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1.
氮肥水平对强筋小麦产量和氮素利用的影响   总被引:1,自引:1,他引:0  
为明确强筋小麦产量与效率相协同的最优施氮量,试验选用‘济麦20’和‘洲元9369’ 2个优质强筋小麦品种为试验材料,设置0、120、180、240、300 kg N/hm 2等5个施氮水平,用烘干法和凯氏定氮法分别测定小麦成熟期干物质量积累和含氮量,用以计算小麦氮素积累及氮素利用相关指标。结果表明,随氮肥投入量的增加,小麦产量呈现先升高后降低的变化趋势,其中‘济麦20’在N180和N240下达最高产量7.28 t/hm 2和7.26 t/hm 2,其较高的产量主要源于相对平衡的产量构成因素以及较高的干物质积累量(平均18.54 t/hm 2);‘洲元9369’在N180下产量最高达7.75 t/hm 2,其较高的产量主要源于较高的单位面积穗数(970.65万/hm 2)、穗粒数(30.83粒)、较高的干物质积累量(20.77 t/hm 2)和收获指数(37.33%)。虽然氮肥偏生产力随着氮肥施用量的增加逐渐下降,但两品种的氮肥回收效率、氮肥农学利用率和氮肥生理利用效率均可在N180条件下达到最高值,其中,‘济麦20’最高值分别为62.67%、5.71 kg/kg、9.11 kg/kg,‘洲元9369’的最高值分别为63.65%、7.33 kg/kg、11.55 kg/kg。综合产量水平和氮素利用相关指标,本区域强筋小麦生产中产量与氮素利用效率相协同的施氮量为180 kg/hm 2。  相似文献   

2.
辽宁春季界限温度发生日期的预报方法研究   总被引:1,自引:1,他引:0  
为了在春季气候预测工作中,尽可能准确地预测辽宁春季稳定通过5℃的日期,采用1961—2010年辽宁省53站逐日气温资料和NCEP/NCAR再分析的月平均位势高度场、海平面气压场资料以及由NOAA重构的月平均海温场资料,通过相关分析方法并开展物理因子的普查工作,寻找辽宁春季稳定通过5℃日期的影响因子,并利用多元线性回归方法建立预报方程。结果表明:1961—2010年辽宁春季气温稳定通过5℃日期随时间有提前出现的趋势;稳定通过5℃日期与2月北大西洋海温、1月西北太平洋海温、2月北极涛动、1月印度洋海温、10月阿留申低压强度和1月北大西洋涛动关系密切;建立的预报稳定通过5℃日期的多元线性回归方程具有显著意义。  相似文献   

3.
Abstract: Jharkhand is at the centre of India's struggles to define ‘the environment’ and ‘economically relevant natural resources’. Although cultural labels are applied by leaders who seek influence in these struggles as well as by many of those people who listen, an ethnonational analytic frame does not help answer the questions: How, why and when has the political idea of environment changed in India? When and why has the Jharkhand movement chosen violent tactics? When and why has the Jharkhand statehood movement realised electoral success? Or, why was Jharkhand state formed? To address such questions, a long range historical‐institutional approach is much more fruitful.  相似文献   

4.
Te-Tzu Chang 《Euphytica》1976,25(1):425-441
Summary Available evidences drawn from biosystematics, evolutionary biology, biogeography, archaeology, history, anthropology, paleo-geology and paleo-meteorology are pooled to reconstruct the series of events that led to the cosmopolitan cultivation of the Asian cultivated rice (O. sativa) and the regionalized planting of the African cultigen (O. glaberrima) in West Africa. The genus Oryza originated in the Gondwanaland continents and, following the fracture of the supercontinent, became widely distributed in the humid tropics of Africa, South America, South and Southeast Asia, and Oceania. The two cultivated species have had a common progenitor in the distant past. Parallel and independent evolutionary processes occurred in Africa and in Asia, following the sequence of: wild perennialwild annualcultivated annual. The weed races also contributed to the differentiation of the cultivated annuals. The corresponding members of the above series are O. longistaminata Chev. et Roehr., O. barthii A. Chev., O. glaberrima Steud., and the stapfii forms of O. glaberrima in Africa; O. rufipogon Griff., O. nivara Sharma et Shastry, O. sativa L., and the spontanea forms of O. sativa in Asia.The differentiation and diversification of the annuals in South Asia were accelerated by marked climatic changes following the last glacial age, dispersal of plants over latitude or altitude, human selection, and manipulation of the cultural environment.Cultivation of rice began in many parts of South and Southeast Asia, probably first in Ancient India. Cultural techniques such as puddling and transplanting were first developed in north and central China and later transmitted to Southeast Asia. Wetland culture preceded dryland culture in China, but in hilly areas of Southeast Asia, dryland cultivation is older than lowland culture. The planting method progressed from shifting cultivation to direct sowing in permanent fields, then to transplanting in bunded fields.Widespread dispersal of the Asian cultigen led to the formation of three eco-geographic races (Indica. Sinica or Japonica, and Javanica) and distinct cultural types in monsoon Asia (upland, lowland, and deep water). Varietal types changed readily within the span of a millenium, largely due to cultivators' preferences, socio-religious traditions, and population pressure. Genetic differentiation developed parallel to the ecologic diversification process.The African cultigen developed later than the Asian cultigen and has undergone less diversification. The wild races in South America and Oceania retain their primitive features mainly due to lack of cultivation pressure or dispersal.Both the African and Asian rices are still undergoing evolutionary changes at habitats where the wild, weed, and cultivated races co-exist.  相似文献   

5.
Sensitivity of different agronomic crops to UV-B radiation was studied under environmentally controlled conditions. UV-B radiation reduced plant height, fresh weight, dry weight and ash contents. The reduction varied among the different species tested. Narrow-leaved plants (mainly C4) were less sensitive to UV-B than broad-leaved plants (mainly C3).  相似文献   

6.
借助GIS空间数据获取、分析与管理能力,基于农用地分等方法的应用和改进,建立了重庆市耕地质量评价模型。评价模型通过分功能模块从机理上实现评价质量控制,就光温/气候潜力加和算法,采用以能值为基础确定标准产量折算系数 ,引入光温潜力协调系数 ;就自然质量分模型,指标区之间因素-分级-分值进行了统一,但保留了因素权重的区域差异性。采用2004-2005年重庆市分区县统计的平均粮食播面单产对自然质量等和利用等进行独立检验,线性相关系数分别达83%和87%,相关性显著。研究得出结论,评价模型有效实现了重庆市耕地质量评价区域间的可比性。  相似文献   

7.
不同蔬菜对重金属汞、铬、砷、镉、铅积累效应的研究   总被引:3,自引:1,他引:2  
为了对辽宁省葫芦岛龙岗区蔬菜生产基地蔬菜生产结构的调整提供科学的参考,采用原子吸收的方法,对该生产基地的土壤与蔬菜中重金属(Hg、Cr、As、Cd、Pb)的含量进行检测。结果表明:该蔬菜基地土壤中Hg的含量平均为0.42 mg/kg,Cr的含量平均为52.20 mg/kg,As的含量平均为34.92 mg/kg,Cd的平均含量为0.93 mg/kg,Pb的含量平均为98.49 mg/kg,说明该地区的土壤中重金属含量基本符合农业生产的要求;该蔬菜基地蔬菜中Hg的含量平均为0.92 μg/kg,Cr的含量平均为120.09 μg/kg,As的含量平均为13.80 μg/kg,Pb的含量平均为94.17 μg/kg,Cd的平均含量为15.65 μg/kg,并且所测定的蔬菜样本中甘蓝在5种重金属的含量上均比其他蔬菜的含量高,但也能符合国家卫生标准。此实验可为该蔬菜区蔬菜生产结构的调整提供一定的参考。  相似文献   

8.
研究Nacl浓度与小麦幼苗生长分裂的关系及对小麦幼苗的遗传损伤。实验结果表明:小麦幼苗生长在含NaCl的介质中,其幼苗生长被抑制,根尖细胞有丝分裂指数下降,幼苗的分裂指数、遗传损伤与盐浓度间有一定的线性关系。结果显示:有丝分裂指数与处理浓度间呈负相关。这表明:NaCl浓度高或作用时间延长时对小麦细胞具有遗传学毒性,小麦幼根细胞有丝分裂指数可以作为监测环境中NaCl含量的定量指标。  相似文献   

9.
研究了不同类型油菜品种外部器官的形成、生长与体內醣、氮及脂肪代谢的关系。产量以甘兰类型较白菜类型高。叶面积高峯出现在盛花期前后,净同化率呈“S”形曲线。现蕾抽苔期醣代谢起着主导作用,绝大多数同化产物分配在茎中,同时需肥最多。种子成熟过程含油量的增长,主要由醣转化而成。  相似文献   

10.
Abstract: West Kalimantan (West Borneo) has a history of violent communal conflict.1 It also has extensive forests that have been looted for decades. The argument will be that these two are linked, but not by the grievances of the forest dwellers. Except in its first few days, the two main episodes of 1997 and 1999 were not driven mainly by grievances among marginal groups. Rather, explanations based on the ‘resource curse’ carry more weight. These focus attention on the contested nature of the state, rather than on rebellious activities of marginal groups. When state institutions were thrown into disarray by the sudden resignation of President Suharto in 1998, Dayak militants already close to state power rewrote the rules of local politics by demonstratively ‘cleansing’ certain areas of an unpopular immigrant minority. This theatrical manoeuvre impressed political rivals sufficiently to allow Dayaks to gain control over several timber‐rich districts, which had a thriving black economy. Malays later imitated these techniques to stem the tide.  相似文献   

11.
Potato has a variety of reproductive uniquenesses besides its clonal propagation by tubers. These traits are controlled by a different kind of genetic control. The reproductive information has been applied to enable interspecific hybridization to enhance valuable traits, such as disease and pest resistances, from the tuber-bearing Solanum gene pool. While progress has been made in potato breeding, many resources have been invested due to the requirements of large populations and long time frame. This is not only due to the general pitfalls in plant breeding, but also due to the complexity of polyploid genetics. Tetraploid genetics is the most prominent aspect associated with potato breeding. Genetic maps and markers have contributed to potato breeding, and genome information further elucidates questions in potato evolution and supports comprehensive potato breeding. Challenges yet remain on recognizing intellectual property rights to breeding and germplasm, and also on regulatory aspects to incorporate modern biotechnology for increasing genetic variation in potato breeding.  相似文献   

12.
ABSTRACT The surge in U.S. wage inequality over the past several decades is now commonly attributed to an increase in the returns paid to skill. Although theories differ with respect to why, specifically, this increase has come about, many agree that it is strongly tied to the increase in the relative supply of skilled (i.e., highly educated) workers in the U.S. labor market. A greater supply of skilled labor, for example, may have induced skill‐biased technological change or generated greater stratification of workers by skill across firms or jobs. Given that metropolitan areas in the U.S. have long possessed more educated populations than non‐metropolitan areas, these theories suggest that the rise in both the returns to skill and wage inequality should have been particularly pronounced in cities. Evidence from the U.S. Census over the period of 1950 to 1990 supports both implications.  相似文献   

13.
14.
Abstract: This paper considers the convergence of immigration/globalisation and education in New Zealand. The issues of immigrant students at Epsom Normal Primary School were raised nationally in 1995, and this incident serves as a useful departure point to consider some of the challenges involved in bridging the gap between immigration and education. Educational immigration is a notion used by Belich (2001) amongst others, to suggest that immigrants arrive in New Zealand in order to bypass full cost fees paid by international students. This notion, while useful, is challenged. Research undertaken in North Shore City as well as official immigration figures show the complexities of the issue: immigrant communities may be indirect recruiters of these students, but there are also an increasing number of international students becoming permanent residents. Either way, education providers face particular challenges with migrant students, not only in terms of English language abilities, but also in the lack of financial incentive migrant students give to an education provider relative to international students’ contributions. These micro issues are placed in perspective when returning to considering the transient nature of many young migrants exploring opportunities in a globalised world.  相似文献   

15.
不同花生品种氮磷钾钙硫吸收、分配和利用的差异   总被引:1,自引:0,他引:1  
通过大田随机区组试验,研究优化施肥条件下,不同花生品种氮磷钾钙硫吸收、分配和利用的差异,旨在为豫南花生产区不同品种花生合理施用氮磷钾钙硫肥提供技术支撑。结果表明,花生仁中氮(N)、磷(P)、硫(S)含量最高,其中,‘驻花1号’的N、‘开农71’的P、‘冀花13’的S含量最高,分别为5.150%、0.558%、0.277%;花生茎叶中钾(K)、钙(Ca)含量最高,其中‘中花16’茎叶中K、‘中花24’茎叶中Ca含量最高,分别为1.637%、0.940%。花生仁中N、P、S积累量最高,其中,‘豫花40’花生仁中N、P、S积累量最高,分别为288.436、25.505、15.263 kg/hm2;花生茎叶中K、Ca积累量最高,其中‘豫花37’、‘中花24’茎叶中K、Ca积累量最高,分别为80.760、54.084 kg/hm2。每形成100 kg荚果需求的N、P2O5、K2O、CaO、S养分量分别3.920~5.042、0.905~1.293、1.626~2.721、0.777~1.150、0.270~0.343 kg。本试验条件下,每形成100 kg荚果,‘豫花22’需求的氮最低,‘中花24’需求的磷最低,‘商花5号’需求的钾、钙、硫最低;‘驻花1号’需求的氮最高,‘开农71’需求的磷、钾、硫最高,‘中花24’需求的钙最高。  相似文献   

16.
研究了3个四棱豆品种在湖南怀化地区境内不同区域的生育期特性、主要农艺学性状及其适应性。结果表明:四棱豆在怀化地区最适于每年的4月底至5月中下旬播种;并且这3个四棱豆品种均表现出较强的适应性,其中适应性最强的品种是桂丰一号,其产量高,抗病力强,具有极大的推广价值。  相似文献   

17.
This paper explores land use conflicts between non-farm neighbors and farmers to illustrate the usefulness of the concepts of interdependence, rules, and property rights when doing rural development. Recognizing interdependence and its implications helps economic analysis focus on and understand the types of rules and institutions having the most influence on economic behavior, and thus identify policy alternatives. The resolution of land uses conflicts, for example, unavoidably changes the bundle of rights associated with land, andinfluences who can impose costs of whom; it makes a difference if a large farm has the right to produce odors, flies, or noise that reduces their neighbors' abilities to enjoy theneighbors' own land, or if instead, neighbors have the right to use their property without experiencing farm-produced odors, flies or noise the farm may be unable to use its own land for agriculture without being inconvenienced.  相似文献   

18.
MiniMax是从美国引进的一个生育期短、植株矮、籽粒小的大豆遗传资源,具有成为大豆基础研究模式材料的潜力。本文从3个方面对MiniMax的形态特征和生长发育特性进行了系统研究: (1)参照DUS测试指南,观察、记载了该品系的植物学特性;(2)设置短日照(12 h)和长日照(16 h)两种光周期处理,结合不同播期试验(春播模拟低温、夏播模拟高温),观察不同光、温条件对其生育期、株高、籽粒大小的影响;(3)利用与生育期、株高、籽粒大小等性状相关SSR标记,解析该品系在这些位点的等位变异特点。结果表明,MiniMax在北京夏播自然光照条件下,生育期63.1 d,株高39.0 cm,百粒重4.6 g。不同光、温处理对其籽粒大小影响较小,而对株高和生育期影响较大。MiniMax的光周期敏感度和光温综合敏感度接近于中国北方春大豆早熟品种,而温度敏感度与黄淮夏大豆品种相当。在短日+高温条件下,MiniMax的营养生长期及全生育期短、植株矮、籽粒小,可作为生长周期短、占地面积小的研究材料;而在长日+高温条件下,其生育期长、植株高、占用空间大。在MiniMax中检测到与生育期相关的QTL 5个(FT 2-1、Pod mat 13-3、R7 2-2、R3 1-3和R7 1-3),与株高相关的QTL 5个(Pl ht 13-3、Pl ht 17-2、Pl ht 13-2、Pl ht 7-2和Pl ht 11-3),与籽粒大小相关的QTL 5个(Sd wt 6-4、Sd wt 7-3、Sd wt 10-1、Sd wt 12-3和Sd wt 13-8)。作者认为,MiniMax籽粒小,在适宜的光温条件下具有生育期较短、株高矮、占用空间小等特点,可作为大豆研究模式材料使用。  相似文献   

19.
摘 要:为促进景天科多肉植物侧芽的萌发,于2015—2016年对虹之玉、姬胧月等6种多肉开展试验,通过茎基摘叶、喷施6-BA等方式促进侧芽的萌发。结果表明,摘除植株茎部2/3的叶片,并向裸露的茎部喷施浓度为1000 mg/L的6-BA溶液,每周喷施1次,共喷施5次,每次每条茎的喷施量为5 mL,即可有效促进景天科多肉植物茎上侧芽的萌发。【结论】:根茎喷施赤霉素可有效促进景天科多肉植物的侧芽萌发。  相似文献   

20.
During the long process of evolution, plants have adapted to their environments through the biosynthesis of secondary metabolites (SM) using the acetate-malonate pathway, mevalonic acids pathway, or shikimic acid pathway, leading to resistance to different pests. As a major cash crop, cotton can produce many secondary metabolites with insecticidal activity, and show self-defense mechanisms under biotic stress conditions. These characteristics of cotton ensure reduced pest incidence and maintenance of ecological balance. This paper discusses the types of SMs, their synthesis, and insect resistance of cotton secondary metabolites in relation to their defense function. We propose possible pest-control strategies using secondary metabolites in cotton.  相似文献   

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