华阳河湖群叶绿素a浓度的季节动态和空间分布     

吴奇丽  张坤  陈欢  姜芳媛  林志  周忠泽 《水生态学杂志》2019,40(2):66-72

为了探究华阳河湖群叶绿素a浓度的季节动态与空间分布规律,2016年4月(春季)、7月(夏季)、10月(秋季)和2017年1月(冬季),对华阳河湖群叶绿素a的季节动态及环境因子进行调查,在龙感湖、黄大湖和泊湖分别设置9个(S_1～S_9)、8个(S_(10)～S_(17))和7个(S_(18)～S_(24))采样点,共计24个采样点;通过分层聚类法分析叶绿素a的时空分布特征,并运用主成分分析法探讨了华阳河湖群叶绿素a与环境因子的关系。结果显示,华阳河湖群水体叶绿素a浓度呈现明显的时空分布特征,叶绿素a年均值为7.18μg/L,变化范围0.27～66.61μg/L,最大值出现在2016年10月(秋季),最小值出现在2017年1月(冬季);叶绿素a浓度的季节变化呈现夏、秋季较高,春、冬季较低的动态特征。在空间变化上,叶绿素a浓度在龙感湖最高,其次是泊湖,黄大湖最低。运用分层聚类分析法将华阳河湖群的叶绿素a的时空特征分为三类;主成分分析表明,水体中营养盐是影响叶绿素a季节动态和空间分布的主要环境因子,总氮在3个湖泊中与叶绿素a显著正相关,总磷与叶绿素a在泊湖和黄大湖呈负相关,而在龙感湖呈正相关。研究表明,越冬水鸟的排泄物对叶绿素a的时空分布有重要影响。  相似文献   

杉木无性系生长和木材品质性状遗传变异研究   总被引：1，自引：0，他引：1  

李荣丽  黄寿先  梁机  周传明  何长虹  李龙梅  唐国强 《广西农业科学》2014,45(9):1626-1631

[目的]研究杉木无性系生长性状和木材品质性状的遗传变异规律,为广西杉木栽培区选择优良无性系、提高广西杉木人工林经营效益提供参考.[方法]对34个杉木无性系的单株材积、木材基本密度和管胞形态性状进行方差分析,估算无性系重复力、遗传相关和遗传增益等遗传参数,采用多性状综合指数选择方法选出生长性状与木材品质兼优的杉木无性系并估算遗传增益.[结果]杉木的生长性状具有丰富的遗传变异,变异系数较大的是材积、胸径和树高,其变异系数分别为41.06％、16.44％和12.41％.杉木无性系间的胸径、树高、材积、木材基本密度、管胞长度和管胞宽度差异极显著（P＜0.01）,管胞长宽比差异显著（P＜0.05）,且无性系重复力除管胞长宽比外均在0.5以上.木材密度与胸径、树高、材积、管胞长度、管胞宽度在表型相关和遗传相关上呈负相关.采用多性状综合选择指数法选出3个优良无性系,其胸径、树高、材积、木材基本密度、管胞长度、管胞宽度、管胞长宽比的遗传增益分别为9.83％、7.58％、24.60％、-3.92％、4.65％、2.12％和1.26％.[结论]杉木无性系间具有良好的选择潜力,采用多性状综合指数选择法可以选出生长性状与木材品质兼优的杉木无性系.  相似文献   

南阳黑猪与栾川黑猪的种群遗传关系研究   总被引：1，自引：0，他引：1       下载免费PDF全文

江燕  钟晓琳  王明民  李红军  翟磊  高腾云 《家畜生态学报》2013,34(5):11-15

利用10个微卫星位点对南阳黑猪和栾川黑猪的遗传关系进行研究。计算并统计了平均观察等位基因数、平均有效等位基因数、平均多态信息含量、平均期望杂合度、平均观察杂合度、遗传相似系数和遗传距离等遗传参数,并进行t检验分析。结果表明,10个微卫星位点在南阳黑猪46个个体中共检测到116个等位基因,平均每个位点有11.6个等位基因;在栾川黑猪30个个体中共检测到88个等位基因,平均每个位点8.8个。各遗传参数t检验分析结果显示:南阳黑猪与栾川黑猪间均有极显著性差异(P<0.01)。南阳黑猪和栾川黑猪群体间遗传相似系数为0.7317,遗传距离为0.3124。研究表明,南阳黑猪与栾川黑猪两群体间存在显著遗传分化,因而可能属于不同的黑猪品种。  相似文献   

陕西省农田土壤有机质时空变异与驱动因子定量研究     

王琦  常庆瑞  落莉莉  蒋丹垚  黄勇 《农业机械学报》2022,53(11):349-359

为揭示土壤有机质(Soil organic matter, SOM)时空变异性与驱动因子响应机制,保障区域耕地可持续利用与粮食安全,应用地理探测器、地统计和重心偏移方法对陕西省SOM含量时空变异格局与驱动因子进行研究。结果表明：整体上,陕西省2017年SOM分布呈南高北低格局,平均含量(质量比)为15.63g/kg,较2007年提升8.61%;空间上,2017年SOM含量重心整体向西南偏移,陕南向西迁移,关中向东迁移,陕北向西南偏移;2017年SOM含量空间变异主导驱动因子为土壤全氮含量(q为0.74);2007—2017年间,土壤全氮含量、年平均气温、机械总动力对SOM含量空间变异的驱动力提升较大;2007—2017年,自然与人文因素共同驱动SOM含量时空变异,但人类活动对两因素均具有重要影响。  相似文献   

磷素对含沙水流流体变异特性影响     

张元元  高建恩  李文证  高哲  王照润  王鹭 《水土保持学报》2024,38(1):22-30,39

[目的] 为探明磷素对含沙水流流体变异特性的影响。[方法] 采用自制双竖管流变仪,研究了磷素对不同浓度含沙水流流体类型、流变参数及流体发生变异的临界阈值的影响。[结果] (1)磷素浓度、泥沙浓度及泥沙理化性质是影响含沙水流发生流体变异的主要因素。在25 ℃下,过磷酸钙浓度每增加0.1 g/cm³,黏滞系数和宾汉极限剪切力分别增加0.48~1.47 mPa·s和3.49~6.84 N/m²。(2)随着磷素和泥沙含量的增大,含磷素的含沙水流由牛顿流体变异为宾汉流体。构建并验证了磷-泥沙水流黏滞系数和宾汉极限剪切力等流变参数的计算模型。(3)给出了磷-泥沙水流流体变异的临界浓度阈值。当磷素浓度从0增加至0.45 g/cm³时,含沙水流的流体变异临界浓度阈值降低49%,说明磷素的存在加速了含沙水流的流体变异。[结论] 磷素的增加使得侵蚀水流更容易由牛顿流体变异为宾汉流体,从而影响侵蚀流内部的能量耗散过程,研究结果为深入认识侵蚀污染水流的输移机制提供了新的科学基础。  相似文献   

Between‐site and ‐year variation in the relative susceptibility of native Scottish Pinus sylvestris populations to dothistroma needle blight          下载免费PDF全文

S. Fraser  M. S. Mullett  S. Woodward  A. V. Brown 《Plant pathology》2016,65(3):369-379

Dothistroma needle blight (DNB), caused by Dothistroma septosporum, is currently the disease causing most concern in British pine plantations. Previous artificial inoculation (AI) experiments showed that native Scottish Scots pine (Pinus sylvestris) populations vary in susceptibility to DNB. However, it is unclear if the relative susceptibility of Scots pine populations observed in these experiments can be replicated under natural conditions. It is also unknown whether relative susceptibility of Scots pine populations varies between sites or years. To answer these two questions, young Scots pine plants from six native Scottish populations (Abernethy, Allt Broighleachan, Amat, Beinn Eighe, Glen Cannich and Glen Loyne) were exposed to natural D. septosporum inoculum at two Scottish sites (Culbin and Torrs Warren) between 2012 and 2014. DNB disease incidence and severity was assessed each October. Relative susceptibilities of the Scots pine populations varied between sites and across years. In two of the three years at Torrs Warren (2012 and 2014), the relative susceptibilities of the populations were strongly positively correlated with those observed in previous AI experiments. In these years, trees from Glen Loyne and Glen Cannich were the most susceptible. Conversely, there was no correlation between the relative susceptibilities seen in any year at Culbin with those observed in AI experiments. At Culbin, Beinn Eighe was the most susceptible population. Across both sites, there was a strong positive relationship between total summer precipitation and DNB severity (R = 0·93, t = 8·2, P = 0·001).  相似文献   

北热带亚高山土壤肥力垂直分异特征          下载免费PDF全文

张燕  王平  谭小爱  杨镇文  尹正吉 《林业调查规划》2022,(6):31-35

对北热带亚高山地区红河蝴蝶谷不同海拔（105~3 012 m）单项肥力空间变异及综合肥力分布特征进行研究,通过区分表层（0~20 cm）和亚表层（20~40 cm）,按同层五点混合法采集58个垂直土壤样本,测定土壤肥力指标含量,采用变异系数及修正内梅罗指数法计算单项肥力及土壤综合肥力。研究结果表明,研究区各层土壤单项肥力指标的变异系数在0.11~0.86范围,均属于中等变异,其中,亚表层的pH变异系数接近弱变异,有机质和全氮的变异系数接近强变异,有机质、速效钾、全氮在不同土层变异差异显著;蝴蝶谷土壤综合肥力一般（P为0.9~1.8）,需密切关注,防止肥力下降导致森林生态效益降低;表层和亚表层土壤的综合肥力随着海拔的升高均呈上升趋势,在海拔2 100 m以上区域,表层土壤综合肥力系数明显高于亚表层。以期为北热带山地土壤肥力及生态环境管护、保育、农业生产等提供参考价值。  相似文献   

Characterisation of sweet stem sorghum genotypes for bio-ethanol production     

Precious Mangena  Hussein Shimelis  Mark Laing 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2018,68(4):323-333

In an effort to characterise and select promising sweet stem sorghum genotypes with enhanced biofuel productivity, the present study investigated phenotypic variability present among diverse sweet stem sorghum genotypes based on ethanol production and related agronomic traits. One hundred and ninety genotypes were evaluated. Data were subjected to variance, cluster, correlation, path coefficient and principal component analyses. Significant differences (P?<?0.01) were detected among tested genotypes for all measured traits. Days to flowering varied from 62 to 152 with a mean of 93. Plant height varied from 90 to 420?cm with a mean of 236?cm. Stem diameter ranged from 7 to 31?mm with a mean of 16?mm. Biomass yield varied from 6.668 to 111.2?t?ha^?1 with a mean of 30?t?ha^?1. Stalk dry matter content ranged from 17.2% to 44.2% with a mean of 29.8%, while fibre content varied from 8.92% to 34.8% with a mean of 17.2%. The stalk brix yield varied from 3.3% to 18.9% with a mean of 12.1%. Ethanol productivity ranged from 240.9 to 5500?l?ha^?1 with a mean of 1886?l?ha^?1. The best ethanol producing genotypes were AS203, AS391, AS205, AS251 and AS448. Days to flowering, plant height, stalk brix and stem diameter exerted the greatest indirect effects on ethanol production through higher biomass production. Biomass yield had the greatest direct effect on ethanol production. Therefore, the above traits should be considered during breeding sorghum for bio-ethanol production. Also, the traits had high heritability values, hence selection should provide for good genetic gains. Overall, the above sweet stem sorghum genotypes are useful genetic resources for breeding of sorghum with enhanced bio-ethanol production.  相似文献   

Can within field yield variation be explained using horizontal penetrometer resistance and electrical conductivity measurements? Results from three Swedish fields     

Elisabeth Bölenius  Johanna Wetterlind  Thomas Keller 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2018,68(8):690-700

Spatial variations in yield occur in all agricultural fields to some degree. Knowledge of the reasons for these variations, especially temporally stable yield patterns, is needed in order to improve productivity by changing production methods or inputs. This information must be provided in a simple, cost-effective way. This study investigated whether field-scale measurements of penetration resistance (PR) could identify temporally stable yield patterns without complementary measurements of other properties. The PR measurements were also compared with field-scale apparent electrical conductivity (ECa) measurements and correlations between yield and PR and yield and ECa were investigated. Measurements with a newly constructed horizontal penetrometer and a non-invasive proximal electromagnetic induction sensor were carried out in three fields in east-central Sweden. The measurements were made once in each field, apart from one field where PR was measured twice in one season. The sensor measurements were compared with crop yield measured over the course of several years. The horizontal penetrometer was able to identify low-yielding areas in one field. However, single measurements of PR or ECa were insufficient to consistently identify yield variations. Parts of the fields showed more consistent patterns, with stronger correlations between PR, ECa and yield. PR and ECa data were better at explaining yield variations in drier years, but showed diverging patterns in different fields and neither showed a much stronger correlation to yield than the other. In future studies, simultaneous measurement of soil water content is recommended and also PR measurements at a water content drier than field capacity.  相似文献   

基于信号特征分析的植物体表电信号记录模式选择   总被引：1，自引：0，他引：1  

王子洋  范利锋  王永千  李进海  周桥  黄岚  王忠义 《农业工程学报》2018,34(5):137-143

为了探索不同耦合记录模式所记录植物体表波形数据特征,选择德抗961型小麦与含羞草2类植物,分别对每株植物进行直流耦合、交流耦合同步信号记录。分析光诱导下小麦所产生的局部电位中直流耦合记录与交流耦合记录的数据差异。小麦局部电位直流耦合与交流耦合记录数据波形峰峰值差异可达25倍以上;基于短时傅里叶变换,功率密度时频分布图显示直流耦合记录到的信号局部电位的频谱主要在0.2 Hz以内。而含羞草的变异电位的上述2种耦合模式记录的波形差异相对较小,功率密度时频分布图中可以反映其信号功率谱分布在0.6 Hz以内。通过记录不同下限截止频率的数据,小麦的光诱导电信号更加清晰的反映耦合方式对信号的影响,进一步地,通过含羞草变异电位的传导特性与对小麦钙通道阻滞的对照试验来验证所测信号的真实性。因此,针对不同植物及其植物电信号本身的特点,应选择适合的耦合记录方式。  相似文献