.  相似文献   

焉耆盆地气候变化和人类活动对生态系统服务 价值的影响研究     

哈丽旦·司地克  玉素甫江·如素力  麦麦提吐尔逊·艾则孜 《中国生态农业学报》2016,24(5):684-694

环境变化下的生态服务功能研究,对生态环境与社会经济持续发展具有重要的科学意义和应用价值。本文以新疆焉耆盆地作为研究对象,基于Landsat遥感影像数据、DEM数据和气象要素数据,运用非参数气候变化突变点检验(MK,Mann-Kendall-Sneyers test)、趋势分析方法(Mann-Kendall,MK),通过计算生态服务价值(ESV)和土地利用/覆盖变化(LUCC)动态度,对新疆焉耆盆地近40 a(1973—2014年)生态服务功能的变化及其驱动因素进行了分析。结果显示:1)生态系统服务价值和功能的变化是气候变化和人类活动共同作用的结果;2)山区冰川面积的缩小是山区生态服务价值减少的主要原因;3)平原区的生态系统服务价值以2004年为转折点呈现先减少后增加的趋势,整个研究区的生态服务价值分别为1973年85.86×108元、1977年94.46×108元、1994年84.15×108元、2004年89.40×108元和2014年96.47×108元,这与降水量和蒸发量变化趋势吻合。人类活动如长期开垦、扩大绿洲面积和有益的气候变化支撑(降水量增加、蒸发量减少)是平原区生态服务价值增加的主要原因。在山区,生态服务价值随着降水量、蒸发量的变化而变化,在绿洲区生态服务价值的变化是人类开荒耕地、还林、还耕,以及人工栽培芦苇等活动和气候变暖共同作用的结果。  相似文献   

农村社会主义核心价值观大众化研究——以湖北省通城县水口村为例     

李旺珍 《安徽农业科学》2016,(2):279-281

以湖北省咸宁市通城县大坪乡水口村为研究样本,通过问卷调查、深度访谈、实地考察等方式,分析了水口村社会主义核心价值观大众化普及现状及存在问题,提出从村委、村民、学校三方面着手,通过上下联动制定实施方案、提高村民综合素质增强认知认同、夯实理论基础促进实践养成的方式,有效推进社会主义核心价值观大众化建设。  相似文献