Aluminum (Al)-tolerance of different cultivars shows considerable differences. Elevation of rhizosphere pH is an external Al-resistant mechanism of plants. To elucidate the correlation between Al tolerance and the capacity of plants to modify the rhizosphere pH at different Al-tolerant levels, a comparative study on the wheat (Triticum aestivum L.) cultivars ET8 (Al-tolerant) and ES8 (Al-sensit...

Phytoextraction of soil Cd and Zn may require reduction in soil pH in order to achieve high metal uptake. Reducing the pH of high metal soil, however, could negatively affect soil ecosystem function and health. The objectives of this study were to characterize the quantitative causal relationship between pH and soil biological activities in two Zn and Cd contaminated soils and to investigate th...

The biological availability of iron in the rhizosphere was assessed by evaluating ice nucleation activity (INA) expressed in situ by Pseudomonas fluorescens Pf-5 containing a transcriptional fusion (pvd-inaZ) of an iron-regulated promoter to an ice nucleation reporter gene (inaZ). Pf-5 containing pvd-inaZ expresses INA that is inversely related to the iron availability of a growth medium (J. E....

The presence of Eriophorum angustifolium in mine tailings of pyrite maintains a neutral pH, despite weathering, thus lowering the release of toxic elements into acid mine drainage water. We investigated if the presence of slightly elevated levels of free toxic elements triggers the plant rhizosphere to change the pH towards neutral by increasing organic acid content. Plants were treated with a ...

Better understanding of the processes controlling arsenic bioavailability in the rhizosphere is important to enhance plant arsenic accumulation by hyperaccumulators. This greenhouse experiment was conducted to evaluate the chemical characteristics of the rhizosphere of two arsenic hyperaccumulators Pterisvittata and Pterisbiaurita. They were grown for 8 weeks in rhizopots containing arsenic-con...

Soil salinity is a major factor relating microbial communities to environmental stress in the microbial selection process as stress can reduce bacterial diversity. In the San Joaquin Valley (SJV) of California, the problem of increasing salinity and consequently, decreasing crop productivity, due to reuse of saline drainage water are major concerns. An experiment was conducted in a closed, reci...

Silicon (Si) is important in mitigating abiotic and biotic plant stresses, yet many agricultural soils, such as those of the rainfed production areas of the South African sugar industry, are deficient in plant-available Si, making Si supplementation necessary. However, Si uptake by sugarcane (Saccharum spp. hybrids) is limited even where silicate amendments improve soil Si status. Rhizosphere p...

Many arable lands have accumulated large reserves of residual phosphorus (P) and a relatively large proportion of soil P is less available for uptake by plants. Root released organic anions are widely documented as a key physiological strategy to enhance P availability, while limited information has been generated on the contribution of rhizosphere organic anions to P utilization by crops grown...