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1.
冗余概念的界定与冗余产生的生态学机制   总被引:11,自引:1,他引:10  
冗余是指这样的生命实体,由于其存在,导致生物个体、种群、群落乃至生态系统水平上的对人类有益的功能输出降低,通过管理措施或育种手段剔除这部分‘冗余’实体,个体、种群、群落乃至生态系统水平上对人类有益的功能就会得到加强,我们把这样的生命实体叫做冗余。或者简单地说,冗余是指对目标产量输出构成影响的各种水平的生物有机体过多或过于庞大的部分。冗余的产生过程是整个生命有机体的总体功能扩展过程,冗余的产生和存在,有助于增强有机体的稳定性,提高其适应自然环境波动的能力。根据其影响的水平,冗余可发生在个体、种群及群落等水平上。植物在个体及群体水平上的补偿及超补偿可以通过剔除各生命系统中不同水平上的冗余实现,即剔除冗余有助于目标物种或目标器官产量的提高,并且这种提高是以对波动环境适应能力和抗扰动能力的降低为代价的。  相似文献   

2.
小麦双基因型混合种群的稳态效应研究   总被引:3,自引:1,他引:2  
在作物生产中,不但要高产,稳产更为重要,因为大多数作物种植者处在易变多样的环境中。生产实践证明,在易变多样的生态系统中,靠单一基因型作物种群来达到既高产又稳产的目的是很困难的。根据生物多样性稳态学原理可知,若将同种作物的两个或两个以上纯系品种或品系按一定的比例组成混合种群,肯定能够提高作物群体产量的稳产性。有关作物双基因型混合种群的稳产效应研究,国内外已有许多研究报道,但大多为抗病稳产方面的研究,有关其它逆境方面的稳产效应研究报道较少。1989~1993年我们利用耐盐性不同的小麦品种,在山东省鲁北地区的盐碱土地上…  相似文献   

3.
一在人类极力开发自然的同时,也带来了比较严重的环境问题,例如,水域污染严重;酸雨正在发展;地球温度上升及野生动物大量灭绝等。目前发展中国家单纯为了提高作物产量而大量使用化肥和化学农药杀虫剂。造成水域的严重污染和水体的富营养化,严重影响了水生生物的生存和人类身体健康。实践证明,植物抗病性能的迅速衰退,是作物产量提高的重要限制因子;由于长期大量使用化学农药,不仅增加投资和污染环境,而且害虫的抗性在不断提高。因此,深入研究植物抗性机理,培育高产、抗病虫能力强的作物新品种、开发无  相似文献   

4.
种子包衣是一种高效、新兴的种子处理技术。该技术将外源性材料与种子紧密结合,从而提高种子性能,最终提高作物产量和品质。植物有益微生物(plant beneficial microorganisms, PBM)是指能够促进植物养分吸收、增强其对生物和非生物胁迫的耐受力,并促进植物生长或减少农业化学投入的微生物。因此,PBM可以作为一种微生物种子包衣剂。微生物种子包衣作为一种能够显著提高作物产量、经济效益和农业系统的可持续性发展的革新性技术,因其生态安全性和社会经济效益被认为是传统农业技术有前途的替代品。本文综述了微生物种子包衣技术及其在作物生产中的应用,并对其局限性和不一致性进行讨论。  相似文献   

5.
半干旱区作物根系生长冗余的生态学分析   总被引:24,自引:3,他引:21  
干旱是威胁农业生产的一个常见因子。在水分有限条件下,植物往往产生庞大的根系;这是自然选择的必然结果,是一个进化上稳定的生长对策(ESS)。但作物产量是一个种群水平上的属性;个体的ESS并不能优化整个群体的产量。我们提出在半干旱雨养农业地区作物受自然选择的影响在根系生长上往往失之于过快或过大,出现了“冗余”。通过育种或管理措施降低根系生长冗余可提高作物产量。  相似文献   

6.
主要农作物高产高效抗逆的生理基础研究   总被引:1,自引:0,他引:1  
本项目是通过对我国主要农作物在现有高、中、低产的各个水平上的产量形成生理学研究,建立以最少的资源投入而获得最大增产效益的理论体系,并提出适合我国特点的高产高效抗逆的作物生产和调控原则。主要研究内容如下。 1 提高作物对光、肥、水的利用效率的研究 1.1 作物高产的光合生理基础与提高光合作用效率的研究。其目标在于确定个体与群体光合在产量建成中的作用和地位,寻找进一步挖掘光合潜力、减少已同化的碳量损失的途径。 1.1.1 同一种碳同化类型(C_3或C_4)的不同作物种间、品种间光合速率的差异及其内在原因  相似文献   

7.
农田生物多样性与害虫综合治理   总被引:60,自引:1,他引:59  
在现代农田生态系统中 ,人类为了满足自身的需要 ,通常把自然界的植物群落改造成大面积种植单种特定的作物 ,人为地排除其他植物种类的竞争以提高作物的产量。由于单一化的作物不断取代自然植被 ,降低了农田的物种和生境多样性 ,结果导致农田生态系统的不稳定和害虫问题的更加恶化。影响农田生物多样性的因素很多 ,如地理位置、气候类型、环境条件、作物品种、种间关系、人类的栽培活动等。根据现有的生态学原理和研究成果 ,人类可以通过采用适当的措施来恢复和强化农田生物多样性 ,提高天敌的控制潜能 ,减少害虫发生的可能性 ;这些措施包括合理安排混作的时空格局 ,通过轮作进行间断性耕种 ,对多年生作物采用地面覆盖植被 ,利用不同品种以提高作物的遗传多样性 ,等等。在设计农田生物多样性的管理策略时 ,必须同时考虑当地气候、地理 ,植被 ,作物 ,土壤等因素的变化 ,因为在特定的生境条件下 ,这些因素可能增加或减少害虫发生的机会  相似文献   

8.
农业活动及转基因作物对农田生物多样性的影响   总被引:2,自引:2,他引:0  
农田生物多样性是生态系统生物多样性的重要组成部分,但较少受到关注.近50年来,由于农业活动引起的环境污染、生境破碎和单一化种植等严重威胁着农田生物多样性.为了了解各因素对农田生物多样性的影响程度,优化农田管理措施,以提高农作物产量并降低环境影响,本文综述了种植方式、地膜覆盖、农药和化肥使用等农业活动及转基因作物对我国农田生物多样性的影响.农药和化肥的过度使用对农田生物多样性的影响最大;而转基因作物对农田生物多样性的影响受诸多因素影响,如携带的转基因性状等.需要加强转基因作物生态环境影响评价研究,特别是对农田生物多样性的潜在影响.农业生产活动应当与农田生物多样性保护密切结合,不仅有利于提高农作物产量,同时也可减少对环境的负面影响.  相似文献   

9.
旱地小麦理想株型与生长冗余   总被引:3,自引:0,他引:3       下载免费PDF全文
自1968年Donald提出作物理想株型(ideotype)以来,众多学者在如何减少生长冗余、塑造理想株型方面做了大量努力,在旱地小麦育种策略和栽培管理模式创新方面取得了一定进展。而该方面的进展有限,不同领域的研究者对理想株型和生长冗余的认识存在严重分歧。综述了近年来旱地小麦理想株型研究进展,以过去20年黄土高原雨养农业区的观测数据为主进行了集成分析,将产量分别与根系生物量、地上生物量和株高等指标进行回归分析,勾画了旱地小麦在根系、茎秆和分蘖等器官中生长冗余的演变趋势,对生长冗余产生的生态学机制展开了分析,并对理想株型与生长冗余的互作关系进行了讨论。已有的研究进展表明,旱地小麦理想株型演变是一个不断消减生长冗余,但又无法完全消除冗余的复杂过程,一定程度的冗余存在是理想株型发生的物质基础。旱地小麦理想株型育种必须以基因型和环境互作关系为基础,通过减少个体间的竞争强度和个体大小不整齐性,促进物质和能量更多地向籽粒迁移,最终提高种群产量。综上所述,旱地小麦理想株型选择需建立在生长冗余理论基础上,根据生态学基本原理对基因型和表现型进行耦合分析与选择权衡。  相似文献   

10.
浅谈作物的最大生产力和实际生产力   总被引:1,自引:0,他引:1  
随着世界人口的与日俱增和耕地面积的日益减少,作物生产力研究显得具有时代意义。本文根据近年来的作物产量资料,对作物理论最大生产力,实际产量记录和大面积高产状况等问题作一简要介绍,以展示作物产量前景。  相似文献   

11.
Osmolyte accumulation (OA) is frequently cited as a key putative mechanism for increasing yields of crops subjected to drought conditions. The hypothesis is that OA results in a number of benefits that sustain cell and tissue activity under water-deficit conditions. It has been proposed as an effective tolerance mechanism for water deficits, which could be enhanced in crops by traditional plant breeding, marker-assisted selection or genetic engineering, to generate drought-tolerant crops. However, field studies examining the association between OA and crop yield have tended to show no consistent benefit. The few, often-cited, investigations with positive associations were obtained under severe water deficits with extremely low yields or conditions with special water-supply scenarios when much of the benefit is plant survival. Under conditions where water deficits threaten crop survival, yields are so low that even large fractional yield gains offer little practical benefit to growers. Indeed, the often-cited benefit of turgor maintenance in cells is likely to result in crop behaviour that is exactly opposite to what is beneficial to crops. The one clear mechanism identified in this review for beneficial yield responses to OA is in the maintenance of root development in order to reach water that may be available deeper in the soil profile.  相似文献   

12.
Time series data on crop yields for two main wind-pollinated crops (barley and wheat) and for three crops benefitting from insect pollination (turnip rapeseed, caraway, and black currant), were compiled from official agricultural statistics. In Finland, these statistics are available at aggregate national level, and at the level of each of the 15 provinces of the country. Yields of wind-pollinated crops have steadily increased in Finland, while yields of insect-pollinated crops have been highly variable. The largest crop benefitting from insect pollination is turnip rapeseed, which shows first a clear tendency to increased yields from 1980 to 1993, after which there has been a continuous decline in yields at the national average level. Regionally, the trends in turnip rapeseed yield show large variation, so that in six provinces of Finland, the trend has been significantly decreasing; in five provinces, there has been no significant trend; and in two provinces, there has been a significant linear increase in yields. Yield trends in the two other insect-pollinated crops, caraway and black currants, show similar trend variations. However, at the national average level, caraway yields show no significant trend, while black currant yields have increased during the past 6 years. The possible impact on the trends of insect-pollinated crops of three explanatory variables was analyzed. Significant linear correlation was found between the yield trends (slope of the trends) in rapeseed, and the extent of using neonicotinoid seed dressing in the provinces; the magnitude of yield decline in turnip rapeseed increased, as the use of neonicotinoid seed dressing increased. Similar significant linear correlation was found for the magnitude of yield decline in turnip rapeseed and the complexity of the agricultural landscape in each province; yield trend changed from negative to positive as the proportion of agricultural land of the total terrestrial land area declined from 28% to below 10%. The availability of honey bee colonies with respect to the growing area of crops benefitting from insect pollination also had a linear, significant impact on turnip rapeseed yield trends: yields tended to decline in provinces, where the supply of managed pollinators with respect to demand was low, but tended to increase in provinces, where the number of honey bee colonies were over 30% of the estimated demand. As neither the landscape complexity (proportion of arable land of total terrestrial land area), nor the number of honey bee colonies for pollination have changed significantly over the past 10–20 years, these factors cannot explain the observed differences in the yield trends of the examined insect-pollinated crops. It appears that only the uptake of neonicotinoid insecticide seed dressing about 15 years ago can explain the crop yield declines in several provinces, and at the national level for turnip rapeseed, most likely via disruption of pollination services by wild pollinators.  相似文献   

13.
Growing crops for bioenergy or biofuels is increasingly viewed as conflicting with food production. However, energy use continues to rise and food production requires fuel inputs, which have increased with intensification. Focussing on the question of food or fuel is thus not helpful. The bigger, more pertinent, challenge is how the increasing demands for food and energy can be met in the future, particularly when water and land availability will be limited. Energy crop production systems differ greatly in environmental impact. The use of high-input food crops for liquid transport fuels (first-generation biofuels) needs to be phased out and replaced by the use of crop residues and low-input perennial crops (second/advanced-generation biofuels) with multiple environmental benefits. More research effort is needed to improve yields of biomass crops grown on lower grade land, and maximum value should be extracted through the exploitation of co-products and integrated biorefinery systems. Policy must continually emphasize the changes needed and tie incentives to improved greenhous gas reduction and environmental performance of biofuels.  相似文献   

14.
Bees are in decline potentially leading to reduced pollination and hence production of insect-pollinated crops in many countries. It is however still unclear whether the consequences of pollinator shortages differ among countries with different environmental and societal conditions. Here, we calculated economic gains attributed to insect (particularly bee) pollination (EVIP) as well as their contribution to the total value of crop production (vulnerability), and analyzed their temporal trends and inter-annual variability from 1991 to 2009 for each country of the European Union (EU). To understand which factors drive country-specific differences in pollinator dependency and stability of insect-dependent crop yields, we further asked whether EVIP, vulnerability and stability of yields were influenced by a country's climate, the number of wild bee species and/or managed honeybee hives per country, and (agricultural) gross domestic product (GDP).Across Europe, crop pollination by insects accounted for 14.6 [±3.3] billion EUR annually (EVIP), which equaled 12 (±0.8)% of the total economic value of annual crop production. Gains strongly varied among countries. Both EVIP and vulnerability increased (and the inter-annual variation of vulnerability decreased) significantly from the colder northern to the warmer Mediterranean EU countries, in parallel with increases in the number of wild bee species. Across years, economic importance of pollination increased in all but three EU countries. Apples were the most important insect-pollinated crop in the EU, accounting for 16% of the EU's total EVIP. Our results show that whereas dependency on insect pollination increased from the colder north to the warmer south, variation in economic gain from insect pollination decreased, indicating that Mediterranean countries had more stable yields of pollinator-dependent crops across years and thus more reliable gains from pollination services.  相似文献   

15.
中国农业生态系统昆虫授粉功能量与服务价值评估   总被引:1,自引:0,他引:1  
所有开花植物中大约有80%的物种需要动物作为授粉媒介。系统介绍了中国重要栽培作物花的结构和类型,授粉过程、媒介和方式,作物对昆虫授粉的依赖程度,昆虫授粉功能与服务的概念,以及昆虫授粉功能量与服务价值量的评估方法;同时评估了我国各省农业生态系统中昆虫对重要作物的授粉功能量与服务价值量。结果表明:粮食作物、水果作物、蔬菜作物和经济作物不同程度的依赖昆虫授粉。根据2015年主要农作物产量、作物产品价格、昆虫授粉依赖程度等数据,计算得出昆虫对我国22类主要农作物的授粉功能量为1.8亿吨农产品产量和授粉服务价值为8860.5亿元(占当年GDP的1.3%),具有巨大的经济价值。2015年昆虫对主要栽培作物的授粉功能量和服务价值排在前五名的都是山东、河南、河北、陕西和新疆,年授粉服务价值均大于500亿元,反映出这5个省的主要农作物对昆虫授粉依赖程度较高。昆虫对作物的授粉功能量评价有助于了解昆虫对作物生物量或产量的生物学和生态学效应以及作物对昆虫授粉的需求。昆虫对作物的授粉服务价值评估有助于掌握昆虫授粉为人类所带来的经济效应或经济价值,并帮助决策维持或增强授粉昆虫多样性和种群数量的人力、物力和财力投入。  相似文献   

16.
Summary Application of zinc sulphate mixed with compost/poultry manure proved to be equivalent to the effect of dipping the seedling roots in 4% ZnO suspension with respect to rice yields but Zn-amended organic manures were superior to other treatments with regards to total Zn uptake. A marked residual effect of soil applied treatments was recorded on the succeeding maize crop. Application of poultry manure alone was about one and a half times more effective than compost alone in increasing the rice and maize grain yields. Poultry manure surpassed compost in increasing zinc uptake by the crops and at the same time it built up more available Zn in soil than compost for the following crop. The magnitude of yields and Zn uptake response were magnified when zinc sulphate was applied along with organic manures. Application of 25 kg zinc sulphate/ha alone had the same effect as 50 quintals poultry manure alone or 12.5 kg zinc sulphate applied with 50 quintals compost/ha with respect to crop yields. A significant positive correlation was, recorded in both the crops between Zn concentration in grain or straw and their respective yields.  相似文献   

17.
间接性害虫为害与作物产量损失的关系Ⅰ.食叶害虫   总被引:2,自引:1,他引:1  
本文将繁多的农作物害虫分为间接性害虫和直接性害虫。间接性害虫造成的作物的某类器官或组织的损失率小于产量损失率。食叶害虫是间接性害虫中的一大类。作物对叶面积损失的产量反应很不一致,从完全失收到增产10倍。影响叶面积损失与产量关系的首要因素通常是作物在受害时的生长阶段。在叶面积损失率一定时,处于生长中期(最终营养库迅速增大期)的作物出现最大程度减产。在损失率过大,上部功能叶受害,为害持续时间过长,作物矮秆紧凑,水、肥及气象条件不良以及损失的叶面积分布不均匀等情形下,叶片受害后易于减产;反之则减产较少甚至增产。从分散的材料中归纳出这一基本关系,对当前广泛开展的食叶害虫的产量损失评价工作可能有参考和改进意义。  相似文献   

18.
Global average yields of the world's main food crops have increased over the past 50 years, and these yield increases have varied over time. For most crops, yields have grown significantly faster during periods of higher demand growth, and the contribution of yield growth to output growth has varied between crops. These variations reflect the range of measures available to growers to enhance yields of each crop, which are typically not fully deployed during periods of low demand growth and low relative price. This paper applies two methods using consistent, long‐term historic relationships to demonstrate that crop yield, area and price changes are not independent, and that area changes and yield changes in response to market signals are different for different crops and regions. One of these methods is used to show the expected percentages of exogenous estimates of overall demand growth that will be met by yield growth and by land use change for a range of biofuel crops. The estimated percentage of incremental output growth delivered by yield growth is 78% for EU cereals, with the remainder being met by area growth.  相似文献   

19.
Pollinators are beneficial for many wild and crop plants. As a mass-flowering crop, oilseed rape has received much focus in terms of its pollination requirements but despite a threefold increase in area of cultivation of this crop in Ireland over the past 5 years, little is known about its pollination here. We surveyed the flower visiting insects found in commercial winter oilseed rape fields and evaluated the importance of different pollinator groups, investigated the contribution of insect pollination to oilseed rape seed production, and estimated the economic value of insect pollination to the crop at a national level. Our data showed that winter oilseed rape is visited by a wide variety of insect species, including the honeybee, bumblebees, solitary bees, and hoverflies. The honeybee, Eristalis hoverflies and bumblebees (especially Bombus sensu stricto and B. lapidarius) were the best pollinators of winter oilseed rape based on the number of pollen grains they carry, visitation rates per flower and their relative abundance per field. Exclusion of pollinators resulted in a 27 % decrease in the number of seeds produced, and a 30 % decrease in seed weight per pod in winter crops, with comparable values from a spring oilseed rape field also. The economic value of insect pollination to winter oilseed rape was estimated as €2.6 million per annum, while the contribution to spring oilseed rape was €1.3 million, resulting in an overall value of €3.9 million per annum. We can suggest the appropriate conservation and management of both honeybees and wild pollinators in agricultural areas to ensure continued provision of pollination services to oilseed rape, as a decrease in insect numbers has the potential to negatively influence crop yields.  相似文献   

20.
Ecological intensification of agriculture implies managing ecological processes to improve performance of agricultural systems. However, impacts on relevant ecological functions such as insect pollination from other crop management factors are poorly explored. Pest insects and crop resources such as water availability can directly affect crop yields, but it is unknown if there are indirect effects through effects on insect pollination. With a factorial experiment, we examined how irrigation and control of pollen beetles affected crop attractiveness and pollinator visitation in an open-pollinated spring oilseed rape cultivar. We studied how irrigation and pest control modified the production of flowers and nectar in oilseed rape, and if this in turn affected the flower-visitation of honey bees and bumble bees. Pest control increased the number of oilseed rape flowers by 69%, and the amount of nectar per flower with 36%, but for the latter only in non-irrigated plots. Furthermore, we found higher pollinator densities in plots with reduced pollen beetle densities. Pest control also reduced the number of non-legitimate flower visits, suggesting higher pollination efficiency in plots with reduced pollen beetle densities. We show that crop management affects the value of mass-flowering crops as a resource for pollinating insects. Development of pest control tools that are harmless to pollinators could increase the value of flowering crops as food resources for pollinating insects.  相似文献   

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