Effects of Lime, Compost, and Mycorrhiza on the Growth and Heavy Metal Concentration of Flamingia sp.

Abstract

Metal leachates from abandoned mine sites endanger plants, animals, and humans as these enter the food chain. A technique to reduce availability of heavy metals to the ecosystem was proposed. This made use of Flamingia sp., a forage legume, to facilitate the removal of heavy metals from mine soil samples obtained from Paracale, Camarines Nolle, Bicol Province Growth promotion and heavy metal-tolerance in plants were assessed using varied combinations of soil supplements (consisting of lime, compost, and mycorrhizal fungi). Experiments conducted were. (1) an experiment which determined the combination of lime and compost concentrations that would raise acidic mine soil pH from 4.5 to 6.5; (2) an experiment which determined the effects of commercialized and indigenous mycorrhizal fungi inoculations on the growth of Flanungia sp. seedlings in garden and mine soils; and (3) an experiment which determined the effects of lime, compost, commercialized and indigenous mycorrhizal fungi inoculations, and their combinations on the growth and heavy metal uptake of Flamingia sp. seedlings grown in mine soils. A 0.01 gram of lime combined with 10 grams of compost raised acidic mine soil pH from 4.5 to 6.5. Plants inoculated with commercialized mycorrhizal fungi generally showed better growth than uninoculated plants in garden soil. Validated using Duncaifs New Multiple Range Test (DMRT) at 0.1% level of significance and Least Significant Difference (LSD) at p<0.05, results showed that plants under compost treatments were taller (12.54cm) and had greater diy weights (1.48g/plant) when compared with plants under noncompost treatments (8.16cm height and 0.76g/plant dry weights). However, higher nodulation (22 nodules) and mycorrhizal infection (44.05%) were observed among plants without compost treatments over those plants with compost treatments (that is, at 8 nodules and 11.9%, respectively). Copper and cadmium concentrations in leaves of Flamingia sp. were shown to be greatest in plants inoculated with indigenous mycorrhizal fungi and lime but without compost treatment. Lead concentration and copper, cadmium, and lead uptakes in leaves were also significant among uninoculated plants with lime-compost treatment. Addition of lime and compost significantly improved the height of Flamingia sp.