基于Copula函数的开都河年径流预测     

魏光辉 《国际沙棘研究与开发》2016,(7)

河川径流量的准确预测对于水库调度、区域水资源优化配置具有重要意义.本文以新疆开都河为例,运用Copula函数将自变量和因变量的相关程度和相关模式有机结合,构建两变量联合分布函数,研究两变量与联合分布之间的相依结构;在此基础上,根据样本值未知的因变量边缘分布与联合分布关系,结合样本值己知的自变量概率分布,对因变量未知值进行预测.结果表明:基于Copula函数的预测方法原理明晰、计算简便、性能稳定、预测精度较高.  相似文献   

Impact of deferred grazing and fertilizer on herbage production,soil seed reserve and nutritive value of native pastures in steep hill country of southern Australia          下载免费PDF全文

Z. N. Nie  R. P. Zollinger  R. Behrendt 《Grass and Forage Science》2015,70(3):394-405

Developing sustainable grazing management systems based on perennial species is critical to preventing land degradation in marginal land classes. A field study was conducted from 2002 to 2006 to identify the impacts of deferred grazing (no defoliation of pastures for a period generally from spring to autumn) and fertilizer application on herbage accumulation, soil seed reserve and nutritive value in a hill pasture in western Victoria, Australia. Three deferred grazing strategies were used: short‐term deferred grazing (no defoliation between October and January), long‐term deferred grazing (no defoliation from October to the autumn break) and optimized deferred grazing (withholding time from grazing commenced between annual grass stem elongation and seed head emergence and concluded in February/March). These treatments were applied with two fertilizer levels (with or without fertilizer at 50 kg phosphorus ha^?1 and 2000 kg lime ha^?1 applied in year 1 only) in a factorial arrangement and two additional treatments: continuous grazing (CG) and no grazing (NG) in year 1. The deferred grazing treatments on average produced herbage dry matter of 4773 kg ha^?1, the NG produced 4583 kg ha^?1 and the CG produced 3183 kg ha^?1 in year 4 (2005–06) of the experiment. Deferred grazing treatments with and without fertilizer application produced an average of 5135 and 4411 kg DM ha^?1 respectively. Averaged over 4 years, deferred grazing increased the germinable seed pool of perennial grasses by 200% and annual grasses by 50% (except optimized deferred grazing that considerably decreased the annual grass seed pool) compared with the CG. The best of the deferred grazing strategies increased the digestibility of pastures by 7% compared with the CG. The results demonstrated that deferred grazing from spring to autumn followed by rotational grazing could be an effective tool to increase herbage production and soil seed pool and improve the digestibility of native pastures in the steep hill country of southern Australia.  相似文献   

气候变化对台兰河年平均径流量的影响     

王志杰  王新辉  旦木仁加甫  耿曙萍 《干旱区研究》2014,31(1):125-130

以台兰河为研究对象,选用台兰水文站1957-2011年平均流量序列,采用SPSS统计软件对其55 a序列进行趋势分析。结果显示：台兰河径流与降水量的年内分配极不均匀,径流主要集中在夏秋两季,降水量集中在春夏两季,径流与降水量集中期主要分布在7月。识别和提取台兰河年平均流量时间序列的趋势函数QS(t),获得了相应的趋势回归模型;台兰河年平均流量序列存在1957-1981年、1981-1999年、1999-2011年3个时段呈递减→递增→递减变化态势;降水、气温变化是影响台兰河不同时段年平均流量变化的主要因素,年平均径流量变化趋势与气温、降水变化趋势一致。  相似文献   

Distribution of herbicide‐resistant acetyl‐coenzyme A carboxylase alleles in Lolium rigidum across grain cropping areas of South Australia     

J M Malone  P Boutsalis  J Baker  C Preston 《Weed Research》2014,54(1):78-86

Resistance to the acetyl‐coenzyme A carboxylase (ACCase)‐inhibiting herbicides in Lolium rigidum is widespread in grain cropping areas of South Australia. To better understand the occurrence and spread of resistance to these herbicides and how it has changed with time, the carboxyl transferase (CT) domain of the ACCase gene from resistant L. rigidum plants, collected from both random surveys of the mid‐north of Southern Australia over 10 years as well as stratified surveys in individual fields, was sequenced and target site mutations characterised. Amino acid substitutions occurring as a consequence of these target site mutations, at seven positions in the ACCase gene previously correlated with herbicide resistance, were identified in c. 80% of resistant individuals, indicating target site mutation is a common mechanism of resistance in L. rigidum to this herbicide mode of action. Individuals containing multiple amino acid substitutions (two, and in two cases, three substitutions) were also found. Substitutions at position 2041 occurred at the highest frequency in all years of the large area survey, while substitutions at position 2078 were most common in the single farm analysis. This study has shown that target site mutations leading to amino acid substitutions in ACCase of L. rigidum are widespread across South Australia and that these mutations have likely evolved independently in different locations. The results indicate that seed movement, both within and between fields, may contribute to the spread of resistance in a single field. However, over a large area, the independent appearance and selection of target site mutations conferring resistance through herbicide use is the most important factor.  相似文献   

新疆荒漠一年生植物区系组成、分布及资源类型     

杜佳倩  刘彤  王寒月  赵文轩  王杰  徐文斌 《干旱区研究》2022,39(1):185-209

荒漠一年生植物生长速度快、繁殖力强,具有重要的饲用、药用和生态价值.通过文献资料与标本采集信息的考证和野外调查,明确了新疆荒漠一年生植物的物种数量、分布特征及资源类型.结果 表明:新疆荒漠一年生植物共有236种,隶属于20科109属,其中藜科为优势科,猪毛菜属为优势属.科可划分为4个分布区类型,以世界广布科为主,占总科...  相似文献   

大果型芒果枝梢处理技术研究     

米泽民  Yusuf  Mahamood  Alh.  Aliyu  Udubo  Mailambu  Waziri 《中国农学通报》2011,27(13):223-226

尼日利亚北方芒果是树体生长在雨季,而果实生长在旱季。需要在芒果生产中组织一套顺应当地的气候、适合当地生产条件的综合配套技术。为此笔者设计并进行试验。试验证明,在树形选择上以多主枝开心形和少主枝开心形为好;当年生枝梢的留枝量以280条/株为佳;在施肥和修剪上以2次施肥和2次修剪为技术路线的综合配套技术。为当地芒果生产水平的提高,制定相应的技术措施。  相似文献   

40%烟嘧·莠去津WG防除玉米田1年生杂草的效果     

周素香  戴家平  刘福海  张永红 《现代农业科学》2009,(2):93-94

田间试验结果表明,40%烟嘧·莠去津WG2375-2875g/h㎡能有效防除玉米田1年生杂草。药后28d,对狗尾草、稗草、马唐、青葙和鸭跖草的株防效达88.7%-92.3%,鲜重防效达92.9%-96.2%,对玉米安全性好,且增产效果显著。  相似文献   

白杨河流域年降水量多年变化特性分析     

阿里亚&#;阿不都克热木  阿不都沙拉木  塔伊阿不都卡德尔  买买提&#;阿布来提 《现代农业科学》2009,(4):210-213

利用长系列雨量站资料,采用数理统计法分析年降水量的多年变化,并对1956～2005、1956～1979、1971～2005、1980～2005年等短系列年降水量的系列代表性作出分析评价,为合理选用水文系列提供依据。对白杨河水资源调查评价和水资源综合规划具有重要的参考价值,可在生产实践中应用。  相似文献   

使它隆乳油对小麦田阔叶杂草的药效试验   总被引：2，自引：0，他引：2  

崔乘幸  刘鸣韬  陈锡岭 《湖南农业科学》2009,(10):70-71,74

以200g/L使它隆乳油防治猪殃殃、荠菜、大巢菜、播娘蒿等常见的小麦田间一年生阔叶杂草,结果表明,此浓度药剂对这些小麦田间杂草有较好的防治作用,对不同的杂草防治效果略有不同。药后45d,对猪殃殃、荠菜、大巢菜、播娘蒿等的株防效可达81．58％～96．43％,鲜重防效达90．00％～97．94％。对小麦安全性好,增产效果显著。  相似文献   

反季节莲雾叶片养分周年变化规律初探     

吴能义  刘志崴  郭泽成  王平  易杰祥  麦全法  林尤奋 《热带作物学报》2012,32(2):4-6

研究了反季节莲雾叶片养分周年变化规律,结果表明：莲雾开花对叶片N、P、Mg 含量有一定影响,而叶片K、Ca含量受莲雾果实生长发育影响较大;在莲雾幼果期和壮果期喷施叶面肥对于补充叶片Ca、Mg含量有一定效果。并根据不同时期莲雾叶片养分含量的变化提出施肥建议。  相似文献