A gene for hybrid necrosis in an inbred line of rye (Secale cereale L.)     

Graham J. Scoles 《Euphytica》1985,34(1):207-211

Summary An inbred line of rye (Secale cereale L.) has been found to carry a gene for hybrid necrosis. This gene was detected in crosses with a highly crossable wheat (Triticum aestivum L.) genotype which carries the gene Ne₂. This appears to be the first report of a gene for hybrid necrosis being present in the rye genome.  相似文献   

Progress in mapping agronomic genes in apple (The European Apple Genome Mapping Project)   总被引：4，自引：0，他引：4  

Graham J. King 《Euphytica》1994,77(1-2):65-69

Summary The progress of the European Apple Genome Mapping Project is described. Populations segregating for a range of agronomic genes have been established in six European countries. The need for robust methods of analysis has been identified, especially with regard to the development of molecular markers. Isozyme systems, RAPDs, RFLPs and amplified genes are being used to construct a reference genetic linkage map. Standardisation and precise definition of both genotypic and phenotypic measurements has been recognised as being essential for future exploitation of genetic markers in apple breeding. Phenotypic measurements are being replicated in different geographical locations over several years. Statistical and genetic analyses are aimed at defining components of genetic variation which account for ‘genes’, as defined by apple breeders. A relational database is being constructed which will combine disparate sources of data relating to the genetics of apple. Comparative mapping has been identified as an efficient means of expanding genetic knowledge within and between Rosaceae genomes.  相似文献   

Leaf litter decomposition in a chaparral ecosystem, Southern California     

S.A. Quideau  R.C. Graham  P.F. Hendrix 《Soil biology & biochemistry》2005,37(11):1988-1998

Decomposition losses from leaves of three evergreen chaparral species, scrub oak (Quercus dumosa), ceanothus (Ceanothus crassifolius), and manzanita (Arctostaphylos glauca), were quantified over a 2-y field exposure using litterbags. Changes in ash-free dry mass, C, and N were monitored at 2- to 6-month intervals at four replicate sites composed of patches of these three chaparral species. Three proximate C fractions were extracted from fresh and decomposing litter samples: polar and non-polar extractives (EXT), acid-solubles (ACID), and acid-insolubles (KLIG). The chemical structure of fresh and decomposed litter was additionally characterized using high-resolution solid-state ¹³C NMR spectroscopy, while morphological properties were examined by scanning electron microscopy (SEM). After 2 y, the litters had lost between 20.7%±1.2 (Ceanothus) and 35.2%±6.8 (Quercus) of their original ash-free dry mass. The manzanita decomposed at a significantly faster rate than the other two litter types during the first few months of field exposure. Yet, after 2 y, mass loss was greater for the oak. Differences in decomposition rates could not be accounted for based on a single litter quality index. Fresh manzanita exhibited a significantly higher N content, which could explain its initially faster decay rate. Fresh oak litter, on the other hand, had a relatively high ACID and O-alkyl C (O-ALK) content, which may have been responsible for its decay pattern. Fresh ceanothus contained a relatively low KLIG content, yet it decomposed more slowly than the two other species. The solid-state ¹³C NMR spectra of the ceanothus litter had two peaks characteristic of proanthocyanidins, which likely contributed to the recalcitrance of this litter type. SEM revealed that ceanothus leaf surfaces were left nearly unchanged after field exposure. In comparison, the oak and manzanita leaf surfaces were pitted and covered by microbial growth to the point of being unrecognizable. Taken together, our results indicate that a combination of biological, physical and chemical factors need to be examined to clarify the different decomposition rates and patterns of these three chaparral species.  相似文献   

Organic matter status and the size,activity and metabolic diversity of the soil microflora as indicators of the success of rehabilitation of mined sand dunes     

M.?H.?Graham  R.?J.?HaynesEmail author 《Biology and Fertility of Soils》2004,39(6):429-437

The effectiveness of the rehabilitation of mined sand dunes on the northern coast of KwaZulu–Natal, South Africa, was assessed based on measurements of the total and labile organic matter content and the size, activity and metabolic diversity of the soil microflora. Soil was sampled (0–10 cm) after 0, 5, 10, 20 and 25 years of rehabilitation and compared with soil under undisturbed native forest and under long-term commercial pine forest. Following topsoil removal, stockpiling and respreading on reformed dunes, there was a massive loss of organic C such that, at time zero, organic C content was only 24% of that present under native forest. Soil organic C content increased progressively during rehabilitation until, after 25 years, it represented 93% of that present under native forest. The pattern of change in light-fraction C, KMnO₄-extractable C, water-soluble C, microbial biomass C, basal respiration and arginine ammonification rate was broadly similar to that for organic C, but the extent of the initial loss and the magnitude of the subsequent increase differed. Microbial biomass C, water-soluble C and KMnO₄-extractable C, expressed as a percentage of organic C, declined during rehabilitation as humic substances progressively accumulated. Principal component (PC) analysis of catabolic response profiles to 36 substrates revealed that the catabolic diversity of microbial communities differed greatly between native forest, commercial pine forest, 0 years and 10 years of rehabilitation. On the PC1 axis, values for soils under native forest and after 25 years rehabilitation were similar, but there was still separation on the PC2 axis. The main factor explaining variation in response profiles on the PC1 axis was organic C content; and the greatest catabolic diversity occurred in soils under native forest and after 25 years of rehabilitation.  相似文献   

Effects of one-year administration of ethylenethiourea upon the thyroid of the rat     

S L Graham  W H Hansen  K J Davis  C H Perry 《Journal of agricultural and food chemistry》1973,21(3):324-329

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Spatiotemporally interactive growth dynamics in selected South African forests: Edaphoclimatic environment, crowding and climate effects     

Armin H.W. Seydack  Graham DurrheimJosua H. Louw 《Forest Ecology and Management》2011,261(7):1152-1169

Stand-level tree diameter growth patterns were explored for evergreen moist forests in the southern Cape, South Africa. Results of standard multiple regression analyses, involving 934 permanent sample plots with data spanning a 10-year interval, revealed that stand-level increment of canopy species in the canopy layer (>30 cm dbh) was significantly determined by inherent species-specific growth capacities (species composition of the stand), water availability, forest matrix crowding and tree condition impairment (age-related manifestations of reduced vitality indicated by signs of crown die-back, damage and stem rot). In contrast, stand-level increment of trees of canopy species in the subcanopy layer (10-20 cm dbh) was prominently shaped by light availability, as mainly determined by the degree of canopy-level disturbance (mortality rate of trees >30 cm dbh), crowding (canopy-level overhead and forest matrix crowding) and proximity to conspecific adults (within 6-8 m). In addition to species-inherent and resource factors, considerable variation in stand-level growth resulted from site-climate interactions. For 507 of the permanent sample plots, increment data was available for two consecutive 10-year intervals; permitting the analysis of spatiotemporal interactions of growth patterns (repeated measures ANOVA). In the Knysna forests higher canopy-level increment rates were associated with the moister southerly facing slope sites in comparison with the drier northerly facing and ridge sites during the first increment period. During the second increment period, increment rates on the drier, but better illuminated sites had increased disproportionately. In contrast, in the Tsitsikamma forests, higher increment rates during the second increment period were encountered on moister flat bottomland sites (with extended periods of subsoil wetness) than on the comparatively drier southerly facing slope sites (increment period × site-based water availability × forests interaction). In both forests relatively higher growth performance of subcanopy-level trees during the second increment period was associated with stands experiencing conditions of enhanced light availability. Atmospheric temperatures were higher during the second increment period (mean periodic T_max: + 0.64 °C). The detected spatiotemporal interactions were interpreted as site × climate interactions where site-related conditions of favourable light or water availability resulted in enhanced temperature-linked growth responses during the second increment period. A metabolic performance trade-off model provided a framework for the interpretation of these complex site-climate interactions by placing the patterns of forest growth into an ecophysiological explanatory context.  相似文献   

Statistical methods helping and hindering environmental science and management     

Graham?B.?McBrideEmail author 《Journal of Agricultural, Biological & Environmental Statistics》2002,7(3):300-305

Environmental scientists face the reality that many of their journals’ editors and referees routinely insist that results be accompanied by statements of statistical significance, obtained from two-sided tests of point-null hypotheses. Many in these three groups of people appear only vaguely a ware of the arbitrarinessoften invoked by this procedure and of the information sterility in a single p-value. The interpretation to be made of the failure of a test to attain such significance is not clear. For such reasons, some colleagues (and senior statisticans) have called current usage of the procedures into serious question. Some reasons for this dislocation and some of the more dramatic consequences for environmental science and management are presented. Interval and Bayesian approaches can offer remedies.  相似文献   

Postharvest rind breakdown of ‘Nules Clementine’ mandarin is influenced by ethylene application, storage temperature and storage duration   总被引：1，自引：0，他引：1  

Paul J.R. Cronje  Graham H. Barry  Marius Huysamer 《Postharvest Biology and Technology》2011,60(3):192-201

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Mantle plume helium in submarine basalts from the galapagos platform   总被引：1，自引：0，他引：1  

Graham DW  Christie DM  Harpp KS  Lupton JE 《Science (New York, N.Y.)》1993,262(5142):2023-2026

Helium-3/helium-4 ratios in submarine basalt glasses from the Galapagos Archipelago range up to 23 times the atmospheric ratio in the west and southwest. These results indicate the presence of a relatively undegassed mantle plume at the Galápagos hot spot and place Galápagos alongside Hawaii, Iceland, and Samoa as the only localities known to have such high helium-3/helium-4 ratios. Lower ratios across the rest of the Galápagos Archipelago reflect systematic variations in the degree of dilution of the plume by entrainment of depleted material from the asthenosphere. These spatial variations reveal the dynamics of the underlying mantle plume and its interaction with the nearby Galápagos Spreading Center.  相似文献   

Aerial vision: unique adaptation in an intertidal fish     

J B Graham  R H Rosenblatt 《Science (New York, N.Y.)》1970,168(931):586-588

Mnierpes macrocephalus, a clinid fish of rocky shores of the eastern tropical Pacific, makes frequent terrestrial sojourns. The normal fish eye is myopic in air because of curvature of the cornea. This is overcome in Mnierpes by the presence of two flattened corneal surfaces.  相似文献