Gigliola Puppi

Different ability of three Mediterranean oak species to tolerate progressive water stress

Inter-comparisons in the gas exchange patterns and root characteristics under both well-watered and drought conditions were done in three-years-old seedlings of three oak species (Quercus cerris L., Q. frainetto Ten., and Q. ilex L.) growing in controlled environment. Well-watered Q. cerris had greater physiological performances than other oaks, but under drought it was not able to face the water stress showing also structural modifications such as reduction of root length and average diameter. On the other hand, Q. ilex maintained root growth both in drought or well-watered soils. Moreover, it was able to keep open stomata also under water stress, although stomatal conductance (gs) was low. Q. frainetto had an intermediate position in regard to its physiological and root structural characteristics between Q. cerris and Q. ilex under drought stress. For all oaks the relationship between gs and the ratio of sub-stomatal and ambient CO2 concentration (Ci/Ca) highlighted the dynamic adaptation of gs to the increase of hydraulic resistances of leaf, stem, and roots portions, more evident during the air humidity change and progressive soil dehydration. This suggests a well-triggered above-and under-ground mechanism to endure the drought stress.

Fungal mycelium and decomposition of needle litter in three contrasting coniferous forests

The fungal mycelium ingrowth and the rates of mass loss and respiration of needle litter of Pinus pinea, Pinus laricio, Pinus sylvestris, and Abies alba were investigated, in three coniferous forests, over a 3-year period by means of a composite set of incubations. In the early stages, the fungal flora of the decomposing needles was dominated by dematiaceous hyphomycetes and coelomycetes. Basidiomycetes reached a peak after 6 months on pine needles, but were absent from the N-rich needles of A. alba. Soil fungi (Penicillium, Trichoderma, Absidia, Mucor sp. pl.) became most frequent in later stages. At the end of the study period, the total mycelium amount showed the lowest values in all pine needles incubated in the P. laricio forest and the highest ones in P. pinea needles incubated in the P. pinea forest. In all data sets, as in data for boreal forests examined for comparison, the concentration of litter fungal mycelium versus litter mass loss followed a common exponential model. However, in later stages, the amount of litter fungal mycelium was very close to that of the humus at the incubation site, thus supporting the hypothesis of a logistic growth pattern. Respiration rates of decomposing litters varied with season and decreased with litter age to values close to those of the humus at the incubation site. Respiration of water-saturated litter was negatively correlated with the total mycelium concentration, and this was consistent with the observation that in far-decomposed litter only a minor fraction of the total mycelium is alive.

Recherches sur la rhizosphère de Loudetia simplex C. E. Hubbard, graminée typique de la savane en Côte d'Ivoire: Rapport final

Abstract Research on the rhizosphere of Loudetia simplex C. E. Hubbard, typical grass of Ivory Coast.—Investigations on the rhizosphere microflora of Loudetia simplex, spontaneous grass in Lamto savannah of Ivory Coast, were carried out. Sampling was made at five different periods in the year to point out differences connected to climatic factors. Quantitative data of total microflora—bacteria, actinomycetes and fungi—are listed for each root tip sampled. Quantitative and qualitative data of fungal population for each seasonal period are also reported. About two hundred species, including Phycomycetes, Ascomycetes, Basidiomycetes and Fungi Imperfecti, were identified. The most frequent genera are Penicillium and Aspergillus. The occurrence of Rhinocladiella indica, Chaetomium fusisporale and Gongronella butleri is taxonomically and ecologically remarkable. Rhizosphere and soil fungal populations are compared, in order to evaluate the degree of specialization of the species recorded. The genus Aspergillus ...

Indagini micologiche preliminari nella Foresta di Taï in Costa d'Avorio. Note su Aspergillus longivesica Huang et Raper

Abstract Preliminary mycological investigations in Ivory Coast Tai Forest. Notes on Aspergillus longivesica Huang et Raper.—Mycological investigations on tropical forest soils, to establish suitable isolament techniques are carried out. From the isolaments by adding lactic acid or streptomycin sulphate to the media with the purpose to limit the bacterial growth, resulted 205 and 144 fungal strains respectively. Remarkable is the presence of Mortierella isabellina, Oidiodendron griseum, and Penicillium cyclopium. The second isolament in tropical soils of Aspergillus longivesica is pointed out as of particular interest.

Observations sur la microflore fongique des feuilles vertes et sénescentes de Loudetia simplex

Abstract Observations on the mycoflora of green and senescent leaves of Loudetia simplex.—Leaves of Loudetia simplex, a common grass of the moist savannah of Ivory Coast, were collected at different growth stages at the end of the life cycle (December) and during the growing period of the plant (June). The study was carried out by indirect techniques, plating on PDA in Petri dishes aliquots of a suspension 1:1000 (fresh weight/volume) of ground leaves. The isolates belong mainly to Fungi Imperfecti; the distribution of the Fungi includes 20 Moniliaceae, 13 Dematiaceae, 15 Tuberculariaceae, 4 Melanconiales, 9 Sphaeropsidales, 1 Ascomycetes and a number of sterile hyphae, mainly with dark mycelium. Most of the isolates are commonly recorded on leaves (Cephalosporium acremonium group, Cladosporium cladosporioides, Fusarium spp., Monodictys, Phoma). Also present Nigrospora sphaerica, which seems a typical phyllosphere inhabitant in tropical regions. Even if the data correspond only to two sampling periods the...