首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 187 毫秒
1.
旱地保护性耕作土壤风蚀模型研究   总被引：1，自引：0，他引：1  
在分析国外风蚀模型资料的基础上,建立了适用于保护性耕作的风蚀模型。该模型以小时为步长,根据气象数据、地表土壤水分、秸秆残茬覆盖率及地表粗糙度,模拟不同耕作体系下农田土壤风蚀流失量情况;针对保护性耕作的特点,考虑到残茬覆盖对土壤含水量和地表粗糙度的影响;通过田间风蚀测定数据的验证,证明所建立的保护性耕作风蚀模型的模拟值与实测值比较吻合。  相似文献   

2.
坡度对黄土坡面径流溶质迁移特征的影响   总被引：6，自引：0，他引：6  
通过田间模拟降雨试验,分析了坡度对坡面物质迁移特性的影响.结果显示,坡度对坡面物质迁移的影响十分显著;降雨强度一定时,坡度达到15°左右时,径流量达到最大;坡度对径流养分流失量的影响是通过径流量起主导作用,径流量大相应径流携带养分流失总量增加.利用幂函数对径流溶质浓度变化过程进行了拟合,结果显示幂函数可以很好反映田间坡面溶质随地表径流变化过程,说明在侵蚀环境下径流溶质浓度变化过程符合幂函数.  相似文献   

3.
豫西黄土坡耕地保护性耕作保水效果研究   总被引：13，自引：0，他引：13  
采用田间模拟小区和田间自然小区试验相结合的方法,研究了不同处理条件下降雨入渗、休闲期降水的贮蓄率、不同土壤层次间接纳降水的增量、冬小麦产量及水分利用效率等因素。研究结果表明,保护性耕作有延缓径流,增加降雨入渗的作用,其稳定入渗率是保护性耕作的1.22～6.67倍,在降雨强度为68mm/h时其地表产生径流时间比传统耕作晚6～15min;免耕和深松处理土体内的含水量、接纳降水的能力明显高于传统耕作,休闲期两个处理降雨贮蓄率分别比对照高出6.5%和7.4%,冬小麦产量分别高17.78%和16.1%,水分利用效率分别高1.52kg/(mm·hm2)和1.00kg/(mm·hm2)。  相似文献   

4.
径流曲线数模型(SCS-CN)参数λ在黄土丘陵区的率定   总被引：9，自引：0，他引：9  
径流曲线敷模型(SCS-CN)用来计算降雨形成的地表径流量,参数λ是模型中的重要参数之一.本文在对径流曲线数模型参λ敏感性分析的基础上,应用黄土丘陵区径流场62场实测降雨资料对参数λ与地表坡度关系进行了定量分析.结果表明,曲线教模型所描述的参数λ=0.2适合于黄土丘陵缓坡地,参数λ随着坡度的增大而减小;同时用实测降雨资料进行标定模型验证,得出径流量的预测值与实测值接近,其效率系数E=0.94,与直接运用模型计算径流量比较,效率系数有较显著提高.  相似文献   

5.
模拟降雨条件下苏南黄壤产流起始时间及影响因素研究   总被引：1，自引：0，他引：1  
运用人工模拟降雨装置研究了暴雨条件下苏南典型丘陵土壤上纯草、纯灌、灌草3种经营模式下坡度、降雨强度、土壤前期含水量、植被覆盖度对开始产生径流时间的影响。研究表明:纯草模式下影响开始产流时间的最主要因子为土壤前期含水量,同时建立了3种植被组合下影响开始产流时间的多因子回归方程。通过方程,由植被覆盖度、坡度、土壤前期含水量和降雨强度四个易于获得的因子可预测不同植被组合下开始产生径流的时间。  相似文献   

6.
保护性耕作技术对农田环境的影响研究   总被引：10，自引：1，他引：10       下载免费PDF全文
根据保护性耕作在我国的实施情况并结合国外已有研究结果,我们认为保护性耕作的内涵为：保护性耕作措施就是对农田实行少耕或免耕,尽可能减少对土壤的扰动,并以秸秆覆盖地表,达到减少劳动强度和生产投入,防止农田风蚀和水蚀并提高土壤肥力和抗旱能力的一种农田耕作技术。并对保护性耕作措施在改善农田作物生长环境方面的作用：有效提高农田水分利用效率;有效保持水土,大幅度地减少水土流失,减少大部分的田间起沙,降低农田地表土壤养分和水分的流失;有效提高土壤生物和微生物的数量与活性,增加土壤肥力,改善土壤结构,降低地表温度,减少地表蒸发等方面的最新研究成果进行了综述。此外,还叙述了保护性耕作对农田病虫害和杂草的影响。最后提出了在我国开展保护性耕作的必要性及其工作重点。  相似文献   

7.
辽西易旱区不同耕作方式对土壤物理性能的影响   总被引：4，自引：0，他引：4  
比较了不同耕作方式对土壤水分、温度、容重、孔隙性状和养分的影响。结果表明,保护性耕作有抑制蒸发保墒作用,分别表现在苗期0-20cm土层以及作物生长发育后期40cm以下土层,提高了水分利用率,其中留茬覆盖可以比传统耕作提高16.53%,增产幅度可达13.56%;保护性耕作的土壤温度低于传统耕作,尤其留茬覆盖表现最为明显,其降低土壤温度的效应主要发生在苗期和土壤表层;保护性耕作方式提高了毛管孔隙度,提高了涵养水分的作用,但土壤容重的增加影响作物的播种和出苗;保护性耕作对土壤有机质和速效养分的变化有着一定的影响,但各种方式间差异不显著;在辽宁省西部干旱和半干旱地区建议采用以留茬覆盖为主的保护性耕作方式。  相似文献   

8.
土壤水分下渗机制及其在半干旱区产流模拟中的应用   总被引：2，自引：0，他引：2  
尽管目前提出了许多流域水文模型,但多数模型更适用于湿润地区,将这些模型移植到半干旱半湿润地区,往往模拟结果并不理想。为了研究半干旱半湿润地区流域的产流机制,本文通过描述土壤水分的垂直运动过程,建立了湿润峰和饱和带上界面的移动方程,给出了土壤水的动态下渗过程,并据此将径流分为地表径流和壤中流,建立了流域产流模型。还以滦河水系的柳河流域作为研究对象,尝试性地进行了降雨径流的模拟。结果表明:模型的确定性系数达到77.2%以上,用于该流域的产流计算是可行的。  相似文献   

9.
不同保护性耕作下冬小麦田杂草滋生情况调查研究   总被引：7，自引：0，他引：7  
采用随机调查的方法,对不同保护性耕作处理下冬小麦田间杂草的种类和数量进行调查研究,发现不同的耕作处理对杂草种类和数量的消长有很大的影响.传统耕作、免耕、秸秆深松覆盖、高留茬深松覆盖四种处理,以免耕条件下杂草的种类和数量最多,秸秆深松覆盖、高留茬深松覆盖是控制冬小麦田间杂革滋生的一种有效措施.不同保护性耕作处理使冬小麦田间杂草种类与各杂草相对丰度均发生变化,各处理间Shannon多样性指教(H')和Mamclef物种丰富度指数(D)均存在差异,其原因可能是由于不同保护性耕作处理造成各处理间生态环境、土壤养分和土壤水分的不同,各种杂草的生长因而受其不同影响所致.  相似文献   

10.
通过在坡度为20°耕地和荒草坡面对降水、土壤水密集观测,结合模拟降雨实验,从降雨入渗、蒸散发等过程分析讨论了影响黄土高原丘陵沟壑区坡地土壤水分动态的主要因素。结果表明:1)降雨入渗量△S主要受控于雨强和降雨量,坡耕地的入渗量随着雨强增加而衰减的速度快于荒坡,坡耕地有利于中等雨强大雨的下渗,雨强增大时两坡面的降雨转化率逐渐接近,且植被的再分配作用凸显,甚至使短历时暴雨时坡耕地的入渗速度低于荒坡,长历时的大、暴雨或连续降雨利于深层入渗,坡面耕作或在裸地上种植冰草后降雨转化率增约50%;2)7月～10月上旬为土壤水补给期,土壤水分在枯水年及平水年处于负平衡,在丰水年获得补给,最终以蒸散发消耗;3)荒地主要耗水层在20cm,耕地土壤水分活跃层及作物主要耗水层延伸至30cm。总体上,农作物增大蒸散发量、增加土壤水分利用深度,农业生产活动对减少降雨径流、增加土壤水资源量、强化水分小循环有重要作用。  相似文献   

11.
Fifteen species of dermestid beetles were recorded at ‘Evolution Canyon’ (EC), Lower Nahal Oren, Mt. Carmel, Israel. They represent ~35% of known Israeli dermestid species. The following three species were recorded for the first time in Israel:Trogoderma svriaca Dalla Torre, 1911;Ctesias svriaca Ganglbauer, 1904; andAnthrenus (s.str.) jordaniens Pic, 1934. Adults of 13 species were collected on the more solar radiated, warmer and climatically more fluctuating south-facing slope (SFS); ten species were collected on the opposite, north-facing slope (NFS), which was cooler and climatically more stable. The abundance of adult dermestid beetles was 1.9 times higher on the SFS than on the NFS (86 and 47, respectively). Species richness and abundance distribution at EC (three collecting stations on each slope and one at the valley bottom) were significantly negatively correlated with the plant cover that consisted of trees and bushes (Spearmanr s ,P=0.007 and 0.039, respectively) and perennials (Spearmanr s ,P=0.039 and 0.077, respectively), indicating that non-woody plants were preferred by adult dermestid beetles.  相似文献   

12.
Recent data on the epidemiology of the common mycotoxigenic species of Fusarium, Alternaria, Aspergillus and Penicillium in infected or colonized plants, and in stored or processed plant products from the Mediterranean area are reviewed. Emphasis is placed on the toxigenicity of the causal fungal species and the natural occurrence of well known mycotoxins (aflatoxins, ochratoxins, fumonisins, trichothecenes, zearalenone, patulin, Alternaria-toxins and moniliformin), as well as some more recently described compounds (fusaproliferin, beauvericin) whose toxigenic potential is not yet well understood. Several Fusarium species reported from throughout the Mediterranean area are responsible of the formation of mycotoxins in infected plants and in plant products, including: Fusarium graminearum, F. culmorum, F. cerealis, F. avenaceum, F. sporotrichioides and F. poae, which produce deoxynivalenol, nivalenol, fusarenone, zearalenone, moniliformin, and T-2 toxin derivatives in wheat and other small grains affected by head blight or scab, and in maize affected by red ear rot. Moreover, strains of F. verticillioides, F. proliferatum, and F. subglutinans, that form fumonisins, beauvericin, fusaproliferin, and moniliformin, are commonly associated with maize affected by ear rot. Fumonisins, were also associated with Fusarium crown and root rot of asparagus and Fusarium endosepsis of figs, caused primarily by F. proliferatum. Toxigenic A. alternata strains and associated tenuazonic acid and alternariols were commonly found in black mould of tomato, black rot of olive and citrus, black point of small cereals, and black mould of several vegetables. Toxigenic strains of A. carbonarius and ochratoxin A were often found associated with black rot of grapes, whereas toxigenic strains of A. flavus and/or P. verrucosum, forming aflatoxins and ochratoxin A, respectively, were found in moulded plant products from small cereals, peanuts, figs, pea, oilseed rape, sunflower seeds, sesame seeds, pistachios, and almonds. Finally, toxigenic strains of P. expansum and patulin were frequently found in apple, pear and other fresh fruits affected by blue mould rot, as well as in derived juices and jams.  相似文献   

13.
We first discuss the diversity of fruit fly (Diptera: Tephritidae) parasitoids (Hymenoptera) of the Neotropics. Even though the emphasis is on Anastrepha parasitoids, we also review all the information available on parasitoids attacking flies in the genera Ceratitis, Rhagoletis, Rhagoletotrypeta, Toxotrypana and Zonosemata. We center our analysis in parasitoid guilds, parasitoid assemblage size and fly host profiles. We also discuss distribution patterns and the taxonomic status of all known Anastrepha parasitoids. We follow by providing a historical overview of biological control of pestiferous tephritids in Latin American and Florida (U.S.A.) and by analyzing the success or failure of classical and augmentative biological control programs implemented to date in these regions. We also discuss the lack of success of introductions of exotic fruit fly parasitoids in various Latin American countries. We finish by discussing the most pressing needs related to fruit fly biological control (classical, augmentative, and conservation modalities) in areas of the Neotropics where fruit fly populations severely restrict the development of commercial fruit growing. We also address the need for much more intensive research on the bioecology of native fruit fly parasitoids.  相似文献   

14.
《干旱区科学》2014,(6):782-782
正Journal of Arid Land(JAL)is an international journal(ISSN 1674-6767;CN 65-1278/K)for the natural sciences,sponsored by the Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences and Science Press.It is published by Science Press and Springer-Verlag Berlin Heidelberg bimonthly.JAL publishes original,innovative,and integrative research from arid and semiarid regions,ad  相似文献   

15.
Broad bean mottle virus (BBMV) was transmitted from infected to healthy faba-bean plants by the curculionid weevilsApion radiolus Kirby,Hypera variabilis Herbst,Pachytychius strumarius Gyll,Smicronyx cyaneus Gyll, andSitona lineatus L. The latter appeared to be an efficient vector: acquisition and inoculation occurred at the first bite, the rate of transmission was c. 41%, and virus retention lasted for at least seven days.S. lineatus transmitted the virus from faba bean to lentil and pea, but not to the three genotypes of chickpea tested. This is the first report on the generaHypera, Pachytychius, andSmicronyx as virus vectors, and onA. radiolus, H. variabilis, P. strumarius, andS. cyaneus as vectors of BBMV.Out of 351 samples of food legumes with symptoms suggestive of virus infection, 16, 11, 19, and 17% of the samples of chickpea, lentil, pea, and common bean, respectively, were found infected when tested for BBMV in DAS-ELISA. This is the first report on the natural occurrence of BBMV in chickpea, lentil, pea, and common bean. The virus should be regarded as a food-legume virus rather than a faba-bean virus solely, and is considered an actual threat to food legume improvement programmes.  相似文献   

16.
A collection of 38 PVY isolates from seed potato batches, originating from several Western European countries, was characterized by using current biological, serological and molecular tools differentiating PVY strains and groups. The correlation between the three kinds of tests was good but not absolute. No single serological or PCR method was able to discriminate among the five isolate groups found. Twenty-nine isolates belonged to the PVYN strain and six to the PVYO strain. No PVYC was found. Two other isolates reacted serologically like PVYO, but were unable to elicit a hypersensitive response from the Nytbr gene and probably represent the PVYZ group. At the molecular level, these two isolates showed a combination of both PVYO and PVYN and could be recombinants of these strains. Another isolate reacted serologically like PVYO, but induced vein necrosis in tobacco, like PVYN-Wilga. Some PVYN isolates caused tuber ring necrosis in glasshouse conditions. These might belong to the PVYNTN group. The PVYNTN, PVYN-Wilga and PVYZ groups probably represent pathotypes within strains PVYN and PVYO, respectively. The present study also confirms previous reports showing a high genetic variation at the 5 end within the PVYN strain.  相似文献   

17.
The phenology of the autumn leafroller,Syndemis musculana, a local pest of apple, was studied in order to forecast larval emergence. From 1983–1986, peak flight as determined with sexpheromone traps was always between 13–18 May. The duration of embryonic development was determined at various constant temperatures and used to estimate the periods of egg hatch in these four years. Each year, most eggs should have hatched in the second decade of June.Differences in attack rates between apple cultivars seem to be explained largely by the variation in picking time. Larvae are only half grown at the beginning of harvest (cv. James Grieve), and have gone into hibernation when the latest variety (cv. Golden Delicious) is picked. Moreover, the varieties Cox's Orange Pippin and Belle de Boskoop, picked about half time, are liable to receive additional damage by caterpillars brought with the picked fruits into storage.Various hymenopterous parasites were reared from caterpillars. As the only leafroller in the orchard which hibernates as mature larva,S. musculana may promote winter survival of some parasitoids, like the eulophidColpyclypeus florus.Samenvatting De fenologie van de herfstbladroller (Syndemis musculana Hübner), een incidentele plaag op appel, werd nader bepaald met het doel het uitkomen van de eieren te kunnen voorspellen. In 1983–1986 viel de piekvlucht, bepaald met behulp van feromoonvallen, steeds tussen 13 en 18 mei.De ontwikkelingsduur van de eieren bij verschillende constante temperaturen werd gebruikt om de periode van uitkomen te schatten. De meeste eieren zullen ieder jaar in de eerste helft van juni uitkomen.Geconstateerde verschillen in schade tussen appelrassen blijken goeddeels terug te voeren op verschillen in pluktijdstip. De rupsen van de herfstbladroller zijn pas half-was als de eerste appels eind augustus geplukt worden, terwijl tegen het einde van de oogst begin oktober de meeste al in winterslaap zijn. Met name tussentijdse rassen, als Cox's Orange Pippin and Schone van Boskoop, lopen extra schade op doordat grotere rupsen met de geplukte vruchten in de kist terecht komen.Uit de rupsen werden negen, al van andere boomgaardbladrollers bekende, sluipwespen gekweekt, Omdat deze bladrollersoort, als enige in de boomgaard, als volgroeide rups overwintert, lijkt zij bij uitstek geschikt als winterwaard.This study was carried out at the Experimental Orchard De Schuilenburg, Schuilenburg 3, 4041 BK Kesteren, the Netherlands, to which address correspondence should be addressed.  相似文献   

18.
Liriomyza cicerina (Diptera: Agromyzidae) is an important pest on chickpea in Turkey. The objective of this study was to determine the parasitoids and rates of parasitism ofL. cicerina on chickpea (Cicer arietinum L.) during the 2005 and 2006 seasons in ?anl?urfa province, Turkey. Leaves with mines were sampled weekly and kept in the laboratory to observe and count emerging leafminer and parasitoid adults. Eight parasitoid species were collected: the braconidsOpius monilicornis Fischer andOpius tersus Foerster and the eulophidsDiaulinopsis arenaria (Erdös) andNeochrysocharis formosa (Westwood), which occurred in both the winter and summer seasons;Diglyphus crassinervis Erdös,Neochrysocharis ambitiosa Hansson,Neochrysocharis sericea (Erdös) andPediobius metallicus (Nees), which occurred only in the summer growing areas.Diaulinopsis arenaria was the predominant parasitoid with 4–7.7% parasitism rate whileN. ambitiosa andO. monilicornis were the second and third most predominant species. The results of these trials show that sinceDia. arenaria occurred throughout every season, it could potentially be used for control of the leafminerL. cicerina.  相似文献   

19.
Systematic information on the quantitative impact of Z ygogramma bicolorata on the biology of P arthenium hysterophorus is crucial as the seeds of this weed continue to germinate from the accumulated soil seed bank throughout the year in the form of different germinating flushes, while the activity of the beetle ceases during winter as it enters diapause. Therefore, plant–herbivore interactions need to be explored to develop predictions of the overall impact of the introduced beetle on the weed. The findings revealed that defoliation by Z . bicolorata had a significant impact on the plant height, density and flower production in flushes F 3, F 4 and F 5, but not in F 1 and F 2 that exhibited longer periodicity, profuse branching, a longer flowering period and maximum flower production and contributed mostly to the existing seed soil bank. Therefore, total depletion of the existing soil seed bank was not possible. Consequently, the effect of augmentative field releases of laboratory‐reared beetles was explored on F 1 and F 2 in February for three consecutive years (2011–2013). Before initiating the trial, random soil samples were taken from the plots that were assigned to the paired treatments (i.e. with the beetle and without the beetle [insecticide‐treated]) and it was found that the seed bank in those samples did not differ. The single release of Z . bicolorata adults at five per plant at the six‐leaf stage significantly reduced the soil seed bank, compared to without the biocontrol agent, irrespective of the flushes at the end of the season.  相似文献   

20.
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号