Mycorrhizal association of some agroforestry tree species in two social forestry nurseries

Mycorrhizal colonization of different agroforestry tree species in two social forestry nurseries was investigated. Percentage of Arbuscular mycorrhizal (AM) infection, number of resting spores and AM fungi species varies both in tree species as well as in two different nurseries. This variation is attributed to various factors such as mycorrhizal status and other management practices. In both nurseries, Glomus species dominated in all tree species followed by Sclerocystic, Gigaspora, Acaulospora, Scutellospora and Entrophospora. Interestingly, Azadirachta indica and Terminalia catappa have shown maximum and minimum infection respectively in both nurseries. Certainly, mycorrhizae could contribute substantially to achieve better results.Key words: Arbuscular mycorrhizal fungi, agroforestry tree species

Culturable bacteria community development in postglacial soils of Ecology Glacier, King George Island, Antarctica

Glacier forelands are excellent sites in which to study microbial succession because conditions change rapidly in the emerging soil. Development of the bacterial community was studied along two transects on lateral moraines of Ecology Glacier, King George Island, by culture-dependent and culture-independent approaches (denaturating gradient gel electrophoresis, DGGE). Environmental conditions such as cryoturbation and soil composition affected both abundance and phylogenetic diversity of bacterial communities. Microbiocenosis structure along transect 1(severe cryoturbation) differed markedly from that along transect 2 (minor cryoturbation). Soil physical and chemical factors changed along the chronosequence (time since exposure) and influenced the taxonomic diversity of cultivated bacteria (CB), particularly along transect 2. Arthrobacter spp. played a pioneer role, and were present in all soil samples, but were most abundant along transect 1. Cultivated bacteria isolated from transect 2 were taxonomically more diverse than those cultivated from transect 1; those from transect 1 tended to express a broader range of enzyme and assimilation activities. Our data suggest that cryoturbation is a major factor in controlling bacterial community development in postglacial soils, shed light on microbial succession in glacier forelands, and add a new parameter to models that describe succession phenomena