Analyses of the community compositions of root rot pathogenic fungi in the soybean rhizosphere soil

Soybean ( Glycine max [L.] Merr.) root rot is an important disease of soybean under continuous cropping, and root rot is widely distributed throughout the world. This disease is extremely harmful, and it is difficult to prevent and control. The study aimed to elucidate the composition of root rot pathogenic fungal communities in the continuous cropping of soybean. In this study, we employed PCRDGGE technology to analyze the communities of root rot pathogenic fungi in soybean rhizosphere soil subjected to continuous cropping during a season with a high incidence of root rot in Heilongjiang province, China, the main soybean producing area in China. The results of 13 DGGE bands were analyzed by phylogenetic revealed that the predominant root rot pathogenic fungi in rhizosphere soil in the test area were Pythium ultimum and Fusarium species. The results of cluster analysis showed that the duration of continuous cropping, the soybean variety and the plant growth stage all had significant effects on the diversity of root rot pathogenic fungi in rhizosphere soil.

Levels of some heavy Metals in Cocoyam ( Colocasia esculentum ) grown on Soil receiving Effluent from a Paint Industry

The levels of some heavy metals in soil samples and tubers of cocoyam ( Colocasia esculentum ) grown on soil receiving paint wastes (PWS) has been investigated using Atomic Absorption spectrophotometer (Unicam 939/959 model). Similar analyses were carried out for the same plant from a control area. The studies revealed that although the P.W.S contained abnormally high levels of Pb (474.14mgkg-1) and Cu (137.85mgkg-1). The paint waste tuber (PWT) recorded low levels of these metals: Pb (2.13mgkg-1) and Cu (13.85mgkg-1) respectively. Correlation analysis tested at 0.05 level of significance show that no significant correlation existed between the metals levels in the soil and the level in the tuber. In all cases the levels of the metals in the tubers were well below the upper limit documented for unpolluted plant. The results however suggest the ineffectiveness of the use of Colocasia esculentum as a bioindicator for heavy metal pollution in soil.