Star fruit (Averrhoa carambola) plants tend to accumulate significant amounts of Mn in their tissues. However, information regarding the form in which the plant stores the excess is scarce. For a deeper understanding of this aspect, star fruit plantlets were grown in nutritive solutions of Furlani (1999) with increasing levels of Mn (0, 0.5, 25 and 50 mg L-1), and after 30, 60, 90 and 120 days the tissues were collected and subjected to a sequence of extracting solutions: water, […]

The use of plants for phytoremediation of metal-contaminated areas is an emerging technology, and studies concerning heavy metal tolerance, absorption and distribution in plants are essential for the success of such programs. This study was carried out to evaluate the tolerance, absorption and distribution of lead (Pb) in vetiver grass [Vetiveria zizanioides (L.) Nash], mimosa [Desmanthus virgatus (L.) Willd] and mesquite trees [Prosopis juliflora (SW) DC] subjected to increasing lead doses in solution. The experiment was conducted under a screenhouse, […]

The objectives of the present study were to evaluate the effects of arbuscular mycorrhiza, the plant P nutritional status and increasing levels of P in nutrient solution on Zn toxicity to Trema micrantha (L.) Blum. In a first experiment trema seedlings were grown in a substrate with increasing P rates [0, 100, 200 and 400 mg dm-3 as Ca(H2PO4)2], besides a mycorrhizal treatment inoculated with Glomus etunicatum (Ge). After 60 days of growth, the plants were transferred to pots with Clark’s nutrient solution […]

Aluminum tolerant wheat varieties can present increased efficiency of phosphorus use in presence of aluminum. A greenhouse experiment was conducted in 1994 to compare the wheat cultivars (Toropi) and (CNT 8), considered efficient and inefficient, respectively, in relation to phosphorus use. Nutrient solutions containing two phosphorus (1.6 and 32.3 µmol L-1) and two aluminum (0.0 and 37.0 µmol L-1) concentrations were tested. Root morphology and phosphate use were established for the plants, which were harvested from the pots on the 31th day. Roots of the Toropi […]

An experiment was carried out at the Soil Science Department of Federal University of Lavras (MG), from November/1999 to January/2000, aiming to evaluate the survival of strain and isolates of rhizobia, in heavy metal contaminated soil.The possible relationship between rhizobia tolerance in culture medium and its survival in contaminated soil was also verified.From a group of 60strains/isolates tested at a previous study for metal tolerance in YMA medium, two out of the most tolerant microorganisms [BR-4406 (strain recommended as inoculant […]

Ectomycorrhizal symbiosis can play a crucial role in protecting plant roots from heavy metals. However, a high heavy metal contamination can inhibit ectomycorrhizal fungi growth and activity, negatively influencing mycorhizal symbiosis. The growth of nine isolates of Pisolithus tinctorius, two of Suillus bovinus and one of Scleroderma sp. was assessed to evaluate the effect of Zn, Cd, Cu and Pb contaminated soil-sand mixes added to the liquid culture media, at different proportions. Addition of contaminated soil to the media reduced […]

Ectomycorrhizal fungi are able to tolerate toxic heavy-metal concentrations in host plants, although being also negatively affected by excessive metal. Isolates of Pisolithus tinctorius and Scleroderma bovinus were grown for 20 days at 28°C in a liquid medium with increasing levels of Zn, Cu and Cd sulfates in 125 mL conical flasks containing 50 mL of MMN medium, adjusted to pH 4.8. Fungi growth was inhibited by heavy metal increasing concentration, which was different for fungi and metals. The 50% […]