Les microorganismes auxiliaires de ľétablissement des symbioses mycorhiziennes

Microorganisms stimulating the establishment of mycorrhizal symbiosis (a review). A review of the literature on the relationships between rhizospheric microbial communities and mycorrhizal development shows very strong interactions. Many cases of stimulation by microorganisms of the symbiosis establishment and stability have been reported. The stimulating microorganisms of the symbiosis establishment and stability have been reported. The stimulating microorganisms belong to a wide range of taxonomic groups and some of them are very closely associated with the mycorrhizal fungus in its symbiotic form, suggesting a co-evolution toward mutual benefit. The positive interactions can be the result of a number of mechanisms: direct trophic effects, detoxication, indirect effects through action on the root, antagonism to other microorganisms inhibiting the mycorrhizal development. The practical implications of the present knowledge on the subject are discussed, leading to the conclusion that some sort of integrated biological control of mycorrhizal symbioses is worth developing, in order to improve the efficiency of mycorrhizal inoculation.     

Etude experimentale du transport de Pinoculum de Ceratocystis fimbriata f. platani par ľeau ?une riviere

Dissemination of Ceratocystis fimbriata f. platani inoculum by river water . C. fimbriata was detected up to 108 m downstream from pieces of diseased plane tree placed in a fixed site in a river in Southern France. Assessment of C. fimbriata was realized by a trapping method with healthy wood.     

Recherche sur la nutrition azotée de plusieurs souches1 de ĽArmillaria mellea

Investigation of nitrogen nutrition in different strains of Armillaria mellea. I. Utilisation of different sources of nitrogen. The assimilation of different forms of nitrogen - NO₃-, NH₄+ and L-asparagine by isolates of Armillaria mellea from France and Poland was investigated. Both the growth aspect, in which mycelial biomass production was related to the utilisation of nitrogen sources, and the morphological aspect, involving aerial mycelium, sclerotia and rhizomorphs, were studied. Significantly difterent effects were recorded for the influence of nitrogen source, the period of growth and their interaction on the growth of various isolates. Different nitrogen sources significantly affected sclerotial and rhizomorph formation. Isolates of A. mellea, geographically and genetically different, were shown to be also physiologically specialised as was also C. tabescens.     

Etude de la relation entre la pluviosité et l' accumulation du fluor dans les forêts résineuses soumises à une pollution fluorée

On the relationship between precipitation and fluoride accumulation in coniferous forests under fluoride influence . In forests under the influence of airborne fluorides a relationship of the form F = 2.92 C^1.137/P^0.508 was found. The fluoride accumulation F relates to the F-contents in dry matter of fir needles (ppm), C means F-output in tons and P precipitations in mm.y^?1.     

Etude comparative du contenu phénolique du genre Quercus et de ses zoocécidies

Comparative Study of Phenolic Contents in Oak Galls. Determinations on galls of Quercus show that phenolic compounds and especially tannins do not systematically accumulate in these proliferations. On the contrary, their phenolic content is highly variable and differs between species. Their composition depends apparently not only on the pathogenic agent and the attacked organ, but also on the physiological state of the plant.     

Distribution du fluor chez Populus nigra L. en zone polluée Mise en évidence d'une accumulation radiculaire

The distribution of fluoride in polluted poplars. Detection of fluoride accumulation in roots. In poplars polluted by fluoride, high concentrations of fluoride were detected in the lower part of the trunk, mainly in the cortical zone, and in the roots. This indicates that there is a basipetal translocation of fluoride from the leaves towards storage organs such as roots. This translocation of fluoride appears to be largely subordinate to the translocation of calcium.     

La variabilité de la sensibilité du Hêtre (Fagus sylvatica L.) à Nectria coccinea,un des agents de la maladie de l'écorce

Variability of Fagus sylvatica susceptibility to Nectria coccinca, one of the agents of beech bark disease . N. coccinea was inoculated into wounds of young beeches raised from seeds of 6 bark diseased trees and 6 healthy ones in the same stand of the forest of Lyons. Classifieation of the progenies, according to the size of the necrosis, is in good agreement with the health of the mother trees. N. coccinca susceptibility of beech has a genetic origin.     

Mise en évidence d'une relation entre la teneur en fluor et la chute de production dans les forêts résineuses soumises à une pollution fluorée

The relationship between fluoride content of needles and decrease in yield in conifer forests subject to fluorine pollution . In conifer forests (Picca abies Lk.), subject to fluoride pollution, a logarithmic correlation exists between the F-content of unwashed needles and the decrease in wood production.     

Test ?inhibition de ľactivité cambiale du Peuplier par Hypoxylon mammatum: mise au point et application

Test of inhibition of cambial activity of poplar by H. mammatum: development and application. A test was developed in vitro in order to estimate the inhibition of hosts’cambium by H. mammatum and applied to a large number of poplar clones. Toxicity of the culture filtrate appears to be selective but not necessarily specific.     

Synthèse en culture pure de ľassociation mycorrhizienne Pinus cembra L. + Suillus placidus Bonord

Pure culture synthesis of Pinus cembra mycorrhizae + Suillus placidus. The fungus forms an extremely thick mantle and a strongly developed Hartig net.     

Ľinoculation ectomycorhizienne des plants feuillus sur tourbe fertilisée: résultats sur chêne pédonculé (Quercus robur L.) avec quatres souches fongiques

Ectomycorrhizal inoculation of hardwood planting stocks on fertilized peat: results with pedunculate oak (Quercus robur L.) and four fungal strains. Pedunculate oak seedlings were inoculated in the nursery with three ectomycorrhizal fungi. Results are discussed in connexion with the type of inoculum and the interactions between microbial populations in the substrate.     

Physiologie in vitro des basidiospores de Melampsora pinitorqua Conséquences pour la compréhension des infections

Physiology of in vitro germination of Melampsora pinitorqua Rostr. basidiospores; consequences for the understanding of the infection process. The in vitro germination of Melampsora pinitorqua Rostr. basidiospores is affected by several environmental factors: temperature, moisture, and by host substances: shoot diffusates, epicuticular waxes, terpenes. The failure of basidiospore spraying inoculations and the possible resistance factors of pines are discussed in view of the results obtained.