Effect of season and different fungi on phenolics in response to xylem wounding and inoculation in Eucalyptus nitens     

K. M. BARRY  N. W. DAVIES  C. L. MOHAMMED 《Forest Pathology》2002,32(3):163-178

Pot‐grown and plantation‐grown Eucalyptus nitens trees (approximately 2 and 3 years old, respect‐ively) were experimentally wounded and inoculated with different fungi and in different seasons. Decay lesion development and defence zones were assessed. Two zones were described, a narrow brown decay interface (interface reaction zone, IRZ) and a diffuse zone beyond this being either pale brown or purple (reaction zone, RZ). The total phenol levels in the reaction zone were determined. Selected phenolics (pedunculagin, tellimagrandin 1, tetragalloylglucose, pentagalloylglucose and catechin) were quantified by liquid chromatography–mass spectrometry (LC–MS). A range of fungi (mainly decay‐causing) were used to inoculate wounds and the results indicated that more extensive decay lesions were generally associated with greater production of soluble phenols in response. Sterile inoculations and weakly aggressive fungi were associated with no or little xylem discoloration, whereas aggressive fungi elicited more discoloration and phenolic accumulation in advance of infection. This indicates that phenol accumulation is not a generalized response to wounding, but a variable response due to the interaction between microorganisms and sapwood. In plantation‐grown trees examined 6 months after wounding, purple reaction zones were commonly associated with large decay lesions. Seasonal differences in decay column area caused by Ganoderma applanatum were not significant 1 month after wounding and inoculation.  相似文献   

Sheet Mulching as an Aid to Broadleaved Tree Establishment II. Comparison of Various Sizes of Black Polythene Mulch and Herbicide Treated Spot   总被引：1，自引：0，他引：1  

DAVIES  R. J. 《Forestry》1988,61(2):107-124

Eight experiments, each having 15 treatments, were established.Sites with clayey, loamy and sandy soils were used. The treatmentsincluded herbicide spots of various sizes up to whole plotskept weed-free; polythene mats of various sizes up to wholeplots (10 x 8 m) covered in polythene; and polythene mats ofvarious sizes with the rest of the weeds within the plot treatedwith herbicide. In each experiment survival or growth or both increased thefurther weeds were kept from the trees. Growth was increasedmost on the sandy site. Survival was increased most in the experimentwhich used poor quality oak plants - from zero in the controltreatment to 63 per cent in the whole-plot polythene treatment.Herbicide spots were generally better than polythene mats whenthe area treated was less than one square metre per tree, butnot so good when larger areas were treated: this is attributedto weeds rooting under the mulches. Growth was increased whenthe weeds around the mulches were killed. Accidental herbicidedamage, voles gnawing the trees from beneath the mulches, andsoil anaerobism on poorly drained sites also influenced theresults.  相似文献   

The Importance of Weed Control and the Use of Tree Shelters for Establishing Broadleaved Trees on Grass-Dominated Sites in England   总被引：1，自引：0，他引：1  

DAVIES  R. J. 《Forestry》1985,58(2):167-180

The results of seven experiments are used to illustrate themechanisms of weed competition and its effects. Studies of soilmoisture tension and foliar nutrient content indicated thatcompetition was primarily for moisture and nutrients reducingthe survival and growth of young trees. These effects are greateron soils with poor moisture retention, or where the climateresults in high soil moisture deficits. To be effective, weedcontrol must eliminate root competition. This can be done bycultivation, herbicides or mulching; cutting weeds above groundlevel is ineffective. Tree shelters accelerate the height growthof young trees and protect them from mammals and herbicide drift.  相似文献   

The effect of herbicides on respiration and transformation of nitrogen in two soils III. Lenacil, terbacil, chlorthiamid and 2,4,5-T     

J.A.P. MARSH  H.A. DAVIES 《Weed Research》1978,18(1):57-62

The effects of lenacil, terbacil, chlorthiamid and 2,4,5-T at 100 ppm on carbon dioxide evolution, oxygen uptake and nitrogen transformation in two soils have been investigated for several months in the laboratory. The herbicides had no effect on CO₂ output from either Boddington Barn soil (organic carbon content 1.6%, pH 6.1) or Triangle soil (organic carbon content 3.7%, pH 4.8) apart from 2,4,5-T which reduced it sometimes. All the herbicides caused temporary reductions in O₂. uptake, but in Triangle soil treated with 2,4,5-T a significant reduction was observed during the second half of the incubation. 2,4,5-T and to a lesser extent chlorthiamid, reduced nitrification in Triangle soil. All the herbicides slightly increased mineralization of nitrogen except 2,4,5-T which had variable effects in Triangle soil.  相似文献   

Subterranean clover mottle virus: another virus from Australia with encapsidated viroid-like RNA     

R. I. B. FRANCKI  J. W. RANDLES  T. HATTA  C. DAVIES  P. W. G. CHU  G. D. McLEAN 《Plant pathology》1983,32(1):47-59

A new virus, subterranean clover mottle virus (SCMoV) was found at several locations in Western Australia in Trifolium subterraneum L. (subterranean clover) with severe disease symptoms. Paiticles of the virus were shown to share many physical properties with members of the sobemo-virus group. However, in addition to the single-stranded RNA of M_J about 1.5 × 10⁶ which is characteristic of sobemoviruses, SCMoV particles also contained circular and linear viroid-like RNAs of two size classes, one about 400 and the other about 300 nucleotides long. At present it is not clear if the two types of viroid-like RNAs are components of the same SCMoV strain or of closely related strains of the virus which are able to confect subterranean clover.
SCMoV was shown to be serologically related to lucerne transient streak virus (LTSV). However, the relationship was remote and whereas most high-titred antisera to LTSV reacted with SCMoV particles, antisera to SCMoV failed to recogaize those of LTSV. Neither SCMoV nor LTSV are serologically related to velvet tobacco mottle virus (VTMoV) or Solanum nodiflorum mottle virus (SNMV). However, particles of all four viruses have many physical and chemical properties in common, including RNA complements consisting of both virus-like and viroid-like RNAs. Because of their affinities and unique RNA complements, we suggest that SCMoV, LTSV, VTMoV and SNMV may warrant inclusion in a new taxonomic group.  相似文献   

Reply     

DH DAVIES  S. PIDFORD 《Australian veterinary journal》1991,68(12):411-411

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Clinical nutrition     

MIKE DAVIES 《The Journal of small animal practice》1991,32(6):269-269

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Chamber for microelectrode studies in the cerebral cortex     

DAVIES PW 《Science (New York, N.Y.)》1956,124(3213):179-180

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Fate of fertilizer nitrogen.   总被引：3，自引：0，他引：3  

D. BARRACLOUGH  E. L. GEENS  G. P. DAVIES  J. M. MAGGS 《European Journal of Soil Science》1985,36(4):593-603

Results are presented from a three year lysimeter investigation, employing single (¹⁵NH₄NO₃) and double (¹⁵NH₄¹⁵NO₃) labelled ammonium nitrate to study the uptake of soil and fertilizer nitrogen by cut ryegrass at 250, 500 and 900 kg N ha^?1 a^?1. Average annual recoveries of nitrogen were equivalent to 99,76 and 50% of the nitrogen added at 250, 500 and 900 kg N ha^?1, respectively. At 250 kg N ha^?1 the difference between the overall nitrogen recovery and the fertilizer recovery was almost entirely attributable to pool substitution resulting from mineralization/immobilization turnover (MIT). At 900 kg N ha^?1 both the low overall recovery of nitrogen and the low fertilizer recovery reflected the large excess of available nitrogen over crop requirements. No evidence of ‘priming’ was obtained. Analysis of the results from single and double labelled lysimeters using simultaneous equations indicated that at 250 kg N ha^?1,～70% of the nitrogen in the crop was derived from the ammonium pool. At 500 kg N ha^?1 this dropped to 64%, while at 900 kg N ha^?1 the figure was 59%. There was a suggestion that at the lower application rates, preferential uptake of ammonium was occurring but that as N supply exceeded crop requirements, nitrate was the major N source. Despite the preferential exploitation of the ammonium pool, at 250 and 500 kg N ha^?1 pool substitution resulting from MIT resulted in lower recoveries of fertilizer ammonium compared with fertilizer nitrate.  相似文献   

POLYPHENOLS IN PLANT, HUMUS, AND SOIL III. STABILIZATION OF GELATIN BY POLYPHENOL TANNING     

R. I. DAVIES  C. B. COULSON  D. A. LEWIS 《European Journal of Soil Science》1964,15(2):299-309

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