Investigations on resistance of oats to Heterodera avenae: Location of resistance genes     

B. H. Chew  R. Cook  H. Thomas 《Euphytica》1981,30(3):669-673

Summary By using 15 available mono/nullisomic lines of Sun II back ground, the Heterodera avenae resistance gene in Nelson (from Avena sativa CI 3444) and Panema (from A. sterilis I. 376) were located on monosome XV. Genes with smaller effects were located on monosomes VIII and X. The absence of these genes derived from Sun II would increase cyst production on plants lacking major resistance genes.  相似文献   

Impacts of the ancient Maya on soils and soil erosion in the central Maya Lowlands     

T. Beach  N. Dunning  S. Luzzadder-Beach  D.E. Cook  J. Lohse 《CATENA》2006

Many studies across the central and southern Maya Lowlands of Belize, Guatemala, Honduras, and Mexico have produced records of land degradation, mostly sedimentation and soil erosion, during the ancient Maya period from before 1000 BC to the Maya Collapse of c. AD 900. This paper provides new data from two sites (Blue Creek and Cancuén), synthesizes more than a decade of the authors' research in Guatemala, Belize, and Mexico, and synthesizes other findings from this region. These research projects analyzed more than 100 excavations in upland and depression sites, cored lakes and wetland sediments, and studied sediments in the field and laboratory using radiocarbon dating, a battery of soil chemistry tests, stratigraphic analysis, magnetic susceptibility, elemental analyses, and artifact identification. Our objective was to date when sedimentation and soil erosion occurred, identify stable surfaces, and correlate them with the state of knowledge about past land use. These findings indicate three general epochs of accelerated soil erosion and identified two major paleosols. The three waves of soil erosion occurred in the Preclassic period (c. 1000 BC to AD 250), the Late Classic (AD 550 to 900), and in the last several decades. The major paleosol (‘Eklu'um’) in these sites is a well-developed Mollisol or Vertisol that started forming in the early Holocene and was buried in either the Preclassic or Classic periods (AD 250 to 900). At some sites the Eklu'um paleosol lies beneath sediments with a fainter paleosol, which in turn lies buried below Classic period and later sediments. This picture shows higher than expected soil erosion linked to the region's first pioneer farmers in the Preclassic and less than expected soil erosion in the Late Classic when population peaked and land use was the most intensive. In other regions like Cancuén, Guatemala, however, most soil erosion occurred during the Maya Late Classic (AD 550–830). Erosion here was intense but short-lived: depressions record 1–3 m of aggradation in two centuries. A third epoch of accelerated soil loss and aggradation arose with the rapid land use changes brought by new pioneers during the last several decades.  相似文献   

Climate change and forest decline: A review of the red spruce case     

Edward R. Cook  Arthur H. Johnson 《Water, air, and soil pollution》1989,48(1-2):127-140

Climate change as a contributor to the decline of red spruce is investigated. Previous climatic response model results are reviewed and more detailed time-dependent modeling of tree growth-climate interactions are performed using the Kalman filter. These new results show that there is a clear temporal and elevational dependence in the response of red spruce to climate. Influence of abnormally warm prior-August temperatures become increasingly time-dependent with decreasing elevation, which is contrary to the elevational gradient in the severity of decline. Thus, this variable, which had been implicated in red spruce declines from previous studies, is unlikely to be a primary cause of the current decline. However, it may be implicated in earlier declines at low elevations. Prior-December temperatures are influential at all elevations, but time-dependent only at the highest elevational zone. The emergence of a strongly time-dependent prior-November temperature response is clearly associated with a time-trend in the temperature record. Thus, it is likely that red spruce is responding, in a transient sense, to changing climate. An additional transient response to current-July temperatures is not associated with any unusual behavior in the data and is, as yet, unexplained. These results show that red spruce is not in equilibrium with its climatic environment, which may have made it more susceptible to damage caused by natural and anthropogenic factors.  相似文献   

Utilization of volatile fatty acids in ruminants. IV. Relative activities of acetyl CoA synthetase and acetyl CoA hydrolase in mitochondria and intracellular localization of acetyl CoA synthetase   总被引：5，自引：0，他引：5  

S Quraishi  R M Cook 《Journal of agricultural and food chemistry》1972,20(1):91-95

  相似文献   

Metabolism of xenobiotics in ruminants. Use of activated carbon as an antidote for pesticide poisoning in ruminants     

K A Wilson  R M Cook 《Journal of agricultural and food chemistry》1970,18(3):437-440

  相似文献   

Metabolism of xenobiotics in ruminants. IV. Storage and excretion of HEOD in Holstein cows     

K A Wilson  R M Cook 《Journal of agricultural and food chemistry》1972,20(2):391-394

  相似文献   

Degradation of [(14)C]carfentrazone-ethyl under aerobic aquatic conditions.     

S A Elmarakby  D Supplee  R Cook 《Journal of agricultural and food chemistry》2001,49(11):5285-5293

Carfentrazone-ethyl (CF-E) is an aryl triazolinone reduced-risk herbicide for use on corn, wheat, and soybean. As part of the assessment of its metabolic fate, the aerobic aquatic metabolism of [(14)C]CF-E at a concentration of 0.22 microg/g was investigated. Two separate aquatic sediments (silty clay loam and clay loam soils, flooded with water) were used in the study. At each of eight samplings throughout the 30-day study, the distribution of radioactivity between surface water, sediment, and volatile fractions was assessed. At zero time, the majority of the applied radioactivity was contained in the water layer (83-90%), declining to 70-80% after 30 days. This was coupled with an increase in the percent radioactivity in the soil layer from 4-6% at day 0 to 13-19% after 30 days. Nonextractable soil residues and volatile degradation products were formed in negligible amounts. Analysis of the incubation extracts from either aquatic sediment indicated a rapid conversion (<2 days) of the parent CF-E ester to carfentrazone-chloropropionic acid. Over time, increasing amounts of a cascade of acidic degradation products comprising >90% of the applied radioactivity were formed. Identification of these degradation products was initially achieved through chromatographic comparison with reference synthetic standards and subsequently confirmed using LC-MS analysis. A degradation pathway for CF-E under aerobic aquatic conditions is proposed.  相似文献   

A Navy witnout Fuel?     

Cook CS 《Science (New York, N.Y.)》1978,200(4349):1438

  相似文献   

Height, weight and age at menarche and the "critical weight" hypothesis     

F E Johnston  R M Malina  M A Galbraith  R E Frisch  R Revelle  S Cook 《Science (New York, N.Y.)》1971,174(14):1148-1149

  相似文献   

RNA complementary to a herpesvirus alpha gene mRNA is prominent in latently infected neurons   总被引：107，自引：0，他引：107  

J G Stevens  E K Wagner  G B Devi-Rao  M L Cook  L T Feldman 《Science (New York, N.Y.)》1987,235(4792):1056-1059

  相似文献