Eco-microbiological studies on the roots of psammophytes, costal sand dunes, northwestern coast of Egypt

الملخص EN

Eight dominant psammophytes were studied, these species are: Echium sericum, Ononis vaginalis, Euphorbia paralias, Jasonia maritima, Pancratium maritima, Lotus polyphyllus, Amophyla arenaria and Aeluropus lagopoides.

The root characteristics of each species were estimated in each soil depth including the root length, number of lateral roots, fresh and dry weights, water content, and the ratio of specific root length (SRL), the root / shoot ratio (RSR) and root / shoot biomass (RSB).

The soil supporting each species from different depths was analyzed physically and chemically.

The microorganisms of the rhizosphere of each plant species were isolated and counted.

The roots of most deep and shallow-rooted species under study are elongated in the depth of soil (15-30cm) excluding Echium sericum and Amophylla arenaria.

Most of the lateral roots are concentrated in the surface depths of the soil in each of deep and shallow roots.

The fresh and dry weights of roots decrease with the increase of soil depth in the deep roots versus the shallow roots where the weight increases with the increase of soil depth.

Jasonia maritima is charactarized by the highest value of water content of the root reached 54.5 %.

The values of SRL and RSR were higher in the deep roots than in the shallow roots versus the value of RSB, which were higher in the shallow roots.

In most of the rhizosphere of the plant species invistigated, the total bacterial counts was the highest, while the total number of fungal counts was the lowest.

There are clear variations between the total numbers of microbical types among the rhizosphere of the eight species.

The total microbial counts decreased parallel with the increase of soil depth in the most rhizosphere invistigated species execluding the total count of actinomycetes which increased with the increase of soil depth.

Eighteen microbial isolates could be isolated from the rhizosphere of deep-rooted species, while seventeen microbial isolates were isolated from the rhizosphere of shallow-rooted species.